McPherson spectrometers, spectrographs and monochromators, instruments and systems for Spectroscopy through the optical electromagnetic spectrum.

S. P. Nikitin, C. Manka, J. Grun, and J. Bowles

Abstract
Contactless measurements of water temperature are utilized in a number of sciences, such as oceanography, climatology, and biology. Previously reported Raman spectroscopy techniques exploited the changes in the shapes of water Raman bands. Interpretation of these changes is difficult since these bands are composed of multiple lines, each influenced not only by temperature but also by pressure and salinity. This paper presents a proof-of-principal demonstration of a contactless technique which determines water temperature from the ratio of Stokes and anti-Stokes intensities of the water 180 cm^?1 Raman band. This ratio is not sensitive to pressure and salinity, allowing reliable determination of water temperature.

Rev. Sci. Instrum. 83, 033105 (2012)

Nanocrystalline Graphite Growth on Sapphire by Carbon Molecular Beam Epitaxy

S. K. Jerng, D. S. Yu, Y. S. Kim, Junga Ryou, Suklyun Hong, C. Kim, S. Yoon, D. K. Efetov, P. Kim, and S. H. Chun

Abstract
We report the fabrication of nanocrystalline graphite films on sapphire substrates of various cutting directions by using solid carbon source molecular beam epitaxy. Raman spectra show a systematic change from amorphous carbon to nanocrystalline graphite with a cluster diameter of several nanometers, depending on the growth temperature. The symmetry of the substrate seems to have little effect on the film quality. Simulations suggest that the strong bonding between carbon and oxygen may lead to orientational disorders. Transport measurements show a Dirac-like peak and a carrier type change by the gate voltage.

J. Phys. Chem. C 2011, 115, 4491-4494

Spectroscopic diagnostics for liquid lithium divertor studies on National Spherical Torus Experiment

Soukhanovskii VA, Roquemore AL, Bell RE, Kaita R, Kugel HW.

Abstract
The use of lithium-coated plasma facing components for plasma density control is studied in the National Spherical Torus Experiment (NSTX). A recently installed liquid lithium divertor (LLD) module has a porous molybdenum surface, separated by a stainless steel liner from a heated copper substrate. Lithium is deposited on the LLD from two evaporators. Two new spectroscopic diagnostics are installed to study the plasma surface interactions on the LLD: (1) A 20-element absolute extreme ultraviolet (AXUV) diode array with a 6 nm bandpass filter centered at 121.6 nm (the Lyman-a transition) for spatially resolved divertor recycling rate measurements in the highly reflective LLD environment, and (2) an ultraviolet-visible-near infrared R=0.67 m imaging Czerny-Turner spectrometer for spatially resolved divertor D I, Li I-II, C I-IV, Mo I, D(2), LiD, CD emission and ion temperature on and around the LLD module. The use of photometrically calibrated measurements together with atomic physics factors enables studies of recycling and impurity particle fluxes as functions of LLD temperature, ion flux, and divertor geometry.

Rev Sci Instrum. 2010 Oct;81(10):10D723.

H_α Emission as a feedback control sensor for reactive sputter deposition of nano-structured, diamond-like carbon coatings

C. Christopher Klepper, Eric P. Carlson, Robert C. Hazelton, Edward J. Yadlowsky, Bao Feng, Mahmoud A. Taher, and Harry M. Meyer, III

Abstract
This paper discusses the potential use of the hydrogen atomic line emission at 656.3 nm (H_α ) as an effective in-situ sensor for a closed-loop control system to improve the reproducibility of reactive sputter deposition of nano-structured, metal-containing, hydrogenated, diamond-like carbon (Me:DLC:H) coatings. The paper includes experimental results showing a good correlation between H_α emission in the process plasma and the formation of metal-carbide, an important component of these coatings. The first attempts at actual feedback-control of the process showed that this sensor can be effective, at least over the stage of the deposition when mostly carbides are formed in the coating. A spectrally resolved analysis of the H_α emission for the various stages of the deposition have shown that the emission profile is dominated by a “hot” component ( ~10–20 eV), which can be attributed to dissociative excitation of molecular hydrogen (H₂). The molecular hydrogen is understood to evolve from the coating as a result of carbon incorporation from the reactive gas (C₂H₂) and is particularly sensitive to metal carbide formation in the film, when most of the hydrogen is released from the surface in molecular form.

IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 33, NO. 2, APRIL 2005

Resonance Raman study of the phonon spectra in superconducting Bi-2212 and Y-123

M. Rübhausenb , M.V. Kleina, D. Budelmannb, B. Schulzb, P. Guptasarmac, M.S. Williamsenc, R. Liangd, D.A. Bonnd and W.N. Hardyd

Abstract
We studied the variation of phonon spectra with incident photon energy E_i in two superconducting samples, optimally doped YBCO (T_c=93.6 K) and overdoped Bi-2212 (T_c=82 K). Our results highlight the layered nature of the cuprates. Especially the buffer layers that are thought to be responsible for the doping of the CuO₂ planes show complex phonon spectra. In Bi-2212 we find an activation of up to 13 phonon modes for a resonance that allows transitions into the Bi–O layers at 3.8 eV. For Y-123 we find also an activation of phonon modes as well as a huge matrix element when transitions into the chains at around 4.1 eV are possible. We also investigate the variation of the line shape of the O(II)–O(III) mode as a function of incident photon energy.

Journal of Physics and Chemistry of Solids 2006, Volume 67, Issues 1-3, Pages 312-315

Fully reflective deep ultraviolet to near infrared spectrometer and entrance optics for resonance Raman spectroscopy

B. Schulz, J. Bäckström, D. Budelmann, R. Maeser, M. Rübhausen, M. V. Klein, E. Schoeffel, A. Mihill and S. Yoon

Abstract
We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000 nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO₃, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4 eV

Review of scientific instruments 2005, Volume 76, no7, pp. 073107.1-073107.12

Orbital ordering in LaMnO₃ investigated by resonance Raman spectroscopy

Krüger R, Schulz B, Naler S, Rauer R, Budelmann D, Bäckström J, Kim KH, Cheong SW, Perebeinos V, Rübhausen M.

Abstract
Orbital ordering leads to an unconventional excitation spectrum that we investigate by resonance Raman scattering using incident photon energies between 1.7 and 5.0 eV. We use spectral ellipsometry to determine the corresponding dielectric function. Our results show resonant behavior of the phonon Raman cross section when the laser frequency is close to the orbiton-excitation energy of 2 eV in LaMnO3. We show an excellent agreement between theoretical calculations based on the Franck-Condon mechanism activating multiphonon Raman scattering in first order of the electron-phonon coupling and the experimental data of phonons with different symmetries.

Physical Review Letters, vol. 92, Issue 9, id. 097203

Primary realization of a spectral irradiance scale employing monochromator-based cryogenic radiometry between 200 nm and 20 µm

E W M van der Ham, H C D Bos and C A Schrama

Abstract
Here we report on an alternative approach for making spectral irradiance measurements of radiation sources traceable, employing our monochromator-based absolute cryogenic radiometer (ACR) facility to its full extent. The method makes use of the continuously tunable absolute radiant flux emerging from the ACR facility to characterize and calibrate the spectral irradiance responsivity of a second adjacent double-monochromator system. This system will be part of a new facility at NMi-VSL, called SIR, that will be used to measure spectral irradiance distributions of radiation sources from the ultraviolet to the far infrared. Following this traceability route, a fully characterized high-temperature Planckian radiator is not needed. Proof-of-principle measurements in the visible part of the spectrum show very encouraging results. Although the new facility is under construction, the theoretical background and a schematic description will be presented in this paper.

2003 Metrologia 40 S177-S180

Picosecond relaxation of Ni-centers in II–VI semiconductors

R. Heitz, A. Hoffmann and I. Broser

Abstract
The internal relaxation processes of the 3d-center Ni²⁺ and the recombination of photogenerated holes with Ni⁺-centers are investigated by means of time resolved luminescence spectroscopy of the ³T₁(P)-³T₁(F) Ni²⁺ transition in ZnS, CdS, ZnSe and CdSe. Ultrafast recombination processes starting at the ³T₁(P)-states with time constants down to 60 ps are observed. In addition to the detected dipole transitions, which are allowed by a strong admixture of p-like wavefunctions to the 3d-states of Ni²⁺, competing nonradiative recombination processes are important. Radiative and nonradiative transition rates are determined. The excitation processes of the ³T₁(P)-³T₁(F) luminescence are studied in cw and time resolved experiments. Free holes are trapped at Ni⁺-centers forming shallow effective mass-like states, trapping times of 30 ps in ZnS and 50 ps in CdS are observed. The subsequent intracenter relaxation to the luminescent ³T₁(P)-state takes place within a few picoseconds by radiotionless cascade processes involving the ¹T₂(G)-state. After some nanoseconds the dynamical behaviour of the Ni²⁺-luminescence is determined by energy transfer processes between shallow donors and the Ni²⁺-centers. The investigations give evidence of strong electronic coupling of the Ni²⁺ (d-d)-transitions to the host

Optical Materials I 1992, 75-83

Picosecond energy transfer between excitons and defects in II-IV semiconductors

R.Heitz, C.Fricke, A.Hoffmann and I.Broser

Abstract
The luminescences of bound excitons in various II-IV semiconductors are studied by means of time resolved spectroscopy at liquid helium temperatures. A general trend of increasing lifetimes with increasing binding energies is in reasonable agreement with the theory of Rashba and Gurgenishvili indicating a predominant radiative decay. It is shown that the investigation of the dynamics of weakly bound excitons provides the possibility to determine parameters of the free exciton. An effective exciton mass of 1.06m0 for ZnO and a free excitan oscillator strength of 0.0014 for ZnS are determined. The limits of the model in case of deeply bound excitons as well as the nonradiative decay channels are discussed. The observed luminescence risetimes due to the formation of bound exciton complexes after generation of free excitons are investigated.

Materials Science Forum Vol. 83-87 (1992) pp. 1241-1246

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Models 205 and 205f

Remote Raman Spectroscopy for Planetary Exploration: A Review

S. Michael Angel, Nathaniel R Gomer, Shiv K Sharma, and Chris McKay

Abstract
In this review, we discuss the current state of standoff Raman spectroscopy as it applies to remote planetary applications, including standoff instrumentation, the technique's ability to identify biologically and geologically important analytes, and the feasibility to make standoff Raman measurements under various planetary conditions. This is not intended to be an exhaustive review of standoff Raman and many excellent papers are not mentioned. Rather it is intended to give the reader a quick review of the types of standoff Raman systems that are being developed and that might be suitable for astrospectroscopy, a look at specific analytes that are of interest for planetary applications, planetary measurement opportunities and challenges that need to be solved, and a brief discussion of the feasibility of making surface and plume planetary Raman measurements from an orbiting spacecraft.

Applied Spectroscopy, Vol. 66, Issue 2, pp. 137-150 (2012)

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Model 209

Spatial distribution measurement of atomic radiation with an astigmatism-corrected Czerny-Turner-type spectrometer in the Large Helical Device

Motoshi Goto and Shigeru Morita

Abstract
Emission lines in the visible/UV wavelength ranges are observed with 80 lines of sight which cover an entire poloidal cross section of the plasma in the Large Helical Device. The emitted light is received with optical fibers having 100μm diameter and is guided into a 1.33 m Czerny-Turner-type spectrometer based on spherical mirrors for collimating and focusing. A charge-coupled device having 13.3×13.3 mm² area size is used as the detector and the spectra from all the lines of sight are recorded perpendicularly to the wavelength dispersion. The spectrometer is equipped with optics located in front of the entrance slit to correct the difference between the meridional and sagittal focal points, and thus the astigmatism, which otherwise causes severe cross talk between adjacent optical fiber images on the detector, is corrected. Consequently, simultaneous spectral measurement with 80 lines of sight is realized. The Zeeman splitting of a neutral helium line, λ667.8 nm (2 ¹P-3 ¹D), which is caused by the magnetic field for plasma confinement, is measured with the spectrometer. Though the obtained line profile is in general a superposition of several components on the same line of sight, they can be separated according to their different splitting widths. The two-dimensional poloidal distribution of the helium line intensity is obtained with the help of a tomographic technique.

National Institute for Fusion Science, Toki 509-5292, Japan

Charge exchange spectroscopy system calibration for ion temperature measurement in KSTAR

Won-Ha Ko, Hyungho Lee, Dongcheol Seo, and Myeun Kwon

Abstract
The charge exchange spectroscopy (CES) system including collection assemblies, lens design, and cassettes for the KSTAR experiment was installed to obtain profiles of the ion temperature and the toroidal rotation velocity from charge exchange emission between plasma ions and beam neutrals near the plasma axis by using a modulated neutral beam and a background system. We can measure the charge exchange spectra of an impurity line such as the 529 nm line of carbon VI to get ion temperature and rotation profiles in KSTAR. The CES and background systems will have absolute intensity and spectral calibrations using a calibrated source and various spectral lamps. The calibration was done inside the tokamak after all CES systems are installed and the optical systems are slid into the cassettes. This requires that the diagnostic systems are installed near the vacuum vessel inside the cryostat maintaining the superconducting state of the superconducting coils. Repeated spectral calibrations of the spectrometer and charge coupled device for CES will be made in the diagnostic room during the experimental campaign. We show a detailed description of the KSTAR CES system, how to calibrate, and the results of calibration.

Rev. Sci. Instrum. 81, 10D740 (2010); doi:10.1063/1.3496991

Advances in fiber-optic based UV resonance Raman spectroscopy techniques for anatomical and physiological investigations

SCHULZE H. G.; BARBOSA C. J.; GREEK L. S.; TURNER R. F. B.; HAYNES C. A.; KLEIN K.-F.; BLADES M. W.;

Abstract
Ultraviolet resonance Raman spectroscopy (UVRRS) is becoming a very popular spectroscopic method for bioanalytical investigations due to its high sensitivity, lack of fluorescence, and suitability for use in aqueous solutions. We have made a number of technological advances, especially the development of fiber-optic-based technologies, which permit the performance of remote/in-situ UVRRS measurements. We will be reporting on improved optical fiber probes (OFPs) and demonstrate their benefits in performing UVRRS on neurotransmitters, saliva, and urine.

Biomedical applications of Raman spectroscopy. Conference, San Jose CA , ETATS-UNIS (25/01/1999) 1999, vol. 3608, pp. 157-166

Strong photoluminescence in ammonia plasma treated amorphous-SiC thin films deposited by laser ablation

S. Ghosh, P. Bhattacharya, and D. N. Bose

Abstract
Amorphous-SiC films have been deposited by pulsed laser ablation on silicon substrates. Photoluminescence (PL) studies showed two broad bands with peaks at 1.34 and 1.72 eV for these unhydrogenated films. On NH₃ passivation the intensity of the 1.34 eV peak increased by a large factor of 40–50 with full width at half-maximum (FWHM) decreasing to 13.5 meV at 12 K. The activation energy of this level was found to be 24 meV. These results are in contrast with those from unhydrogenated a-Si. A possible mechanism responsible for PL enhancement is discussed.

Applied physics letters 1996, vol. 68, no21, pp. 2979-2981

Advances with tungsten coil atomizers : Continuum source atomic absorption and emission spectrometry

RUST Jennifer A. ; NOBREGA Joaquim A. ; CALLOWAY Clifton P. ; JONES Bradley T. ;

Abstract
Two new tungsten coil spectrometers are described: a continuum source tungsten coil atomic absorption spectrometer and a tungsten coil atomic emission spectrometer. Both devices use a 150 W tungsten coil extracted from a slide projector bulb. The power is provided by a computer-controlled, solid state, constant current 0-10 A supply. The heart of the optical system is a high-resolution spectrometer with a multi-channel detector. The continuum source system employs xenon or deuterium lamps, and is capable of multi-element analyses of complex samples like engine oil, urine, and polluted water. Spiked engine oil samples give mean percent recoveries of 98 ' 9, 104 ' 9, and 93 ' 0.8 for Al, V, and Ni, respectively. Copper, Zn, and Cd are determined in urine samples; while Cd, Co, Yb, and Sr are determined in water samples. Detection limits for Cd, Zn, Cu, Yb, Sr, and Co are: 8, 40, 1, 4, 1, and 4 µg 1-1 The technique of tungsten coil atomic emission spectrometry using a 150 W commercial projector bulb is reported for the first time. Calcium, Ba, and Sr are determined with detection limits of 0.01, 0.5, and 0.1 µg 1^-1. Relative standard deviations are lower than 10% in each case, and Sr is determined in two water standard reference materials.

Atomic spectroscopy 2005, vol. 60, no5, pp. 589-598

Fast high resolution echelle spectroscopy of a laboratory plasma

Cothran, C. D.; Fung, J.; Brown, M. R.; Schaffer, M. J.Richard W. Bormett and Sanford A. Asher

Abstract
An echelle diffraction grating and a multianode photomultiplier tube are paired to construct a high resolution (R=λ/δλ~2.5×10⁴) spectrograph with fast time response for use from the UV through the visible. This instrument has analyzed the line shape of C III impurity ion emission at 229.687 nm over the lifetime (~100 µs) of the hydrogen plasmas produced at SSX. The ion temperature and line of sight average velocity are inferred from the observed thermal broadening and Doppler shift of the line. The time resolution of these measurements is about 1 µs, sufficient to observe the fastest magnetohydrodynamic activity.

Review of scientific instruments 2006, vol. 77, no6

Multichord spectroscopy of the DIII-D divertor region

N.H. BROOKS, A. HOWALD, K. KLEPPER, P. WEST

Abstract
A multichannel spectrometer with high spectral resolution (0.01 nm) and high temporal resolution (0.5 msec) has been configured to collect data simultaneously from eight viewchords spanning the divertor region of DIII-D. Fiberoptically coupled to a wide-field lens with a vertical view of the vessel floor, the instrument will be capable of differentiating the behavior of impurity line emission at the inner and outer divertor strike points, on and off the Advanced Divertor Program (ADP) ring, on the face of the Divertor Material Exposure System (DIMES) probe, and in the region of the lower centerpost. Used with a coarse grating (300 grooves/mm), spectral coverage of each spatial channel is 15 nm with 0.3 nm resolution; used in high order with a 1200 groove/mm grating, the instrument is capable of resolving Doppler profiles. Spatial variation of gas recycling and impurity influx will be studied for both singleand double-null divertor configurations in low and high density operating regimes.

GENERAL ATOMICS PROJECT 3466, APRIL 1992

Dynamics of laser ablation plume penetration through low pressure background gases

David B. Geohegan, Alexander A. Puretzky

Abstract
The dynamics of laser-ablated yttrium plume propagation through background argon have been investigated with fast time- and spatially-resolved plasma diagnostics in order to characterize a general phenomenon believed to be important to film growth by pulsed laser deposition (PLD). During expansion into low-pressure background gases, the ion flux in the laser ablation plasma plume is observed to split into fast and slow components over a limited range of distances including those typically utilized for PLD. Optical absorption and emission spectroscopy are employed to simultaneously identify populations of both excited and ground states of Y and Y⁺ . These are correlated with intensified-CCD (ICCD) photographs of visible plume luminescence and ion fluxes recorded with fast ion probes. These measurements indicate that plume-splitting in background gases is consistent with scattering of target constituents by ambient gas atoms. The momentum transfer from these collisions produces a transition from the initial, ``vacuum'' velocity distribution into a velocity distribution which is significantly slowed in accordance with shock or drag propagation models.

Appl. Phys. Lett. 67, 197 (1995)

Fast high resolution echelle spectroscopy of a laboratory plasma

C.D. Cothran, J. Fung, M.R. Brown, M.J. Schaffer

Abstract
An echelle diffraction grating and a multianode photomultiplier tube are paired to construct a high resolution (R=λ/δλ≈2.5×10⁴) spectrograph with fast time response for use from the UV through the visible. This instrument has analyzed the line shape of C III impurity ion emission at 229.687 nm over the lifetime (≈100 µs) of the hydrogen plasmas produced at SSX. The ion temperature and line of sight average velocity are inferred from the observed thermal broadening and Doppler shift of the line. The time resolution of these measurements is about 1 µs, sufficient to observe the fastest magnetohydrodynamic activity.

Rev. Sci. Instrum. 77, 063504 (2006)

Absolute calibration of a vacuum Czerny–Turner spectrometer in the range 1200–7000 Å

L. Carraro, M. Cortiana, M. E. Puiatti, F. Sattin, P. Scarin, and M. Valisa

Abstract
The vacuum Czerny–Turner high-resolution spectrometer observing the plasma of the reversed-field-pinch device RFX has been absolutely calibrated in the spectral range 1215–7000 Å, in order to measure the emission spectrum in absolute units, with particular reference to the heliumlike carbon and oxygen ion lines. The source used to calibrate the spectrometer in the vacuum and near-ultraviolet region is a deuterium lamp; its spectral radiance was determined by comparison with the synchrotron radiation of the electron storage ring BESSY, in Berlin. A typical error of 35% has been estimated. In the visible a standard tungsten lamp has been used. The calibration has been transferred to an ultragrazing incidence XUV spectrometer by means of the branching-ratio technique, using the intensity ratio between the intercombination 1s² ¹S–1s2p ³P⁰ and the 1s2s ³S–1s2p ³P⁰ transitions of carbon, nitrogen, and oxygen heliumlike ions.

Rev. Sci. Instrum. 66, 613 (1995)

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Model 2061

Noise Reduction Methods Applied to Two-Dimensional Correlation Spectroscopy (2D-COS) Reveal Complementary Benefits of Pre- and Post-treatment

Rod B. Foist, H. Georg Schulze, Andre Ivanov, and Robin F. B. Turner

Abstract
Two-dimensional correlation spectroscopy (2D-COS) is a powerful spectral analysis technique widely used in many fields of spectroscopy because it can reveal spectral information in complex systems that is not readily evident in the original spectral data alone. However, noise may severely distort the information and thus limit the technique's usefulness. Consequently, noise reduction is often performed before implementing 2D-COS. In general, this is implemented using one-dimensional (1D) methods applied to the individual input spectra, but, because 2D-COS is based on sets of successive spectra and produces 2D outputs, there is also scope for the utilization of 2D noise-reduction methods. Furthermore, 2D noise reduction can be applied either to the original set of spectra before performing 2D-COS ("pretreatment") or on the 2D-COS output ("post-treatment"). Very little work has been done on post-treatment; hence, the relative advantages of these two approaches are unclear. In this work we compare the noise-reduction performance on 2D-COS of pretreatment and post-treatment using 1D (wavelets) and 2D algorithms (wavelets, matrix maximum entropy). The 2D methods generally outperformed the 1D method in pretreatment noise reduction. 2D post-treatment in some cases was superior to pretreatment and, unexpectedly, also provided correlation coefficient maps that were similar to 2D correlation spectroscopy maps but with apparent better contrast.

Applied Spectroscopy, Vol. 65, Issue 5, pp. 474-487 (2011)

Thermal Dependence of the Cr-to-Nd Energy Transfer in Lanthanum Lutetium Gallium Garnet

G. Ozen and B. Dibartolo

Abstract
Photoluminescence, excitation, and response to pulsed excitation measurements show the existence of the Cr³⁺-to-Nd³⁺ energy transfer in lanthanum lutetium gallium garnet with an efficiency eta = 0.59 at room temperature. The transfer occurs radiatively and nonradiatively, and both transfer rates are temperature dependent within 15-550 K. The nonradiative transfer rate, calculated as a function of temperature by using the lifetime data of the Cr³⁺ ion in the crystal, increases slowly with increasing temperature.

Applied Spectroscopy, Vol. 53, Issue 11, pp. 1454-1458

Red Antenna States of Photosystem I from Cyanobacteria Synechocystis PCC 6803 and Thermosynechococcus elongatus: Single-Complex Spectroscopy and Spectral Hole-Burning Study

Kerry J. Riley, Tõnu Reinot, Ryszard Jankowiak, Petra Fromme, and Valter Zazubovich

Abstract
Hole-burning and single photosynthetic complex spectroscopy were used to study the excitonic structure and excitation energy-transfer processes of cyanobacterial trimeric Photosystem I (PS I) complexes from Synechocystis PCC 6803 and Thermosynechococcus elongatus at low temperatures. It was shown that individual PS I complexes of Synechocystis PCC 6803 (which have two red antenna states, i.e., C706 and C714) reveal only a broad structureless fluorescence band with a maximum near 720 nm, indicating strong electron-phonon coupling for the lowest energy C714 red state. The absence of zero-phonon lines (ZPLs) belonging to the C706 red state in the emission spectra of individual PS I complexes from Synechocystis PCC 6803 suggests that the C706 and C714 red antenna states of Synechocystis PCC 6803 are connected by efficient energy transfer with a characteristic transfer time of 5 ps. This finding is in agreement with spectral hole-burning data obtained for bulk samples of Synechocystis PCC 6803. The importance of comparing the results of ensemble (spectral hole burning) and single-complex measurements was demonstrated. The presence of narrow ZPLs near 710 nm in addition to the broad fluorescence band at 730 nm in Thermosynechococcus elongatus (Jelezko et al. J. Phys. Chem. B 2000, 104, 8093-8096) has been confirmed. We also demonstrate that high-quality samples obtained by dissolving crystals of PS I of Thermosynechococcus elongatus exhibit stronger absorption in the red antenna region than any samples studied so far by us and other groups.

J. Phys. Chem. B, 2007, 111 (1), pp 286–292

Biophysical and Structural Analysis of a Novel Heme b Iron Ligation in the Flavocytochrome Cellobiose Dehydrogenase

Frederik A. J. Rotsaert, B. Martin Hallberg, Simon de Vries, Pierre Moenne-Loccoz, Christina Divne, V. Renganathan and Michael H. Gold

Abstract
The fungal extracellular flavocytochrome cellobiose dehydrogenase(CDH) participates in lignocellulose degradation. The enzymehas a cytochrome domain connected to a flavin-binding domainby a peptide linker. The cytochrome domain contains a 6-coordinatelow spin b-type heme with unusual iron ligands and coordinationgeometry. Wild type CDH is only the second example of a b-typeheme with Met-His ligation, and it is the first example of a Met-His ligation of heme b where the ligands are arranged ina nearly perpendicular orientation. To investigate the ligationfurther, Met⁶⁵ was replaced with a histidine to create a bis-histidylligated iron typical of b-type cytochromes. The variant isexpressed as a stable 90-kDa protein that retains the flavindomain catalytic reactivity. However, the ability of the mutantto reduce external one-electron acceptors such as cytochromec is impaired. Electrochemical measurements demonstrate a decreasein the redox midpoint potential of the heme by 210 mV. In contrastto the wild type enzyme, the ferric state of the protohemedisplays a mixed low spin/high spin state at room temperatureand low spin character at 90 K, as determined by resonance Raman spectroscopy. The wild type cytochrome does not bind CO,but the ferrous state of the variant forms a CO complex, althoughthe association rate is very low. The crystal structure ofthe M65H cytochrome domain has been determined at 1.9 Åresolution. The variant structure confirms a bis-histidyl ligationbut reveals unusual features. As for the wild type enzyme,the ligands have a nearly perpendicular arrangement. Furthermore, the iron is bound by imidazole N^δ1 and N^ε2nitrogen atoms, rather than the typical N^ε2/N^ε2 coordination encountered in bis-histidyl ligated heme proteins. To our knowledge, this is the first example of a bis-histidyl N^δ1/N^ε2-coordinated protoporphyrin IX iron.

Journal of Physics and Chemistry of Solids Volume 67, Issues 1-3, January-March 2006, Pages 312-315

Peroxodiferric Intermediate of Stearoyl-Acyl Carrier Protein Δ⁹ Desaturase: Oxidase Reactivity during Single Turnover and Implications for the Mechanism of Desaturation

John A. Broadwater, Jingyuan Ai, Thomas M. Loehr,Joann Sanders-Loehr, and Brian G. Fox

Abstract
Combined optical and resonance Raman studies have revealed the formation of an O₂-adduct upon exposure of 4e^- chemically reduced stearoyl-acyl carrier protein Δ⁹ desaturase to stearoyl-ACP and 1 atm O₂. The observed intermediate has a broad absorption band at 700 nm and is remarkably stable at room temperature (t_1/2≈26 min). Resonance Raman studies using ¹⁶O₂ gas reveal vibrational features of a bound peroxide [v_s(Fe-O₂), 442 cm^-1; v_as(Fe-O₂), 490 cm^-1; v(O-O), 898 cm^-1] that undergo the expected mass-dependent shifts when prepared in ¹⁶O¹⁸O or ¹⁸O₂. The appearance of two Fe-O₂ vibrations, each having a single peak of intermediate frequency with ¹⁶O¹⁸O, proves that the peroxide is bound symmetrically between the two iron atoms in a µ-1,2 configuration. The same results have been obtained in the accompanying resonance Raman study of ribonucleotide reductase isoform W48F/D84E [P. Moënne-Loccoz, J. Baldwin, B. A. Ley, T. M. Loehr, and J. M. Bollinger, Jr. (1998) Biochemistry 37, 14659-14663], thus making it likely that other members of the class II diiron enzymes form related peroxodiferric intermediates. Study of the reactivity of peroxodiferric δ9D revealed that this intermediate underwent 2e^- reduction leading to an oxidase reaction and recovery of the resting ferric homodimer. In contrast, biological reduction of the same enzyme preparations using ferredoxin reductase and [2Fe-2S] ferredoxin gave catalytic desaturation with a turnover number of 20-30 min^-1. The profound difference in catalytic outcome for chemically and enzymatically reduced Δ9D suggests that redox-state dependent conformational changes cause partition of reactivity between desaturase and oxidase chemistries. The Δ9D oxidase reaction represents a new type of reactivity for the acyl-ACP desaturases and provides a two-step catalytic precedent for the “alternative oxidase” activity recently proposed for a membrane diiron enzyme in plants and trypanosomes.

Biochemistry, 1998, 37 (42), pp 14664–14671

The Ferroxidase Reaction of Ferritin Reveals a Diferric µ-1,2 Bridging Peroxide Intermediate in Common with Other O₂-Activating Non-Heme Diiron Proteins

Pierre Moënne-Loccoz, Carsten Krebs, Kara Herlihy, Dale E. Edmondson, Elizabeth C. Theil, Boi Hanh Huynh, and Thomas M. Loehr

Abstract
Ferritins are ubiquitous proteins that concentrate, store, and detoxify intracellular iron through oxidation of Fe²⁺ (ferroxidation), followed by translocation and hydrolysis to form a large inorganic mineral core. A series of mutagenesis, kinetics, and spectroscopic studies of ferritin led to the proposal that the oxidation/translocation path involves a diiron protein site. Recent stopped-flow absorption and rapid freeze-quench Mössbauer studies have identified a single peroxodiferric species as the initial transient intermediate formed in recombinant frog M ferritin during rapid ferroxidation [Pereira, S. A., Small, W., Krebs, C., Tavares, P., Edmondson, D. E., Theil, E. C., and Huynh, B. H. (1998) Biochemistry 37, 9871-9876]. To further characterize this transient intermediate and to establish unambiguously the peroxodiferric assignment, rapid freeze-quenching was used to trap the initial intermediate for resonance Raman investigation. Discrete vibrational modes are observed for this intermediate, indicating a single chromophore in a homogeneous state, in agreement with the Mössbauer conclusions. The frequency at 851 cm^-1 is assigned as v(O-O) of the bound peroxide, and the pair of frequencies at 485 and 499 cm^-1 is attributed, respectively, to v_s and v_as of Fe-O₂-Fe. Identification of the chromophore as a µ-1,2 bridged diferric peroxide is provided by the isotope sensitivity of these Raman bands. Similar peroxodiferric intermediates have been detected in a mutant of the R2 subunit of ribonucleotide reductase from Escherichia coli and chemically reduced Δ⁹ stearoyl-acyl carrier protein desaturase (Δ9D), but in contrast, the ferritin intermediate is trapped from the true reaction pathway of the native protein. Differences in the Raman signatures of these peroxide species are assigned to variations in Fe-O-O-Fe angles and may relate to whether the iron is retained in the catalytic center or released as an oxidized product.

Biochemistry, 1999, 38 (17), pp 5290–5295

Visible spectroscopy measurements in the PBFA II ion diode (invited)

J. Bailey, A. L. Carlson, R. L. Morrison and Y. Maron

Abstract
We describe a new visible spectroscopy diagnostic system for measuring plasma properties in the PBFA II applied-B ion diode. The system transports light from the ion diode to a remote screen room where it is recorded by a spectrograph coupled to a streak camera. We developed extensive calibration techniques for measuring the collection efficiency into the fiber link, the effects of the background bremsstrahlung radiation on the fibers, the fiber transmission as a function of wavelength, and the absolute streaked-spectrograph sensitivity as a function of wavelength. We have recorded time-dependent spectral line profiles and intensities from the PBFA II plasma opening switch, the beam-transport gas cell, and the anode plasma. The Stark shift of the LiI 2s-2p transition observed on LiF-anode shots shows that the time-resolved electric field peaks at 7–8 MV/cm, the highest field ever measured using the Stark effect. The potential of these measurements to expand our knowledge of ion-diode physics is being explored. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

Rev. Sci. Instrum. 61, 3075 (1990); doi:10.1063/1.1141686

Biosynthesis of topa quinone cofactor in bacterial amine oxidases. Solvent origin of C-2 oxygen determined by Raman spectroscopy.

Nakamura N, Matsuzaki R, Choi YH, Tanizawa K, Sanders-Loehr J.

Abstract
Resonance Raman spectroscopy is an excellent technique for providing structural information on the 2,4, 5-trihydroxyphenylalanine quinone (TPQ) cofactor in copper-containing amine oxidases. This technique has been used to investigate the copper- and O₂-dependent biosynthesis of the TPQ cofactor in phenylethylamine oxidase (PEAO) and histamine oxidase from Arthrobacter globiformis. Incubation of the holoenzyme in H₂¹⁸O causes frequency shifts at 1684(-26) cm-¹ in PEAO and at 1679(-28) cm^-1 in histamine oxidase, allowing this feature to be assigned to the C=O stretch of a single carbonyl group at the C-5 position. When apoprotein is reacted with Cu(II) and O₂ in the presence of H₂¹⁸O, the resultant holoproteins show increased shifts of -3 to -6 cm^-1 in a number of other vibrational modes, particularly at 411 and 1397 cm^-1. Because these small shifts persist when the H₂¹⁸O-regenerated protein is back-exchanged into H₂¹⁶O, they can be assigned to oxygen isotope substitution at the C-2 postion. No isotope shifts are observed when apoprotein is regenerated with Cu(II) in the presence of ¹⁸O₂. Thus, it is concluded that the C-2 oxygen atom of TPQ originates from H₂O rather than O₂. The isotope dependence of the 1397-cm^-1 mode allows it to be assigned to the C-O moiety at the C-2 position, with its low frequency being indicative of only partial double bond character. Similar frequency shifts due to ¹⁸O at C-2 are observed in the resonance Raman spectra of H₂¹⁸O-regenerated PEAO after derivatization of the C-5 carbonyl with either p-nitrophenylhydrazine (-5 cm^-1 at 480 cm^-1) or methylamine (-5 cm^-1 at 1301 cm^-1). Taken together, these results indicate that the TPQ cofactor in the native enzyme has substantial electron delocalization between the C-2 and C-4 oxygens and that only the C-5 oxygen has predominantly C=O character.

J Biol Chem. 1996 Mar 1;271(9):4718-24.

Characterization of Manganese(II) Binding Site Mutants of Manganese Peroxidase

Katsuyuki Kishi, Margo Kusters-van Someren,‡ Mary B. Mayfield, Jie Sun, Thomas M. Loehr, and Michael H. Gold*

Abstract
A series of site-directed mutants, E35Q, E39Q, and E35Q-D179N, in the gene encoding manganese peroxidase isozyme 1 (mnp1) from Phanerochaete chrysosporium, was created by overlap extension, using the polymerase chain reaction. The mutant genes were expressed in P. chrysosporium during primary metabolic growth under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter. The mutant manganese peroxidases (MnPs) were purified and characterized. The molecular masses of the mutant proteins, as well as UV-vis spectral features of their oxidized states, were very similar to those of the wild-type enzyme. Resonance Raman spectral results indicated that the heme environment of the mutant MnP proteins also was similar to that of the wild-type protein. Steady-state kinetic analyses of the E35Q and E39Q mutant MnPs yielded K_m values for the substrate Mn^II that were ∼50-fold greater than the corresponding K_m value for the wild-type enzyme. Likewise, the k_cat values for Mn^II oxidation were ∼300-fold lower than that for wild-type MnP. With the E35Q-D179N double mutant, the K_m value for Mn^II was ∼120-fold greater, and the kcat value was ∼1000-fold less than that for the wild-type MnP1. Transient-state kinetic analysis of the reduction of MnP compound II by Mn^II allowed the determination of the equilibrium dissociation constants (K_D) and first-order rate constants for the mutant proteins. The K_D values were approximately 100-fold higher for the single mutants and approximately 200-fold higher for the double mutant, as compared with the wild-type enzyme. The first-order rate constants for the single and double mutants were ∼200-fold and ∼4000-fold less, respectively, than that of the wild-type enzyme. In contrast, the K_m values for H₂O₂ and the rates of compound I formation were similar for the mutant and wild-type MnPs. The second-order rate constants for p-cresol and ferrocyanide reduction of the mutant compounds II also were similar to those of the wild-type enzyme.

Biochemistry, 1996, 35 (27), pp 8986–8994

Search for ion dynamics effects on the shift and width of plasma-broadened C I and O I spectral lines

Z. Mijatović, N. Konjević, R. Kobilarov and S. Djurović

Abstract
We report measured Stark shifts and widths of the neutral carbon 5052- and 4932-Å lines and the neutral oxygen 4368-Å line in the plasma of an atmospheric pressure wall stabilized electric arc. Electron densities of (1.4-3.1)×10¹⁶ cm^-3 are measured from the width of the H_β line while electron and gas temperatures in the range from 9300 to 10300 K are determined from plasma composition data. Experimental Stark widths and shifts are compared to theoretical results obtained from semiclassical calculations of Stark broadening parameters using quasistatic and ion-dynamic treatment of the ions. Some indications are found that the inclusion of ion dynamics in the calculation of the shifts of the C I 5052-Å line slightly improves the consistency between theory and experiment.

Phys. RevE.51.613 (1995)

Line shape study of neutral argon lines in plasma of an atmospheric pressure wall stabilized argon arc

S. Djurović, D. Nikolić, Z. Mijatović, R. Kobilarov and N. Konjević

Abstract
We report results of the measurement of the Stark parameters for several visible neutral argon lines. For this study wall stabilized arc is used as a plasma source. Electron densities of (0.74-2.9)×10²² m^-3 are determined from the width of the H_? line and electron temperatures of (9280-10750) K are deduced from plasma composition data. Precision technique for spectral line shape recordings is applied. The deconvolution procedure for asymmetric line profiles is used to determine the Stark broadening parameters from experimental line shapes. The results are compared with theoretical and other experimental data.

2002 Plasma Sources Sci. Technol. 11 A95

Determination of ion-broadening parameter for some Ar I spectral lines

D. Nikolić, S. Djurović, Z. Mijatović, R. Kobilarov , B. Vujičić and M. Ćirišan

Abstract
This paper presents the results of the ion-broadening parameter A determination from experimental profiles of several neutral argon lines. Advanced deconvolution procedure has been used for parameter A determination. Experimental results have been obtained from the wall-stabilized pure argon plasma with electron density range (0.74-2.90)×10²² m^-3 and temperature range 9280-10750 K. These results are compared with available theoretical and other experimental data.

Journal of Quantitative Spectroscopy and Radiative Transfer - Volume 86, Issue 3, 1 July 2004, Pages 285-298

Measurement and temporal behaviour analysis of the plasma-glass boundary layer in a T-tube

M. Pavlov, S Djurović, B. Vujicić, R. Kobilarov and Z. Mijatović

Abstract
Refraction of a laser beam by a flat boundary layer between a plasma and a glass plate was measured and the time development of the layer was analysed. Results of the analysis for the plasma produced in a small T-tube show that the boundary layer thickness increases with time faster than linearly. The boundary layer is negligibly thin during the first 3 μs after the reflected shock front has passed the point of observation. This means that a relatively fast collapse due to cooling through the boundary layer occurs in the second part of the reflected plasma lifetime.

2009 Plasma Sources Sci. Technol. 18 015018

Measurement of Specific Heats Ratio of Hydrogen Plasma

S. Djurović, M. Pavlov

Abstract
Adiabatic expansion of plasma behind the reflected shock front in an electromagnetic shock tube has been verified. Electron densities and temperatures have been measured spectroscopically. Assuming complete local thermal equilibrium, the specific heat ratios of hydrogen plasmas have been determined out of expansion rate per a heavy particle directly from the adiabatic expansion law. Noticeably lower values of the ratio are determined at temperatures where ionization and recombination processes are abundant. The ratios determined in this work are in excellent agreement with theoretical values determined in an earlier work.

Beiträge aus der Plasmaphysik Volume 24, Issue 2, pages-105-112, 1984

Measurements of H_β Stark central asymmetry and its analysis through standard theory and computer simulations

S. Djurović, M. Ćirišan, A. V. Demura, G. V. Demchenko, D. Nikolić, M. A. Gigosos, and M. Á. González

Abstract
Experimental measurements of the center of the H_β Stark profile on three different installations have been done to study its asymmetry in wide ranges of electron density, temperature, and plasma conditions. Theoretical calculations for the analysis of experimental results have been performed using the standard theory and computer simulations and included separately quadrupolar and quadratic Stark effects. Earlier experimental results and theoretical calculations of other authors have been reviewed as well. The experimental results are well reproduced by the calculations at high and moderate densities.

Phys. Rev. E 79, 046402 (2009) [14 pages]

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Model 2062

Contactless monitoring of Ge content and B concentration in ultrathin single and double layer Si_1-xGe_x epitaxial films using multiwavelength micro-Raman spectroscopy

Chun-Wei Chang, Min-Hao Hong, Wei-Fan Lee, Kuan-Ching Lee, Shiu-Ko Jang Jian, Yen Chuang, Yu-Ta Fan, Noriyuki Hasuike, Hiroshi Harima, Takeshi Ueda, Toshikazu Ishigaki, Kitaek Kang, and Woo Sik Yoo

Abstract
Non-contact monitoring of Ge content and B concentration in single and double Si_1-xGe_x epitaxial layers on Si(100) device wafers was attempted using high-resolution, multiwavelength micro-Raman spectroscopy. The Ge content and B concentration determined by secondary ion mass spectroscopy (SIMS) depth profiling showed very strong correlation with the position and full-width-at-half-maximum of the Si-Si peak from the Si_1-xGe_x epitaxial layers as determined by Raman measurements. High resolution X-ray diffraction (HRXRD) characterization was done for all wafers to determine Ge and B sensitivity and form comparisons with Raman and SIMS analysis. The non-destructive, in-line monitoring of Ge content and B concentration of single and double Si_1-xGe_x epitaxial layers with thickness ranging from 5 ~ 120 nm, on small area monitoring pads, was successfully demonstrated by multiwavelength micro-Raman spectroscopy during epitaxial process optimization, material property verification, and quality control applications.

AIP Advances 2, 012124 (2012)

Stress Characterization of Tungsten-Filled Through Silicon via Arrays Using Very High Resolution Multi-Wavelength Raman Spectroscopy

Jeff Gambino, Daniel Vanslette, Bucknell Webb, Cameron Luce, Takeshi Ueda, Toshikazu Ishigaki, Kitaek Kang, and Woo Sik Yoo

Abstract
Stress in Si adjacent to W-filled TSVs has been measured by multiwavelength Raman spectroscopy (probe depth ranging from 290 to 645 nm) and compared to finite element modeling. The stress in Si from the TSVs increases with TSV width and is almost constant at the different depths probed in this study. The Raman signal is mainly due to the sum of the S_x and S_y stress components, perpendicular and parallel to the TSV bars. The S_x component is tensile and the S_y component is compressive, with the S_y component dominant in between the TSVs. However, ~10 um from the edge of the TSV array, the two components are equal in magnitude so that the stress measured by Raman is zero, even though the individual S_x and S_y stresses are considerable. Hence, it is important to use finite element modeling in conjunction with Raman spectroscopy to characterize stresses in TSVs.

Appl. Phys. Lett. 98, 232106 (2011)

Stress evolution in surrounding silicon of Cu-filled through-silicon via undergoing thermal annealing by multiwavelength micro-Raman spectroscopy

W. S. Kwon, D. T. Alastair, K. H. Teo, S. Gao, T. Ueda, T. Ishigaki, K. T. Kang, and W. S. Yoo

Abstract
Three-dimensional stress development was observed in silicon surrounding the Cu-filled through-silicon via (TSV) structures undergoing the thermal annealing process. We show here, using a multiwavelength micro-Raman spectroscopy system, that the behavior of stress development in silicon after annealing step is dependent on the initial stress state as well as the geometry and directionality of the TSV array. The warping of stress curve for postannealed state with a reference of preannealed state is distinctively observed. Furthermore, the introduction of stress-free point is also attributed to the destructive stress interaction from different geometry and direction and initial stress state.

Appl. Phys. Lett. 98, 232106 (2011)

Pu-239/Pu-240 isotope emission spectroscopy in a laser-induced plasma

Coleman A. Smitha,, Max A. Martinezb, D.Kirk Veirsb and David A. Cremersc

Abstract
Laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of plutonium isotope ratios through direct observation of atomic emission from laser-induced plasmas at high resolution. The Pu-239/Pu-240 isotope shift of -0.355 cm^-1 from the plutonium atomic line at 594.52202 nm (Blaise et al., The Atomic Spectrum of Plutonium, Argonne National Laboratory Report ANL-83-95, 1984) is clearly resolved in our plasma conditions. Atomic emission is dispersed through a 2-m spectrometer in double pass mode and collected on an electronically gated, intensified charge-coupled device (ICCD) camera. The integrated peak areas obtained from curve-fitting closely match the Pu-239/Pu-240 isotopic ratios obtained from standard methods of thermal ionization mass spectrometry and gamma spectrometry. The observed plutonium linewidths were 0.19 cm^-1 (0.0067 nm). These linewidths are within the experimental error of the ideal instrument-limited linewidth, which is calculated to be 0.15 cm^-1 (0.0052 nm) based upon the known modulation transfer function for the ICCD system. This linewidth should allow LIBS to be applicable for isotopic ratio measurements for all of the light actinides.

Spectrochimica Acta Part B: Atomic Spectroscopy Volume 57, Issue 5, 31 May 2002, Pages 929-937

320-channel dual phase lock-in optical spectrometer

P. S. Fodor, S. Rothenberger, and J. Jevy

Abstract
The development of a multiple-channel lock-in optical spectrometer (LIOS) is presented, which enables parallel phase-sensitive detection at the output of an optical spectrometer. The light intensity from a spectrally broad source is modulated at the reference frequency, and focused into a high-resolution imaging spectrometer. The height at which the light enters the spectrometer is controlled by an acousto-optic deflector, and the height information is preserved at the output focal plane. A two-dimensional InGaAs focal plane array collects light that has been dispersed in wavelength along the horizontal direction, and in time along the vertical direction. The data is demodulated using a high performance computer-based digital signal processor. This parallel approach greatly enhances (by more than 100x) the speed at which spectrally resolved lock-in data can be acquired. The noise performance of a working system optimized for the 1.3 µm wavelength range is analyzed using a laser diode light source. Time-resolved absorption traces are obtained for InAs quantum dots embedded in a GaAs matrix, and for dispersed films of PbSe nanocrystals.

Rev. Sci. Instrum. 76, 013103 (2005); doi:10.1063/1.1830013

Intensities and self-broadening coefficients of weak water vapor lines in the 720-nm region determined by intracavity laser absorption spectroscopy

SINGH K. and O'BRIEN J. J.

Abstract
The time-resolved quasi-cw form of intracavity laser spectroscopy is used for the quantitative determination of absolute intensities and self-broadening coefficients of weak vibration-rotation lines of water that absorb in the region of the 720-nm band. The studies have been conducted using a 0.68-m-long intracavity absorption cell, and the data are analyzed both by directly fitting the absorption lineshape and by the curve of growth method. Values determined for some of the stronger lines are compared with the ones obtained in previous studies where multipass absorption cells and alternative instrumental techniques were employed. The comparisons show that the accuracy of the intracavity laser spectroscopy technique is comparable to that obtained by the use of other techniques

Journal of molecular spectroscopy 1994, vol. 167, no1, pp. 99-108 (19 ref.)

Intensity measurements of methane lines in the 727 nm band studied by intracavity laser spectroscopy at temperatures down to 77 K

Singh, Kuldip; O'Brien J. J.

Abstract
A time-resolved, quasi-cw form of intracavity laser absorption spectroscopy has been used to measure intensities of vibration-rotation lines of methane in the 727 nm region. Temperatures of 77, 195 and 296 K are employed. A 0.68 meter long, low temperature absorption cell, enclosed inside the resonator cavity of a dye laser, has been used to obtain effective absorption pathlengths of 0.6-4.0 km. Intensities of several vibration-rotation methane lines obtained by directly fitting Voigt profiles to the absorption lines are reported for the first time for absorption in the 727 nm band.

Chemical Physics Letters (ISSN 0009-2614), vol. 229, no. 1-2, p. 29-34

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Model 234/302

Fluorescence Efficiency and Visible Re-emission Spectrum of Tetraphenyl Butadiene Films at Extreme Ultraviolet Wavelengths

V. M. Gehman, S. R. Seibert, K. Rielage, A. Hime, Y. Sun, D.-M. Mei, J. Maassen, D. Moore

Abstract
A large number of current and future experiments in neutrino and dark matter detection use the scintillation light from noble elements as a mechanism for measuring energy deposition. The scintillation light from these elements is produced in the extreme ultraviolet (EUV) range, from 60 - 200 nm. Currently, the most practical technique for observing light at these wavelengths is to surround the scintillation volume with a thin film of Tetraphenyl Butadiene (TPB) to act as a fluor. The TPB film absorbs EUV photons and reemits visible photons, detectable with a variety of commercial photosensors. Here we present a measurement of the re-emission spectrum of TPB films when illuminated with 128, 160, 175, and 250 nm light. We also measure the fluorescence efficiency as a function of incident wavelength from 120 to 250 nm.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 654, 1, 2011, Pages 116-121.

CsBr and CsI UV photocathodes: new results on quantum efficiency and aging

B. K. Singh, E. Shefer, A. Breskin, R. Chechik and N. Avraham

Abstract
We report on the photoemission properties of 300 Å thick transmissive- and 5000 Å thick reflective UV-sensitive CsBr photocathodes. Following post-evaporation heat treatment at 70°C the absolute quantum efficiency is 35% at 150 nm, with a red boundary cut-off at about 195 nm. Extensive aging studies of CsBr and CsI photocathodes, under high photon flux and under ion bombardment in gas avalanche multiplication mode, were carried out for the first time without exposure to air. The results are compared with the previously published data on CsI aging and the methodology of the aging tests is discussed in details.

Nuclear Instruments and Methods in Physics Research Section A, Volume 454, Issue 2-3, p. 364-378.

Generation of sub-30 fs ultraviolet pulses by Raman induced phase modulation in nitrogen

Noack, F.; Steinkellner, O.; Tzankov, P.; Ritze, H.-H.; Herrmann, J.; Kida, Y.

Abstract
We demonstrate compression of ultrashort light pulses in the ultraviolet (UV) by impulsively excited molecular wave-packets in nitrogen filled in a 25 cm long hollow waveguide of 128 µm diameter. After compression with CaF2 prisms the pulse duration was determined by XFROG to be 23 fs with a time-bandwidth product of 0.50. The advantages of our technique are high efficiency and the possibility to use it also for pulses at wavelength shorter than 200 nm. The experimental observations are explained by a theoretical model.

Optics Express, vol. 13, Issue 7, p.2467

VUV fluorescence from selective high-order multiphoton excitation of N₂

Coffee, Ryan N. and Gibson, George N.

Abstract
Recent fluorescence studies suggest that ultrashort pulse laser excitation may be highly selective. Selective high-intensity laser excitation holds important consequences for the physics of multiphoton processes. To establish the extent of this selectivity, we performed a detailed comparative study of the vacuum ultraviolet fluorescence resulting from the interaction of N₂ and Ar with high-intensity infrared ultrashort laser pulses. Both N₂ and Ar reveal two classes of transitions, inner-valence ns←np and Rydberg np←n'l'. From their pressure dependence, we associate each transition with either plasma or direct laser excitation. Furthermore, we qualitatively confirm such associations with the time dependence of the fluorescence signal. Remarkably, only N₂ presents evidence of direct laser excitation. This direct excitation produces ionic nitrogen fragments with inner-valence (2s) holes, two unidentified transitions, and one molecular transition, the N⁺₂ :X ²∑⁺_g←C ²∑⁺_u . We discuss these results in the light of a recently proposed model for multiphoton excitation.

Physical Review A, vol. 69, Issue 5, id. 053407

Calibration of VUV spectrometer-detector system using synchrotron radiation

McPherson, A. ; Rouze, N. ; Westerveld, W.B. ; Risley, J.S.

Abstract
A new technique and apparatus have been developed for the measurement of absolute electron impact photoemission cross sections in the 30--150-nm wavelength range. Synchrotron light is used as the primary intensity standard for the calibration of the detection efficiency of a vacuum ultraviolet (VUV) spectrometer-detector system. A multiadjustable manipulator was used to position precisely a Seya-Namioka-type spectrometer-detector system with respect to a narrow ray of synchrotron radiation. By scanning the beam of synchrotron radiation across the surface of the grating in the spectrometer, precise simulation of the geometry of the light source encountered in the electron impact photoemission mesurement was realized. Analysis of the results underscores the fact that for spectrometer calibrations in the VUV, the calibration procedure depends on the geometry of the experimental source. The simultaneous determination of the absolute apparatus response function of the spectrometer--detector system and the geometrical factors pertaining to the electron impact photoemission source allows photoemission cross sections in the VUV to be determined with unparalleled precision.

Applied Optics (ISSN 0003-6935), vol. 25, Jan. 15, 1986, p. 298-310.

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Model 218

Real-Time Measurement of Combustion Generated Particles with Photofragmentation-Fluorescence

Damm, Christopher J.; Lucas, Donald; Sawyer, Robert F.; Koshland, Catherine P.

Abstract
Excimer laser fragmentation-fluorescence spectroscopy (ELFFS) is a viable technique for real-time monitoring of carbonaceous particles in combustion exhausts. The exhaust from a single-cylinder two-stroke engine is diluted and diverted into the laser interrogation region, resulting in a particle concentration of approximately 1 × 10⁷/cm³. Light from a 193 nm ArF laser photofragments the particles and then produces fluorescence from the atomic carbon fragments at 248 nm, CH fragments at 431 nm, and C₂ fragments at 468 nm. The atomic carbon fluorescence signal is proportional to the number concentration of particles in the laser interrogation region. The 100-shot (1 s) detection limit for particles in the exhaust is 1 mg/m³, expressed as a mass concentration of particulate matter. Interferences from carbon monoxide and carbon dioxide are negligible. The relative fluorescence yield at 248 nm is four times greater from particles than from the gas phase hydrocarbons present in the exhaust. This high yield suggests that the gas phase hydrocarbon interference would not be problematic for measurements of diesel exhaust, where the ratio of particulate carbon to gas phase hydrocarbon is high.

Applied Spectroscopy, Volume 55, Issue 11, Pages 360A-370A and 1435-1572 (November 2001) , pp. 1478-1482(5)

Use of the vacuum ultraviolet spectral region for laser-induced breakdown spectroscopy-based Martian geology and exploration

RADZIEMSKI Leon ; CREMERS David A. ; BENELLI Katharine ; KHOO Cynthia ; HARRIS Ronny D. ;

Abstract
Several elements important to planetary geology (e.g. Br, C, Cl, P, S) and the human exploration of Mars (e.g. toxic elements such as As) have strong emission lines in the purge and vacuum ultraviolet (VUV) spectral region (100-200 nm). This spectral region has not been extensively studied for space applications using geological samples. We studied emissions from the laser-induced breakdown spectroscopy (LIBS) plasma in this region using a sample chamber filled with 7 torr (930 Pa) of CO² to simulate the Martian atmosphere. Pressures down to 0.02 torr were also used to evaluate the effect of the residual CO2 on the spectra and to begin investigating the use of VUV-LIBS for airless bodies such as asteroids and the Moon. Spectra were recorded using a 0.3-m vacuum spectrometer with an intensified CCD (ICCD) camera. The effects of time delay and laser energy on LIBS detection at reduced pressure were examined. The effect of ambient CO² on the detection of C in soil was also evaluated. Lines useful for the spectrochemical analysis of As, Br, C, Cl, P, and S were determined and calibration curves were prepared for these elements. Although LIBS is being developed for stand-off analysis at many meters distance, the experiments reported here were aimed at in-situ (close-up) analysis.

Atomic spectroscopy (ISSN 0584-8547) 2005, vol. 60, no2, pp. 237-248

A far-ultraviolet contamination-irradiation facility for in situ reflectance measurements

Steven R. Meier, June L. Tveekrem and Ritva A. M. Keski-Kuha

Abstract
In this article, a contamination-irradiation facility designed to measure contamination effects on far-ultraviolet optical surfaces is described. An innovative feature of the facility is the capability of depositing a contaminant, photopolymerizing the contaminant with far-ultraviolet light, and measuring the reflectance of the contaminated sample, all in situ. In addition to describing the facility, we present far-ultraviolet reflectance measurements for a contaminated mirror.

Review of scientific instruments (ISSN 0034-6748) 1998, vol. 69, no10, pp. 3642-3644

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Model 219

High-pressure hollow cathode discharges

Karl H Schoenbach, Ahmed El-Habachi, Wenhui Shi and Marco Ciocca

Abstract
Reducing the diameter of the cathode hole in a plane anode - hollow cathode geometry to m has allowed us to generate direct current discharges in argon at atmospheric pressure. Up to pressure times cathode hole diameter (pD) values of approximately 5 Torr cm, and at sub-mA currents, glow discharges (predischarges) are observed with a shape which is determined by the vacuum electric field. In the same pD range, but at higher currents of up to approximately 4 mA, the discharges are of the hollow cathode discharge type. At pD values exceeding 5 Torr cm the predischarges turn into surface discharges along the mica spacer between the electrodes. At currents > 4 mA filamentary, pulsed discharges are observed. Qualitative information on the electron energy distribution in the microdischarges has been obtained by studying the VUV emission from ionized argon atoms and the argon excimer radiation at 130 nm. The results of the spectral measurements indicate the presence of a relatively large concentration of electrons with energies > 15 eV over the entire pressure range. The fact that the current - voltage characteristic of the microdischarges has a positive slope over much of the current range where excimer radiation is emitted indicates the possibility of forming arrays of these discharges and using them in flat panel excimer lamps.

1997 Plasma Sources Sci. Technol. 6 468-477

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Model 225

Determination of the spectral radiance of deuterium lamps using the storage ring Bessy as a primary radiometric standard

Tegeler, Erich

Abstract
The electron storage ring BESSY is a primary radiometric standard of spectral irradiance, which has been used for the calibration of deuterium lamps as radiometric transfer standards of spectral radiance in the wavelength range 115-350 nm. The radiometer used for these measurements is described in detail. For λ > 165 nm the uncertainty of the spectral radiance of the calibrated lamps is if > 3%.

Nuclear Instruments and Methods in Physics Research Section A, Volume 282, Issue 2-3, p. 706-713.

Diagnostics by laser-induced fluorescence in the vacuum ultraviolet of hydrogen molecules with high rovibrational excitation

Thomas Mosbach and H.F. Dobele

Abstract
The population dynamics of molecular hydrogen in its electronic ground state is of particular interest for the understanding negative ion production. The favored process is dissociative attachment of low energy electrons to highly excited electronic ground state molecules. We report on in-situ measurements of the population of these states in a pulsed hydrogen plasma using LIF in the VUV. The measurements are taken after the fast interruption of the discharge current. In the current range investigated the population of the vibrational states is highly suprathermal, and the theoretically predicted plateu in the distribution is clearly observed.

Institut fur Laser und Plasmaphysik, Universitat GH-Essen, D-45117 Essen

Implementation of a normal incidence spectrometer on an electron beam ion trap

S. B. Utter, P. Beiersdorfer, J. R. Crespo López-Urrutia and E. Träbert

Abstract
Spectroscopic instrumentation is one of the keys to the exploration of high-temperature plasmas. The electron beam ion trap EBIT can serve as a tool for precise studies of highly charged ions in the laboratory and can help in setting spectroscopic standards for plasma studies. Recent efforts have focused on investigating the EUV, vacuum ultraviolet VUV , and UV regimes. We present here the implementation of a 1 m normal incidence spectrometer for use on the Lawrence Livermore National Laboratory high-energy EBIT Super-EBIT for spectral analysis of line emission of highly charged ions. Using two different gratings, our study encompasses a wide range of wavelengths spanning the VUV through the visible. Examples of measurements of optical spectra from krypton and argon are given.

Review of scientific instruments 1999, vol. 70 (2), no1, pp. 288-291

Luminescence of Pr³⁺ in SrAl₁₂O₁₉: Observation of two photon luminescence in oxide lattice

A. M. Srivastava and W. W. Beersb

Abstract
The observation of photon-cascade emission (PCE) in Pr³⁺ activated SrAl₁₂O₁₉ under vacuum ultraviolet excitation (VUV) is reported and discussed. In this host lattice, the lowest-energy component of the Pr³⁺ 4f5d excited configuration is located above the ¹S₀ state. The excitation of the Pr³⁺ 4f5d state by VUV photons results in radiative emission originating from the ¹S₀ level state. The subsequent radiative emission from the ¹P₀ state confirms the photon-cascade emission of Pr³⁺ activated SrAl₁₂O₁₉. To the best of our knowledge this is the first observation of PCE in an oxide matrix.

Journal of Luminescence Volume 71, Issue 4, May 1997, Pages 285-290

PtSi–n–Si Schottky-barrier photodetectors with stable spectral responsivity in the 120–250 nm spectral range

K. Solt, H. Melchior and U. Kroth, P. Kuschnerus, V. Persch, H. Rabus, M. Richter, and G. Ulm

Abstract
Front-illuminated PtSi–n–Si Schottky barrier photodiodes have been developed for the ultraviolet and vacuum ultraviolet spectral range. Their spectral responsivity was determined in the 120–500 nm spectral range by use of a cryogenic electrical substitution radiometer operated with spectrally dispersed synchrotron radiation. For wavelengths below 250 nm, the spectral responsivity is about 0.03 A/W, comparable to that of GaAsP Schottky photodiodes. Unlike the GaAsP diodes, the new PtSi–n–Si diodes have a spatially uniform response which is virtually stable after prolonged exposure to short wavelength radiation. Even after a radiant exposure of 150 mJ cm^–2 at wavelength 120 nm, the relative reduction in spectral responsivity remains below 0.2%. Due to these features, this type of photodiode is a promising candidate for use as secondary detector standard in the ultraviolet and vacuum ultraviolet spectral ranges.

Applied physics letters 1996, vol. 69, no24, pp. 3662-3664

Photoelectric emission from negative-electron-affinity diamond (111) surfaces: Exciton breakup versus conduction-band emission

C. Bandis and B. B. Pate

Abstract
We have recently reported that bound electron-hole pairs (Mott-Wannier excitons) are the dominant source of photoelectron emission from specially prepared [‘‘as-polished’’ C(111)-(1×1):H] negative-electron-affinity diamond surfaces for near-band-gap excitation up to 0.5 eV above threshold [C. Bandis and B. B. Pate, Phys. Rev. Lett. 74, 777 (1995)]. It was found that photoexcited excitons transport to the surface, break up, and emit their electron. In this paper, we extend the study of exciton-derived emission to include partial yield (constant final-state) analysis as well as angular distribution measurements of the photoelectric emission. In addition, we find that exciton-derived emission does not always dominate. Photoelectric emission properties of the in situ ‘‘rehydrogenated’’ (111)-(1×1):H diamond surface are characteristically different than emission observed from the as-polished (111)-(1×1):H surface. The rehydrogenated surface has additional downward band bending as compared to the as-polished surface. In confirmation of the assignment of photoelectric yield to exciton breakup emission, we find a significant enhancement of the total electron yield when the downward band bending of the hydrogenated surface is increased. The functional form of the observed total electron yield demonstrates that, in contrast to the as-polished surface, conduction-band electrons are a significant component of the observed photoelectric yield from the in situ hydrogenated (111)-(1×1):H surface. Furthermore, electron emission characteristics of the rehydrogenated surface confirms our assignment of a Fan phonon-cascade mechanism for thermalization of excitons.

Surface science 1996, vol. 350, no1-3, pp. 315-321

Nanosecond time-resolved vacuum ultraviolet spectrometer for ion diode spectroscopy

T. Nash, D. Noack, and A. B. Filuk

Abstract
A 1-m normal incidence spectrometer has been modified for use as a diagnostic of ion diode plasmas. To improve instrumental sensitivity, an elliptical mirror images an anode surface plasma onto the entrance slit of an f/10 normal incidence spectrometer. The detector is a time-resolving copper iodide coated microchannel plate stripline framing camera with 60-µm resolution, limiting instrumental resolution to 1 Å with a 600 l/mm grating in first order. Reflectivity of optics and photoelectron efficiency limit the spectral range from 400 to 2000 Å. With a 600- l/mm grating the detector spans a 600-Å range. Applications of the instrument may include ion source divergence measurements from Doppler broadening, electric field measurements from Stark splittings or shifts, electron temperature from mean ionization state, and magnetic field measurements on high-power Z pinches from Zeeman splitting.

Review of Scientific Instruments; Journal Volume: 64:9, Pages: 2493-2495

High-speed programmable detector system for plasma spectroscopy

H. H. Mai, J. M. Larsen, K. Dimoff and J. Castracane

Abstract
Special electronic scanning circuits have been built to increase the resolution time of an intensified photodiode array assembly used for detecting EUV emission. The system can operate at 1-MHz sampling rate to provide data readout on two parallel output lines. The scanning time of a 1000-element array can be reduced to 500 µs. The system is programmable and can function sequentially at three different frequencies within a single scan. The device is CAMAC compatible and operated remotely by computer. It has been used to record spatial as well as temporal development of EUV radiation from the TEXTOR tokamak plasma.

Review of Scientific Instruments, Volume 57, Issue 5, May 1986, pp.866-873

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Model 248/310G

Photon diagnostics for the seeding experiment at FLASH

F. Curbis? , A. Azima, J. Boedewadt, H. Delsim-Hashemi, M. Drescher, T. Maltezopoulos, V. Miltchev, M. Mittenzwey, J. Rossbach, R. Tarkeshian, M. Wieland, S. Duesterer, J. Feldhaus, T. Laarmann, H. Schlarb, S. Khan, A. Meseck, and R. Ischebeck

Abstract
Starting from next year the technical feasibility of a direct seeding scheme at 30 and 13 nm will be studied at the Free-electron LASer in Hamburg (FLASH). During a major shutdown the SASE-FEL facility will be upgraded and it is planned to install in addition a high-harmonic generation (HHG) seed laser, a new chain of 10m variable gap undulators and a dedicated commissioning beamline for photon diagnostics and pilot time-resolved pump-probe experiments. Besides demonstrating successful seeding at short wavelength, the project aims for time resolution in the 10 fs range to study ultrafast processes by combining the naturally synchronized FEL and optical seed laser pulses. After the extraction of the radiation in a magnetic chicane, a short branch will accommodate intensity and beam monitors and a high-resolution spectrometer. The intensity monitor detects scattered photons from a gold mesh on a shotto-shot basis using micro-channel plates (MCP) and XUV diodes. It is designed to detect photons several orders of magnitude apart in flux, i.e. spanning the wide range from spontaneous emission up to the seeded FEL radiation at gigawatt power level. Simulations of this device are presented as well as calibration measurements carried out at FLASH.

Proceedings of FEL2009, Liverpool, UK; THOB05

Synthesized Light Transients

A. Wirth, M. Th. Hassan, I. Grguraš, J. Gagnon, A. Moulet, T. T. Luu, S. Pabst, R. Santra, Z. A. Alahmed, A. M. Azzeer, V. S. Yakovlev, V. Pervak, F. Krausz, E. Goulielmakis

Abstract
Manipulation of electron dynamics calls for electromagnetic forces that can be confined to and controlled over sub-femtosecond time intervals. Tailored transients of light fields can provide these forces. We report on the generation of subcycle field transients spanning the infrared, visible, and ultraviolet frequency regimes with a 1.5-octave three-channel optical field synthesizer and their attosecond sampling. To demonstrate applicability, we field-ionized krypton atoms within a single wave crest and launched a valence-shell electron wavepacket with a well-defined initial phase. Half-cycle field excitation and attosecond probing revealed fine details of atomic-scale electron motion, such as the instantaneous rate of tunneling, the initial charge distribution of a valence-shell wavepacket, the attosecond dynamic shift (instantaneous ac Stark shift) of its energy levels, and its few-femtosecond coherent oscillations.

Science 14 October 2011: 153.

McPherson's XUV grazing incidence spectrograph for plasma diagnostics and its calibration

K. Koláceka, J. Schmidta, V. Boháceka, M. Rípaa, P. Vrbaa, O. Frolovb, M. Tichýb, A. Jancárekc, M. Vrbovác, E. Skladnik-Sadowskad, M. Sadowskid, and J. Baranowskid

Abstract
The calibration of a McPherson’s fully computer-controlled grazing-incidence spectrograph Model 248/310G (Rowland circle diameter ≈ 1 m) with a MCP/CCD detection system is described. As a DC source of the XUV radiation served the Vacuum UV Hollow Cathode Light Source (McPherson Model 629), which was delivered together with the spectrograph. We concentrated on the MCP-centre- as well as across-MCP-wavelength calibration (a more general theoretical relation than in [1] was found), MCP gain uniformity, and CCD binning linearity. No attention was paid to a resolution of the system, because it changes with the wavelengths and it is determined by properties of the detection system. In general, it is usually much worse than the resolution of the spectrograph itself.

German-Polish Conference on Plasma Diagnostics for Fusion and Applications, Greifswald, Germany, September 4-6, 2002, Paper A 02

Generation of Coherent Soft-X-Ray Radiation Extending Far Beyond the Titanium L Edge

Enikö Seres, József Seres, Ferenc Krausz, and Christian Spielmann

Abstract
Coherent soft-x-ray radiation up to photon energies of 700 eV is obtained by focusing several-mJ, 10-fs near infrared laser pulses into a He gas jet. The observed nearly constant photon yield over several hundred eVs may be attributed to nonadiabatic self-phase matching, originating from a substantial ionization within a fraction of the optical cycle of the driving laser pulse.

Physical review letters 2004, vol. 92, no16, pp. 163002.1-163002.3

Power scaling of a z-pinch extreme ultraviolet source

MCGEOCH Malcolm W. ;

Abstract
A xenon Z-pinch^1,2 generating extreme ultraviolet radiation at the Mo-Si mirror wavelength of 13.5nm has been scaled to emit increased power at a higher repetition frequency. The 25mm long by 3.0mm (FWHM) diameter pinch produces 1.5W of EUV radiation (2.5% bandwidth) into an axial 0.1sr solid angle when operated at 100Hz (100J stored). The measured average pinch liner heat load at 100Hz is 37W cm^-2, corresponding to an average internal wall temperature of 8(PC. Electrode and liner erosion is very slight after more than 10⁶ pulses at 100Hz. Source cleanliness was demonstrated via a two-mirror simulation of a condenser in which throughput was unchanged during a 10⁶ pulse run at 50Hz. Amplitude stability was 12% (3σ) and positional stability was less than 4% of source diameter (lo). 13.5nm output scaled linearly with repetition frequency to more than 150Hz (58J stored). The cost of ownership for this source is estimated to be no greater than for an excimer laser illuminator. A plan is outlined for continued development to >1kHz and usable power of 16W

Proceedings of SPIE, the International Society for Optical Engineering 2000, vol. 3997, pp. 861-866

2-D Light Diffraction from CCD and Intensified Reticon Multichannel Detectors Causes Spectrometer Stray Light Problems

Richard W. Bormett and Sanford A. Asher

Abstract
After the shutdown of the BESSY I electron storage ring, PTB's two normal-incidence monochromator beamlines for the calibration of radiation sources and detectors in the wavelength range from 40 nm to 400 nm were transferred to PTB's new radiometry laboratory at BESSY II. In this paper, the beamlines and their properties are briefly described. First results for the calibration of secondary source standards and detector standards at BESSY II are shown and demonstrate the successful re-establishment of the measurement capabilities. In the ultraviolet, calibration of deuterium lamps was reproduced within 1% and of silicon trap photodetectors within 0.2%.

Applied Spectroscopy, Vol. 48, Issue 1, pp. 1-6

Source and detector calibration in the UV and VUV at BESSY II

M. Richter, J. Hollandt, U. Kroth, W. Paustian, H. Rabus, R. Thornagel and G. Ulm

Abstract
After the shutdown of the BESSY I electron storage ring, PTB's two normal-incidence monochromator beamlines for the calibration of radiation sources and detectors in the wavelength range from 40 nm to 400 nm were transferred to PTB's new radiometry laboratory at BESSY II. In this paper, the beamlines and their properties are briefly described. First results for the calibration of secondary source standards and detector standards at BESSY II are shown and demonstrate the successful re-establishment of the measurement capabilities. In the ultraviolet, calibration of deuterium lamps was reproduced within 1% and of silicon trap photodetectors within 0.2%.

2003 Metrologia 40 S107-S110

Visible spectroscopy measurements in the PBFA II ion diode (invited)

Bailey, J.; Carlson, A. L.; Morrison, R. L.; Maron, Y.

Abstract
We describe a new visible spectroscopy diagnostic system for measuring plasma properties in the PBFA II applied-B ion diode. The system transports light from the ion diode to a remote screen room where it is recorded by a spectrograph coupled to a streak camera. We developed extensive calibration techniques for measuring the collection efficiency into the fiber link, the effects of the background bremsstrahlung radiation on the fibers, the fiber transmission as a function of wavelength, and the absolute streaked-spectrograph sensitivity as a function of wavelength. We have recorded time-dependent spectral line profiles and intensities from the PBFA II plasma opening switch, the beam-transport gas cell, and the anode plasma. The Stark shift of the LiI 2s-2p transition observed on LiF-anode shots shows that the time-resolved electric field peaks at 7–8 MV/cm, the highest field ever measured using the Stark effect. The potential of these measurements to expand our knowledge of ion-diode physics is being explored.

Review of Scientific Instruments, Issue Date: Oct 1990, Volume: 61 Issue:10, On page(s): 3075 - 3080

Influence of current prepulse on capillary-discharge extreme-ultraviolet laser

Tan, C. A. and Kwek, K. H.

Abstract
In this paper the influence of the prepulse current on a capillary-discharge 46.9nm Ne-like Ar extreme-ultraviolet laser is reported. A current pulse with a typical RC shape (decay time of ∼30µs ) was used as a prepulse. Measurements indicate that when the filling pressure is low, the output can be improved by reducing the time delay between the application of the prepulse current and the onset of the main discharge current. For high pressure the reverse is true. This change is most significant for time delays between 2 and 4µs , and beyond these time delays, the effect is less significant. This effect is attributed to the changes in the capillary channel pressure and also to the absorption of the laser emission by the plasma plume ejected during the prepulse. Thus, apart from ensuring a minimal amount of prepulse current to prevent nonuniformity effects, the timing of the application of the prepulse current is also important.

Physical Review A, vol. 75, Issue 4, id. 043808

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Model 251

Charge exchange recombination detection of low-Z and medium-Z impurities in the extreme UV using a digital lock-in technique

Brooks NH, Burrell KH, Isler RC, Meyer O, Pablant NA.

Abstract
More sensitive detection of charge exchange recombination lines from low-Z elements, and first-time detection from the medium-Z elements nickel and copper, has been achieved in DIII-D plasmas with a digital lock-in technique. That portion of the extreme UV spectrum varying synchronously in time with the square-wave modulation of a high energy, neutral heating beam is extracted by forming a scalar product of a correlation function with the data record of each pixel in the linear array detector. The usual, dense array of collisionally excited, metallic lines from the tokamak plasma is strongly suppressed, leaving only a sparse spectrum of lines dominated by charge exchange recombination transitions from fully stripped, low-Z elements. In plasmas with high metal content, charge exchange recombination lines from the Li-like ions of nickel and copper have been positively identified.

Rev Sci Instrum. 2010 Oct;81(10):10D721.

A soft X-ray grating monochromator for undulator radiation

Reininger, R.; Saile, V.

Abstract
One of the new insertion devices to be installed in the expansion of the DORIS storage ring consists of three undulators designed to cover with the first harmonic the photon energy range between 70 and 2000 eV. The concepts for a high-resolution and high-throughput monochromator that will take full advantage of this powerful new beam line are discussed. The final design is a modified SX-700 type monochromator in which the focusing elliptical mirror is replaced by a spherical one. The aberrations due to the new mirror are minimized by elongating the exit slit arm of the conventional SX-700. The ultimate resolution expected is 0.03 eV at 152 eV and 0.6 eV at 1086 eV with a photon flux up to 5 × 10¹¹ photons/(s-100 mA) at the sample. The spot size at the sample position is less than 0.4 × 1.0 mm².

Nuclear Instruments and Methods in Physics Research Section A, Volume 288, Issue 2-3, p. 343-348.

High-resolution EUV spectra of core-excited ²P, ²D⁰ and ²F states of doubly ionised boron

R Bruch, K T Chung, E Trabert, P H Heckmann, B Raith and H R Muller

Abstract
EUV spectra of B III are investigated by means of high-resolution fast-ion spectroscopic measurements. For the first time the decay of several even parity (1s2pnp)²P and odd parity (1s2pnd)²D⁰ core-excited levels has been identified by theoretical calculations where relativistic and mass polarisation effects are considered. The fine-structure splittings of these states are also predicted. The experimental results of this work are used to determine team energies for the B III system. Finally a level scheme for a 6.226 nm laser is proposed.

1984 J. Phys. B: At. Mol. Phys. 17 333-344

Multichannel grazing-incidence spectrometer for plasma impurity diagnosis: SPRED

Fonck, R.J. ; Ramsey, A.T. ; Yelle, R.V.

Abstract
A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable abberation-corrected toroidal diffraction gratings with flat local fields provide simultaneous coverage over the ranges 100-1100 A or 160-1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 msec, but up to seven individual spectral lines can be measured with a 1-msec time resolution. The sensitivity of the system is comparable with that of a conventional grazing-incidence monochromator.

Applied Optics, Vol. 21, Issue 12, pp. 2115-2123

A vacuum ulra-voilet spectrometer (Double SPRED) for the observation of the JET divertor plasma

R.C. Wolf, K.D. Lawson, I. Coffey, R. Giannella, C.J. Hancock, N.C. Hawkes, L.D. Horton, G. Janeschitz, H. Jemmeson, A.C. Maas, C.F. Maggi and M. Di Maio

Abstract
The SPRED spectrometer is a VUV survey instrument that has been successfully employed on a number of plasma machines. Its use of a holographic grating results in a flat focal field, enabling the best spectral resolution to be achieved over the whole extent of the detector. A double SPRED spectrometer having two fixed gratings and two independently controlled detectors has been installed on the JET machine for the observation of the divertor plasma. An additional improvement over previous SPRED designs is the extended wavelength coverage of the detectors. The experimental setup, including the spectrometer design, the VUV detectors, the alignment and control systems are described. The commissioning of the spectrometer on JET has allowed the performance of the instrument to be assessed, in particular its wavelength calibration, spectral resolution, and the effect of the integral shielding to nuclear radiation-induced noise. First results include a comparison with the spectral emission from the bulk plasma of the JET tokamak, observed with a single SPRED instrument, which emphasizes that the dominant emission from the divertor originates from low ionization stages or low Z-impurities such as carbon. Evidance has been found for the localization of the line emission from within the divertor chamber and some features of the divertor VUV radiation during high performance plasmas are described. Future applications are also discussed.

Control of high-order harmonic emission using attosecond pulse trains

J. Biegert; A. Heinrich; C. P. Hauri; W. Kornelis; P. Schlup; M. P. Anscombe; M. B. Gaarde; K. J. Schafer; U. Keller

Abstract
We show that attosecond pulse trains are a natural tool to control strong field processes such as high-order harmonic generation. Coherently combining an attosecond pulse train with an IR driving field, we predict and experimentally confirm enhancement and spectral narrowing of the harmonic yield at photon energies around 90 eV. The use of an attosecond pulse train to seed the harmonic generation process replaces tunneling ionization with a single-photon ionization step, therefore permitting the manipulation of the time-frequency properties of high-order harmonic generation already at the single-atom level.

Journal of Modern Optics, Volume 53, Issue 1 & 2 January 2006 , pages 87 - 96

XUV SPECTROSCOPY IN JET

K. Behringer, B. Denne, G. Maygar, M. Mattoli, N.J. Peacock, J. Ramette, B. Saoutic and J.L. Schwob

Abstract
The 2m extreme grazing incidence XW Schwob-Fraenkel spectrometer has been described in detail [1]. Its use on the TFR tokamak is presented in a parallel paper [2]. The instrument installed on JET differs in that it has two microchannel plates scanning independently two portions of the spectral range from 10 to 335Å. A full scan takes 164 ms, due to the low number of photons. 127 spectra may be taken during a 20s tokamak discharge. The calculated and measured spectral resolution (FWHM) with a 600g/mm Bausch and Lomb grating and 20 µm entrance slit is shown in Fig. 1 for detector positions, y, between 200 and 390 mm (corresponding wavelengths of the central pixels are 85 and 310 Å, respectively).

J. Phys. Colloques 49 (1988) C1-387-C1-390

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Model 247

Vacuum ultraviolet impurity spectroscopy on the Alcator C-Mod tokamak

M. L. Reinke, P. Beiersdorfer, N. T. Howard, E. W. Magee, Y. Podpaly, J. E. Rice, and J. L. Terry

Abstract
Vacuum ultraviolet spectroscopy is used on the Alcator C-Mod tokamak to study the physics of impurity transport and provide feedback on impurity levels to assist experimental operations. Sputtering from C-Mod’s all metal (Mo+W) plasma facing components and ion cyclotron range of frequency antenna and vessel structures (sources for Ti, Fe, Cu, and Ni), the use of boronization for plasma surface conditioning and Ar, Ne, or N₂ gas seeding combine to provide a wealth of spectroscopic data from low-Z to high-Z. Recently, a laser blow-off impurity injector has been added, employing CaF₂ to study core and edge impurity transport. One of the primary tools used to monitor the impurities is a 2.2 m Rowland circle spectrometer utilizing a Reticon array fiber coupled to a microchannel plate. With a 600 lines/mm grating the 80 < λ < 1050 Å range can be scanned, although only 40–100 Å can be observed for a single discharge. Recently, a flat-field grating spectrometer was installed which utilizes a varied line spacing grating to image the spectrum to a soft x-ray sensitive Princeton Instruments charge-coupled device camera. Using a 2400 lines/mm grating, the 10< λ <70 Å range can be scanned with 5–6 nm observed for a single discharge. A variety of results from recent experiments are shown that highlight the capability to track a wide range of impurities.

J. Phys. Colloques 49 (1988) C1-387-C1-390

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NIM/Eagle

Rotational-resolved pulsed field ionization photoelectron bands for H₂+(X ²Σ_g+, v⁺=0, 2, 9 and 11)

S. Stimsona, Y. -J. Chena, M. Evansa, C. -L. Liaoa, C. Y. Nga, C. -W. Hsub and P. Heimannb

Abstract
We present here the assignment and simulation of rotational transitions for the H₂+(X ²Σ_g+, v⁺, 2, 9 and 11) vibronic bands using the Buckingham–Orr–Sichel (BOS) model. The simulation shows that perturbation of PFI-PE rotational line intensities due to near-resonance autoionization decreases as v+ increases. Experimental rotational constants for H₂+(X ²Σ_g+, v⁺, 2, 9 and 11) are determined with higher accuracy than those obtained in previous He I and Ne I photoelectron studies. In agreement with previous experimental and theoretical investigations, only the ΔN=0 and ±2 rotational branches are observed in the PFI-PE spectrum for H₂.

Chemical Physics Letters Volume 289, Issues 5-6, 19 June 1998, Pages 507-515

A High Resolution Study of Low Lying Correlation Satellites in Xenon

R. C. Shiell, M. Evans1, S. Stimson1, C-W. Hsu2, C. Y. Ng1, and J. W. Hepburn

Abstract
The technique of pulsed field ionization–zero kinetic energy photoelectron spectroscopy, typically applied to the investigation of ionic states of atoms and molecules resulting from single electron excitation, has been used to probe the correlation satellite states of xenon between 23.6–24.7 eV. The resulting spectra show the formation of clearly resolved satellite states with intensities of a similar magnitude to that of the 5s5p⁶ 2S_1/2 ionic state. This technique can be extended to other atomic and molecular species to obtain the positions and cross sections for the formation of such states.

Physical review letters 1998, vol. 80, no3, pp. 472-475

High-Resolution Infrared-Vacuum Ultraviolet Photoion and Pulsed Field Ionization-Photoelectron Methods for Spectroscopic Studies of Neutrals and Cations

Xi Xing, Beth Reed, Mi Kyung Bahng, Peng Wang, Hin Koo Woo, Sun Jong Baek, Chee Shing Lam and Cheuk Yiu Ng

Abstract
We show that by scanning the frequency of a single mode infrared (IR) optical parametric oscillator (IR-OPO) laser to excite the molecular species of interest and fixing the frequency of a vacuum ultraviolet (VUV) laser to photoionize the IR excited species, high-resolution IR spectra of polyatomic neutrals can be obtained with high sensitivity. The fact that this IR-VUV-photoion (IR-VUV-PI) method is based on VUV photoionization probe, and thus, allows the identification of the neutral IR absorber, makes it applicable for IR spectroscopy measurements of isotopemers, radicals, and clusters, which usually exist as impure samples. The highly resolved IR-VUV-PI measurements achieved using the single mode IR-OPO laser have made possible the selection of single rovibrational states of CH₃X (X = Br and I), C₂H4, and C₃H₄ for VUV-pulsed field ionization-photoelectron (VUV-PFI-PE) measurements, resulting in rovibrationally resolved photoelectron spectra for these polyatomic molecules. These experiments show that the signal-to-noise ratios of the IR-VUV-PI and IR-VUV-PFI-PE spectra obtained by employing the high-resolution IR-OPO laser are significantly higher than those observed in previous IR-VUV-PI and IR-VUV-PFI-PE studies using a low-resolution IR-OPO laser. Further improvement in sensitivity of IR-VUV-PI and IR-VUV-PFI-PE measurements by using the collinear arrangement of IR-VUV lasers and molecular beam is discussed.

2008 Chin. J. Chem. Phys. 21 193-201

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