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Sample records for 3m vacuum ultraviolet

  1. Vacuum ultraviolet holography

    NASA Technical Reports Server (NTRS)

    Bjorklund, G. C.; Harris, S. E.; Young, J. F.

    1974-01-01

    We report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182-A radiation. The holograms were recorded in polymethyl methacrylate and examined with an electron microscope. A holographic grating with a fringe spacing of 386 A was produced and far-field Fraunhofer holograms of submicron particles were recorded.

  2. Vacuum ultraviolet holography

    NASA Technical Reports Server (NTRS)

    Bjorklund, G. C.; Harris, S. E.; Young, J. F.

    1974-01-01

    The authors report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182 A radiation. The holograms were recorded in polymethyl methacrylate and read out with an electron microscope. A holographic grating with a fringe spacing of 836 A was produced and far-field Fraunhofer holograms of sub-micron particles were recorded.

  3. Z-DNA: vacuum ultraviolet circular dichroism

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.; Keck, P.C.; Takacs, P.Z.

    1981-08-01

    In concentrated salt or ethanolic solutions, the self-complementary copolymer poly(dG-dC)-poly(dG-dC) forms a left-handed double-helical structure that has been termed Z-DNA. The first evidence for this structure came from changes observed in the circular dichroism (CD) spectrum between 230 and 300 nm for low- and high-salt solutions. In 3 M NaCl, the CD spectrum is approximately inverted compared to the B-form spectrum observed in low salt solution. We measured the vacuum ultraviolet CD spectrum of poly(dG-dC)-poly(dG-dC) down to 180 nm under conditions in which the 230- to 300-nm spectrum is inverted. Below 200 nm, where the B form exhibits the large positive peak at 187 nm that is characteristic of right-handed double-helical DNAs, the Z form exhibits a large negative peak at 194 nm and a positive band below 186 nm. Therefore, the Z-form vacuum ultraviolet CD spectrum resembles an inverted and red-shifted B-form spectrum. The magnitudes of the differences observed between the B and Z forms in the CD spectrum below 200 nm are about 10 times greater than those observed between 230 and 300 nm. The vacuum ultraviolet CD spectrum of poly(dG-dC)-poly(dG-dC) is 3 M C/sub 2/O/sub 4/ also is inverted compared to the B-form spectrum; however, between 230 and 300 nm, it is nonconservative with a negative maximum at 290 nm and a weak positive CD signal above 300 nm, presumably reflecting differential light scattering and indicating the existence of molecular aggregates. Our results suggest that the vacuum ultraviolet CD spectrum is sensitive to the handedness of doublehelical DNA structures.

  4. Z-DNA Vacuum ultraviolet circular dichroism

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.; Keck, P.C.; Takacs, P.Z.

    1981-08-01

    In concentrated salt or ethanolic solutions, the self-complementary copolymer poly(dG-dC).poly(dG-dC) forms a left-handed double-helical structure that has been termed ZDNA. The first evidence for this structure came from changes observed in the circular dichroism (CD) spectrum between 230 and 300 nm for low- and high-salt solutions (Pohl, F.M. and Jovin, T.M. (1972) J. Mol. Biol. 67, 675-696). In 3 M NaCl, the CD spectrum is approximately inverted compared to the B-form spectrum observed in low-salt solution. We measured the vacuum ultraviolet CD spectrum of poly(dG-dC).poly(dG-dC) down to 180 nm under conditions in which the 230 to 300 nm spectrum is inverted. Below 200 nm, where the B form exhibits the large positive peak at 187 nm that is characteristic of right-handed double-helical DNAs, the Z form exhibits a large negative peak at 194 nm and a positive band below 186 nm. Therefore, the Z-form vacuum ultraviolet CD spectrum resembles an inverted and red-shifted B-form spectrum. The magnitudes of the differences observed between the Band Z forms in the CD spectrum below 200 nm are about 10 times greater than those observed between 230 and 300 nm. The vacuum ultraviolet CD spectrum of poly(dG-dC).poly(dG-dC) in 3 M Cs/sub 2/SO/sub 4/ also is inverted compared to the B-form spectrum; however, between 230 and 300 nm, it is nonconservative with a negative maximum at 290 nm and a weak positive CD signal above 300 nm, presumably reflecting differential light scattering and indicating the existence of molecular aggregates. Our results suggest that the vacuum ultraviolet CD spectrum is sensitive to the handedness of double-helical DNA structures.

  5. Polarization measurements in the vacuum ultraviolet

    NASA Astrophysics Data System (ADS)

    Kobayashi, K.; West, E. A.; Noble, M.

    2005-08-01

    This paper will describe the Vacuum Ultraviolet (VUV) polarization testing of the Solar Ultraviolet Magnetograph (SUMI) optics. SUMI is being develop for a sounding rocket payload to prove the feasibility of making magnetic field measurements in the transition region. This paper will cover the polarization properties of the VUV calibration polarizers, the instrumental polarization of the VUV chamber, SUMI's toroidal varied-line-space gratings and the SUMI polarimeter.

  6. Atomic Oscillator Strengths in the Vacuum Ultraviolet

    NASA Technical Reports Server (NTRS)

    Nave, Gillian; Sansonetti, Craig J.; Szabo, Csilla I.

    2006-01-01

    We have developed techniques to measure branching fractions in the vacuum ultraviolet using diffraction grating spectroscopy and phosphor image plates as detectors. These techniques have been used to measure branching fractions in Fe II that give prominent emission lines in astrophysical objects.

  7. Vacuum-ultraviolet laser uses superfluid helium

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J. S.

    1979-01-01

    Vacuum ultra violet laser in wavelength around 0.800 microns is produced by using optical pumping to increase lifetimes of excited metastable molecules in super fluid helium. In method, super fluid helium is pumped electronically to produce excited HE2, and then pumped by circularly polarized 0.9096 - micron radiation to aline excited HE2 molecular spins. High power ultraviolet radiation has potential applications in molecular reaction studies, power transmission in space, and biomedical research.

  8. Large-Area Vacuum Ultraviolet Sensors

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Franz, David

    2012-01-01

    Pt/(n-doped GaN) Schottky-barrier diodes having active areas as large as 1 cm square have been designed and fabricated as prototypes of photodetectors for the vacuum ultraviolet portion (wavelengths approximately equal 200 nm) of the solar spectrum. In addition to having adequate sensitivity to photons in this wavelength range, these photodetectors are required to be insensitive to visible and infrared components of sunlight and to have relatively low levels of dark current.

  9. Fluoride coatings for vacuum ultraviolet reflection filters.

    PubMed

    Guo, Chun; Kong, Mingdong; Lin, Dawei; Li, Bincheng

    2015-12-10

    LaF3/MgF2 reflection filters with a high spectral-discrimination capacity of the atomic-oxygen lines at 130.4 and 135.6 nm, which were employed in vacuum ultraviolet imagers, were prepared by molybdenum-boat thermal evaporation. The optical properties of reflection filters were characterized by a high-precision vacuum ultraviolet spectrophotometer. The vulnerability of the filter's microstructures to environmental contamination and the recovery of the optical properties of the stored filter samples with ultraviolet ozone cleaning were experimentally demonstrated. For reflection filters with the optimized nonquarter-wave multilayer structures, the reflectance ratios R135.6 nm/R130.4 nm of 92.7 and 20.6 were achieved for 7° and 45° angles of incidence, respectively. On the contrary, R135.6 nm/R130.4 nm ratio of 12.4 was obtained for a reflection filter with a standard π-stack multilayer structure with H/L=1/4 at 7° AOI. PMID:26836877

  10. Vacuum Ultraviolet Photoionization of Complex Chemical Systems

    NASA Astrophysics Data System (ADS)

    Kostko, Oleg; Bandyopadhyay, Biswajit; Ahmed, Musahid

    2016-05-01

    Tunable vacuum ultraviolet (VUV) radiation coupled to mass spectrometry is applied to the study of complex chemical systems. The identification of novel reactive intermediates and radicals is revealed in flame, pulsed photolysis, and pyrolysis reactors, leading to the elucidation of spectroscopy, reaction mechanisms, and kinetics. Mass-resolved threshold photoelectron photoion coincidence measurements provide unprecedented access to vibrationally resolved spectra of free radicals present in high-temperature reactors. Photoionization measurements in water clusters, nucleic acid base dimers, and their complexes with water provide signatures of proton transfer in hydrogen-bonded and π-stacked systems. Experimental and theoretical methods to track ion-molecule reactions and fragmentation pathways in intermolecular and intramolecular hydrogen-bonded systems in sugars and alcohols are described. Photoionization of laser-ablated molecules, clusters, and their reaction products inform thermodynamics and spectroscopy that are relevant to astrochemistry and catalysis. New directions in coupling VUV radiation to interrogate complex chemical systems are discussed.

  11. Vacuum Ultraviolet Photoionization of Complex Chemical Systems.

    PubMed

    Kostko, Oleg; Bandyopadhyay, Biswajit; Ahmed, Musahid

    2016-05-27

    Tunable vacuum ultraviolet (VUV) radiation coupled to mass spectrometry is applied to the study of complex chemical systems. The identification of novel reactive intermediates and radicals is revealed in flame, pulsed photolysis, and pyrolysis reactors, leading to the elucidation of spectroscopy, reaction mechanisms, and kinetics. Mass-resolved threshold photoelectron photoion coincidence measurements provide unprecedented access to vibrationally resolved spectra of free radicals present in high-temperature reactors. Photoionization measurements in water clusters, nucleic acid base dimers, and their complexes with water provide signatures of proton transfer in hydrogen-bonded and π-stacked systems. Experimental and theoretical methods to track ion-molecule reactions and fragmentation pathways in intermolecular and intramolecular hydrogen-bonded systems in sugars and alcohols are described. Photoionization of laser-ablated molecules, clusters, and their reaction products inform thermodynamics and spectroscopy that are relevant to astrochemistry and catalysis. New directions in coupling VUV radiation to interrogate complex chemical systems are discussed. PMID:26980311

  12. Absorption spectra of typical space materials in the vacuum ultraviolet

    NASA Astrophysics Data System (ADS)

    Muscari, J. A.

    1981-01-01

    In order to develop a data base for potential optical degradation of space vacuum ultraviolet instruments, the collected volatile condensed material (CVCM) transmittance was measured in the wavelength region from 115 nm to 300 nm. The parent outgassing materials included: the adhesives, Ablebond 36-2, Trabond BB-2116, EA-9309, and Scotchweld 2216; the paints, Chemglaze Z-306, Z-306 over 9922 primer, Z-306 over AP-131 primer, Cat-A-Lac 463-3-8, 463-3-8 over primer, 3M Nextel 401-C10, and 401-C10 over 901-P1 primer; the resins, Fiberite 934, Solithane 113/C113-300 Formulation no. 1, and 113/C113-300 Formulation no. 8; the lubricants, Lube-Lok 4306 and RT/Duroid 5813; and the double-sided adhesive tape 3M-415. The effect of thermal vacuum conditioning of selected materials was also studied. The transmittance measurements were used to calculate the absorption coefficient for each of 28 different source materials versus wavelength.

  13. Vacuum ultraviolet detector for gas chromatography.

    PubMed

    Schug, Kevin A; Sawicki, Ian; Carlton, Doug D; Fan, Hui; McNair, Harold M; Nimmo, John P; Kroll, Peter; Smuts, Jonathan; Walsh, Phillip; Harrison, Dale

    2014-08-19

    Analytical performance characteristics of a new vacuum ultraviolet (VUV) detector for gas chromatography (GC) are reported. GC-VUV was applied to hydrocarbons, fixed gases, polyaromatic hydrocarbons, fatty acids, pesticides, drugs, and estrogens. Applications were chosen to feature the sensitivity and universal detection capabilities of the VUV detector, especially for cases where mass spectrometry performance has been limited. Virtually all chemical species absorb and have unique gas phase absorption cross sections in the approximately 120-240 nm wavelength range monitored. Spectra are presented, along with the ability to use software for deconvolution of overlapping signals. Some comparisons with experimental synchrotron data and computed theoretical spectra show good agreement, although more work is needed on appropriate computational methods to match the simultaneous broadband electronic and vibronic excitation initiated by the deuterium lamp. Quantitative analysis is governed by Beer-Lambert Law relationships. Mass on-column detection limits reported for representatives of different classes of analytes ranged from 15 (benzene) to 246 pg (water). Linear range measured at peak absorption for benzene was 3-4 orders of magnitude. Importantly, where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of the number of molecules present in the flow cell in the absence of chemical interferences. This study sets the stage for application of GC-VUV technology across a wide breadth of research areas. PMID:25079505

  14. Vacuum ultraviolet photoionization of carbohydrates and nucleotides.

    PubMed

    Shin, Joong-Won; Bernstein, Elliot R

    2014-01-28

    Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5(')-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C-C and C-O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results. PMID:25669546

  15. Vacuum ultraviolet photoionization of carbohydrates and nucleotides

    SciTech Connect

    Shin, Joong-Won; Bernstein, Elliot R.

    2014-01-28

    Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5{sup ′}-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C–C and C–O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

  16. Measurements of Radiating Flow Fields in the Vacuum Ultraviolet

    NASA Astrophysics Data System (ADS)

    Sheikh, U. A.; Jacobs, C.; Laux, C. O.; Morgan, R. G.; McIntyre, T. J.

    The vacuum ultraviolet (VUV) region of the radiation spectrum spans from 100 nm to 200 nm and is responsible for 30-50 % of the radiative heat flux during peak heating for a lunar return trajectory [1].

  17. Vacuum ultraviolet laser induced fluorescence on a Si atomic beam

    NASA Technical Reports Server (NTRS)

    O'Brian, T. R.; Lawler, J. E.

    1991-01-01

    A broadly applicable vacuum ultraviolet experiment is described for measuring radiative lifetimes of neutral and singly-ionized atoms in a beam environment to 5-percent accuracy using laser induced fluorescence. First results for neutral Si are reported.

  18. Steady State Vacuum Ultraviolet Exposure Facility With Automated Calibration Capability

    NASA Technical Reports Server (NTRS)

    Stueber, Thomas J.; Sechkar, Edward A.; Dever, Joyce A.; Banks, Bruce A.

    2000-01-01

    NASA Glenn Research Center at Lewis Field designed and developed a steady state vacuum ultraviolet automated (SSVUVa) facility with in situ VUV intensity calibration capability. The automated feature enables a constant accelerated VUV radiation exposure over long periods of testing without breaking vacuum. This test facility is designed to simultaneously accommodate four isolated radiation exposure tests within the SSVUVa vacuum chamber. Computer-control of the facility for long, term continuous operation also provides control and recording of thermocouple temperatures, periodic recording of VUV lamp intensity, and monitoring of vacuum facility status. This paper discusses the design and capabilities of the SSVUVa facility.

  19. Regeneration of imprint molds using vacuum ultraviolet light

    NASA Astrophysics Data System (ADS)

    Nakao, Masashi; Yamaguchi, Masanori; Yabu, Shintaro

    2011-04-01

    Etching characteristics of various resins by a vacuum ultraviolet (VUV, λ=172 nm) light have been examined under conditions of exposure time, substrate temperature, radiation distance and ambient oxygen concentration. The VUV light have used to clean the imprinted molds which are contaminated by organic substances such as ultraviolet-resins through many times of imprinting processes, and it has revealed that the VUV light has effectively regenerated the contaminated molds manufactured by quartz, silicon-carbide and nickel.

  20. A polarizer for the vacuum ultraviolet.

    PubMed

    Steinrnetz, D L; Phillips, W G; Wirick, M; Forbes, F F

    1967-06-01

    The construction and optical properties of a MgF(2) double Rochon prism are described. The prism is useful as a polarizer or analyzer in the vacuum uv wavelengths longer than 1300 A. Measurements of MgF(2) transmission and of polarizer angular beam deviation from 1150 AS to 2900 A are presented. PMID:20062113

  1. Polarization Measurements in the Vacuum Ultraviolet

    NASA Technical Reports Server (NTRS)

    West, E. A.; Kobayashi, K.; Noble, M.

    2005-01-01

    This paper will describe the VUV polarization testing of the NSSTC Solar Ultraviolet Magnetograph (SUMI) optics. SUMI is being developed for a sounding rocket payload to prove the feasibility of making magnetic field measurements in the transition region. This paper will cover the polarization properties of the VUV calibration polarizers, the instrumental polarization of the VUV chamber, SUMI's toroidal varied-line-space gratings and the SUMI polarimeter.

  2. Vacuum-ultraviolet spectrum of neutral boron /B I/.

    NASA Technical Reports Server (NTRS)

    Goorvitch, D.; Valero, F. P. J.

    1972-01-01

    Use of a hollow-cathode light source to produce the vacuum-ultraviolet spectrum of B I. One transition is resolved, and four transitions have been remeasured to a higher accuracy than previously because of the sharper lines emitted by the hollow-cathode light source. A revised value for one transition term results from these measurements.-

  3. Ion chambers simplify absolute intensity measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Sampson, J. A. R.

    1966-01-01

    Single or double ion chamber technique measures absolute radiation intensities in the extreme vacuum ultraviolet region of the spectrum. The ion chambers use rare gases as the ion carrier. Photon absorbed by the gas creates one ion pair so a measure of these is a measure of the number of incident photons.

  4. Polarized vacuum ultraviolet and X-radiation

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.

    1978-01-01

    The most intense source of polarized vacuum UV and X radiation is synchrotron radiation, which exhibits a degree of partially polarized light between about 80-100%. However, the radiation transmitted by vacuum UV monochromators can also be highly polarized. The Seya-Namioka type of monochromator can produce partially polarized radiation between 50-80%. For certain experiments it is necessary to know the degree of polarization of the radiation being used. Also, when synchrotron radiation and a monochromator are combined the polarization characteristic of both should be known in order to make full use of these polarization properties. The polarizing effect of monochromators (i.e., diffraction gratings) have been measured at the Seya angle and at grazing angles for various spectral orders. Experimental evidence is presented which shows that the reciprocity law holds for polarization by reflection where the angle of incidence and diffraction are unequal. These results are reviewed along with the techniques for measuring the degree of polarization.

  5. Broadband reflectance coatings for vacuum ultraviolet application

    NASA Technical Reports Server (NTRS)

    Herzig, Howard; Fleetwood, C. M., Jr.; Flint, B. K.

    1987-01-01

    An experimental investigation has obtained results indicating that neither LaF3 nor LiYF4 are acceptable alternatives to MgF2 as coatings for vacuum-deposited aluminum mirrors from which high UV reflectance down to 1150 A is required. Nevertheless, LaF3 may prove useful in those specialized applications in which the suppression of lower wavelength emissions, such as the 1216-A hydrogen line, is desirable.

  6. Communication: vacuum ultraviolet photoabsorption of interstellar icy thiols.

    PubMed

    Bhuin, Radha Gobinda; Sivaraman, Bhalamurugan; Lo, Jen-Iu; Sekhar, B N Raja; Cheng, Bing-Ming; Pradeep, Thalappil; Mason, Nigel John

    2014-12-21

    Following the recent identification of ethanethiol in the interstellar medium (ISM) we have carried out Vacuum UltraViolet (VUV) spectroscopy studies of ethanethiol (CH3CH2SH) from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. These results are compared with those of methanethiol (CH3SH), the lower order thiol also reported to be present in the ISM. VUV spectra recorded at higher temperature reveal conformational changes in the ice and phase transitions whilst evidence for dimer production is also presented. PMID:25527912

  7. Communication: Vacuum ultraviolet photoabsorption of interstellar icy thiols

    NASA Astrophysics Data System (ADS)

    Bhuin, Radha Gobinda; Sivaraman, Bhalamurugan; Lo, Jen-Iu; Sekhar, B. N. Raja; Cheng, Bing-Ming; Pradeep, Thalappil; Mason, Nigel John

    2014-12-01

    Following the recent identification of ethanethiol in the interstellar medium (ISM) we have carried out Vacuum UltraViolet (VUV) spectroscopy studies of ethanethiol (CH3CH2SH) from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. These results are compared with those of methanethiol (CH3SH), the lower order thiol also reported to be present in the ISM. VUV spectra recorded at higher temperature reveal conformational changes in the ice and phase transitions whilst evidence for dimer production is also presented.

  8. Vacuum Ultraviolet Curing of Low-k Organosilicate Dielectrics

    NASA Astrophysics Data System (ADS)

    Zheng, Huifeng

    The goal of this project is to optimize the vacuum-ultraviolet spectrum to identify those wavelengths that will have the most beneficial effect on improving dielectric properties and minimizing damage. To do this, the effects of vacuum-ultraviolet radiation (VUV) on organosilicate glass (SiCOH) will be examined. Changes to the electrical, chemical and mechanical properties of low-k organosilicate dielectrics induced by vacuum-ultraviolet radiation are investigated. VUV-generated changes to the permittivity and dielectric thickness are measured with both capacitance-voltage characteristics and a reflectometer. FTIR measurements are utilized to find the effect of VUV irradiation on chemical properties of SiCOH and XPS with nanoindentation measurements are used to investigate changes in mechanical properties. Measurements of the band gap and defect-state concentrations of SiCOH are made with VUV spectroscopy. These investigations are used to optimize VUV or UV/VUVexposure conditions to determine the wavelengths and intensities that can mitigate processing-induced damage. Thus, a "UV/VUV curing" process can be established and comparisons between UV/VUV curing and conventional industrial UV curing will be made. Investigations have shown that a combined UV/VUV curing could overcome some drawbacks of industrially UV curing and improve properties of dielectrics more efficiently than UV curing.

  9. Vacuum photodiode detectors for broadband vacuum ultraviolet detection in the Saha Institute of Nuclear Physics Tokamak

    NASA Astrophysics Data System (ADS)

    Rao, C. V. S.; Shankara Joisa, Y.; Hansalia, C. J.; Hui, Amit K.; Paul, Ratan; Ranjan, Prabhat

    1997-02-01

    We report on the application of the vacuum photodiode to detect vacuum ultraviolet (VUV) radiation emitted from the Saha Institute of Nuclear Physics (SINP) Tokamak. It is simple to fabricate and provides broadband spectral response in the VUV and ultrasoft x ray (10 eV-1 keV). In our design, a stainless steel photocathode is used, which has a response identical to tungsten in the wavelength range 100-1200 Å. Its surface is passivated, to minimize contamination and monolayer deposition, by electropolishing it. Some representative experimental results illustrating the range of applicability are presented with special emphasis on its performance in disruptive shots.

  10. CIV Polarization Measurements Using a Vacuum Ultraviolet Fabry Perot

    NASA Technical Reports Server (NTRS)

    West, Edward A.

    2009-01-01

    Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry Perot that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Perot.

  11. Absolute photon-flux measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Haddad, G. N.

    1974-01-01

    Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

  12. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  13. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  14. Electroreflectance Spectroscopy of Emersed Gold Electrodes in the Vacuum Ultraviolet.

    NASA Astrophysics Data System (ADS)

    Berg, Steven Lawrence

    Electroreflectance spectra of emersed polycrystalline gold films were measured in the vacuum ultraviolet spectral region from 6eV to 11eV. The measurements were performed using synchrotron radia- tion under high vacuum conditions. Large reflectance differences were observed for an emersion potential difference of 0.8V. The electroreflectance spectra are thought to be due primarily to electrolyte effects, with smaller contributions from the gold. Surface state optical adsorption from the predominantly (111) surface has been speculated to be one contribution. Although these measure- ments are insufficient to draw definite conclusions, they show that electroreflectance spectroscopy on emersed metal electrodes must. be considered as a possible future tool for the study of the metal-electrolyte interface. *DOE Report IS-T-1195. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.

  15. An Extreme Flux Vacuum Ultraviolet/Ultraviolet Beamline For The Measurement Of Biological Circular Dichroism

    SciTech Connect

    Clarke, D.T.; Vasanthi, N.; Shaw, D.; Brown, A.; Todd, B.; Grant, A.F.; Flaherty, J.V.; Mullacrane, I.D.; Miller, M.J.; Bowler, M.A.; Jones, G.R.; Mythen, C.

    2004-05-12

    A new extreme flux vacuum ultraviolet bending magnet beamline (CD12) has been commission at the SRS, Daresbury. The beamline has met all of its designed performance parameters and these are detailed. The clear advantages of SRCD over CD undertaken on conventional instruments are discussed and examples of its capabilities in terms of measurement precision and enhanced signal-to-noise for both steady-state CD and time-resolved CD are given.

  16. Vacuum-Ultraviolet Promoted Oxidative Micro Photoetching of Graphene Oxide.

    PubMed

    Tu, Yudi; Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki

    2016-04-27

    Microprocessing of graphene oxide (GO) films is of fundamental importance in fabricating graphene-based devices. We demonstrate the photoetching of GO sheets using vacuum-ultraviolet (VUV, λ = 172 nm) light under controlled atmospheric pressure. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and differential interference contrast microscopy (DIC) studies revealed that the photoetching of GO films successfully proceeded in the regions exposed to VUV irradiation in the oxygen-containing atmosphere. Precise photoetching of the GO sheets was achieved at a vacuum pressure of 5 × 10(3) Pa with VUV light irradiation for 20 min. This was followed by VUV irradiation in a high vacuum (<10(-3) Pa) and sonication in water. The photoetched GO sheets then transformed into reduced GO (rGO) patterns. The minimum feature fabricated by this method was 2 μm wide lines aligned at an interval of 4 μm. This method provides a cost-effective way to fabricate rGO patterns with fewer boundaries between rGO sheets and offers a better integrity of rGO, which can be promising for further applications in micro mechanics, micro electrochemistry, optoelectronics, etc. PMID:27046164

  17. Nonthermal combined ultraviolet and vacuum-ultraviolet curing process for organosilicate dielectrics

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Guo, X.; Pei, D.; Li, W.; Blatz, J.; Hsu, K.; Benjamin, D.; Lin, Y.-H.; Fung, H.-S.; Chen, C.-C.; Nishi, Y.; Shohet, J. L.

    2016-06-01

    Porous SiCOH films are of great interest in semiconductor fabrication due to their low-dielectric constant properties. Post-deposition treatments using ultraviolet (UV) light on organosilicate thin films are required to decompose labile pore generators (porogens) and to ensure optimum network formation to improve the electrical and mechanical properties of low-k dielectrics. The goal of this work is to choose the best vacuum-ultraviolet photon energy in conjunction with vacuum ultraviolet (VUV) photons without the need for heating the dielectric to identify those wavelengths that will have the most beneficial effect on improving the dielectric properties and minimizing damage. VUV irradiation between 8.3 and 8.9 eV was found to increase the hardness and elastic modulus of low-k dielectrics at room temperature. Combined with UV exposures of 6.2 eV, it was found that this "UV/VUV curing" process is improved compared with current UV curing. We show that UV/VUV curing can overcome drawbacks of UV curing and improve the properties of dielectrics more efficiently without the need for high-temperature heating of the dielectric.

  18. High intensity vacuum ultraviolet and extreme ultraviolet production by noncollinear mixing in laser vaporized media

    NASA Astrophysics Data System (ADS)

    Todt, Michael A.; Albert, Daniel R.; Davis, H. Floyd

    2016-06-01

    A method is described for generating intense pulsed vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) laser radiation by resonance enhanced four-wave mixing of commercial pulsed nanosecond lasers in laser vaporized mercury under windowless conditions. By employing noncollinear mixing of the input beams, the need of dispersive elements such as gratings for separating the VUV/XUV from the residual UV and visible beams is eliminated. A number of schemes are described, facilitating access to the 9.9-14.6 eV range. A simple and convenient scheme for generating wavelengths of 125 nm, 112 nm, and 104 nm (10 eV, 11 eV, and 12 eV) using two dye lasers without the need for dye changes is described.

  19. Electron impact excitation of argon in the extreme vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Mentall, J. E.; Morgan, H. D.

    1976-01-01

    Polarization-free excitation cross sections in the extreme vacuum ultraviolet have been measured for electron impact on Ar. Observed spectral features were those lines of Ar I and Ar II which lie between 700 and 1100 A. Excitation functions were measured for the Ar I resonance line at 1048 A and the Ar II resonance line at 920 A. Peak cross sections for these two lines were found to be (39.4 plus or minus 7.9) x 10 to the -18th and (6.9 plus or minus 1.4) x 10 to the -18th, respectively. At low energies, excitation of the Ar II resonance line is dominated by an electron exchange transition.

  20. Absolute calibration of vacuum ultraviolet spectrograph system for plasma diagnostics

    SciTech Connect

    Yoshikawa, M.; Kubota, Y.; Kobayashi, T.; Saito, M.; Numada, N.; Nakashima, Y.; Cho, T.; Koguchi, H.; Yagi, Y.; Yamaguchi, N.

    2004-10-01

    A space- and time-resolving vacuum ultraviolet (VUV) spectrograph system has been applied to diagnose impurity ions behavior in plasmas produced in the tandem mirror GAMMA 10 and the reversed field pinch TPE-RX. We have carried out ray tracing calculations for obtaining the characteristics of the VUV spectrograph and calibration experiments to measure the absolute sensitivities of the VUV spectrograph system for the wavelength range from 100 to 1100 A. By changing the incident angle, 50.6 deg. -51.4 deg., to the spectrograph whose nominal incident angle is 51 deg., we can change the observing spectral range of the VUV spectrograph. In this article, we show the ray tracing calculation results and absolute sensitivities when the angle of incidence into the VUV spectrograph is changed, and the results of VUV spectroscopic measurement in both GAMMA 10 and TPE-RX plasmas.

  1. Vacuum ultraviolet spectra of uranium hexafluoride/argon mixtures

    NASA Technical Reports Server (NTRS)

    Krascella, N. L.

    1976-01-01

    The transmission properties of room temperature helium at pressures up to 20 atmospheres were determined in the wavelength range from 80 to 300 nm. Similarly, the transmission properties of uranium hexafluoride at 393 K (pressures less than 1.0 mm) were determined in the wavelength range from 80 to about 120 nm. The results show that high pressure helium is sufficiently transparent in the vacuum ultraviolet region (provided trace contaminants are removed) to be utilized as a transparent purge gas in future fissioning gaseous uranium plasma reactor experiments. Absorption cross sections for uranium hexafluoride were calculated from the data between 80 and 120 nm and were of the order of 10 to the -17 power sq cm.

  2. Progress in spectroscopic ellipsometry: Applications from vacuum ultraviolet to infrared

    NASA Astrophysics Data System (ADS)

    Hilfiker, James N.; Bungay, Corey L.; Synowicki, Ron A.; Tiwald, Thomas E.; Herzinger, Craig M.; Johs, Blaine; Pribil, Greg K.; Woollam, John A.

    2003-07-01

    Spectroscopic ellipsometry (SE) is a noncontact and nondestructive optical technique for thin film characterization. In the past 10 yr, it has migrated from the research laboratory into the semiconductor, data storage, display, communication, and optical coating industries. The wide acceptance of SE is a result of its flexibility to measure most material types: dielectrics, semiconductors, metals, superconductors, polymers, biological coatings, and even multilayers of these materials. Measurement of anisotropic materials has also made huge strides in recent years. Traditional SE measurements cover the ultraviolet, visible, and near infrared wavelengths. This spectral range is now acquired within seconds with high accuracy due to innovative optical configurations and charge coupled device detection. In addition, commercial SE has expanded into both the vacuum ultraviolet (VUV) and midinfrared (IR). This wide spectral coverage was achieved by utilizing new optical elements and detection systems, along with UV or Fourier transform IR light sources. Modern instrumentation is now available with unprecedented flexibility promoting a new range of possible applications. For example, the VUV spectral region is capable of characterizing lithographic materials for 157 nm photolithography. The VUV also provides increased sensitivity for thin layers (e.g., gate oxides or self-assembled monolayers) and allows investigation of high-energy electronic transitions. The infrared spectral region contains information about semiconductor doping concentration, phonon absorption, and molecular bond vibrational absorptions. In this work, we review the latest progress in SE wavelength coverage. Areas of significant application in both research and industrial fields will be surveyed, with emphasis on wavelength-specific information content.

  3. Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, E.; Stefi, A.; Kollia, Z.; Palles, D.; Petrou, P. S.; Bourkoula, A.; Koukouvinos, G.; Velentzas, A. D.; Kakabakos, S.; Cefalas, A. C.

    2014-09-01

    Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm-2) or vacuum-ultraviolet irradiation (110-180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance in spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.

  4. Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

    SciTech Connect

    Sarantopoulou, E. Stefi, A.; Kollia, Z.; Palles, D.; Cefalas, A. C.; Petrou, P. S.; Bourkoula, A.; Koukouvinos, G.; Kakabakos, S.; Velentzas, A. D.

    2014-09-14

    Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm⁻²) or vacuum-ultraviolet irradiation (110–180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance in spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.

  5. Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

    2002-01-01

    Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

  6. Permanent gas analysis using gas chromatography with vacuum ultraviolet detection.

    PubMed

    Bai, Ling; Smuts, Jonathan; Walsh, Phillip; Fan, Hui; Hildenbrand, Zacariah; Wong, Derek; Wetz, David; Schug, Kevin A

    2015-04-01

    The analysis of complex mixtures of permanent gases consisting of low molecular weight hydrocarbons, inert gases, and toxic species plays an increasingly important role in today's economy. A new gas chromatography detector based on vacuum ultraviolet (VUV) spectroscopy (GC-VUV), which simultaneously collects full scan (115-240 nm) VUV and UV absorption of eluting analytes, was applied to analyze mixtures of permanent gases. Sample mixtures ranged from off-gassing of decomposing Li-ion and Li-metal batteries to natural gas samples and water samples taken from private wells in close proximity to unconventional natural gas extraction. Gas chromatography separations were performed with a porous layer open tubular column. Components such as C1-C5 linear and branched hydrocarbons, water, oxygen, and nitrogen were separated and detected in natural gas and the headspace of natural gas-contaminated water samples. Of interest for the transport of lithium batteries were the detection of flammable and toxic gases, such as methane, ethylene, chloromethane, dimethyl ether, 1,3-butadiene, CS2, and methylproprionate, among others. Featured is the capability for deconvolution of co-eluting signals from different analytes. PMID:25724098

  7. Vacuum ultraviolet spectropolarimeter design for precise polarization measurements.

    PubMed

    Narukage, Noriyuki; Auchère, Frédéric; Ishikawa, Ryohko; Kano, Ryouhei; Tsuneta, Saku; Winebarger, Amy R; Kobayashi, Ken

    2015-03-10

    Precise polarization measurements in the vacuum ultraviolet (VUV) region provide a new means for inferring weak magnetic fields in the upper atmosphere of the Sun and stars. We propose a VUV spectropolarimeter design ideally suited for this purpose. This design is proposed and adopted for the NASA-JAXA chromospheric lyman-alpha spectropolarimeter (CLASP), which will record the linear polarization (Stokes Q and U) of the hydrogen Lyman-α line (121.567 nm) profile. The expected degree of polarization is on the order of 0.1%. Our spectropolarimeter has two optically symmetric channels to simultaneously measure orthogonal linear polarization states with a single concave diffraction grating that serves both as the spectral dispersion element and beam splitter. This design has a minimal number of reflective components with a high VUV throughput. Consequently, these design features allow us to minimize the polarization errors caused by possible time variation of the VUV flux during the polarization modulation and by statistical photon noise. PMID:25968386

  8. Reflectance measurements of lunar materials in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Hapke, B. W.; Wagner, J. K.; Cohen, A. J.; Partlow, W. D.

    1978-01-01

    The spectral reflectances of materials have been measured in the vacuum ultraviolet region of the spectrum for possible planetary compositional remote-sensing applications. These materials, which include lunar and terrestrial silicate rocks and minerals, have one or more characteristic absorption peaks between about 8 and 13 eV. The peaks are visible in the spectra of powders and rough surfaces as well as polished surfaces. In lunar samples the most prominent peaks are at 10.25 eV, due to augite, and at 9.0 eV, due to anorthite. Spectra of lunar soils have minima between 6 eV (0.20 micron) and 8 eV (0.16 micron) depending on composition. Soils that have high reflectances in the visible have low reflectances in the VUV. The pyroxene content of the soils results in reflectance maxima at about 10 eV (0.12 micron). Peaks due to olivine and augite can be identified in the spectra of meteorites.

  9. A synchrotron beamline for delivering high purity vacuum ultraviolet photons

    SciTech Connect

    Cavasso Filho, R. L.; Homen, M. G. P.; Fonseca, P. T.; Naves de Brito, A.

    2007-11-15

    We report on the current status and performance of the toroidal grating monochromator beamline at the Brazilian Synchrotron Light Laboratory (Laboratorio Nacional de Luz Sincrotron). This beamline provides photons in the vacuum ultraviolet and soft x-ray regions from 12 to 330 eV with three interchangeable gratings. We report on the improvement, which allows the possibility of choosing the light polarization degree from linear to almost circular. Here, we also describe the development of a new apparatus, namely, the mirror-inserted harmonic attenuator and calibrating-device with a long length (MIRHACLLE). All beamlines based on diffraction gratings suffer from the problem of high harmonics contaminations to some extent. The MIRHACLLE provides a way to efficiently suppress high harmonics from 25% to 1 ppm in a grazing incidence bending magnet beamline. Its principle of operation relays on the absorption of the high energy photons in a gas phase region. It allows negligible high harmonics contamination for photon energies ranging from 12 eV to the gas first ionization threshold, 21.6 eV, in the case of neon. We also demonstrate the possibility to use this device for energy calibration and resolution evaluation together with any experiment needing its filtering capabilities. The device is also very cost effective compared to other filters presented previously in the literature.

  10. Solar CIV Vacuum-Ultraviolet Fabry-Perot Interferometers

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; West, Edward A.; Rees, David; McKay, Jack A.; Zukic, Maumer; Herman, Peter

    2006-01-01

    Aims: A tunable, high spectral resolution, high effective finesse, vacuum ultraviolet (VUV) Fabry-Perot interferometer (PPI) is designed for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155 nm). Methods: The integral part of the CIV narrow passband filter package (with a 2-10 pm FWHM) consists of a multiple etalon system composed of a tunable interferometer that provides high-spectral resolution and a static low-spectral resolution interferometer that allows a large effective free spectral range. The prefilter for the interferometers is provided by a set of four mirrors with dielectric high-reflective coatings. A tunable interferometer, a VUV piezoelectric-control etalon, has undergone testing using the surrogate F2 eximer laser line at 157 nm for the CIV line. We present the results of the tests with a description of the overall concept for a complete narrow-band CIV spectral filter. The static interferometer of the filter is envisioned as being hudt using a set of fixed MgF2 plates. The four-mirror prefilter is designed to have dielectric multilayer n-stacks employing the design concept used in the Ultraviolet Imager of NASA's Polar Spacecraft. A dual etalon system allows the effective free spectral range to be commensurate with the prefilter profile. With an additional etalon, a triple etalon system would allow a spectrographic resolution of 2 pm. The basic strategy has been to combine the expertise of spaceflight etalon manufacturing with VUV coating technology to build a VUV FPI which combines the best attributes of imagers and spectrographs into a single compact instrument. Results. Spectro-polarimetry observations of the transition region CIV emission can be performed to increase the understanding of the magnetic forces, mass motion, evolution, and energy release within the solar atmosphere at the base of the corona where most of the magnetic field is approximately force-free. The 2D imaging

  11. Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene.

    PubMed

    Chen, Jun; Cao, Maoqi; Wei, Bin; Ding, Mengmeng; Shan, Xiaobin; Liu, Fuyi; Sheng, Liusi

    2016-02-01

    In this work, photoionization and dissociation of cyclohexene have been studied by means of coupling a reflectron time-of-flight mass spectrometer with the tunable vacuum ultraviolet (VUV) synchrotron radiation. The adiabatic ionization energy of cyclohexene as well as the appearance energies of its fragment ions C6 H9 (+) , C6 H7 (+) , C5 H7 (+) , C5 H5 (+) , C4 H6 (+) , C4 H5 (+) , C3 H5 (+) and C3 H3 (+) were derived from the onset of the photoionization efficiency (PIE) curves. The optimized structures for the transition states and intermediates on the ground state potential energy surfaces related to photodissociation of cyclohexene were characterized at the ωB97X-D/6-31+g(d,p) level. The coupled cluster method, CCSD(T)/cc-pVTZ, was employed to calculate the corresponding energies with the zero-point energy corrections by the ωB97X-D/6-31+g(d,p) approach. Combining experimental and theoretical results, possible formation pathways of the fragment ions were proposed and discussed in detail. The retro-Cope rearrangement was found to play a crucial role in the formation of C4 H6 (+) , C4 H5 (+) and C3 H5 (+) . Intramolecular hydrogen migrations were observed as dominant processes in most of the fragmentation pathways of cyclohexene. The present research provides a clear picture of the photoionization and dissociation processes of cyclohexene in the 8- to 15.5-eV photon energy region. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26889934

  12. Ultrafast electronic dynamics in polyatomic molecules studied using femtosecond vacuum ultraviolet and x-ray pulses

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshinori

    2014-06-01

    Time-resolved velocity map photoelectron imaging is performed using sub-20 fs deep ultraviolet and vacuum ultraviolet pulses to study electronic dynamics of isolated polyatomic molecules. The non-adiabatic dynamics of pyrazine, furan and carbon disulfide (CS2) are described as examples. Also described is sub-picosecond time-resolved x-ray direct absorption spectroscopy using a hard x-ray free electron laser (SACLA) and a synchronous near ultraviolet laser to study ultrafast electronic dynamics in solutions.

  13. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source.

    PubMed

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry. PMID:24387477

  14. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    SciTech Connect

    Sloan Roberts, F.; Anderson, Scott L.

    2013-12-15

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry.

  15. Vacuum Ultraviolet Images of the Large Magellanic Cloud: Erratum

    NASA Astrophysics Data System (ADS)

    Smith, Andrew M.; Cornett, Robert H.; Hill, Robert S.

    1990-06-01

    In the paper "Vacuum Ultraviolet Images of the Large Magellanic Cloud" by Andrew M. Smith, Robert H. Cornett, and Robert S. Hill (Ap. J., 320, 609 [1987]), an error was made in the dereddening formulae for vacuum ultraviolet (VUV) magnitudes on page 613. For 30 Dor dereddening, the formulae should be m_0(1500)_ = m_1500_ - 10.47 x E(B - V)_LMC_ - 8.05 x E(B - V)_Gal_, and m_0(1900)_ = m_1900_ - 8.87 x E(B - V)_LMC_ - 8.28 x E(B - V)_Gal_. For non-30 Dor dereddening, the formulae should be m_0(1500)_ = m_1500_ -8.72 x E(B - V)_LMC_ - 8.05 x E(B - V)_Gal_, and m_0(1900) = m_1900_ - 8.21 x E(B - V)_LMC_ - 8.28 x E(B - V)_Gal_. The ramifications of this error spread through several results. However, it must be noted that the overall effect is to make our original estimates of intrinsic VUV flux too low. As a result, our primary argument on energetics actually becomes stronger: there is ample energy flux in the southwestern Large Magellanic Cloud (LMC) to sustain into the next generation of stars the star-formation front visible in our VUV images. The three tables of observational results are replaced by the results given here in Table 1, in which intrinsic VUV fluxes are corrected (other quantities remain as they were). The discussion of Table 2 needs to be amended. This table compares ionizing fluxes computed by different methods for VUV sources (OB associations) that can be identified with 6 cm radio sources (H II regions). The aggregate ionizing fluxes for this set of objects derived from the two wavelength regimes are no longer so nearly equal as they were. However, as we pointed out, any such equality would be fortuitous, since the two derivations yield results differing by typically a factor of 2 for any given individual association. The discussion of Table 3 also needs to be amended. This table combines ionizing fluxes from OB associations (derived from VU photometry) with ionizing fluxes from 6 cm sources that do not coincide with any OB association. In this

  16. Effect of vacuum ultraviolet and ultraviolet Irradiation on capacitance-voltage characteristics of low-k-porous organosilicate dielectrics

    SciTech Connect

    Sinha, H.; Lauer, J. L.; Nichols, M. T.; Shohet, J. L.; Antonelli, G. A.; Nishi, Y.

    2010-02-01

    High frequency capacitance-voltage (C-V) measurements are used to determine the effects of vacuum ultraviolet (VUV) and ultraviolet (UV) irradiation on defect states in porous low-k organosilicate (SiCOH) dielectrics. The characteristics show that VUV photons depopulate trapped electrons from defect states within the dielectric creating trapped positive charge. This is evidenced by a negative shift in the flat-band voltage of the C-V characteristic. UV irradiation reverses this effect by repopulating the defect states with electrons photoinjected from the silicon substrate. Thus, UV reduces the number of trapped positive charges in the dielectric and can effectively repair processing-induced damage.

  17. Surface photoconductivity of organosilicate glass dielectrics induced by vacuum-ultraviolet radiation

    SciTech Connect

    Zheng, H.; Nichols, M. T.; Pei, D.; Shohet, J. L.; Nishi, Y.

    2013-08-14

    The temporary increase in the electrical surface conductivity of low-k organosilicate glass (SiCOH) during exposure to vacuum-ultraviolet radiation (VUV) is investigated. To measure the photoconductivity, patterned “comb structures” are deposited on dielectric films and exposed to synchrotron radiation in the range of 8–25 eV, which is in the energy range of most plasma vacuum-ultraviolet radiation. The change in photo surface conductivity induced by VUV radiation may be beneficial in limiting charging damage of dielectrics by depleting the plasma-deposited charge.

  18. Polarization measurements in the Vacuum Ultraviolet using SUMI

    NASA Technical Reports Server (NTRS)

    West, E. A.

    2005-01-01

    This paper will describe the VUV polarization testing of the NSSTC Solar Ultraviolet Magnetograph (SUMI) optics. SUMI is being developed for a sounding rocket payload to prove the feasibility of making magnetic field measurements in the transition region. This paper will cover the polarization testing of the SUMI optics and the instrumental polarization of the VUV test facility.

  19. Photon-counting array detectors for space and ground-based studies at ultraviolet and vacuum ultraviolet /VUV/ wavelengths

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.; Bybee, R. L.

    1981-01-01

    The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric photon-counting array detectors, with formats as large as (256 x 1024)-pixels that can be operated in a windowless configuration at vacuum ultraviolet (VUV) and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. This paper describes the construction and modes of operation of (1 x 1024)-pixel and (24 x 1024)-pixel MAMA detector systems that are being built and qualified for use in sounding-rocket spectrometers for solar and stellar observations at wavelengths below 1300 A. The performance characteristics of the MAMA detectors at ultraviolet and VUV wavelengths are also described.

  20. Comparing Vacuum and Extreme Ultraviolet Radiation for Postionization of Laser Desorbed Neutrals from Bacterial Biofilms and Organic Fullerene

    SciTech Connect

    Gaspera, Gerald L.; Takahashi, Lynelle K.; Zhou, Jia; Ahmed, Musahid; Moored, Jerry F.; Hanley, Luke

    2010-12-08

    Vacuum and extreme ultraviolet radiation from 8 - 24 eV generated at a synchrotron was used to postionize laser desorbed neutrals of antibiotic-treated biofilms and a modified fullerene using laser desorption postionization mass spectrometry (LDPI-MS). Results show detection of the parent ion, various fragments, and extracellular material from biofilms using LDPI-MS with both vacuum and extreme ultraviolet photons. Parent ions were observed for both cases, but extreme ultraviolet photons (16-24 eV) induced more fragmentation than vacuum ultraviolet (8-14 eV) photons.

  1. An Undergraduate Vacuum Ultraviolet Spectroscopy Laboratory at Georgia Tech.

    ERIC Educational Resources Information Center

    Stevenson, James R.; Bartlett, Roger J.

    Experimental techniques are taught in a laboratory course designed with some student options available. Eight experiments which use vacuum systems, radiation sources, dispersion and detection systems are outlined. A course outline and time table are given. The final examination is described as 30 minutes of individual practical work and dialogue…

  2. The molecular branching ratio method for calibration of optical systems in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.

    1972-01-01

    The intensity distribution of bands belonging to six molecular band systems is discussed with special emphasis on their usefulness for intensity calibration of optical systems in the vacuum ultraviolet (1000A Lambda 3000A). The theory of molecular band intensities is outlined and the technique of measuring the spectral response curve is described. Several methods for establishing an absolute intensity calibration are discussed.

  3. Thin-film photodetectors for the vacuum ultraviolet spectral region.

    PubMed

    De Cesare, G; Irrera, F; Palma, F; Naletto, G; Nicolosi, P; Jannitti, E

    1997-05-01

    We report on thin-film photodetectors optimized for detecting the vacuum UV and rejection of the visible spectrum of electromagnetic radiation. The devices are made of hydrogenated amorphous silicon and silicon carbide on a glass substrate. At room temperature the photodetectors exhibit quantum efficiencies of 52% at lambda = 58.4 nm, 1% at lambda = 400 nm, and 0.1% at lambda = 650 nm. The response time for UV pulses from an N(2) laser gives signals of 6-mus full width at half-maximum and 500-ns rise time. PMID:18253265

  4. Vacuum ultraviolet radiation/atomic oxygen synergism in materials reactivity

    NASA Technical Reports Server (NTRS)

    Koontz, Steven; Leger, Lubert; Albyn, Keith; Cross, Jon

    1990-01-01

    Experimental results are presented which indicate that low fluxes of vacuum UV (VUV) radiation exert a pronounced influence on the atomic oxygen reactivity of such fluorocarbon and fluorocarbon spacecraft materials as the FEP Teflon and PCTFE that are under consideration for the Space Station Freedom. With simultaneous exposure to VUV fluxes comparable to those experienced in LEO, the reactivity of these materials becomes comparable to that of Kapton; VUV radiation has also been shown to increase the reactivity of Kapton with thermal-energy oxygen atoms.

  5. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-08-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  6. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-01-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  7. Probing Ionic Complexes of Ethylene and Acetylene with Vacuum-Ultraviolet Radiation.

    PubMed

    Bandyopadhyay, Biswajit; Stein, Tamar; Fang, Yigang; Kostko, Oleg; White, Alec; Head-Gordon, Martin; Ahmed, Musahid

    2016-07-14

    Mixed complexes of acetylene-ethylene are studied using vacuum-ultraviolet (VUV) photoionization mass spectrometry and theoretical calculations. These complexes are produced and ionized at different distances from the exit of a continuous nozzle followed by reflectron time-of-flight mass spectrometry detection. Acetylene, with a higher ionization energy (11.4 eV) than ethylene (10.6 eV), allows for tuning the VUV energy and initializing reactions either from a C2H2(+) or a C2H4(+) cation. Pure acetylene and ethylene expansions are separately carried out to compare, contrast, and hence identify products from the mixed expansion: these are C3H3(+) (m/z = 39), C4H5(+) (m/z = 53), and C5H5(+) (m/z = 65). Intensity distributions of C2H2, C2H4, their dimers and reactions products are plotted as a function of ionization distance. These distributions suggest that association mechanisms play a crucial role in product formation closer to the nozzle. Photoionization efficiency (PIE) curves of the mixed complexes demonstrate rising edges closer to both ethylene and acetylene ionization energies. We use density functional theory (ωB97X-V/aug-cc-pVTZ) to study the structures of the neutral and ionized dimers, calculate their adiabatic and vertical ionization energies, as well as the energetics of different isomers on the potential energy surface (PES). Upon ionization, vibrationally excited clusters can use the extra energy to access different isomers on the PES. At farther ionization distances from the nozzle, where the number densities are lower, unimolecular decay is expected to be the dominant mechanism. We discuss the possible decay pathways from the different isomers on the PES and examine the ones that are energetically accessible. PMID:26983013

  8. Vacuum ultraviolet spectrophotometry and effective temperatures of hot stars

    NASA Technical Reports Server (NTRS)

    Brune, W. H.; Mount, G. H.; Feldman, P. D.

    1979-01-01

    Absolutely calibrated ultraviolet stellar spectra from 3100 A to the hydrogen absorption edge at 912 A were obtained on 1977 February 17 by rocket observations above Woomera, Australia. Spectra taken at 15 A resolution have been compared with the observed fluxes from OAO 2 and with recent model-atmosphere fluxes of Kurucz for five hot stars: Gamma (2) Vel, Zeta Pup, Alpha Eri, Beta Cen, and Alpha Vir. The present data give fluxes which are generally lower than those obtained from OAO 2, with the largest deviations of about 20% between 1400 and 1700 A. Agreement with the models is good, although the model fluxes are substantially larger than the observed values below 1200 A. This discrepancy is greater for the higher-temperature stars. Effective temperatures are also determined and are in good agreement with previous results.

  9. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1994-02-01

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with approximately 15-nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy, providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates.

  10. Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs

    SciTech Connect

    Sivaraman, B.; Nair, B. G.; Mason, N. J.; Lo, J.-I.; Cheng, B.-M.; Kundu, S.; Davis, D.; Prabhudesai, V.; Krishnakumar, E.; Raja Sekhar, B. N.

    2013-12-01

    Following the recent report of the first identification of methyl acetate (CH{sub 3}COOCH{sub 3}) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110 K and 120 K.

  11. Description and analysis of a vacuum ultraviolet atomic line source.

    PubMed

    Kikuchi, T T

    1971-06-01

    An intense vacuum uv atomic line source excited in a 2450-MHz microwave discharge cavity is described and analyzed. Additional features are a clean spectrum, very little window deterioration, little or no self-absorption, and easily interchangeable parts. (For the O-atom source only the 1300-A triplet shows up over the 1200-A to 1650-A region.) This source is suitable for the detection of various species by absorption measurement in fast occurring events such as those in ballistic ranges and shock tubes. Atomic line shape theory is used to analyze an O-atom line source with intensity ratios I(1306A): I(1305A): I(1302A):1:2.9:4.5. This source is described by a 2700 +/- 200 K temperature and certain self-absorption parameters as deduced from the measurement of their intensity ratios and their transmission characteristics through known concentrations of O-atoms. A good theoretical fit to the measured transmission validates the assumed uniform source temperature and excitation for the analysis. An f value (f = 0.052 +/- 0.005) for the O-atom 1300-A triplet absorption and a collision diameter of 5.5 +/- 1.0 A between the O-atom and the nitrogen molecule were determined in the course of this study. PMID:20111107

  12. Spontaneous Patterning of High-Resolution Electronics via Parallel Vacuum Ultraviolet.

    PubMed

    Liu, Xuying; Kanehara, Masayuki; Liu, Chuan; Sakamoto, Kenji; Yasuda, Takeshi; Takeya, Jun; Minari, Takeo

    2016-08-01

    A spontaneous patterning technique via parallel vacuum ultraviolet is developed for fabricating large-scale, complex electronic circuits with 1 μm resolution. The prepared organic thin-film transistors exhibit a low contact resistance of 1.5 kΩ cm, and high mobilities of 0.3 and 1.5 cm(2) V(-1) s(-1) in the devices with channel lengths of 1 and 5 μm, respectively. PMID:27184834

  13. Bidirectional Reflectance Function Measurement of Molecular Contaminant Scattering in the Vacuum Ultraviolet

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2006-01-01

    Bi-directional reflectance distribution function (BRDF) measurements of optical surfaces both before and after molecular contamination were done using UV, VUV and visible light. Molecular contamination of optical surfaces from outgassed material has been shown in many cases to proceed from acclimation centers, and to produce many roughly hemispherical "islands" of contamination on the surface. Vacuum Ultraviolet (VW) wavelengths are used here to measure angularly scattered light from optical surfaces.

  14. Laser-induced two-photon blackbody radiation in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Zych, L. J.; Young, J. F.; Harris, S. E.; Lukasik, J.

    1978-01-01

    Experimental measurements of a new type of vacuum-ultraviolet radiation source are reported. It is shown that the maximum source brightness, within its narrow linewidth, is that of a blackbody at the temperature of a metastable storage level. The laser-induced emission at 569 A from a He glow discharge corresponded to a metastable temperature of 22,700 K and was over 100 times brighter than the 584-A He resonance line.

  15. Heats of vaporization of room temperature ionic liquids by tunable vacuum ultraviolet photoionization

    SciTech Connect

    Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; To, Albert; Koh, Christine; Strasser, Daniel; Kostko, Oleg; Leone, Stephen R.

    2009-11-25

    The heats of vaporization of the room temperature ionic liquids (RTILs) N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide, N-butyl-N-methylpyrrolidinium dicyanamide, and 1-butyl-3-methylimidazolium dicyanamide are determined using a heated effusive vapor source in conjunction with single photon ionization by a tunable vacuum ultraviolet synchrotron source. The relative gas phase ionic liquid vapor densities in the effusive beam are monitored by clearly distinguished dissociative photoionization processes via a time-of-flight mass spectrometer at a tunable vacuum ultraviolet beamline 9.0.2.3 (Chemical Dynamics Beamline) at the Advanced Light Source synchrotron facility. Resulting in relatively few assumptions, through the analysis of both parent cations and fragment cations, the heat of vaporization of N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide is determined to be Delta Hvap(298.15 K) = 195+-19 kJ mol-1. The observed heats of vaporization of 1-butyl-3-methylimidazolium dicyanamide (Delta Hvap(298.15 K) = 174+-12 kJ mol-1) and N-butyl-N-methylpyrrolidinium dicyanamide (Delta Hvap(298.15 K) = 171+-12 kJ mol-1) are consistent with reported experimental values using electron impact ionization. The tunable vacuum ultraviolet source has enabled accurate measurement of photoion appearance energies. These appearance energies are in good agreement with MP2 calculations for dissociative photoionization of the ion pair. These experimental heats of vaporization, photoion appearance energies, and ab initio calculations corroborate vaporization of these RTILs as intact cation-anion ion pairs.

  16. Intensity and Energy Level Analysis of the Vacuum Ultraviolet Spectrum of Four Times Ionize Nickel (Ni V)

    NASA Astrophysics Data System (ADS)

    Ward, Jacob Wolfgang; Nave, Gillian

    2016-01-01

    Recent measurements of four times ionized iron and nickel (Fe V & Ni V) wavelengths in the vacuum ultraviolet (VUV) have been taken using the National Institute for Standards and Technology (NIST) Normal Incidence Vacuum Spectrograph (NIVS) with a sliding spark light source with invar electrodes. The wavelengths observed in those measurements make use of high resolution photographic plates with the majority of observed lines having uncertainties of approximately 3mÅ. In addition to observations made with photographic plates, the same wavelength region was observed with phosphor image plates, which have been demonstrated to be accurate as a method of intensity calibration when used with a deuterium light source. This work will evaluate the use of phosphor image plates and deuterium lamps as an intensity calibration method for the Ni V spectrum in the 1200-1600Å region of the VUV. Additionally, by pairing the observed wavelengths of Ni V with accurate line intensities, it is possible to create an energy level optimization for Ni V providing high accuracy Ritz wavelengths. This process has previously been applied to Fe V and produced Ritz wavelengths that agreed with the above experimental observations.

  17. Determination of Hydrocarbon Group-Type of Diesel Fuels by Gas Chromatography with Vacuum Ultraviolet Detection.

    PubMed

    Weber, Brandon M; Walsh, Phillip; Harynuk, James J

    2016-06-01

    A GC-vacuum ultraviolet (UV) method to perform group-type separations of diesel range fuels was developed. The method relies on an ionic liquid column to separate diesel samples into saturates, mono-, di-, and polyaromatics by gas chromatography, with selective detection via vacuum UV absorption spectroscopy. Vacuum UV detection was necessary to solve a coelution between saturates and monoaromatics. The method was used to measure group-type composition of 10 oilsands-derived Synfuel light diesel samples, 3 Syncrude light gas oils, and 1 quality control sample. The gas chromatography (GC)-vacuum UV results for the Synfuel samples were similar (absolute % error of 0.8) to historical results from the supercritical fluid chromatography (SFC) analysis. For the light gas oils, discrepancies were noted between SFC results and GC-vacuum UV results; however, these samples are known to be challenging to quantify by SFC-flame ionization detector (FID) due to incomplete resolution between the saturate/monoaromatic and/or monoaromatic/diaromatic group types when applied to samples heavier than diesel (i.e., having a larger fraction of higher molecular weight species). The quality control sample also performed well when comparing both methods (absolute % error of 0.2) and the results agreed within error for saturates, mono- and polyaromatics. PMID:27125997

  18. Vacuum Ultraviolet and Ultraviolet Radiation-Induced Effect of Hydrogenated Silicon Nitride Etching: Surface Reaction Enhancement and Damage Generation

    NASA Astrophysics Data System (ADS)

    Fukasawa, Masanaga; Miyawaki, Yudai; Kondo, Yusuke; Takeda, Keigo; Kondo, Hiroki; Ishikawa, Kenji; Sekine, Makoto; Matsugai, Hiroyasu; Honda, Takayoshi; Minami, Masaki; Uesawa, Fumikatsu; Hori, Masaru; Tatsumi, Tetsuya

    2012-02-01

    Photon-enhanced etching of SiNx:H films caused by the interaction between vacuum ultraviolet (VUV)/ultraviolet (UV) radiation and radicals in the fluorocarbon plasma was investigated by a technique with a novel sample setup of the pallet for plasma evaluation. The simultaneous injection of UV radiation and radicals causes a dramatic etch rate enhancement of SiNx:H films. Only UV radiation causes the film shrinkage of SiNx:H films owing to hydrogen desorption from the film. Capacitance-voltage characteristics of SiNx:H/Si substrates were studied before and after UV radiation. The interface trap density increased monotonically upon irradiating the UV photons with a wavelength of 248 nm. The estimated effective interface trap generation probability is 4.74 ×10-7 eV-1·photon-1. Therefore, the monitoring of the VUV/UV spectra during plasma processing and the understanding of its impact on the surface reaction, film damage and electrical performance of underlying devices are indispensable to fabricate advanced devices.

  19. Vacuum Ultraviolet and Ultraviolet Spectroscopy of Tb3+- and Eu3+-Doped Na(Sr,Ba)PO4 Phosphate

    NASA Astrophysics Data System (ADS)

    Huang, Yanlin; Cao, Yonggang; Jiang, Chuanfang; Shi, Liang; Tao, Ye; Seo, Hyo Jin

    2008-08-01

    The Eu3+- and Tb3+-doped NaSr0.65Ba0.35(PO4) phosphors were prepared by high-temperature solid-state reaction. X-ray powder diffraction (XRD) analyses confirm the pure crystalline phase of Olgite mineral. Scanning electron microscopy (SEM) measurements indicate that these phosphors have good surface-crystalline with a narrow size distribution. Vacuum ultraviolet (VUV) synchrotron radiation and ultraviolet (UV) spectroscopy were applied to study the luminescence properties of these phosphors. The bands near 147 nm in the VUV excitation spectra of those doped samples are attributed to the PO43- absorption in the host. The excitation and emission spectra indicate that the phosphors can be effectively excited for NaSr0.65Ba0.35(PO4):Eu3+ and NaSr0.65Ba0.35(PO4):Tb3+ by 147 nm and exhibit a red and green light, respectively. The Commission International de I'Eclairage (CIE) chromaticity coordinates for Eu3+- and Tb3+-activated phosphors are calculated. Considering the high luminescence intensity, excellent color purity and chemical stability, NaSr0.65Ba0.35(PO4):RE (RE = Eu3+, Tb3+) are attractive red- and green-emitting plasma display panel phosphors.

  20. Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics

    NASA Astrophysics Data System (ADS)

    Choudhury, F. A.; Ryan, E. T.; Nguyen, H. M.; Nishi, Y.; Shohet, J. L.

    2016-07-01

    This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH3 bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH3 bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH3 bond concentration was observed when the same samples were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ˜250 nm do not result in Si-CH3 depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH3 although direct photolysis of air species does not occur above ˜242nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.

  1. Analysis of Fe V and Ni V Wavelength Standards in the Vacuum Ultraviolet

    NASA Astrophysics Data System (ADS)

    Ward, Jacob Wolfgang; Nave, Gillian

    2015-01-01

    The recent publication[1] by J.C. Berengut et al. tests for a potential variation in the fine-structure constant in the presence of high gravitational potentials through spectral analysis of white-dwarf stars.The spectrum of the white-dwarf star studied in the paper, G191-B2B, has prominent Fe V and Ni V lines, which were used to determine any variation in the fine-structure constant via observed shifts in the wavelengths of Fe V and Ni V in the vacuum ultraviolet region. The results of the paper indicate no such variation, but suggest that refined laboratory values for the observed wavelengths could greatly reduce the uncertainty associated with the paper's findings.An investigation of Fe V and Ni V spectra in the vacuum ultraviolet region has been conducted to reduce wavelength uncertainties currently limiting modern astrophysical studies of this nature. The analyzed spectra were produced by a sliding spark light source with electrodes made of invar, an iron nickel alloy, at peak currents of 750-2000 A. The use of invar ensures that systematic errors in the calibration are common to both species. The spectra were recorded with the NIST Normal Incidence Vacuum Spectrograph on phosphor image plate and photographic plate detectors. Calibration was done with a Pt II spectrum produced by a Platinum Neon Hollow Cathode lamp.[1] J. C. Berengut, V. V. Flambaum, A. Ong, et al Phys. Rev. Lett. 111, 010801 (2013)

  2. Size dependence of luminescent properties for hexagonal YBO3:Eu nanocrystals in the vacuum ultraviolet region

    NASA Astrophysics Data System (ADS)

    Wei, Zheng-Gui; Sun, Ling-Dong; Liao, Chun-Sheng; Jiang, Xiao-Cheng; Yan, Chun-Hua; Tao, Ye; Hou, Xue-Ying; Ju, Xin

    2003-06-01

    The vacuum ultraviolet (VUV) spectra of the nanosized YBO3:Eu crystals, which have already been prepared by a more facile sol-gel pyrolysis process at a relatively low annealing temperature in our previous work, were investigated and compared to the bulk synthesized by conventional solid-state reactions. In the emission spectra, the size dependence of color purity in YBO3:Eu under VUV irradiation is in good agreement with our previous results obtained under ultraviolet excitation, and a relatively better color purity could be obtained in the YBO3:Eu phosphors with a smaller particle size. Moreover, the VUV excitation spectra of nanocrystals are also distinctly different from those of the bulk and submicrosized samples. The size dependence of the Eu-O charge transfer process, the B3O99- ion absorption, and the Y-O excitonic transition, as well as the quenching concentration, were reported and discussed.

  3. Reflectance and substrate currents of dielectric layers under vacuum ultraviolet irradiation

    SciTech Connect

    Sinha, H.; Straight, D. B.; Lauer, J. L.; Fuller, N. C.; Engelmann, S. U.; Zhang, Y.; Antonelli, G. A.; Severson, M.; Nishi, Y.; Shohet, J. L.

    2010-11-15

    The reflectance of low-k porous organosilicate glass (SiCOH) as a function of photon energy under synchrotron vacuum ultraviolet (VUV) radiation was measured using a nickel mesh reflectometer. The authors found that during VUV irradiation, the reflectance of SiCOH and the substrate current were inversely correlated. Thus, reflectance can be inferred from substrate current measurements and vice versa. The authors conclude that reflectance or substrate current measurements can determine the photon energies that are absorbed and, therefore, cause dielectric damage during processing. Thus, reducing the flux of deleterious photon energies in processing systems can minimize dielectric damage.

  4. Test of prototype ITER vacuum ultraviolet spectrometer and its application to impurity study in KSTAR plasmas.

    PubMed

    Seon, C R; Hong, J H; Jang, J; Lee, S H; Choe, W; Lee, H H; Cheon, M S; Pak, S; Lee, H G; Biel, W; Barnsley, R

    2014-11-01

    To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found. PMID:25430310

  5. Molecular branching ratio method for intensity calibration of optical systems in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.

    1972-01-01

    A state-of-the-art review is given of the molecular branching ratio method for intensity calibration in the vacuum ultraviolet. Ways are described for determining both relative and quantitative responses in the wavelength range 1000 A to 3000 A. The molecular band systems which are discussed are the following: H2(B 1 Sigma u +)-(X 1 Sigma g +), H2(C 1 Pi u)-(X 1 Sigma g +), N2(A 1 Pi g)-(X 1 Sigma g +), CO(A 1 Pi)-(X 1 Sigma +), NO(A 2 Sigma +)-(X 2 Pi r), and NO(+) (A 1 Pi)-(X 1 Sigma +).

  6. Vacuum ultraviolet light source utilizing rare gas scintillation amplification sustained by photon positive feedback

    NASA Technical Reports Server (NTRS)

    Aprile, Elena (Inventor); Chen, Danli (Inventor)

    1995-01-01

    A source of light in the vacuum ultraviolet (VUV) spectral region includes a reflective UV-sensitive photocathode supported in spaced parallel relationship with a mesh electrode within a rare gas at low pressure. A high positive potential applied to the mesh electrode creates an electric field which causes drifting of free electrons occurring between the electrodes and producing continuous VUV light output by electric field-driven scintillation amplification sustained by positive photon feedback mediated by photoemission from the photocathode. In one embodiment the lamp emits a narrow-band continuum peaked at 175 nm.

  7. CIV Polarization Measurements using a Vacuum Ultraviolet Fabry-Perot Interferometer

    NASA Technical Reports Server (NTRS)

    West, Edward; Gary, G. Allen; Cirtain, Jonathan; David, John; Kobayashi, Ken; Pietraszewski, Chris

    2009-01-01

    Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-P rot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry P rot.

  8. Proton transfer in acetaldehyde and acetaldehyde-water clusters: Vacuum ultraviolet photoionization experiment and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Kostko, Oleg; Troy, Tyler P.; Bandyopadhyay, Biswajit; Ahmed, Musahid

    2015-03-01

    Acetaldehyde, a probable human carcinogen and of environmental importance, upon solvation provides a test bed for understanding proton transfer pathways and catalytic mechanisms. In this study, we report on single photon vacuum ultraviolet photoionization of small acetaldehyde and acetaldehyde-water clusters. Appearance energies of protonated clusters are extracted from the experimental photoionization efficiency curves and compared to electronic structure calculations. The comparison of experimental data to computational results provides mechanistic insight into the fragmentation mechanisms of the observed mass spectra. Using deuterated water for isotopic tagging, we observe that proton transfer is mediated via acetaldehyde and not water in protonated acetaldehyde-water clusters.

  9. Dissociative excitation of vacuum ultraviolet emission features by electron impact on molecular gases. 3: CO2

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; Borst, W. L.; Zipf, E. C.

    1972-01-01

    Vacuum ultraviolet multiplets of C I, C II, and O I were produced by electron impact on CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focused electron gun used is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are presented. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.

  10. Vacuum Ultraviolet Radiation Desorption of Molecular Contaminants Deposited on Quartz Crystal Microbalances

    NASA Technical Reports Server (NTRS)

    Albyn, Keith; Burns, Dewitt

    2006-01-01

    Recent quartz crystal microbalance measurements made in the Marshall Space Flight Center, Photo-Deposition Facility, for several materials, recorded a significant loss of deposited contaminants when the deposition surface of the microbalance was illuminated by a deuterium lamp. These measurements differ from observations made by other investigators in which the rate of deposition increased significantly when the deposition surface was illuminated with vacuum ultraviolet radiation. These observations suggest that the accelerated deposition of molecular contaminants on optically sensitive surfaces is dependant upon the contaminant being deposited and must be addressed during the materials selection process by common material screening techniques.

  11. Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy

    SciTech Connect

    Jiang, Rui; Mou, Daixiang; Wu, Yun; Huang, Lunan; Kaminski, Adam; McMillen, Colin D.; Kolis, Joseph; Giesber, Henry G.; Egan, John J.

    2014-03-15

    We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 10{sup 14} photon/s. We demonstrate that this energy range is sufficient to measure the k{sub z} dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.

  12. Possibility of using sources of vacuum ultraviolet irradiation to solve problems of space material science

    NASA Technical Reports Server (NTRS)

    Verkhoutseva, E. T.; Yaremenko, E. I.

    1974-01-01

    An urgent problem in space materials science is simulating the interaction of vacuum ultraviolet (VUV) of solar emission with solids in space conditions, that is, producing a light source with a distribution that approximates the distribution of solar energy. Information is presented on the distribution of the energy flux of VUV of solar radiation. Requirements that must be satisfied by the VUV source used for space materials science are formulated, and a critical evaluation is given of the possibilities of using existing sources for space materials science. From this evaluation it was established that none of the sources of VUV satisfies the specific requirements imposed on the simulator of solar radiation. A solution to the problem was found to be in the development of a new type of source based on exciting a supersonic gas jet flowing into vacuum with a sense electron beam. A description of this gas-jet source, along with its spectral and operation characteristics, is presented.

  13. Facility and Methods Developed for Simulated Space Vacuum Ultraviolet Exposure Testing of Polymer Films

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

    2002-01-01

    Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the Sun in the space environment can degrade polymer films, producing changes in their optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultralightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. The NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of combined or sequential simulated space environmental exposures to determine combined damaging effects with other aspects of the space environment, which include solar ultraviolet radiation, solar flare x-rays, electron and proton radiation, atomic oxygen (for low-Earth-orbit missions), and temperature effects. Because the wavelength sensitivity of VUV damage is not well known for most materials, Glenn's VUV facility uses a broad-spectrum deuterium lamp with a magnesium fluoride window that provides output between 115 and 200 nm. Deuterium lamps of this type were characterized by the National Institute of Standards and Technology and through measurements at Glenn. Spectral irradiance measurements show that from approximately 115 to 160 nm, deuterium lamp irradiance can be many times that of air mass zero solar irradiance, and as wavelength increases above approximately 160 nm, deuterium lamp irradiance decreases in comparison to the Sun. The facility is a cryopumped vacuum chamber that achieves a system pressure of approximately 5310(exp -6) torr. It contains four individual VUV-exposure compartments in vacuum, separated by water-cooled copper walls to minimize VUV radiation and any sample contamination cross interactions between compartments. Each VUV-exposure compartment contains a VUV deuterium lamp, a motor-controlled sample stage coupled with a

  14. Absolute calibration of a hydrogen discharge lamp in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Nealy, J. E.

    1975-01-01

    A low-pressure hydrogen discharge lamp was calibrated for radiant intensity in the vacuum ultraviolet spectral region on an absolute basis and was employed as a laboratory standard source in spectrograph calibrations. This calibration was accomplished through the use of a standard photodiode detector obtained from the National Bureau of Standards together with onsite measurements of spectral properties of optical components used. The stability of the light source for use in the calibration of vacuum ultraviolet spectrographs and optical systems was investigated and found to be amenable to laboratory applications. The lamp was studied for a range of operating parameters; the results indicate that with appropriate peripheral instrumentation, the light source can be used as a secondary laboratory standard source when operated under preset controlled conditions. Absolute intensity measurements were recorded for the wavelengths 127.7, 158.0, 177.5, and 195.0 nm for a time period of over 1 month, and the measurements were found to be repeatable to within 11 percent.

  15. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    PubMed Central

    Gasper, Gerald L.; Takahashi, Lynelle K.; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F.; Hanley, Luke

    2010-01-01

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 – 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics and extracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms. PMID:20712373

  16. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    SciTech Connect

    Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F; Hanley, Luke

    2010-08-04

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.

  17. CIV Vacuum Ultraviolet Fabry-Perot Interferometers for Transition-Region Magnetography

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; West, Edward A.; Rees, David; Zukic, Maumer; Herman, Peter; Li, Jianzhao

    2006-01-01

    The vacuum ultraviolet region allows remote sensing of the upper levels of the solar atmosphere where the magnetic field dominates the physics. Obtaining an imaging interferometer that observes the transition region is the goal of this program. This paper gives a summary of our instrument development program (1998-2005) for a high-spectral-resolution, piezoelectric tunable Vacuum Ultraviolet Fabry-Perot Interferometer (VUV FPI) for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CN (155nm). A VUV interferometer will allow us to observe the magnetic field, flows, and heating events in the mid-transition region. The MSFC VUV FPI has measured values of FWHM approx. 9pm, FSR approx. 62pm, finesse approx. 5.3 and transmittance approx. 50% at 157nm. For the measurements, the University of Toronto's F2 eximer laser was used as an appropriate proxy for CIV 155nm. This has provided the first tunable interferometer with a FWHM compatible to VUV filter magnetograph.

  18. Absolute Intensities of the Vacuum Ultraviolet Spectra in a Metal-Etch Plasma Processing Discharge

    SciTech Connect

    Aragon, B.P.; Blain, M.G.; Hamilton, T.W.; Jarecki, R.L.; Woodworth, J.R.

    1998-12-09

    In this paper we report absolute intensities of vacuum ultraviolet and near ultraviolet emission lines (4.8 eV to 18 eV ) for aluminum etching discharges in an inductively coupled plasma reactor. We report line intensities as a function of wafer type, pressure, gas mixture and rf excitation level. IrI a standard aluminum etching mixture containing C12 and BC13 almost all the light emitted at energies exceeding 8.8 eV was due to neutral atomic chlorine. Optical trapping of the WV radiation in the discharge complicates calculations of VUV fluxes to the wafer. However, we see total photon fluxes to the wailer at energies above 8.8 eV on the order of 4 x 1014 photons/cm2sec with anon- reactive wafer and 0.7 x 10 `4 photons/cm2sec with a reactive wtier. The maj ority of the radiation observed was between 8.9 and 9.3 eV. At these energies, the photons have enough energy to create electron-hole pairs in Si02, but may penetrate up to a micron into the Si02 before being absorbed. Relevance of these measurements to vacuum-W photon-induced darnage of Si02 during etching is discussed.

  19. Absolute intensities of the vacuum ultraviolet spectra in a metal-etch plasma processing discharge

    SciTech Connect

    Woodworth, J.R.; Blain, M.G.; Jarecki, R.L.; Hamilton, T.W.; Aragon, B.P.

    1999-11-01

    In this article we report absolute intensities of vacuum ultraviolet (VUV) and near ultraviolet emission lines (4.8{endash}18 eV) for discharges used to etch aluminum in a commercial inductively coupled plasma reactor. We report line intensities as functions of wafer type, pressure, gas mixture, and radio frequency excitation level. In a standard aluminum etching mixture containing Cl{sub 2} and BCl{sub 3} almost all the light emitted at energies exceeding 8.8 eV was due to neutral atomic chlorine. Optical trapping of the VUV radiation in the discharge complicates calculations of VUV fluxes to the wafer. However, we measured total photon fluxes to the wafer at energies above 8.8 eV on the order of 4{times}10{sup 14}&hthinsp;photons/cm{sup 2}&hthinsp;s with a nonreactive wafer and 0.7{times}10{sup 14}&hthinsp;photons/cm{sup 2}&hthinsp;s with a reactive wafer. The majority of the radiation was between 8.9 and 9.3 eV. At these energies, the photons have enough energy to create electron-hole pairs in SiO{sub 2} and may penetrate up to a micron into the SiO{sub 2} before being absorbed. Relevance of these measurements to VUV photon-induced damage of SiO{sub 2} during etching is discussed. {copyright} {ital 1999 American Vacuum Society.}

  20. Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol-Water Clusters

    SciTech Connect

    Kostko, Oleg; Belau, Leonid; Wilson, Kevin R.; Ahmed, Musahid

    2008-04-24

    In this work, we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH+(n = 1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH n(H2O)H+ (n = 2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH+, (CH3OH)2+, (CH3OH)nH+ (n = 1-9), and (CH3OH)n(H2O)H+ (n = 2-9) as a function of photon energy. With an increasein the water content in the molecular beam, there is an enhancement of photoionization intensity for the methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations.

  1. Vacuum Ultraviolet Radiation Effects on DC93-500 Silicone Film Studied

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Yan, Li

    2005-01-01

    A space-qualified silicone polymer, DC93-500 (Dow Corning, Midland, MI), has been used as a spacecraft solar cell adhesive and has been proposed for use in a Fresnel lens solar concentrator for space power applications. Applications of DC93-500 for exterior space system surfaces require an understanding of its overall space environmental durability. Vacuum ultraviolet (VUV) radiation is among the space environment elements that can be hazardous to the properties of DC93-500, causing degradation in optical and mechanical properties. For materials or components that have not been tested previously for long-duration performance in space, such as DC93-500 in freestanding film form, ground laboratory testing is an important tool for assuring durability. However, differences between the space environment and ground laboratory testing environments lead to complexities in interpreting the ground test results. Two important differences between space and laboratory vacuum ultraviolet exposure conditions are irradiance spectra and light intensity. These important differences were the basis for laboratory experiments conducted to examine VUV wavelength dependence and VUV intensity dependence of DC93-500 degradation. Testing conducted at the NASA Glenn Research Center along with additional data provided through a grant with the University of Nebraska-Lincoln, has advanced the understanding of VUV effects on DC93-500 and has provided important conclusions regarding the use of ground laboratory VUV testing to predict the space environment performance of DC93-500.

  2. Low temperature performance of photomultiplier tubes illuminated in pulsed mode by visible and vacuum ultraviolet light

    NASA Astrophysics Data System (ADS)

    Araújo, H. M.; Chepel, V. Yu.; Lopes, M. I.; Marques, R. Ferreira; Policarpo, A. J. P. L.

    1997-01-01

    Detecting the ultraviolet scintillation light of the liquefied rare gases, in particular liquid xenon, requires the use of photomultiplier tubes (PMTs) in a temperature range where their operation is not ensured by manufacturers. Simultaneously, monitoring of the PMTs should be done in the visible for technical reasons. Bialkali photocathodes, that present high quantum efficiency and low dark noise, exhibit a very strong increase of electrical resistivity upon cooling that, apart from other reasons, can lead to operation failure at low temperature. Photomultiplier tubes with bialkali photocathodes and quartz windows (two EMI 9750Q and one Philips XP 2020Q) and another with S11-type photocathode and glass window (FEU 85A) were tested down to -160 °C with a pulsed light source, both in the visible region and at the xenon scintillation wavelength in the vacuum ultraviolet. For the visible range, the results obtained with bialkali photomultipliers display a sharp drop of response at about -100 °C, depending on the count rate, regardless of the wavelength, and a shift of the spectral sensitivity curve towards shorter wavelengths. Concerning the vacuum ultraviolet region, a significant increase of the response was observed between room temperature and that of the efficiency drop. For some photomultiplier tubes, the response as a function of temperature was observed to depend on their past history, probably due to mechanical effects arising in the multiplier system upon cooling. It is concluded that photomultipliers with bialkali photocathode can, in principle, be used for the detection of liquid xenon scintillation, although they have to be carefully monitored while in operation.

  3. Effects of space vacuum and solar ultraviolet irradiation (254 nanometers) on the colony forming ability of Bacillus subtilis spores

    NASA Technical Reports Server (NTRS)

    Buecker, H.; Horneck, G.; Wollenhaupt, H.

    1973-01-01

    Bacillus subtilis spores are highly resistant to harsh environments. Therefore, in the Apollo 16 Microbial Response to Space Environment Experiment (M191), these spores were exposed to space vacuum or solar ultraviolet irradiation, or both, to estimate the change of survival for terrestrial organisms in space. The survival of the spores was determined in terms of colony-forming ability. Comparison of the flight results with results of simulation experiments on earth applying high vacuum or ultraviolet irradiation, or both, revealed no remarkable difference. Simultaneous exposure to both these space factors resulted in a synergistic effect (that is, an ultraviolet supersensitivity). Therefore, the change of survival in space is assumed to depend on the degree of protection against solar ultraviolet irradiation.

  4. Further studies on MgF(2)-overcoated aluminum mirrors with highest reflectance in the vacuum ultraviolet.

    PubMed

    Canfield, L R; Hass, G; Waylonis, J E

    1966-01-01

    MgF(2)-overcoated aluminum films with high-vacuum ultraviolet reflectance have been the subject of further investigations of the preparation parameters affecting their reflectance, and of the effect of aging and exposure to conditions likely to be encountered in their applications. Techniques for monitoring the thickness of MgF(2) by reflectance measurements with ultraviolet light and by complete evaporation of weighed quantities of MgF(2) are described. It is shown that MgF(2)-protected aluminum mirrors retain their high-vacuum ultraviolet reflectance during extended exposure to air, ultraviolet irradiation, and bombardment with 1-MeV electrons and 5-MeV protons, and that such mirrors can be easily cleaned if contaminated with oil. PMID:20048784

  5. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    SciTech Connect

    Takahashi, Jun-ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-15

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH{sub 4}), a nitrogen source (N{sub 2} or NH{sub 3}), and H{sub 2}O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF{sub 2}, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH{sub 4}-N{sub 2}-H{sub 2}O), comet-type (CO-NH{sub 3}-H{sub 2}O), and primitive-Earth-type (CO-N{sub 2}-H{sub 2}O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10{sup -5}, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  6. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    NASA Astrophysics Data System (ADS)

    Takahashi, Jun-Ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-01

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH4), a nitrogen source (N2 or NH3), and H2O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF2, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH4-N2-H2O), comet-type (CO-NH3-H2O), and primitive-Earth-type (CO-N2-H2O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10-5, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  7. Free-electron laser sources of extreme-ultraviolet radiation and their vacuum requirements

    SciTech Connect

    Newnam, B.E.

    1990-01-01

    Recent development of free-electron laser (FEL) component technologies should enable these devices to operate in the extreme-ultraviolet, well below 100 nm. When fully developed, FELs represent the next generation of coherent-radiation sources with peak- and average-power outputs surpassing those of any existing, continuously tunable photon source by many orders of magnitude. An rf-linac-based, multiple-FEL facility, spanning the spectral range from 1 nm to 100 {mu}m, is proposed. To enable such a facility to operate without significant degradation over long periods, contamination of certain of the FEL components must be prevented. Requirements for ultra-high vacuum and restricted contamination from outgassing from chamber walls are discussed. 73 refs., 11 figs., 4 tabs.

  8. Luminescence from Vacuum-Ultraviolet-Irradiated Cosmic Ice Analogs and Residue

    NASA Technical Reports Server (NTRS)

    Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier D. F.; Allamandola, Louis J.

    2003-01-01

    Here we report a study of the optical luminescent properties for a variety of vacuum-ultraviolet (VUV)-irradiated cosmic ice analogs and the complex organic residues produced. Detailed results are presented for the irradiated, mixed molecular ice: H2O: CH3OH:NH3:CO(100:50:1:1), a realistic representation for an interstellar/precometary ice that reproduces all the salient infrared spectral features associated with interstellar ices. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure is described. It is suggested that this type of luminescent behavior might be applicable to solar system and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification.

  9. Luminescence from Vacuum-Ultraviolet-Irradiated Cosmic Ice Analogs and Residues

    NASA Technical Reports Server (NTRS)

    Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier D. F.; Allamandola, Louis J.

    2003-01-01

    Here we report a study of the optical luminescent properties for a variety of vacuum-ultraviolet (VUV)- irradiated cosmic ice analogs and the complex organic residues produced. Detailed results are presented for the irradiated, mixed molecular ice: H2O:CH3OH:NH3:CO (100:50:1:1), a realistic representation for an interstellar/precometary ice that reproduces all the salient infrared spectral features associated with interstellar ices. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure is described. It is suggested that this type of luminescent behavior might be applicable to solar system and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification.

  10. Vacuum ultraviolet photochemical selective area atomic layer deposition of Al2O3 dielectrics

    NASA Astrophysics Data System (ADS)

    Chalker, P. R.; Marshall, P. A.; Dawson, K.; Brunell, I. F.; Sutcliffe, C. J.; Potter, R. J.

    2015-01-01

    We report the photochemical atomic layer deposition of Al2O3 thin films and the use of this process to achieve area-selective film deposition. A shuttered vacuum ultraviolet (VUV) light source is used to excite molecular oxygen and trimethyl aluminum to deposit films at 60°C. In-situ QCM and post-deposition ellipsometric measurements both show that the deposition rate is saturative as a function of irradiation time. Selective area deposition was achieved by projecting the VUV light through a metalized magnesium fluoride photolithographic mask and the selectivity of deposition on the illuminated and masked regions of the substrate is a logarithmic function of the UV exposure time. The Al2O3 films exhibit dielectric constants of 8 - 10 at 1 MHz after forming gas annealing, similar to films deposited by conventional thermal ALD.

  11. Coupling of a vacuum-ultraviolet-radiation source to a processing system

    SciTech Connect

    Chatterton, J. D.; Upadhyaya, G. S.; Shohet, J. L.; Lauer, J. L.; Bathke, R. D.; Kukkady, K.

    2006-08-15

    A hollow capillary array is examined as a coupling window between an electron cyclotron resonance plasma vacuum ultraviolet (vuv) source and a separate processing chamber. The transmission of vuv through the capillary array as a function of wavelength is measured and shown to agree with theoretical calculations. A silicon wafer with a dielectric surface is then placed in the processing chamber and exposed to vuv, both with and without the capillary array. A Kelvin probe is used to measure the surface charge induced on the wafer by photoemission in both cases, which confirms the previously measured transmission values. The results show that a capillary array can efficiently couple vuv radiation from a source to a processing chamber without significant modification in the spectrum and its resulting effects on a material.

  12. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube.

    NASA Astrophysics Data System (ADS)

    Meyer, Scott Andrew

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 times 10 ^{17} and 9 times 10^{17} cm ^{-3}. The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  13. The effects of plasma exposure and vacuum ultraviolet irradiation on photopatternable low-k dielectric materials

    SciTech Connect

    Nichols, M. T.; Mavrakakis, K.; Shohet, J. L.; Lin, Q.

    2013-09-14

    The effects of plasma exposure and vacuum-ultraviolet (VUV) irradiation on photopatternable low-k (PPLK) dielectric materials are investigated. In order to examine these effects, current-voltage measurements were made on PPLK materials before and after exposure to a variety of inert plasma-exposure conditions. In order to examine the effects of photon irradiation alone, PPLK samples were also exposed to monochromatic synchrotron radiation with 10 eV photon energy. It was found that plasma exposure causes significant degradation in electrical characteristics, resulting in increased leakage-currents and decreased breakdown voltage. X-ray photoelectron spectroscopy measurements also show appreciable carbon loss near the sample surface after plasma exposure. Conversely, VUV exposure was found to increase breakdown voltage and reduce leakage-current magnitudes.

  14. Electronic Excitations in B12As2 and their Temperature Dependence by Vacuum Ultraviolet Ellipsometry

    SciTech Connect

    S Bakalova; Y Gong; C Cobet; N Esser; Y Zhang; J Edgar; Y Zhang; M Dudley; M Kuball

    2011-12-31

    The dielectric response function of epitaxial B{sub 12}As{sub 2} films on 4H-SiC was determined at room temperature and at 10 K in the spectral region of 3.6-9.8 eV, i.e., in the vacuum ultraviolet (VUV) spectral region, by synchrotron ellipsometry. The experimental dielectric function was simulated with the critical point parabolic band model. The parameters of the dispersive structures were derived by numerical fitting of the experimental data to the proposed model. New high energy optical transitions are resolved at 5.95, 7.8 and 8.82 eV and their lineshape and origin are discussed. The temperature dependence of the critical point energies and transition strengths was determined, and the excitonic effect is considered.

  15. Realization of time-resolved two-vacuum-ultraviolet-photon ionization

    NASA Astrophysics Data System (ADS)

    Peralta Conde, A.; Kruse, J.; Faucher, O.; Tzallas, P.; Benis, E. P.; Charalambidis, D.

    2009-06-01

    Ultrafast dynamics of excited molecules is studied through time-resolved two-vacuum-ultraviolet (vuv)-photon ionization using a nonlinear volume autocorrelator unit. The two-vuv-photon process is induced by the intense fifth harmonic radiation of a femtosecond Ti:sapphire laser. In a proof-of-principle experiment, ultrafast dynamics of excited ethylene and oxygen molecules are investigated. Molecular decay times are deduced by comparing the experimental data with the results of a numerical model that accounts for the spatial and temporal characteristics of the harmonic field. The present experiments pave a convenient way for time domain investigations in the vuv-xuv spectral region in all states of matter at few femtosecond to subfemtosecond temporal scales.

  16. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17)/cu cm. The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  17. Vacuum ultraviolet circularly polarized coherent femtosecond pulses from laser seeded relativistic electrons

    NASA Astrophysics Data System (ADS)

    Čutić, N.; Lindau, F.; Thorin, S.; Werin, S.; Bahrdt, J.; Eberhardt, W.; Holldack, K.; Erny, C.; L'Huillier, A.; Mansten, E.

    2011-03-01

    We have demonstrated the generation of circularly polarized coherent light pulses at 66 nm wavelength by combining laser seeding at 263 nm of a 375 MeV relativistic electron bunch with subsequent coherent harmonic generation from an elliptical undulator of APPLE-II type. Coherent pulses at higher harmonics in linear polarization have been produced and recorded up to the sixth order (44 nm). The duration of the generated pulses depends on the temporal overlap of the initial seed laser pulse and the electron bunch and was on the order of 200 fs. Currently, this setup is the only source worldwide producing coherent fs-light pulses with variable polarization in the vacuum ultraviolet.

  18. Fragmentation and dimerization of aliphatic amino acid films induced by vacuum ultraviolet irradiation

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahito; Kaneko, Fusae; Koketsu, Toshiyuki; Nakagawa, Kazumichi; Yamada, Toru

    2008-10-01

    The chemical reaction of aliphatic amino acid, such as alanine (Ala) and leucine (Leu), in the solid phase induced by vacuum ultraviolet (VUV) irradiation was studied by high-performance liquid chromatography technique and mass spectroscopic method. Quantum efficiencies of dimerization of Ala in the solid phase obviously showed irradiated VUV wavelength dependence. The values of quantum efficiencies of formation of Ala dimer were determined to be 5.7×10-5, 1.3×10-3, and 2.4×10-4 for 208, 183, and 87 nm irradiation, respectively. VUV-induced fragment desorption from Ala and Leu films has also been examined by mass spectroscopic method. Observed mass spectra clearly indicated that both the deamination and decarboxylation reactions were common in both Ala and Leu films, and the dissociation of side chain occurred only in Leu film.

  19. Vacuum ultraviolet reflectance spectra of groups L, LL, and E chondrites and of achondrites

    NASA Technical Reports Server (NTRS)

    Wagner, J. K.; Cohen, A. J.; Hapke, B. W.; Partlow, W. D.

    1980-01-01

    The reflectance spectra of individual meteorites of all classes are being measured in the vacuum ultraviolet (VUV) spectral wavelength region from 89 to 248 nm to evaluate the potential of VUV spectroscopy as a remote sensing method for planetary studies. In the present investigation, specimens of 15 group L chondrites, 13 group LL chondrites, 7 group E chondrites, and 18 achondrites were studied. Spectra were measured of both polished thin sections and powders of the meteorites, where both were available. Attention is given to measurements of mineral standards, shock effects, and meteorite data. It is concluded that the VUV spectra of meteorites should provide a useful basis for comparisons with spectra of asteroids and comet nuclei taken from spacecraft. VUV spectroscopy should make it possible to identify the major minerals present in a meteorite or asteroid.

  20. A synchrotron-radiation-based variable angle ellipsometer for the visible to vacuum ultraviolet spectral range

    SciTech Connect

    Neumann, M. D. Cobet, C.; Esser, N.; Kaser, H.; Kolbe, M.; Gottwald, A.; Richter, M.

    2014-05-15

    A rotating analyzer spectroscopic polarimeter and ellipsometer with a wide-range θ-2θ goniometer installed at the Insertion Device Beamline of the Metrology Light Source in Berlin is presented. With a combination of transmission- and reflection-based polarizing elements and the inherent degree of polarization of the undulator radiation, this ellipsometer is able to cover photon energies from about 2 eV up to 40 eV. Additionally, a new compensator design based on a CaF{sub 2} Fresnel rhomb is presented. This compensator allows ellipsometric measurements with circular polarization in the vacuum ultraviolet spectral range and thus, for example, the characterization of depolarizing samples. The new instrument was initially used for the characterization of the polarization of the beamline. The technical capabilities of the ellipsometer are demonstrated by a cohesive wide-range measurement of the dielectric function of epitaxially grown ZnO.

  1. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3x10(exp 17) and 9x10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  2. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  3. Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS2.

    PubMed

    Pankratov, V; Hoszowska, J; Dousse, J-Cl; Huttula, M; Kis, A; Krasnozhon, D; Zhang, M; Cao, W

    2016-01-13

    We report on vacuum ultraviolet (VUV) excited photoluminescence (PL) spectra emitted from a chemical vapor deposited MoS2 few-layered film. The excitation spectrum was recorded by monitoring intensities of PL spectra at ~1.9 eV. A strong wide excitation band peaking at 7 eV was found in the excitation. The PL excitation band is most intensive at liquid helium temperature and completely quenched at 100 K. Through first-principles calculations of photoabsorption in MoS2, the excitation was explicated and attributed to transitions of electrons from p- and d- type states in the valence band to the d- and p-type states in the conduction band. The obtained photon-in/photon-out results clarify the excitation and emission behavior of the low dimensional MoS2 when interacting with the VUV light sources. PMID:26648394

  4. In situ measurements of scattering from contaminated optics in the Vacuum Ultraviolet

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Linton, Roger C.; Whitaker, Ann F.

    1990-01-01

    NASA's In Situ Contamination Effects Facility has been used to measure the time dependence of the angular reflectance from molecularly contaminated optical surfaces in the vacuum ultraviolet. The light scattering measurements are accomplished in situ on optical surfaces in real time during deposition of molecular contaminants. The measurements are taken using noncoherent VUV sources with the predominant wavelengths being the krypton resonance lines at 1236 and 1600 angstroms. Detection of the scattered light is accomplished using a set of three solar blind VUV photomultipliers. An in-plane VUV BRDF (bidirectional reflectance distribution function) experiment is described and details of the on-going program to characterize optical materials exposed to the space environment is reported.

  5. Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

    PubMed Central

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region. PMID:25302320

  6. Vacuum ultraviolet emission from microwave Ar-H{sub 2} plasmas

    SciTech Connect

    Espinho, S.; Felizardo, E.; Tatarova, E.; Dias, F. M.; Ferreira, C. M.

    2013-03-18

    Vacuum ultraviolet emission from Ar-H{sub 2} wave driven microwave (2.45 GHz) plasmas operating at low pressures (0.1-1 mbar) has been investigated. The emitted spectra show the presence of the Ar resonance lines at 104.8 and 106.7 nm and of the Lyman-{alpha},{beta} atomic lines at 121.6 nm and 102.6 nm, respectively. The increase of the hydrogen amount in the mixture results in an abrupt increase of the Werner and Lyman molecular bands intensity. The Lyman-{beta} intensity shows little changes in the range of 5%-30% of hydrogen in the mixture while the Lyman-{alpha} intensity tends to decrease as the percentage of hydrogen increases.

  7. Theoretical Calculations of Photoabsorption of Several Alicyclic Molecules in the Vacuum Ultraviolet Region

    SciTech Connect

    Matsuzawa, Nobuyuki; Ishitani, Akihiko; Dixon, David A.; Uda, Tsuyoshi

    2001-06-13

    In order to aid in the design of transparent materials for use as photoresists for F2 lithography (157 nm), we have performed time-dependent density functional theory (TD-DFT) calculations of the photoabsorption of molecules in the vacuum ultraviolet region. The application of this TD-DFT method to the prediction of photoabsorption was benchmarked using model molecules such as formaldehyde, and an empirical equation for correcting the calculated transition energy was obtained. The TD-DFT method with the empirical correction equation provides dramatically more accurate results than those obtained with the CIS (single-excitation configuration interaction) method, which we employed in previous studies. We used it to predict the photoabsorption of various molecules such as methanol, t-butylalcohol, acetic acid, methyl acetate, cycloalkane, norbonane, tricyclodecane, tetrahydropyrane, adamantane, maleic anhydride and their fluorinated derivatives.

  8. Very low thermally induced tip expansion by vacuum ultraviolet irradiation in a scanning tunneling microscope junction

    NASA Astrophysics Data System (ADS)

    Riedel, D.; Delacour, C.; Mayne, A. J.; Dujardin, G.

    2009-10-01

    The thermal and photoelectronic processes induced when a vacuum ultraviolet (VUV) laser irradiates the junction of a scanning tunneling microscope (STM) are studied. This is performed by synchronizing the VUV laser shots with the STM scan signal. Compared to other wavelengths, the photoinduced thermal STM-tip expansion is not observed when the VUV radiation is freed from spurious emissions. Furthermore, we demonstrate that the purified VUV photoinduced transient signal detected in the tunnel current is entirely due to photoelectronic emission and not combined with thermionic processes. The ensuing photoelectron emission is shown to be independent of the tip-surface distance while varying linearly with the pure VUV laser intensity. These results illustrate a strong decoupling between phonons and photoelectrons which allows a very weak STM-tip expansion.

  9. Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1999-01-01

    Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

  10. Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations

    SciTech Connect

    Palmer, Michael H. Ridley, Trevor E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Hoffmann, Søren Vrønning E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it Jones, Nykola C. E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Coreno, Marcello E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Grazioli, Cesare; Zhang, Teng; and others

    2015-10-28

    New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two ππ* states of {sup 1}A{sub 1} (higher oscillator strength) and {sup 1}B{sub 2} (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 2{sup 2}B{sub 1} ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b{sub 1}3s and 6b{sub 2}3s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures.

  11. Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations

    NASA Astrophysics Data System (ADS)

    Palmer, Michael H.; Ridley, Trevor; Hoffmann, Søren Vrønning; Jones, Nykola C.; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Zhang, Teng; Biczysko, Malgorzata; Baiardi, Alberto; Peterson, Kirk

    2015-10-01

    New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two ππ* states of 1A1 (higher oscillator strength) and 1B2 (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 22B1 ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b13s and 6b23s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures.

  12. Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations.

    PubMed

    Palmer, Michael H; Ridley, Trevor; Hoffmann, Søren Vrønning; Jones, Nykola C; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Zhang, Teng; Biczysko, Malgorzata; Baiardi, Alberto; Peterson, Kirk

    2015-10-28

    New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two ππ* states of (1)A1 (higher oscillator strength) and (1)B2 (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 2(2)B1 ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b13s and 6b23s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures. PMID:26520509

  13. Devices useful for vacuum ultraviolet beam characterization including a movable stage with a transmission grating and image detector

    DOEpatents

    Gessner, Oliver; Kornilov, Oleg A; Wilcox, Russell B

    2013-10-29

    The invention provides for a device comprising an apparatus comprising (a) a transmission grating capable of diffracting a photon beam into a diffracted photon output, and (b) an image detector capable of detecting the diffracted photon output. The device is useful for measuring the spatial profile and diffraction pattern of a photon beam, such as a vacuum ultraviolet (VUV) beam.

  14. A new optical scheme for large-extraction small-aberration vacuum-ultraviolet synchrotron radiation beamlines.

    PubMed

    Moreno, Thierry

    2016-09-01

    Vacuum-ultraviolet radiation delivered by bending-magnet sources is used at numerous synchrotron radiation facilities worldwide. As bending-magnet radiation is inherently much less collimated compared with undulator sources, the generation of high-quality intense bending-magnet vacuum-ultraviolet photon beams is extremely demanding in terms of the optical layout due to the necessary larger collection apertures. In this article, an optimized optical layout which takes into account both the optical and electron beam properties is proposed. This layout delivers an improved beam emittance of over one order of magnitude compared with existing vacuum-ultraviolet bending-magnet beamlines that, up to now, do not take into account electron beam effects. The arrangement is made of two dedicated mirrors, a cylindrical and a cone-shaped one, that focus independently both the horizontal and the vertical emission of a bending-magnet source, respectively, and has been already successfully applied in the construction of the infrared beamline at the Brazilian synchrotron. Using this scheme, two vacuum-ultraviolet beamline designs based on a SOLEIL synchrotron bending-magnet source are proposed and analysed. They would be useful for future upgrades to the DISCO beamline at SOLEIL and could be readily implemented at other synchrotron radiation facilities. PMID:27577766

  15. Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Fierro, A.; Beeson, S.; Laity, G.; Trienekens, D.; Joshi, R. P.; Dickens, J.; Neuber, A.

    2016-04-01

    Experimental observation of photoionization capable extreme ultraviolet and vacuum ultraviolet emission from nanosecond timescale, developing low temperature plasmas (i.e. streamer discharges) in atmospheric air is presented. Applying short high voltage pulses enabled the observation of the onset of plasma formation exclusively by removing the external excitation before spark development was achieved. Contrary to the common assumption that radiative transitions from the b{{}1}{{\\Pi}u} (Birge-Hopfield I) and b{{}\\prime 1}Σu+ (Birge-Hopfield II) singlet states of N2 are the primary contributors to photoionization events, these results indicate that radiative transitions from the c{{4\\prime}1}Σu+ (Carroll-Yoshino) singlet state of N2 are dominant in developing low temperature plasmas in air. In addition to c{}4\\prime transitions, photoionization capable transitions from atomic and singly ionized atomic oxygen were also observed. The inclusion of c{{4\\prime}1}Σu+ transitions into a statistical photoionization model coupled with a fluid model enabled streamer growth in the simulation of positive streamers.

  16. Photodegradation of haloacetonitriles in water by vacuum ultraviolet irradiation: Mechanisms and intermediate formation.

    PubMed

    Kiattisaksiri, Pradabduang; Khan, Eakalak; Punyapalakul, Patiparn; Ratpukdi, Thunyalux

    2016-07-01

    Photodegradation of haloacetonitriles (HANs), highly carcinogenic nitrogenous disinfection by-products, in water using vacuum ultraviolet (VUV, 185 + 254 nm) in comparison with ultraviolet (UV, only 254 nm) was investigated. Monochloroacetonitrile (MCAN), dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), and dibromoacetonitrile (DBAN) were species of HANs studied. The effect of gas purging and intermediate formation under VUV were examined. The results show that the pseudo first order rate constants for the reduction of HANs under VUV were approximately 2-7 times better than UV. The order of degradation efficiency under VUV and UV was MCAN < DCAN < TCAN < DBAN. The degradation efficiencies of individual HANs under VUV were higher than those of mixed HANs, suggesting competitive effects among HANs. Under nitrogen purging, the removal rate constants of mixed HANs was much higher than that of the aerated condition by 34.4, 34.9, 10.1, and 3.8 times for MCAN, DCAN, TCAN, and DBAN, respectively. The major degradation mechanism for HANs was different depending on HANs species. Degradation intermediates of HANs such as 2-chloropropionitrile, 2,2-dimethylpropanenitrile, and fumaronitrile were produced from the substitution, addition, and polymerization reactions. In addition, chlorinated HANs with lower number of chlorine atom including MCAN and DCAN were found as intermediates of DCAN and TCAN degradation, respectively. PMID:27101477

  17. Effect of vacuum-ultraviolet irradiation on the dielectric constant of low-k organosilicate dielectrics

    SciTech Connect

    Zheng, H.; Shohet, J. L.; Ryan, E. T.; Nishi, Y.

    2014-11-17

    Vacuum ultraviolet (VUV) irradiation is generated during plasma processing in semiconductor fabrications, while the effect of VUV irradiation on the dielectric constant (k value) of low-k materials is still an open question. To clarify this problem, VUV photons with a range of energies were exposed on low-k organosilicate dielectrics (SiCOH) samples at room temperature. Photon energies equal to or larger than 6.0 eV were found to decrease the k value of SiCOH films. VUV photons with lower energies do not have this effect. This shows the need for thermal heating in traditional ultraviolet (UV) curing since UV light sources do not have sufficient energy to change the dielectric constant of SiCOH and additional energy is required from thermal heating. In addition, 6.2 eV photon irradiation was found to be the most effective in decreasing the dielectric constant of low-k organosilicate films. Fourier Transform Infra-red Spectroscopy shows that these 6.2 eV VUV exposures removed organic porogens. This contributes to the decrease of the dielectric constant. This information provides the range of VUV photon energies that could decrease the dielectric constant of low-k materials most effectively.

  18. Effects of Various Wavelength Ranges of Vacuum Ultraviolet Radiation on Teflon FEP Film Investigated

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; McCracken, Cara A.

    2004-01-01

    Teflon Fluorinated Ethylene Propylene (FTP) films (DuPont) have been widely used for spacecraft thermal control and have been observed to become embrittled and cracked upon exposure to the space environment. This degradation has been attributed to a synergistic combination of radiation and thermal effects. A research study was undertaken at the NASA Glenn Research Center to examine the effects of different wavelength ranges of vacuum ultraviolet (VUV) radiation on the degradation of the mechanical properties of FEP. This will contribute to an overall understanding of space radiation effects on Teflon FEP, and will provide information necessary to determine appropriate techniques for using laboratory tests to estimate space VUV degradation. Research was conducted using inhouse facilities at Glenn and was carried out, in part, through a grant with the Cleveland State University. Samples of Teflon FEP film of 50.8 microns thickness were exposed to radiation from a VUV lamp from beneath different cover windows to provide different exposure wavelength ranges: MgF2 (115 to 400 nm), crystalline quartz (140 to 400 nm), and fused silica (FS, 155 to 400 nm). Following exposure, FEP film specimens were tensile tested to determine the ultimate tensile strength and elongation at failure as a function of the exposure duration for each wavelength range. The graphs show the effect of ultraviolet exposure on the mechanical properties of the FEP samples.

  19. Photooxidation of plasma polymerized polydimethylsiloxane film by 172 nm vacuum ultraviolet light irradiation in dilute oxygen

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.

    2006-08-01

    Plasma polymerized polydimethylsiloxane films irradiated under different partial pressures of oxygen with a 172nm vacuum ultraviolet light were investigated in order to clarify the roles of molecular oxygen and photons in photooxidation. The thickness, densities, surface roughness, elemental compositions, and molecular structures of the irradiated and unirradiated films were examined by using glazing incidence x-ray reflectivity, Rutherford backscattering, infrared, and x-ray absorption (XAS) spectroscopies. Photooxidation is hardly promoted by irradiation in a high vacuum of 1×10-4Pa, though photodesorption of the methyl group and formation of Si-H bonds were observed. Silica films thicker than 140nm were formed at room temperature by irradiating them in low pressure oxygen gases. The degree of oxidation was smaller for the oxygen pressure of 10kPa than for 83Pa. Si K-edge XAS was performed to clarify the change of coordination environment of silicon by photooxidation in dilute oxygen flow containing less than 5ppm of molecular oxygen.

  20. System for time-discretized vacuum ultraviolet spectroscopy of spark breakdown in air

    SciTech Connect

    Ryberg, D.; Fierro, A.; Dickens, J.; Neuber, A.

    2014-10-15

    A system for time-discretized spectroscopic measurements of the vacuum ultraviolet (VUV) emission from spark discharges in the 60-160 nm range has been developed for the study of early plasma-forming phenomena. The system induces a spark discharge in an environment close to atmospheric conditions created using a high speed puff value, but is otherwise kept at high vacuum to allow for the propagation of VUV light. Using a vertical slit placed 1.5 mm from the discharge the emission from a small cross section of the discharge is allowed to pass into the selection chamber consisting of a spherical grating, with 1200 grooves/mm, and an exit slit set to 100 μm. Following the exit slit is a photomultiplier tube with a sodium salicylate scintillator that is used for the time discretized measurement of the VUV signal with a temporal resolution limit of 10 ns. Results from discharges studied in dry air, Nitrogen, SF{sub 6}, and Argon indicate the emission of light with wavelengths shorter than 120 nm where the photon energy begins to approach the regime of direct photoionization.

  1. Vacuum Ultraviolet Radiation and Atomic Oxygen Durability Evaluation of HST Bi-Stem Thermal Shield Materials

    NASA Technical Reports Server (NTRS)

    Dever, Joyce; deGroh, Kim K.

    2002-01-01

    Bellows-type thermal shields were used on the bi-stems of replacement solar arrays installed on the Hubble Space Telescope (HST) during the first HST servicing mission (SMI) in December 1993. These thermal shields helped reduce the problem of thermal gradient- induced jitter observed with the original HST solar arrays during orbital thermal cycling and have been in use on HST for eight years. This paper describes ground testing of the candidate solar array bi-stem thermal shield materials including backside aluminized Teflon(R)FEP (fluorinated ethylene propylene) with and without atomic oxygen (AO) and ultraviolet radiation protective surface coatings for durability to AO and combined AO and vacuum ultraviolet (VOV) radiation. NASA Glenn Research Center (GRC) conducted VUV and AO exposures of samples of candidate thermal shield materials at HST operational temperatures and pre- and post-exposure analyses as part of an overall program coordinated by NASA Goddard Space Flight Center (GSFC) to determine the on-orbit durability of these materials. Coating adhesion problems were observed for samples having the AO- and combined AO/UV-protective coatings. Coating lamination occurred with rapid thermal cycling testing which simulated orbital thermal cycling. This lack of adhesion caused production of coating flakes from the material that would have posed a serious risk to HST optics if the coated materials were used for the bi-stem thermal shields. No serious degradation was observed for the uncoated aluminized Teflon(R) as evaluated by optical microscopy, although atomic force microscopy (AFM) microhardness testing revealed that an embrittled surface layer formed on the uncoated Teflon(R) surface due to vacuum ultraviolet radiation exposure. This embrittled layer was not completely removed by AO erosion, No cracks or particle flakes were produced for the embrittled uncoated material upon exposure to VUV and AO at operational temperatures to an equivalent exposure of

  2. A Study of the Laser-Induced Breakdown Spectroscopy of Carbon in the Ultraviolet Wavelength Range Under Vacuum Conditions

    NASA Astrophysics Data System (ADS)

    Pan, Congyuan; Du, Xuewei; Zeng, Qiang; Yu, Yunsi; Wang, Shengbo; Wang, Qiuping

    2015-08-01

    The influence of a vacuum on the laser-induced breakdown spectroscopy (LIBS) of carbon in the ultraviolet wavelength range is studied. Experiments are performed with graphite using a LIBS system, which consists of a 1064 nm Nd:YAG laser, a vacuum pump, a spectrometer and a vacuum chamber. The vacuum varies from 10 Pa to 1 atm. Atomic lines as well as singly and doubly charged ions are confirmed under the vacuums. A temporal evolution analysis of intensity is performed for the atomic lines of C I 193.09 nm and C I 247.86 nm under different vacuum conditions. Both time-integrated and time-resolved intensity evolutions under vacuums are achieved. The lifetimes of the two atomic lines have similar trends, which supports the point of view of a ‘soft spot’. Variations of plasma temperature and electron density under different vacuums are measured. This study is helpful for research on carbon detection using LIBS under vacuum conditions. supported by the National Special Fund for the Development of Major Research Equipment and Instruments of China (No. 2014YQ120351)

  3. Interpretation of the vacuum ultraviolet photoabsorption spectrum of iodobenzene by ab initio computations.

    PubMed

    Palmer, Michael H; Ridley, Trevor; Hoffmann, Søren Vrønning; Jones, Nykola C; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Biczysko, Malgorzata; Baiardi, Alberto; Limão-Vieira, Paulo

    2015-04-01

    Identification of many Rydberg states in iodobenzene, especially from the first and fourth ionization energies (IE1 and IE4, X(2)B1 and C(2)B1), has become possible using a new ultraviolet (UV) and vacuum-ultraviolet (VUV) absorption spectrum, in the region 29 000-87 000 cm(-1) (3.60-10.79 eV), measured at room temperature with synchrotron radiation. A few Rydberg states based on IE2 (A(2)A2) were found, but those based on IE3 (B(2)B2) are undetectable. The almost complete absence of observable Rydberg states relating to IE2 and IE3 (A(2)A2 and B(2)B2, respectively) is attributed to them being coupled to the near-continuum, high-energy region of Rydberg series converging on IE1. Theoretical studies of the UV and VUV spectra used both time-dependent density functional (TDDFT) and multi-reference multi-root doubles and singles-configuration interaction methods. The theoretical adiabatic excitation energies, and their corresponding vibrational profiles, gave a satisfactory interpretation of the experimental results. The calculations indicate that the UV onset contains both 1(1)B1 and 1(1)B2 states with very low oscillator strength, while the 2(1)B1 state was found to lie under the lowest ππ(∗) 1(1)A1 state. All three of these (1)B1 and (1)B2 states are excitations into low-lying σ(∗) orbitals. The strongest VUV band near 7 eV contains two very strong ππ(∗) valence states, together with other weak contributors. The lowest Rydberg 4b16s state (3(1)B1) is very evident as a sharp multiplet near 6 eV; its position and vibrational structure are well reproduced by the TDDFT results. PMID:25854238

  4. Vacuum ultraviolet spectral emission properties of Ga, In and Sn droplet-based laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Brandstätter, Markus; Abhari, Reza S.

    2016-08-01

    The Emission Spectra of gallium, indium and tin droplet-based laser produced plasmas are presented in the Vacuum Ultraviolet (VUV) emission range from 30 nm to 160 nm. The Ga ion transitions are investigated in detail as a function of background pressure level and laser irradiance. Different wavelength emission regions were detected according to the level of background gas. At short wavelengths (i.e. 30-50 nm) the line emission from the higher charge states is reduced with increasing pressure, while at longer wavelengths (i.e. 100-160 nm) the trend is inverted, as the plasma emission intensity of the lower charge states increases with higher background gas pressure level. The emitted lines are fitted with Voigt profiles to determine the electron density. The electron temperature is obtained from a fit based on the Planck distribution. These estimations are then used to identify the relevant processes that lead to the different charge state emissions as a function of background gas. Langmuir Probe measurements are also reported for evaluating the ion kinetic energy as a function of background gas. The gallium spectra are calibrated in units of spectral radiance, together with spectra from indium and tin. This calibration allows absolute power estimations from the light source in the VUV region. The presented experimental results are relevant as fundamental plasma emission spectroscopic measurements in an almost unexplored wavelength region as well as for applications such as Extreme Ultraviolet Lithography to determine the so-called Out-of-Band (OoB) radiation emission and for metrology applications for future inspection tools.

  5. High-intensity coherent vacuum ultraviolet source using unfocussed commercial dye lasers

    NASA Astrophysics Data System (ADS)

    Albert, Daniel R.; Proctor, David L.; Floyd Davis, H.

    2013-06-01

    Using two or three commercial pulsed nanosecond dye lasers pumped by a single 30 Hz Nd:YAG laser, generation of 0.10 mJ pulses at 125 nm (6 × 1013 photons/pulse) has been demonstrated by resonance enhanced four-wave mixing of collimated (unfocussed) laser beams in mercury (Hg) vapor. Phase matching at various vacuum ultraviolet (VUV) wavelengths is achieved by tuning one laser in the vicinity of the 6 1S0 → 6 3P1 resonance near 253.1 nm. A number of different mixing schemes are characterized. Our observations using broadband lasers (˜0.15 cm-1 bandwidths) are compared to previous calculations pertaining to four-wave mixing of low intensity narrowband laser beams. Prospects for further increases in pulse energies are discussed. We find that VUV tuning curves and intensities are in good agreement with theoretical predictions. The utility of the VUV light source is demonstrated by "soft universal" single-photon VUV ionization in crossed molecular beam studies and for generation of light at 130.2 nm for oxygen atom Rydberg time-of-flight experiments.

  6. a Measurement of the Optical Oscillator Strengths of Noble Gas Resonance Transitions in the Vacuum Ultraviolet

    NASA Astrophysics Data System (ADS)

    Ligtenberg, Robert Coenraad Gerard

    We report the results of an accurate measurement of optical oscillator strengths of the prominent resonance lines of He, Ne, Ar and Kr in the vacuum ultraviolet. To measure the oscillator strength of a resonance line we make use of the absorption of the resonance radiation as it passes through the gas to a detector. The transmission of this radiation through a layer of gas of finite thickness is measured as a function of the number density of the gas. The transmission function is fitted to this data to obtain the absorption oscillator strength. The accuracy of the present measurements ranges from 2.5% to 4% and is reflected in the uncertainties presented below. The results are for He I (58.4 nm) 0.2683 +/- 0.0075 (2.8%), He I (53.7 nm) 0.0717 +/- 0.0024 (3.4%), Ne I (74.4 nm) 0.01017 +/- 0.00030 (2.9%), Ne I (73.6 nm) 0.1369 +/- 0.0035 (2.6%), Ar I (106.7 nm) 0.0616 +/- 0.0021 (3.4%), Ar I (104.8 nm) 0.2297 +/- 0.0093 (4.0%), Kr I (123.6 nm) 0.1751 +/- 0.0049 (2.8%) and Kr I (116.5 nm) 0.1496 +/- 0.0038 (2.5%).

  7. Laser-assisted vacuum arc extreme ultraviolet source: a comparison of picosecond and nanosecond laser triggering

    NASA Astrophysics Data System (ADS)

    Beyene, Girum A.; Tobin, Isaac; Juschkin, Larissa; Hayden, Patrick; O’Sullivan, Gerry; Sokell, Emma; Zakharov, Vassily S.; Zakharov, Sergey V.; O’Reilly, Fergal

    2016-06-01

    Extreme ultraviolet (EUV) light generation by hybrid laser-assisted vacuum arc discharge plasmas, utilizing Sn-coated rotating-disc-electrodes, was investigated. The discharge was initiated by localized ablation of the liquid tin coating of the cathode disc by a laser pulse. The laser pulse, at 1064 nm, was generated by Nd:YAG lasers with variable energy from 1 to 100 mJ per pulse. The impact of shortening the laser pulse from 7 ns to 170 ps on the EUV generation has been investigated in detail. The use of ps pulses resulted in an increase in emission of EUV radiation. With a fixed discharge energy of ~4 J, the EUV conversion efficiency tends to plateau at ~2.4  ±  0.25% for the ps laser pulses, while for the ns pulses, it saturates at ~1.7  ±  0.3%. Under similar discharge and laser energy conditions, operating the EUV source with the ps-triggering resulted also in narrower spectral profiles of the emission in comparison to ns-triggering. The results indicate an advantage in using ps-triggering in laser-assisted discharges to produce brighter plasmas required for applications such as metrology.

  8. Contribution of Vacuum-Ultraviolet Transitions of Molecular Nitrogen to Radiative Heat Flux During Atmospheric Reentry

    NASA Astrophysics Data System (ADS)

    Liebhart, Heiko; Fertig, Markus; Herdrich, Georg; Fasoulas, Stefanos; Roser, Hans-Peter

    2011-02-01

    Within this work we investigate the radiative properties of molecular nitrogen with respect to the highly excited electronic states giving rise to radiative transitions occurring in the spectral range of Vacuum-Ultraviolet (VUV) radiation. This is done in order to shed light on the role of VUV radiation of molecular nitrogen in the radiative heat load encountered by a vessel during highspeed atmospheric reentry. The considered transitions bands are the Lyman - Birge - Hopfield (a1IIg - X1Σ+g ), Birge - Hopfield I (b1Πu - X1Σ+g ), Birge-Hopfield II(b Σu -X Σg ), Caroll - Yoshino (c'41Σ+u - X1Σ+g ), Worley - Jenkins (c31IIu - X1Σ+g ), Worley (o31IIu - X1Σ+g ), and e Σu - X Σg band. The approach to retrieve the relevant parameters for the line by line radiation simulation follows common methods of calculation, which are the re- construction of the potential energy function via the Rydberg-Klein-Rees (RKR) method and subsequently solving the correspond- ing radial Schrodinger equation. Absorption and emission spectra are then calculated for a known equilibrium test condition of air plasma to illustrate the contribution of the VUV transitions to the radiation. The influence of the VUV radiation on the heat load experienced by a reentry vehicle is illustrated with an exemplary CFD calculation.

  9. Electrical behavior and vacuum ultraviolet radiation efficiency of monofilamentary xenon dielectric barrier discharges

    SciTech Connect

    Merbahi, N.; Ledru, G.; Sewraj, N.; Marchal, F.

    2007-06-15

    In this paper we report the experimental investigation of a pure xenon monofilamentary dielectric barrier discharge (DBD), using a high voltage power supply. Stable microdischarges were achieved and studied in the pressure range of 100-400 Torr, at frequencies between 10 and 40 kHz. Successive 3 ns exposure time snapshots of the discharge clearly show how it built up. Its diameter was about 0.26 mm. The discharge voltage and current were determined from the measurement of the supply voltage and current. Compared to those in argon, the current pulses were shorter (less than 30 ns, above 200 Torr) and had much higher peak values. Ignition voltages were also higher in the heavier gas. Electrical energy and vacuum ultraviolet radiation energy of the second continuum of xenon were both independent of frequency. They both varied almost linearly with pressure. The measured DBD vuv efficiency of a single xenon microdischarge reported here was between 55% and 60%, and the maximum value was reached for 200 Torr. These values were twice those reported for multifilamentary discharges working with a sinusoidal supply. They were similar to those obtained for multifilamentary dielectric barrier discharges excited with short voltage pulses.

  10. The effects of vacuum ultraviolet radiation on low-k dielectric films

    SciTech Connect

    Sinha, H.; Ren, H.; Nichols, M. T.; Lauer, J. L.; Shohet, J. L.; Tomoyasu, M.; Russell, N. M.; Jiang, G.; Antonelli, G. A.; Fuller, N. C.; Engelmann, S. U.; Lin, Q.; Ryan, V.; Nishi, Y.

    2012-12-01

    Plasmas, known to emit high levels of vacuum ultraviolet (VUV) radiation, are used in the semiconductor industry for processing of low-k organosilicate glass (SiCOH) dielectric device structures. VUV irradiation induces photoconduction, photoemission, and photoinjection. These effects generate trapped charges within the dielectric film, which can degrade electrical properties of the dielectric. The amount of charge accumulation in low-k dielectrics depends on factors that affect photoconduction, photoemission, and photoinjection. Changes in the photo and intrinsic conductivities of SiCOH are also ascribed to the changes in the numbers of charged traps generated during VUV irradiation. The dielectric-substrate interface controls charge trapping by affecting photoinjection of charged carriers into the dielectric from the substrate. The number of trapped charges increases with increasing porosity of SiCOH because of charge trapping sites in the nanopores. Modifications to these three parameters, i.e., (1) VUV induced charge generation, (2) dielectric-substrate interface, and (3) porosity of dielectrics, can be used to reduce trapped-charge accumulation during processing of low-{kappa} SiCOH dielectrics. Photons from the plasma are responsible for trapped-charge accumulation within the dielectric, while ions stick primarily to the surface of the dielectrics. In addition, as the dielectric constant was decreased by adding porosity, the defect concentrations increased.

  11. Vacuum-ultraviolet-induced charge depletion in plasma-charged patterned-dielectric wafers

    SciTech Connect

    Upadhyaya, G. S.; Shohet, J. L.; Kruger, J. B.

    2009-03-01

    Plasma-induced charging of patterned-dielectric structures during device fabrication can cause structural and electrical damage to devices. In this work, we report on vacuum-ultraviolet (VUV) radiation-induced charge depletion in plasma-charged patterned-silicon-oxide dielectric wafers. Charge depletion is studied as a function of photon energy and the aspect ratio of hole structures. The wafers were charged in a plasma and subsequently exposed to monochromatic-synchrotron-VUV. Surface-potential measurements after VUV exposure showed that photon energies less than 11 eV were beneficial in depleting the plasma-induced charge from the patterned-dielectric wafers. In addition, for a given photon-flux density and for photon energies less than 11 eV, VUV-induced charge depletion decreases with increasing hole aspect ratio. The results are explained with a physically plausible equivalent-circuit model, which suggests that both electron photoinjection from Si into the oxide and oxide surface conductivity play an important role in the charge-depletion process.

  12. Resonantly enhanced method for generation of tunable, coherent vacuum-ultraviolet radiation

    DOEpatents

    Glownia, J.H.; Sander, R.K.

    1982-06-29

    Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but no higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

  13. Gas chromatography-vacuum ultraviolet spectroscopy for analysis of fatty acid methyl esters.

    PubMed

    Fan, Hui; Smuts, Jonathan; Bai, Ling; Walsh, Phillip; Armstrong, Daniel W; Schug, Kevin A

    2016-03-01

    A new vacuum ultraviolet (VUV) detector for gas chromatography was recently developed and applied to fatty acid methyl ester (FAME) analysis. VUV detection features full spectral acquisition in a wavelength range of 115-240nm, where virtually all chemical species absorb. VUV absorption spectra of 37 FAMEs, including saturated, monounsaturated, and polyunsaturated types were recorded. Unsaturated FAMEs show significantly different gas phase absorption profiles than saturated ones, and these classes can be easily distinguished with the VUV detector. Another advantage includes differentiating cis/trans-isomeric FAMEs (e.g. oleic acid methyl ester and linoleic acid methyl ester isomers) and the ability to use VUV data analysis software for deconvolution of co-eluting signals. As a universal detector, VUV also provides high specificity, sensitivity, and a fast data acquisition rate, making it a powerful tool for fatty acid screening when combined with gas chromatography. The fatty acid profile of several food oil samples (olive, canola, vegetable, corn, sunflower and peanut oils) were analyzed in this study to demonstrate applicability to real world samples. PMID:26471553

  14. International Test Program for Synergistic Atomic Oxygen and Vacuum Ultraviolet Radiation Exposure of Spacecraft Materials

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K.

    2001-01-01

    The components and materials of spacecraft in low Earth orbit can degrade in thermal and optical performance through interaction with atomic oxygen and vacuum ultraviolet (VUV) radiation, which are predominant in low Earth orbit. Because of the importance of low Earth orbit durability and performance to manufacturers and users, an international test program for assessing the durability of spacecraft materials and components was initiated. Initial tests at the NASA Glenn Research Center consisted of exposure of samples representing a variety of thermal control paints, multilayer insulation materials, and Sun sensors that have been used in space. Materials donated from various international sources were tested alongside materials whose performance is well known, such as Teflon FEP, Kapton H, or Z-93-P white paint. The optical, thermal, or mass loss data generated during the tests were then provided to the participating material suppliers. Data were not published unless the participant donating the material consented to publication. The test program is intended to give spacecraft builders and users a better understanding of degradation processes and effects so that they can improve their predictions of spacecraft performance.

  15. Internal energies of ion-sputtered neutral tryptophan and thymine molecules determined by vacuum ultraviolet photoionization.

    PubMed

    Zhou, Jia; Takahashi, Lynelle K; Wilson, Kevin R; Leone, Stephen R; Ahmed, Musahid

    2010-05-01

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi(3)(+) indicates that the ion-sputtered parent molecules have approximately 2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi(3)(+) ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis. PMID:20353160

  16. Vacuum ultraviolet electron impact excitation of the styrene molecule: cross sections and oscillator strengths

    NASA Astrophysics Data System (ADS)

    Boechat-Roberty, H. M.; Lucas, C. A.; Lopes, M. C. A.; Rocco, M. L. M.; de Souza, G. G. B.

    2009-05-01

    The vacuum ultraviolet electronic excitation of the styrene molecule has been studied in the 0-50 eV energy range, using angle-resolved electron-energy-loss spectroscopy at an incident energy of 1 keV. Intense new features have been observed at 10.3, 11.8, 13.7 and 17.1 eV. They were tentatively assigned to high-energy transitions originating from σ electrons or to double excitations involving π electrons. The absolute generalized oscillator strengths and absolute inelastic differential cross sections have been determined for the band centred at 5.3 eV, associated with the 2,3 1A'<--1 1A' transitions. The absolute elastic differential cross section has also been determined over an angular range of 2.5°-22.0°. The valence photoabsorption spectrum of styrene, derived from the electron-energy-loss spectrum, is compared to a previously measured benzene spectrum in the 3-45 eV energy range.

  17. Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser

    DOE PAGESBeta

    Allaria, Enrico; Diviacco, Bruno; Callegari, Carlo; Finetti, Paola; Mahieu, Benoît; Viefhaus, Jens; Zangrando, Marco; De Ninno, Giovanni; Lambert, Guillaume; Ferrari, Eugenio; et al

    2014-12-02

    The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independentmore » instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.« less

  18. Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser

    SciTech Connect

    Allaria, Enrico; Diviacco, Bruno; Callegari, Carlo; Finetti, Paola; Mahieu, Benoît; Viefhaus, Jens; Zangrando, Marco; De Ninno, Giovanni; Lambert, Guillaume; Ferrari, Eugenio; Buck, Jens; Ilchen, Markus; Vodungbo, Boris; Mahne, Nicola; Svetina, Cristian; Spezzani, Carlo; Di Mitri, Simone; Penco, Giuseppe; Trovó, Mauro; Fawley, William M.; Rebernik, Primoz R.; Gauthier, David; Grazioli, Cesare; Coreno, Marcello; Ressel, Barbara; Kivimäki, Antti; Mazza, Tommaso; Glaser, Leif; Scholz, Frank; Seltmann, Joern; Gessler, Patrick; Grünert, Jan; De Fanis, Alberto; Meyer, Michael; Knie, André; Moeller, Stefan P.; Raimondi, Lorenzo; Capotondi, Flavio; Pedersoli, Emanuele; Plekan, Oksana; Danailov, Miltcho B.; Demidovich, Alexander; Nikolov, Ivaylo; Abrami, Alessandro; Gautier, Julien; Lüning, Jan; Zeitoun, Philippe; Giannessi, Luca

    2014-12-02

    The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independent instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.

  19. Conformation-specific pathways of beta-alanine: a vacuum ultraviolet photoionization and theoretical study.

    PubMed

    Zhang, Lidong; Pan, Yang; Guo, Huijun; Zhang, Taichang; Sheng, Liusi; Qi, Fei; Lo, Po-Kam; Lau, Kai-Chung

    2009-05-21

    We report a photoionization and dissociative photoionization study of beta-alanine using IR laser desorption combined with synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry. Fragments at m/z = 45, 44, 43, and 30 yielded from photoionization are assigned to NH(3)CH(2)CH(2)(+), NH(2)CHCH(3)(+), NH(2)CHCH(2)(+), and NH(2)CH(2)(+), respectively. Some new conformation-specific dissociation channels and corresponding dissociation energies for the observed fragments are established and determined with the help of ab initio G3B3 calculations and measurements of photoionization efficiency (PIE) spectra. The theoretical values are in fair agreement with the experimental results. Three low-lying conformers of the beta-alanine cation, including two gauche conformers G1+, G2+ and one anti conformer A+ are investigated by G3B3 calculations. The conformer G1+ (intramolecular hydrogen bonding N-H...OC) is found to be another precursor in forming the NH(3)CH(2)CH(2)(+) ion, which is complementary to the previously reported formation pathway that only occurs with the conformer G2+ (intramolecular hydrogen bonding O-H...N). Species NH(2)CHCH(2)(+) may come from the contributions of G1+, G2+, and A+ via different dissociation pathways. The most abundant fragment ion, NH(2)CH(2)(+), is formed from a direct C-C bond cleavage. Intramolecular hydrogen transfer processes dominate most of the fragmentation pathways of the beta-alanine cation. PMID:19400571

  20. Design of an ultrashort optical transmission cell for vacuum ultraviolet spectroscopy of supercritical fluids.

    PubMed

    Janik, Ireneusz; Marin, Timothy W

    2015-01-01

    We present the design and characteristics of an ultrathin flow cell optimized for vacuum ultraviolet transmission spectroscopy experiments on supercritical fluids. The cell operates satisfactorily at pressures up to 300 bar and temperatures up to 390 °C. The variable path length concept of the cell allows for optical transmission studies of analytes ranging from dense condensed-phase systems to gas-phase systems. The path length of the cell can be adjusted from hundreds of nanometers to hundreds of micrometers by an exchange of a variable thickness spacer sandwiched between two sapphire windows. In the path length range from nanometers to single micrometers, metal vapor deposited on one or both of the two sandwiched optical windows constitute the spacer. Spacers with thicknesses of 2 μm and greater can be constructed from simple commercially available metal foils. The cell has been used to measure the lowest-lying absorption band of water in both the vapor and condensed phases from room temperature up to and above the critical point. It has also found application in the studies of aqueous ions and nonaqueous liquids including various common organic solvents and carbon dioxide. PMID:25638117

  1. Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: Wavelength, pressure and temperature dependency.

    SciTech Connect

    Chakraborty, Subrata; Davis, Ryan; Ahmed, Musahid; Jackson, Teresa L.; Thiemens, Mark H.

    2012-01-03

    Several absorption bands exist in the VUV region of Carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. An experimental investigation of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ~13 to 11 eV) from the Advanced Light Source Synchrotron and direct measurement of the associated oxygen isotopic composition of the products are presented here. A wavelength dependency of the oxygen isotopic composition in the photodissociation product was observed. Slope values (δ'{sup 18}O/ δ'{sup 17}O) ranging from 0.76 to 1.32 were observed in oxygen three-isotope space (δ'{sup 18}O vs. δ'{sup 17}O) which correlated with increasing synchrotron photon energy, and indicate a dependency of the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope separation was observed for photodissociation at the 105 and 107 nm synchrotron bands and are found to be associated with accidental predissociation of the vibrational states ({nu} = 0 and 1) of the upper electronic state E{sup 1}Π. For each synchrotron band, a large (few hundred per mil) extent of isotopic fractionation was observed and the range of fractionation is a combination of column density and exposure time. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.

  2. Internal Energies of Ion-Sputtered Neutral Tryptophan and Thymine Molecules Determined by Vacuum Ultraviolet Photoionization

    SciTech Connect

    Zhou, Jia; Takahashi, Lynelle; Wilson, Kevin R.; Leone, Stephen R.; Ahmed, Musahid

    2010-03-11

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi3 + indicates that the ion-sputtered parent molecules have ~;;2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi3 + ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis.

  3. Initiation techniques and the vacuum-ultraviolet-radiation efficiency of a stabilized multichannel surface discharge

    NASA Astrophysics Data System (ADS)

    Tcheremiskine, V. I.; Uteza, O. P.; Sentis, M. L.; Mikheev, L. D.

    2006-01-01

    Multichannel surface discharges possess a number of advantageous characteristics for the optical pumping of photochemically driven lasers. This work reports on a type of large-area low-inductance sources of intense UV-VUV (vacuum-ultraviolet) radiation based on spatially stabilized multichannel discharges in gases. The discharges consist of several dozens of closely located parallel plasma channels initiated synchronously along a dielectric surface on the area of several hundred square centimeters. In comparison with a large-area diffuse surface discharge, the plasma confinement within relatively thin channels greatly improves the efficiency of the discharge emission in the VUV spectral range. Several techniques are introduced, which allow a synchronous formation and homogeneous development of multiple spatially stabilized discharge channels. Technical efficiency of the discharge radiation within the spectral range of 120-200nm reaches 5% and an effective brightness temperature of the radiating plasma exceeds 20kK. Synchronous operation of a number of multichannel discharge modules producing high-intensity submicrosecond optical pulses is demonstrated, which is of importance for the pump source scaling and geometrical adaptation.

  4. Comparison of surface vacuum ultraviolet emissions with resonance level number densities. I. Argon plasmas

    SciTech Connect

    Boffard, John B. Lin, Chun C.; Culver, Cody; Wang, Shicong; Wendt, Amy E.; Radovanov, Svetlana; Persing, Harold

    2014-03-15

    Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. The highly energetic photons can induce surface damage by driving surface reactions, disordering surface regions, and affecting bonds in the bulk material. In argon plasmas, the VUV emissions are due to the decay of the 1s{sub 4} and 1s{sub 2} principal resonance levels with emission wavelengths of 104.8 and 106.7 nm, respectively. The authors have measured the number densities of atoms in the two resonance levels using both white light optical absorption spectroscopy and radiation-trapping induced changes in the 3p{sup 5}4p→3p{sup 5}4s branching fractions measured via visible/near-infrared optical emission spectroscopy in an argon inductively coupled plasma as a function of both pressure and power. An emission model that takes into account radiation trapping was used to calculate the VUV emission rate. The model results were compared to experimental measurements made with a National Institute of Standards and Technology-calibrated VUV photodiode. The photodiode and model results are in generally good accord and reveal a strong dependence on the neutral gas temperature.

  5. The use of vacuum ultraviolet irradiation to oxidize SO₂ and NOx for simultaneous desulfurization and denitrification.

    PubMed

    Ye, Junhui; Shang, Jing; Li, Qian; Xu, Weiwei; Liu, Jia; Feng, Xiang; Zhu, Tong

    2014-04-30

    A simple and efficient method for simultaneous desulfurization and denitrification via vacuum ultraviolet (VUV) irradiation and with no additional chemicals is presented. The simultaneous removal of 90% SO2 and 96% NOx (NO+NO2) was achieved from the simulated flue gas under the irradiation from a low-pressure mercury lamp with main wavelengths of 185 and 254 nm, respectively. The composition, flow rate, and temperature of the simulated flue gas, as well as the VUV light intensity, were evaluated as the factors impacting on the efficiency of SO2 and NOx removal. The OH, HO2, O, and O3 produced from the photolysis of H2O and O2 were concluded as the major reactive oxygen species that oxidized SO2 and NOx. The additional OH and HO2 generated through the reactions of NO+HO2 and SO2+OH/HO2 improved treatment efficiency, while the oxidation products of NOx, e.g., NO2, HNO2, HNO3, and HNO4, consumed massive reactive oxygen species (such as O, OH, and HO2) and thereby reducing the removal efficiencies. The main reaction products were characterized as H2SO4 and HNO3 by ion chromatography, which could be used as chemical or fertilizer raw materials. PMID:24632363

  6. Sterilization of Bacillus atrophaeus using OH radicals supplied by vacuum ultraviolet method

    NASA Astrophysics Data System (ADS)

    Yonetamari, Kenta; Tokumitsu, Yusuke; Yonemori, Seiya; Ono, Ryo; Yasuda, Hachiro; Mizuno, Akira

    2015-09-01

    Sterilization by cold plasma has widely been performed. It is well known that reactive oxygen species (ROS) has a potential of sterilization. However, it is not clear which ROS is effective on sterilization because a lot of types of ROS are produced in plasma. In this study, sterilization effect of OH radicals by vacuum ultraviolet (VUV) method was investigated. This method utilizes photodissociation reaction to produce ROS so it can produce ROS selectively. Wet and dry helium with and without 1% O2 gas was used to demonstrate sterilization effect of OH radicals. Gases were flowed in a quartz tube (inner diameter 2 mm, outer diameter 4 mm) at a flow rate of 1.5 L/min. The produced ROS flowed out of the quartz tube nozzle. A Xe2 excimer lamp emitting 172 +/- 7 nm VUV light was placed parallel to the quartz tube with a distance of 8 mm. The distance between the lower end of the lamp and the nozzle of quartz tube was changed from 3 to 15 cm. As a target of sterilization, Bacillus atrophaeus (ATCC 9372) was used. The density of OH radicals was measured using laser-induced fluorescence (LIF). As a result, sterilization using VUV method was verified. This result showed that OH radicals sterilized the bacteria.

  7. On the Dynamics of Xylene Isomers Excited in the Vacuum-Ultraviolet (VUV) Region.

    PubMed

    Papadopoulou, Christina C; Kaziannis, Spiridon; Kosmidis, Constantine

    2016-08-01

    We report on the dynamics of electronically excited o-, m-, and p-xylene on the femtosecond timescale by employing the vacuum-ultraviolet pump-IR probe mass spectrometry technique. The molecules were excited by the fifth harmonic (λ=160 nm) of a Ti:sapphire laser at a superposition of the S3 valence with several Rydberg states. The relaxation pathways were investigated by studying the parent P(+) and the fragment [P-H](+) and [P-CH3 ](+) time-resolved signals generated after interaction with the fundamental beam (λ=800 nm). Relaxation from the excited valence states was found to depend on the relative positions of the methyl groups on the ring. An increasing trend in the order o

  8. The vacuum ultraviolet beamline/endstations at NSRL dedicated to combustion research.

    PubMed

    Zhou, Zhongyue; Du, Xuewei; Yang, Jiuzhong; Wang, Yizun; Li, Chaoyang; Wei, Shen; Du, Liangliang; Li, Yuyang; Qi, Fei; Wang, Qiuping

    2016-07-01

    An undulator-based vacuum ultraviolet (VUV) beamline (BL03U), intended for combustion chemistry studies, has been constructed at the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China. The beamline is connected to the newly upgraded Hefei Light Source (HLS II), and could deliver photons in the 5-21 eV range, with a photon flux of 10(13) photons s(-1) at 10 eV when the beam current is 300 mA. The monochromator of the beamline is equipped with two gratings (200 lines mm(-1) and 400 lines mm(-1)) and its resolving power is 3900 at 7.3 eV for the 200 lines mm(-1) grating and 4200 at 14.6 eV for the 400 lines mm(-1) grating. The beamline serves three endstations which are designed for respective studies of premixed flame, fuel pyrolysis in flow reactor, and oxidation in jet-stirred reactor. Each endstation contains a reactor chamber, an ionization chamber where the molecular beam intersects with the VUV light, and a home-made reflectron time-of-flight mass spectrometer. The performance of the beamline and endstations with some preliminary results is presented here. The ability to detect reactive intermediates (e.g. H, O, OH and hydroperoxides) is advantageous in combustion chemistry research. PMID:27359154

  9. Determination of ionization energies of small silicon clusters with vacuum?ultraviolet (VUV) radiation

    SciTech Connect

    Kostko, Oleg; Leone, Stephen R.; Duncan, Michael A.; Ahmed, Musahid

    2009-09-23

    In this work we report on single photon vacuum ultraviolet photoionization of small silicon clusters (n=1-7) produced via laser ablation of Si. The adiabatic ionization energies (AIE) are extracted from experimental photoionization efficiency (PIE) curves with the help of Frank?Condon simulations, used to interpret the shape and onset of the PIE curves. The obtained AIEs are (all energies are in eV): Si (8.13+-0.05), Si2 (7.92+-0.05), Si3 (8.12+-0.05), Si4 (8.2+-0.1), Si5 (7.96+-0.07), Si6 (7.8+-0.1), and Si7 (7.8+-0.1). Most of the experimental AIE values are in good agreement with ab initio electronic structure calculations. To explain observed deviations between the experimental and theoretical AIEs for Si4 and Si6, a theoretical search of different isomers of these species is performed. Electronic structure calculations aid in the interpretation of the a2PIu state of Si2+ dimer in the PIE spectrum. Time dependent density functional theory (TD-DFT) calculations are performed to reveal the energies of electronically excited states in the cations for a number of Si clusters.

  10. Permanent hydrophilic modification of polypropylene and poly(vinyl alcohol) films by vacuum ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Belmonte, Guilherme Kretzmann; Charles, German; Strumia, Miriam Cristina; Weibel, Daniel Eduardo

    2016-09-01

    Polypropylene (PP) and Poly(vinyl alcohol) (PVA) both synthetics polymers but one of them biodegradable, were surface modified by vacuum ultraviolet (VUV) irradiation. After VUV irradiation in an inert nitrogen atmosphere, the films were exposed to oxygen gas. The treated films were characterized by water contact angle measurements (WCA), optical profilometry, FTIR-ATR, XPS, UPS and NEXAFS techniques. PP and PVA VUV-treated films reached superhydrophilic conditions (WCAs <10°) in about 30 min of irradiation under our experimental conditions. It was observed that when the WCAs reached about 35-40° the hydrophilicity was permanent in both polymers. These results contrasted with typical plasma treatments were a rapid hydrophobic recovery with aging time is usually observed. UPS and XPS data showed the presence of new functionalities on the PP and PVA surfaces that were assigned to COO, Cdbnd O, Csbnd O and Cdbnd C functional groups. Finally, grafting of styrene (ST) as a typical monomer was tested on PP films. It was confirmed that only in the VUV irradiated region an efficient grafting of ST or polymerized ST was found. Outside the irradiated regions no ST grafted was observed. Our results showed the potential use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region.

  11. Secondary Structure Prediction of Protein Constructs Using Random Incremental Truncation and Vacuum-Ultraviolet CD Spectroscopy

    PubMed Central

    Pukáncsik, Mária; Orbán, Ágnes; Nagy, Kinga; Matsuo, Koichi; Gekko, Kunihiko; Maurin, Damien; Hart, Darren; Kézsmárki, István; Vertessy, Beata G.

    2016-01-01

    A novel uracil-DNA degrading protein factor (termed UDE) was identified in Drosophila melanogaster with no significant structural and functional homology to other uracil-DNA binding or processing factors. Determination of the 3D structure of UDE is excepted to provide key information on the description of the molecular mechanism of action of UDE catalysis, as well as in general uracil-recognition and nuclease action. Towards this long-term aim, the random library ESPRIT technology was applied to the novel protein UDE to overcome problems in identifying soluble expressing constructs given the absence of precise information on domain content and arrangement. Nine constructs of UDE were chosen to decipher structural and functional relationships. Vacuum ultraviolet circular dichroism (VUVCD) spectroscopy was performed to define the secondary structure content and location within UDE and its truncated variants. The quantitative analysis demonstrated exclusive α-helical content for the full-length protein, which is preserved in the truncated constructs. Arrangement of α-helical bundles within the truncated protein segments suggested new domain boundaries which differ from the conserved motifs determined by sequence-based alignment of UDE homologues. Here we demonstrate that the combination of ESPRIT and VUVCD spectroscopy provides a new structural description of UDE and confirms that the truncated constructs are useful for further detailed functional studies. PMID:27273007

  12. High-intensity vacuum-ultraviolet generator utilizing a surface-discharge diode

    NASA Astrophysics Data System (ADS)

    Sagae, Michiaki; Sato, Eiichi; Oizumi, Teiji; Hayasi, Yasuomi; Tamakawa, Yoshiharu; Yanagisawa, Toru

    1995-05-01

    The fundamental studies on a high-intensity flash vacuum-ultraviolet (VUV) generator for producing water-window flash x rays are described. This generator consisted of the following essential components: a high- voltage power supply, a coaxial high-voltage pulser having a 0.2 (mu) F condenser, a Krytron pulser as a trigger device, a turbo molecular pump, and a VUV tube. The VUV tube employed a surface-discharge ferrite substrate having two copper electrodes and was evacuated by the pump with a pressure of 1.3 X 10-3 Pa. The condenser in the pulser was charged from 10 to 30 kV by the power supply, and the electric charges in the condenser were discharged to the radiation tube after closing a gap switch by the Krytron pulser. Then the flash VUV rays were generated. The maximum output voltage from the pulser was almost equivalent to the charged voltage, and both the tube voltage and current displayed damped oscillations. The maximum values of the tube voltage and current were approximately 23 kV and 13 kA, respectively. Since the effective accelerating voltage was substantially decreased by the substrate, soft x rays were easily generated. The pulse durations of the VUV rays including water window x rays were nearly equivalent to those of the damped oscillations of the voltage and current, and their values were less than 30 microsecond(s) .

  13. Chiroptical study of α-aliphatic amino acid films in the vacuum ultraviolet region.

    PubMed

    Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Kaneko, Fusae; Nakagawa, Kazumichi

    2010-11-11

    A series of natural circular dichroism (CD) and absorption spectra for films of α-aliphatic amino acids--such as alanine, aminobutyric acid, norvaline, norleucine, valine, leucine, and isoleucine--in the vacuum ultraviolet (VUV) region were observed with the absolute values of optical constants at the undulator-based CD beamline TERAS BL5. Preliminary predictions of some CD spectra were also performed, based on quantum-chemical calculations using the crystal structure. Although the absorption spectra show similar features to each other, significant differences between the CD spectra were found, especially in the 7-8 eV region. The CD spectra of aliphatic amino acids with branched alkyl groups in the side-chain--such as valine, leucine, and isoleucine--exhibit strong negative CD peaks in this energy region. In contrast, the corresponding CD peaks were weak or absent in the spectra of amino acids with straight alkyl groups. Our simple calculation, and the absorption spectra of alkanes, suggest that this difference partly originates from the contribution of the alkyl group. Clear discrepancies between the CD spectra of these amino acids in solutions and those in the solid state were also observed; this is probably caused by the different molecular structures in each state. Our results clearly indicated that CD spectra in the VUV region were very sensitive to the conformations of chiral molecules. PMID:20958008

  14. Vacuum Ultraviolet Photon-stimulated Oxidation of Buried Ice: Graphite Grain Interfaces

    NASA Astrophysics Data System (ADS)

    Shi, J.; Grieves, G. A.; Orlando, T. M.

    2015-05-01

    The vacuum ultraviolet (VUV) synthesis of CO and CO2 on ice-coated graphite and isotopic labeled 13C graphite has been examined for temperatures between 40 and 120 K. The results show that CO and CO2 can be formed at the buried ice:graphite interface with Lyα photon irradiation via the reaction of radicals (O and OH) produced by direct photodissociation and the dissociative electron attachment of the interfacial water molecules. The synthesized CO and CO2 molecules can desorb in hot photon-dominated regions and are lost to space when ice coated carbonaceous dust grains cycle within the protoplanetary disks. Thus, the nonthermal formation of CO and CO2 at the buried ice:grain interface by VUV photons may help regulate the carbon inventory during the early stage of planet formation. This may contribute to the carbon deficits in our solar system and suggests that a universal carbon deficit gradient may be expected within astrophysical bodies surrounding center stars.

  15. Outgassing Measurements for Three Materials, Combined with Vacuum Ultraviolet Radiation Illumination of the Volatile Condensable Materials

    NASA Technical Reports Server (NTRS)

    Albyn, Keith

    2005-01-01

    The photolysis of three organic materials, by vacuum ultraviolet (VUV) radiation, has been quantified using 15-MHz temperature-controlled quartz microbalances (TQCM's). The rate at which molecular species, released from the individual samples, condensed on two TQCM s was measured for periods of up to 139.9-hours. The individual samples were heated in an effusion cell and the emitted molecular species collected on a pair of TQCM's which were maintained at -40 degrees Celsius. At several points during the deposition measurement, the deposition surface of one TQCM was illuminated by a 30 Watt deuterium lamp, and the loss of material from that surface was observed. V W illumination of the TQCM, concurrent with condensation, reduced the rate that material was lost from the deposition surface. These measurements present a contrasting picture of molecular deposition, in the presence of VUV, to that presented by other investigators who observed an enhanced rate of molecular deposition, when the deposition surface was illuminated by VUV.

  16. High-resolution vacuum-ultraviolet photoabsorption spectra of 1-butyne and 2-butyne

    SciTech Connect

    Jacovella, U.; Holland, D. M. P.; Boyé-Péronne, S.; Gans, B.; Oliveira, N. de; Joyeux, D.; Archer, L. E.; Lucchese, R. R.; Xu, H.; Pratt, S. T.

    2015-07-21

    The absolute photoabsorption cross sections of 1- and 2-butyne have been recorded at high resolution by using the vacuum-ultraviolet Fourier-Transform spectrometer at the SOLEIL Synchrotron. Both spectra show more resolved structure than previously observed, especially in the case of 2-butyne. In this work, we assess the potential importance of Rydberg states with higher values of orbital angular momentum, l, than are typically observed in photoabsorption experiments from ground state molecules. We show how the character of the highest occupied molecular orbitals in 1- and 2-butyne suggests the potential importance of transitions to such high-l (l = 3 and 4) Rydberg states. Furthermore, we use theoretical calculations of the partial wave composition of the absorption cross section just above the ionization threshold and the principle of continuity of oscillator strength through an ionization threshold to support this conclusion. The new absolute photoabsorption cross sections are discussed in light of these arguments, and the results are consistent with the expectations. This type of argument should be valuable for assessing the potential importance of different Rydberg series when sufficiently accurate direct quantum chemical calculations are difficult, for example, in the n ≥ 5 manifolds of excited states of larger molecules.

  17. Resonantly enhanced method for generation of tunable, coherent vacuum ultraviolet radiation

    DOEpatents

    Glownia, James H.; Sander, Robert K.

    1985-01-01

    Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but to higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

  18. Si nanocrystals embedded in SiO{sub 2}: Optical studies in the vacuum ultraviolet range

    SciTech Connect

    Pankratov, V.; Osinniy, V.; Kotlov, A.; Nylandsted Larsen, A.; Bech Nielsen, B.

    2011-01-15

    Photoluminescence excitation and transmission spectra of Si nanocrystals of different diameters embedded in a SiO{sub 2} matrix have been investigated in the broad visible-vacuum ultraviolet spectral range using synchrotron radiation. The dependence of the photoluminescence excitation spectra on the nanocrystals size was experimentally established. It is shown that the photoluminescence excitation and absorption spectra are significantly blueshifted with decreasing Si nanocrystal size. A detailed comparison of photoluminescence excitation and absorption spectra with data from theoretical modeling has been done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO{sub 2} matrix on the optical and luminescence properties of the embedded Si nanocrystals is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO{sub 2} and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO{sub 2}.

  19. Steady-State Vacuum Ultraviolet Exposure Facility With Automated Lamp Calibration and Sample Positioning Fabricated

    NASA Technical Reports Server (NTRS)

    Sechkar, Edward A.; Steuber, Thomas J.; Banks, Bruce A.; Dever, Joyce A.

    2000-01-01

    The Next Generation Space Telescope (NGST) will be placed in an orbit that will subject it to constant solar radiation during its planned 10-year mission. A sunshield will be necessary to passively cool the telescope, protecting it from the Sun s energy and assuring proper operating temperatures for the telescope s instruments. This sunshield will be composed of metalized polymer multilayer insulation with an outer polymer membrane (12 to 25 mm in thickness) that will be metalized on the back to assure maximum reflectance of sunlight. The sunshield must maintain mechanical integrity and optical properties for the full 10 years. This durability requirement is most challenging for the outermost, constantly solar-facing polymer membrane of the sunshield. One of the potential threats to the membrane material s durability is from vacuum ultraviolet (VUV) radiation in wavelengths below 200 nm. Such radiation can be absorbed in the bulk of these thin polymer membrane materials and degrade the polymer s optical and mechanical properties. So that a suitable membrane material can be selected that demonstrates durability to solar VUV radiation, ground-based testing of candidate materials must be conducted to simulate the total 10- year VUV exposure expected during the Next Generation Space Telescope mission. The Steady State Vacuum Ultraviolet exposure facility was designed and fabricated at the NASA Glenn Research Center at Lewis Field to provide unattended 24-hr exposure of candidate materials to VUV radiation of 3 to 5 times the Sun s intensity in the wavelength range of 115 to 200 nm. The facility s chamber, which maintains a pressure of approximately 5 10(exp -6) torr, is divided into three individual exposure cells, each with a separate VUV source and sample-positioning mechanism. The three test cells are separated by a water-cooled copper shield plate assembly to minimize thermal effects from adjacent test cells. Part of the interior sample positioning mechanism of one

  20. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    NASA Astrophysics Data System (ADS)

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias

    2015-01-01

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  1. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    SciTech Connect

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman Kroth, Simone; Paustian, Wolfgang; Richter, Mathias

    2015-01-15

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  2. Photoluminescence performance of thulium doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} under irradiation of ultraviolet and vacuum ultraviolet lights

    SciTech Connect

    Wang, Zhaofeng; Li, Yezhou; Liu, Xiong; Wei, Xingmin; Chen, Yueling; Zhou, Fei; Wang, Yuhua

    2014-11-15

    Highlights: • A novel blue-emitting phosphor Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was reported. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} exhibited excellent thermal and irradiation stability. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was found to possess high color purity. - Abstract: In this work, we synthesized Tm{sup 3+} doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} phosphors and investigated their photoluminescence properties under the excitation of ultraviolet and vacuum ultraviolet lights. The crystal structure analysis and variation of cell parameters confirm that Tm{sup 3+} ions have been successfully doped in the structure of Li{sub 4}SrCa(SiO{sub 4}){sub 2} host by occupying the sites of Ca{sup 2+} with the coordination number of 6. The luminescence results suggest that Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} is a good blue-emitting phosphor when excited by ultraviolet and vacuum ultraviolet irradiations. In addition, it is observed that there is nearly no degradation for Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} after undergoing thermal and irradiation treatments. Possible mechanisms for the luminescence processes are proposed on the basis of the discussion of excitation and emission spectra. In particular, the emission color of Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} by excitation of 147 and 172 nm irradiations is very close to the standard blue color, suggesting that it could be potentially applied in plasma display panels and mercury-free fluorescence lamps.

  3. Interpretation of the vacuum ultraviolet photoabsorption spectrum of iodobenzene by ab initio computations

    SciTech Connect

    Palmer, Michael H. Ridley, Trevor E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Hoffmann, Søren Vrønning E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it Jones, Nykola C. E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Coreno, Marcello E-mail: vronning@phys.au.dk E-mail: marcello.coreno@elettra.eu E-mail: malgorzata.biczysko@sns.it; Grazioli, Cesare; and others

    2015-04-07

    Identification of many Rydberg states in iodobenzene, especially from the first and fourth ionization energies (IE{sub 1} and IE{sub 4}, X{sup 2}B{sub 1} and C{sup 2}B{sub 1}), has become possible using a new ultraviolet (UV) and vacuum-ultraviolet (VUV) absorption spectrum, in the region 29 000-87 000 cm{sup −1} (3.60-10.79 eV), measured at room temperature with synchrotron radiation. A few Rydberg states based on IE{sub 2} (A{sup 2}A{sub 2}) were found, but those based on IE{sub 3} (B{sup 2}B{sub 2}) are undetectable. The almost complete absence of observable Rydberg states relating to IE{sub 2} and IE{sub 3} (A{sup 2}A{sub 2} and B{sup 2}B{sub 2}, respectively) is attributed to them being coupled to the near-continuum, high-energy region of Rydberg series converging on IE{sub 1}. Theoretical studies of the UV and VUV spectra used both time-dependent density functional (TDDFT) and multi-reference multi-root doubles and singles-configuration interaction methods. The theoretical adiabatic excitation energies, and their corresponding vibrational profiles, gave a satisfactory interpretation of the experimental results. The calculations indicate that the UV onset contains both 1{sup 1}B{sub 1} and 1{sup 1}B{sub 2} states with very low oscillator strength, while the 2{sup 1}B{sub 1} state was found to lie under the lowest ππ{sup ∗} 1{sup 1}A{sub 1} state. All three of these {sup 1}B{sub 1} and {sup 1}B{sub 2} states are excitations into low-lying σ{sup ∗} orbitals. The strongest VUV band near 7 eV contains two very strong ππ{sup ∗} valence states, together with other weak contributors. The lowest Rydberg 4b{sub 1}6s state (3{sup 1}B{sub 1}) is very evident as a sharp multiplet near 6 eV; its position and vibrational structure are well reproduced by the TDDFT results.

  4. Line spectrum and ion temperature measurements from tungsten ions at low ionization stages in large helical device based on vacuum ultraviolet spectroscopy in wavelength range of 500–2200 Å

    SciTech Connect

    Oishi, T. Morita, S.; Goto, M.; Huang, X. L.; Zhang, H. M.

    2014-11-15

    Vacuum ultraviolet spectra of emissions released from tungsten ions at lower ionization stages were measured in the Large Helical Device (LHD) in the wavelength range of 500–2200 Å using a 3 m normal incidence spectrometer. Tungsten ions were distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal and polyethylene tube. Many lines having different wavelengths from intrinsic impurity ions were observed just after the tungsten pellet injection. Doppler broadening of a tungsten candidate line was successfully measured and the ion temperature was obtained.

  5. Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization.

    PubMed

    Vaikkinen, Anu; Haapala, Markus; Kersten, Hendrik; Benter, Thorsten; Kostiainen, Risto; Kauppila, Tiina J

    2012-02-01

    A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (μAPPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different μAPPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in μAPPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production. PMID:22229729

  6. Photoionization of epichlorohydrin enantiomers and clusters studied with circularly polarized vacuum ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Daly, Steven; Powis, Ivan; Garcia, Gustavo A.; Soldi-Lose, Héloïse; Nahon, Laurent

    2011-02-01

    The photoionization of enantiomerically pure epichlorohydrin (C3H5OCl) has been studied using linearly and circularly polarized vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum was recorded and the first three bands assigned using molecular orbital calculations for the expected conformers, although uncertain experimental conformer populations and an anticipated breakdown in Koopmans' theorem leave some ambiguity. Measurements of the photoelectron circular dichroism (PECD) were obtained across a range of photon energies for each of these bands, using electron velocity map imaging to record the angular distributions, during which a record PECD chiral asymmetry factor of 32% was observed. A comparison with calculated PECD curves clarifies the assignment achieved using ionization energies alone and further suggests a likely relative population of the conformers. Threshold photoelectron-photoion coincidence methods were used to study the ionic fragmentation of epichlorohydrin. Fragment ion appearance energies show nonstatistical behavior with clear indications that the cationic epoxide ring is unstable and lower energy decay channels proceeding via ring breaking are generally open. Extensive neutral homochiral clusters of epichlorohydrin may be formed in supersonic molecular beam expansions seeded in Ar. Electron angular distribution measurements made in coincidence with dimer and trimer ions are used to effect an examination of the PECD associated with ionization of size-selected neutral cluster species, and these results differ clearly from PECD of the neutral monomer. The shifted ionization thresholds of the n-mers (n = 2, …, 7) are shown to follow a simple linear relationship, but under intense beam expansion conditions the monomer deviates from this relationship, and the monomer electron spectra tail to below the expected monomer adiabatic ionization potential (IP). PECD measurements made in coincidence with monomer ions obtained

  7. Vacuum-Ultraviolet photoionization studies of the microhydrationof DNA bases (Guanine, Cytosine, Adenine and Thymine)

    SciTech Connect

    Belau, L.; Wilson, K.R.; Leone, S.R.; Musahid, Ahmed

    2007-01-22

    In this work, we report on a photoionization study of the microhydration of the four DNA bases. Gas-phase clusters of water with DNA bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] are generated via thermal vaporization of the bases and expansion of the resultant vapor in a continuous supersonic jet expansion of water seeded in Ar. The resulting clusters are investigated by single-photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for the DNA bases and the following water (W) clusters: G, GW{sub n} (n = 1-3); C, CW{sub n} (n = 1-3); A, AW{sub n} (n = 1,2); and T, TW{sub n} (n = 1-3). Appearance energies (AE) are derived from the onset of these PIE curves (all energies in eV): G (8.1 {+-} 0.1), GW (8.0 {+-} 0.1), GW{sub 2} (8.0 {+-} 0.1), and GW{sub 3} (8.0); C (8.65 {+-} 0.05), CW (8.45 {+-} 0.05), CW{sub 2} (8.4 {+-} 0.1), and CW{sub 3} (8.3 {+-} 0.1); A (8.30 {+-} 0.05), AW (8.20 {+-} 0.05), and AW{sub 2} (8.1 {+-} 0.1); T (8.90 {+-} 0.05); and TW (8.75 {+-} 0.05), TW{sub 2} (8.6 {+-} 0.1), and TW{sub 3} (8.6 {+-} 0.1). The AEs of the DNA bases decrease slightly with the addition of water molecules (up to three) but do not converge to values found for photoinduced electron removal from DNA bases in solution.

  8. Flash vacuum-ultraviolet generator having a mercury-anode tube

    NASA Astrophysics Data System (ADS)

    Sagae, Michiaki; Sato, Eiichi; Oizumi, Teiji; Yamamoto, Mariko; Takabe, Akihito; Sakamaki, Kimio; Ojima, Hidenori; Takayama, Kazuyoshi; Tamakawa, Yoshiharu; Yanagisawa, Toru

    1995-09-01

    The fundamental studies on a flash vacuum-ultraviolet (VUV) generator for producing water- window x rays are described. this generator consisted of the following essential components: a high-voltage power supply, a polarity-inversion-type high-voltage pulser having a 15 nF condenser, a thyristor pulser as a trigger device, a turbo molecular pump, and a VUV tube. The VUV tube employed a mercury anode, and the ferrite cathode was embedded in the anode. The pressure in the tube was primarily determined by the steam pressure of mercury as a function of temperature. The condenser in the pulser was charged from -10 to -30 kV by the power supply, and the electric charges in the condenser were discharged to the radiation tube after closing a gap switch by the thyristor pulser. As the high electron flows from the cathode electrode evaporated the anode electrode, VUV rays were then produced. The maximum output voltage from the pulser was approximately -1 times the charging voltage, and both the tube voltage and current displayed damped oscillations. The maximum values of the tube voltage and current were 14 kV and 2.0 kA, respectively. Since the effective accelerating voltage was substantially decreased by the ferrite cathode, soft x rays were easily generated. The pulse durations of the VUV rays including water-window x rays were nearly equivalent to those of the damped oscillations of the voltage and current, and their values were less than 15 microsecond(s) .

  9. Vacuum ultraviolet of hydrogenated amorphous carbons. II. Small hydrocarbons production in Photon Dominated Regions

    NASA Astrophysics Data System (ADS)

    Alata, I.; Jallat, A.; Gavilan, L.; Chabot, M.; Cruz-Diaz, G. A.; Munoz Caro, G. M.; Béroff, K.; Dartois, E.

    2015-12-01

    Context. Hydrogenated amorphous carbons (a-C:H) are a major component of the carbonaceous solids present in the interstellar medium. The production and existence of these grains is connected in particular with the balance between their photolysis, radiolysis, and hydrogenation. During grain processing, H2 and other small organic molecules, radicals, and fragments are released into the gas phase. Aims: We perform photolytic experiments on laboratory produced interstellar a-C:H analogues to monitor and quantify the release of species and compare to relevant observations in the interstellar medium. Methods: Hydrogenated amorphous carbon analogues at low temperature are exposed to ultraviolet (UV) photons, under ultra-high vacuum conditions. The species produced are monitored using mass spectrometry and post irradiation temperature-programmed desorption. Additional experiments are performed using deuterated analogues and the species produced are unambiguously separated from background contributions. We implement the laboratory measured yields for the released species in a time dependent model to investigate the effect of the UV photon irradiation of hydrogenated amorphous carbons in a photon dominated region, and estimate the associated time scale. Results: The UV photolysis of hydrogenated amorphous carbons leads to the production of H2 molecules and small hydrocarbons. The model shows that the photolytic evolution of a-C:Hs in photon dominated regions, such as the Horsehead Nebula, can raise the abundance of carbonaceous molecules by several orders of magnitude at intermediate visual extinctions, i.e., after the C+ maximum and before the dense cloud conditions prevail where models generally show a minimum abundance for such carbonaceous species. The injection time peak ranges from a thousand to ten thousand years in the models, considering only the destruction of such grains and no re-hydrogenation. This time scale is consistent with the estimated advection front of

  10. Vacuum-ultraviolet photoionization and mass spectrometric characterization of lignin monomers coniferyl and sinapyl alcohols.

    PubMed

    Takahashi, Lynelle K; Zhou, Jia; Kostko, Oleg; Golan, Amir; Leone, Stephen R; Ahmed, Musahid

    2011-04-21

    The fragmentation mechanisms of monolignols under various energetic processes are studied with jet-cooled thermal desorption molecular beam (TDMB) mass spectrometry (MS), 25 keV Bi(3)(+) secondary ion MS (SIMS), synchrotron vacuum-ultraviolet secondary neutral MS (VUV-SNMS) and theoretical methods. Experimental and calculated appearance energies of fragments observed in TDMB MS indicate that the coniferyl alcohol photoionization mass spectra contain the molecular parent and several dissociative photoionization products. Similar results obtained for sinapyl alcohol are also discussed briefly. Ionization energies of 7.60 eV ± 0.05 eV for coniferyl alcohol and <7.4 eV for both sinapyl and dihydrosinapyl alcohols are determined. The positive ion SIMS spectrum of coniferyl alcohol shares few characteristic peaks (m/z = 137 and 151) with the TDMB mass spectra, shows extensive fragmentation, and does not exhibit clear molecular parent signals. VUV-SNMS spectra, on the other hand, are dominated by the parent ion and main fragments also present in the TDMB spectra. Molecular fragmentation in VUV-SNMS spectra can be reduced by increasing the extraction delay time. Some features resembling the SIMS spectra are also observed in the desorbed neutral products. The monolignol VUV-SNMS peaks shared with the TDMB mass spectra suggest that dissociative photoionization of ion-sputtered neutral molecules predominate in the VUV-SNMS mass spectra, despite the extra internal energy imparted in the initial ion impact. The potential applications of these results to imaging MS of biomolecules are discussed. PMID:21410275

  11. Photoionization of epichlorohydrin enantiomers and clusters studied with circularly polarized vacuum ultraviolet radiation.

    PubMed

    Daly, Steven; Powis, Ivan; Garcia, Gustavo A; Soldi-Lose, Héloïse; Nahon, Laurent

    2011-02-14

    The photoionization of enantiomerically pure epichlorohydrin (C(3)H(5)OCl) has been studied using linearly and circularly polarized vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum was recorded and the first three bands assigned using molecular orbital calculations for the expected conformers, although uncertain experimental conformer populations and an anticipated breakdown in Koopmans' theorem leave some ambiguity. Measurements of the photoelectron circular dichroism (PECD) were obtained across a range of photon energies for each of these bands, using electron velocity map imaging to record the angular distributions, during which a record PECD chiral asymmetry factor of 32% was observed. A comparison with calculated PECD curves clarifies the assignment achieved using ionization energies alone and further suggests a likely relative population of the conformers. Threshold photoelectron-photoion coincidence methods were used to study the ionic fragmentation of epichlorohydrin. Fragment ion appearance energies show nonstatistical behavior with clear indications that the cationic epoxide ring is unstable and lower energy decay channels proceeding via ring breaking are generally open. Extensive neutral homochiral clusters of epichlorohydrin may be formed in supersonic molecular beam expansions seeded in Ar. Electron angular distribution measurements made in coincidence with dimer and trimer ions are used to effect an examination of the PECD associated with ionization of size-selected neutral cluster species, and these results differ clearly from PECD of the neutral monomer. The shifted ionization thresholds of the n-mers (n = 2, ..., 7) are shown to follow a simple linear relationship, but under intense beam expansion conditions the monomer deviates from this relationship, and the monomer electron spectra tail to below the expected monomer adiabatic ionization potential (IP). PECD measurements made in coincidence with monomer ions obtained

  12. Investigating the effective range of vacuum ultraviolet-mediated breakdown in high-power microwave metamaterials

    SciTech Connect

    Liu, Chien-Hao Neher, Joel D. Booske, John H. Behdad, Nader

    2014-10-14

    Metamaterials and periodic structures operating under high-power excitations are susceptible to breakdown. It was recently demonstrated that a localized breakdown created in a given region of a periodic structure can facilitate breakdown in other regions of the structure where the intensity of the incident electromagnetic fields may not be high enough to cause breakdown under normal circumstances. It was also demonstrated that this phenomenon is due to the generation of vacuum ultraviolet radiation at the location of the initial discharge, which propagates to the neighboring regions (e.g., other unit cells in a periodic structure) and facilitates the generation of a discharge at a lower incident power level. In this paper, we present the results of an experimental study conducted to determine the effective range of this physical phenomenon for periodic structures that operate in air and in pure nitrogen gas at atmospheric pressure levels. It is demonstrated that when breakdown is induced in a periodic structure using a high-power pulse with a frequency of 9.382 GHz, duration of 0.8 μs, and peak power level of 25 kW, this phenomenon is highly likely to happen in radii of approximately 16–17 mm from the location of the initial discharge under these test conditions. The results of this study are significant in designing metamaterials and periodic structures for high-power microwave applications as they suggest that a localized discharge created in such a periodic structure with a periodicity less than 16–17 mm can spread over a large surface and result in a distributed discharge.

  13. Vacuum ultraviolet photolysis of hydrogenated amorphous carbons . I. Interstellar H2 and CH4 formation rates

    NASA Astrophysics Data System (ADS)

    Alata, I.; Cruz-Diaz, G. A.; Muñoz Caro, G. M.; Dartois, E.

    2014-09-01

    Context. The interstellar hydrogenated amorphous carbons (HAC or a-C:H) observed in the diffuse medium are expected to disappear in a few million years, according to the destruction time scale from laboratory measurements. The existence of a-C:H results from the equilibrium between photodesorption, radiolysis, hydrogenation and resilience of the carbonaceous network. During this processing, many species are therefore injected into the gas phase, in particular H2, but also small organic molecules, radicals or fragments. Aims: We perform experiments on interstellar a-C:H analogs to quantify the release of these species in the interstellar medium. Methods: The vacuum ultraviolet (VUV) photolysis of interstellar hydrogenated amorphous carbon analogs was performed at low (10 K) to ambient temperature, coupled to mass-spectrometry detection and temperature-programed desorption. Using deuterium isotopic substitution, the species produced were unambiguously separated from background contributions. Results: The VUV photolysis of hydrogenated amorphous carbons leads to the efficient production of H2 molecules, but also to small hydrocarbons. Conclusions: These species are formed predominantly in the bulk of the a-C:H analog carbonaceous network, in addition to the surface formation. Compared with species made by the recombination of H atoms and physisorbed on surfaces, they diffuse out at higher temperatures. In addition to the efficient production rate, it provides a significant formation route in environments where the short residence time scale for H atoms inhibits H2 formation on the surface, such as PDRs. The photolytic bulk production of H2 with carbonaceous hydrogenated amorphous carbon dust grains can provide a very large portion of the contribution to the H2 molecule formation. These dust grains also release small hydrocarbons (such as CH4) into the diffuse interstellar medium, which contribute to the formation of small carbonaceous radicals after being dissociated

  14. Vacuum-Ultraviolet Photoionization and Mass Spectrometric Characterization of Lignin Monomers Coniferyl and Sinapyl Alcohols

    SciTech Connect

    Takahashi, Lynelle K.; Zhou, Jia; Kostko, Oleg; Golan, Amir; Leone, Stephen R.; Ahmed, Musahid

    2011-02-09

    The fragmentation mechanisms of monolignols under various energetic processes are studied with jet-cooled thermal desorption molecular beam (TDMB) mass spectrometry (MS), 25 keV Bi3+ secondary ion MS (SIMS), synchrotron vacuum-ultraviolet secondary neutral MS (VUV-SNMS) and theoretical methods. Experimental and calculated appearance energies of fragments observed in TDMB MS indicate that the coniferyl alcohol photoionization mass spectra contain the molecular parent and several dissociative photoionization products. Similar results obtained for sinapyl alcohol are also discussed briefly. Ionization energies of 7.60 eV ? 0.05 eV for coniferyl alcohol and<7.4 eV for both sinapyl and dihydrosinapyl alcohols are determined. The positive ion SIMS spectrum of coniferyl alcohol shares few characteristic peaks (m/z = 137 and 151) with the TDMB mass spectra, shows extensive fragmentation, and does not exhibit clear molecular parent signals. VUV-SNMS spectra, on the other hand, are dominated by the parent ion and main fragments also present in the TDMB spectra. Molecular fragmentation in VUV-SNMS spectra can be reduced by increasing the extraction delay time. Some features resembling the SIMS spectra are also observed in the desorbed neutral products. The monolignol VUV-SNMS peaks shared with the TDMB mass spectra suggest that dissociative photoionization of ion-sputtered neutral molecules predominate in the VUV-SNMS mass spectra, despite the extra internal energy imparted in the initial ion impact. The potential applications of these results to imaging mass spectrometry of bio-molecules are discussed.

  15. DELICIOUS III: A multipurpose double imaging particle coincidence spectrometer for gas phase vacuum ultraviolet photodynamics studies

    NASA Astrophysics Data System (ADS)

    Garcia, G. A.; Cunha de Miranda, B. K.; Tia, M.; Daly, S.; Nahon, L.

    2013-05-01

    We present a versatile double imaging particle coincidence spectrometer operating in fully continuous mode, named DELICIOUS III, which combines a velocity map imaging device and a modified Wiley-McLaren time of flight momentum imaging analyzer for photoelectrons and photoions, respectively. The spectrometer is installed in a permanent endstation on the DESIRS vacuum ultraviolet (VUV) beamline at the French National Synchrotron Radiation Facility SOLEIL, and is dedicated to gas phase VUV spectroscopy, photoionization, and molecular dynamics studies. DELICIOUS III is capable of recording mass-selected threshold photoelectron photoion coincidence spectra with a sub-meV resolution, and the addition of a magnifying lens inside the electron drift tube provides a sizeable improvement of the electron threshold/ion mass resolution compromise. In fast electron mode the ultimate kinetic energy resolution has been measured at ΔE/E = 4%. The ion spectrometer offers a mass resolution—full separation of adjacent masses—of 250 amu for moderate extraction fields and the addition of an electrostatic lens in the second acceleration region allows measuring the full 3D velocity vector for a given mass with an ultimate energy resolution of ΔE/E = 15%, without sacrificing the mass resolution. Hence, photoelectron images are correlated both to the mass and to the ion kinetic energy and recoil direction, to access the electron spectroscopy of size-selected species, to study the photodissociation processes of state-selected cations in detail, or to measure in certain cases photoelectron angular distributions in the ion recoil frame. The performances of DELICIOUS III are explored through several examples including the photoionization of N2, NO, and CF3.

  16. Quantum-state Dependence of Product Branching Ratios in Vacuum Ultraviolet Photodissociation of N2

    NASA Astrophysics Data System (ADS)

    Song, Yu; Gao, Hong; Chung Chang, Yih; Hammouténe, D.; Ndome, H.; Hochlaf, M.; Jackson, William M.; Ng, C. Y.

    2016-03-01

    The branching ratios for the N(4S) + N(2D), N(4S) + N(2P), and N(2D) + N(2D) channels are measured for the photodissociation of {{{N}}}2({X}1{{{{Σ }}}g}+;v\\prime\\prime =0,J\\prime\\prime ) in the vacuum ultraviolet (VUV) region of 100,808-122,159 cm-1 using the VUV-VUV pump-probe approach combined with velocity-map-imaging-photoion detection. No evidence of forming the ground-state N(4S) + N(4S) products is found. No potential barrier is observed for the N(2D) + N(2D) channel, but the N(4S) + N(2P) channel has a small potential barrier of ≈740 cm-1. The branching ratios are found to depend on the symmetry of predissociative N2 states instead of the total VUV excitation energy, indicating that N2 photodissociation is nonstatistical. When the branching ratios for N(4S) + N(2D) and N(4S) + N(2P) products are plotted as a function of the VUV excitation energy for the valence N2 1Πu and {}1{{{{Σ }}}{{u}}}+ states, oscillations in these ratios are observed demonstrating how these channels are competing with each other. These data can be used to select both the velocity and internal states of the atomic products by picking the quantum state that is excited. High-level ab initio potential energy curves of the excited N2 states are calculated to provide insight into the mechanisms for the observed branching ratios. The calculations predict that the formation of both N(4S) + N(2D) and N(4S) + N(2P) channels involves potential energy barriers, in agreement with experimental observations. A discussion of the application of the present results to astronomy, planetary sciences, and comets is given.

  17. Vibronic and Rydberg series assignments in the vacuum ultraviolet absorption spectrum of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Shastri, Aparna; Singh, Param Jeet; Krishnakumar, Sunanda; Mandal, Anuvab; Raja Sekhar, B. N.; D'Souza, R.; Jagatap, B. N.

    2014-11-01

    We report a comprehensive photoabsorption study of nitrous oxide (N2O) in the vacuum ultraviolet (45,000-95,000 cm-1) region using synchrotron radiation. The observed spectrum comprises of a few valence transitions and low lying Rydberg series converging to the two spin-orbit components (2П1/2,3/2) of the ground state of N2O+. Spectral analysis is aided by extensive quantum chemical calculations of vertical excited states, oscillator strengths and potential energy curves using the time dependent density functional theory. Vibronic bands observed in the first absorption system (45,000-60,000 cm-1) are assigned to hot band progressions in υ2‧ originating from v″=1 or 2. New insights into the assignment of the well-formed progression of bands in the X1Σ+→C1П system (60,000-72,000 cm-1) are afforded by consideration of the Renner-Teller interaction. A set of molecular vibrational parameters (ω2=467 cm-1, x22=-2.9, ε=-0.24) for the C1П state are derived from a fitting of the experimental data. The 3pπ1Σ+ state at ~77,600 cm-1 shows a large quantum defect (0.96) which is explained as arising due to mixed valence-Rydberg character. In the 85,000-95,000 cm-1 region, a number of absorption features are observed with greater clarity than in earlier photoabsorption studies and assigned to Rydberg series of type nlλ (n=3,4; l=s,p,d; λ=σ,π,δ) and accompanying vibronic bands. This work has resulted in clarification of several discrepancies in earlier Rydberg series assignments. Additionally, the 3pπ 3Σ- Rydberg state at 85,788 cm-1, the valence transition 7σ→3π (1П) at 87,433 cm-1 and the 3dλ Rydberg series in the 91,700-92,600 cm-1 region are assigned for the first time.

  18. Airborne intercomparison of vacuum ultraviolet fluorescence and tunable diode laser absorption measurements of tropospheric carbon monoxide

    NASA Astrophysics Data System (ADS)

    Holloway, John S.; Jakoubek, Roger O.; Parrish, David D.; Gerbig, Christoph; Volz-Thomas, Andreas; Schmitgen, Sandra; Fried, Alan; Wert, Brian; Henry, Bruce; Drummond, James R.

    2000-01-01

    During the fall 1997 North Atlantic Regional Experiment (NARE 97), two separate intercomparisons of aircraft-based carbon monoxide measurement instrumentation were conducted. On September 2, CO measurements were simultaneously made aboard the National Oceanic and Atmospheric Administration (NOAA) WP-3 by vacuum ultraviolet (VUV) fluorescence and by tunable diode laser absorption spectroscopy (TDLAS). On September 18, an intercomparison flight was conducted between two separate instruments, both employing the VUV fluorescence method, on the NOAA WP-3 and the U.K. Meteorological Office C-130 Hercules. The results indicate that both of the VUV fluorescence instruments and the TDLAS system are capable of measuring ambient CO accurately and precisely with no apparent interferences in 5 s. The accuracy of the measurements, based upon three independent calibration systems, is indicated by the agreement to within 11% with systematic offsets of less than 1 ppbv. In addition, one of the groups participated in the Measurement of Air Pollution From Satellite (MAPS) intercomparison [Novelli et al., 1998] with a different measurement technique but very similar calibration system, and agreed with the accepted analysis to within 5%. The precision of the measurements is indicated by the variability of the ratio of simultaneous measurements from the separate instruments. This variability is consistent with the estimated precisions of 1.5 ppbv and 2.2 ppbv for the 5 s average results of the C-130 and the WP-3 instruments, respectively, and indicates a precision of approximately 3.6% for the TDLAS instrument. The excellent agreement of the instruments in both intercomparisons demonstrates that significant interferences in the measurements are absent in air masses that ranged from 7 km in the midtroposphere to boundary layer conditions including subtropical marine air and continental outflow with embedded urban plumes. The intercomparison of the two VUV instruments that differed widely

  19. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    NASA Technical Reports Server (NTRS)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  20. Observation of new excitation channel of cerium ion through highly vacuum ultraviolet transparent LiCAF host crystal

    NASA Astrophysics Data System (ADS)

    Kozeki, Toshimasa; Suzuki, Yuji; Sakai, Masahiro; Ohtake, Hideyuki; Sarukura, Nobuhiko; Liu, Zhenlin; Shimamura, Kiyoshi; Nakano, Kenji; Fukuda, Tsuguo

    2001-07-01

    The transmission spectra of LiCaAlF 6 (LiCAF) and LiSrAlF 6 (LiSAF) are investigated in the ultraviolet (UV) and the vacuum ultraviolet (VUV) region. The transmission edge of LiCAF (112 nm) shows almost the same value as that of LiF. Taking into account difficulties of material processing and polishing due to the cleavage or the hydroscopic nature of LiF, LiCAF is regarded as a more suitable optical material in the UV and the VUV region. Moreover, the new excitation channel around 112 nm is discovered for Ce : LiCAF crystal. This excitation is originated not from absorption of Cerium ions but from absorption around the bandgap of the host crystal.

  1. Surface potential due to charge accumulation during vacuum ultraviolet exposure for high-k and low-k dielectrics

    SciTech Connect

    Ren, H.; Sinha, H.; Sehgal, A.; Nichols, M. T.; Shohet, J. L.; Antonelli, G. A.; Nishi, Y.

    2010-08-16

    The surface potential due to charge accumulation during vacuum ultraviolet irradiation of high-k and low-k thin dielectric films is measured. Measurement of the substrate current, which is the sum of the charge-accumulation and photoinjection currents, allows an in situ monitoring of the charge accumulation during irradiation. The relationship between the substrate current and the calculated in situ surface potential is also found, eliminating the need for a separate surface-potential measurement. With a high photon dose, the surface potential and substrate current reach a steady-state value with no further net charge accumulation.

  2. Exciton-exciton interactions in CdWO{sub 4} irradiated by intense femtosecond vacuum ultraviolet pulses

    SciTech Connect

    Kirm, M.; Nagirnyi, V.; Feldbach, E.; De Grazia, M.; Carre, B.; Merdji, H.; Guizard, S.; Geoffroy, G.; Gaudin, J.; Fedorov, N.; Martin, P.; Vasil'ev, A.; Belsky, A.

    2009-06-15

    Exciton-exciton interaction is experimentally revealed and quantitatively analyzed in a wide band-gap scintillator material CdWO{sub 4}. Under high-intensity femtosecond vacuum ultraviolet excitation, the CdWO{sub 4} luminescence is quenched, while its decay becomes essentially nonexponential. We propose an analytical model, which successfully reproduces the decay kinetics recorded in a wide range of excitation densities. The dipole-dipole interaction between excitons leading to their nonradiative decay is shown to be the main cause of a nonproportional response common for many scintillators.

  3. Fluorescence yields from photodissociative excitation of HCOOH, HCOOCH3, and CH3COOH in the vacuum-ultraviolet region

    NASA Technical Reports Server (NTRS)

    Suto, Masako; Wang, Xiuyan; Lee, L. C.

    1988-01-01

    The photoexcitation processes of HCOOH, HCOOCH3, and CH3COOH were studied in the vacuum-ultraviolet region by using synchroton radiation and a pulsed discharge lamp as light sources. The absorption and fluorescence cross sections of these molecules were measured in the 106-250-nm region. Fluorescences were detected from photoexcitation of HCOOH and HCOOCH3, but not from CH3COOH. Fluorescence produced at 123.9 nm was dispersed and identified as the excited OH and HCOO radicals. Fluorescence quantum yields of HCOOH and HCOOCH3 increase with decreasing excitation wavelengths with maxima of 5 and 0.3 percent at 106 nm, respectively.

  4. Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions

    NASA Astrophysics Data System (ADS)

    Wakui, Kentaro; Hayasaka, Kazuhiro; Ido, Tetsuya

    2014-09-01

    Vacuum ultraviolet (VUV) radiation around 159 nm is obtained toward direct excitation of a single trapped ^{115}{In}+ ion. An efficient fluoride-based VUV output coupler is employed for intracavity high-harmonic generation of a Ti:S oscillator. Using this coupler, where we measured its reflectance to be about 90 %, an average power reaching 6.4 \\upmu W is coupled out from a modest fundamental power of 650 mW. When a single comb component out of 1.9 × 105 teeth is resonant to the atomic transition, 100s of fluorescence photons per second will be detectable under a realistic condition.

  5. High-Resolution Electronics: Spontaneous Patterning of High-Resolution Electronics via Parallel Vacuum Ultraviolet (Adv. Mater. 31/2016).

    PubMed

    Liu, Xuying; Kanehara, Masayuki; Liu, Chuan; Sakamoto, Kenji; Yasuda, Takeshi; Takeya, Jun; Minari, Takeo

    2016-08-01

    On page 6568, T. Minari and co-workers describe spontaneous patterning based on the parallel vacuum ultraviolet (PVUV) technique, enabling the homogeneous integration of complex, high-resolution electronic circuits, even on large-scale, flexible, transparent substrates. Irradiation of PVUV to the hydrophobic polymer surface precisely renders the selected surface into highly wettable regions with sharply defined boundaries, which spontaneously guides a metal nanoparticle ink into a series of circuit lines and gaps with the widths down to a resolution of 1 μm. PMID:27511534

  6. Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions

    NASA Astrophysics Data System (ADS)

    Wakui, Kentaro; Hayasaka, Kazuhiro; Ido, Tetsuya

    2014-12-01

    Vacuum ultraviolet (VUV) radiation around 159 nm is obtained toward direct excitation of a single trapped ion. An efficient fluoride-based VUV output coupler is employed for intracavity high-harmonic generation of a Ti:S oscillator. Using this coupler, where we measured its reflectance to be about 90 %, an average power reaching 6.4 W is coupled out from a modest fundamental power of 650 mW. When a single comb component out of 1.9 10 teeth is resonant to the atomic transition, 100s of fluorescence photons per second will be detectable under a realistic condition.

  7. Specific features of modeling of nonequilibrium radiation behind the shock wave in air in the vacuum ultraviolet spectral range

    NASA Astrophysics Data System (ADS)

    Gorelov, V. A.; Kireev, A. Yu.

    2016-01-01

    A physical-chemical model of generation of nonequilibrium molecular radiation in the vacuum ultraviolet (VUV) spectral range behind the shock wave in air for shock wave velocities from 4.5 to 9.5 km/s is developed. Experimental results obtained in a shock tube in investigations of photoionization of air ahead of the shock wave front are used for verification of the numerical model of VUV radiation in the wavelength range from 85 to 105 nm. Model calculations show that nonequilibrium VUV radiation arises in a very thin high-temperature layer behind the shock wave front and is affected by heavy particles and electrons.

  8. Effects of vacuum ultraviolet and ultraviolet irradiation on ultrathin hafnium-oxide dielectric layers on (100)Si as measured with electron-spin resonance

    SciTech Connect

    Ren, H.; Shohet, J. L.; Cheng, S. L.; Nishi, Y.

    2010-05-10

    The effects of vacuum ultraviolet (VUV) (7.2 eV) and UV (4.9 eV) irradiation on hafnium-oxide dielectric layers were studied with electron-spin resonance to detect defect states. Silicon dangling-bond defects (P{sub b} centers) and positively charged oxygen vacancies (E{sup '} centers) were detected with g-factor fitting. VUV irradiation increases the level of P{sub b} states, while UV decreases the level of P{sub b} states but increases the level of E{sup '} states significantly. Rapid thermal annealing appears to mitigate these effects. Absolute values of the defect-state concentrations are presented.

  9. Polarization selection rules and optical transitions in terbium activated yttrium tantalate phosphor under x-ray, vacuum-ultraviolet, and ultraviolet excitations

    SciTech Connect

    Nazarov, Mihail; Tsukerblat, Boris; Byeon, Clare Chisu; Arellano, Ivan; Popovici, Elisabeth-Jeanne; Noh, Do Young

    2009-01-01

    The terbium-activated yttrium tantalite (YTaO4:Tb{sup 3{sup +}}) phosphor is of great interest due to the interesting spectroscopic properties of rare earth ions in crystals and also practical use in x-ray imaging. Using the group-theoretical approach, we analyze the selection rules for the transition between Stark components of Tb{sup 3{sup +}} in symmetry of the actual crystal field and the polarization for the allowed transitions. The luminescence upon UV, vacuum-ultraviolet (VUV), and x-ray excitation is presented and discussed. The YTaO4:Tb{sup 3{sup +}} phosphors are found to be efficient VUV-excited luminescent materials that could be used not only in x-ray intensifying screens, but also in mercury-free fluorescent lamps or plasma display panels.

  10. Vacuum and ultraviolet radiation effects on binders and pigments for spacecraft thermal control coatings

    NASA Technical Reports Server (NTRS)

    Progar, D. J.; Wade, W. R.

    1971-01-01

    An evaluation of several silicone resin binders and powdered inorganic pigments for potential use in spacecraft thermal-control paint formulations is presented. The pigments were selected on the basis of a hypothesis relating the heat of formation of a compound to the compound's resistance to ultra-radiation-induced degradation. Reflectance measurements were made in situ to determine degradation rates due to ultraviolet radiation. The tested polydimethylsiloxane resins were not significantly affected by long exposures to ultraviolet radiation. All the pigments, which were dispersed in a polydimethylsiloxane resin, were degraded by ultraviolet radiation as determined by an increase of solar absorptance. For the materials evaluated in this study, no evidence was found to indicate that pigments with high heats of formation were resistant to ultraviolet degradation.

  11. Exploiting single photon vacuum ultraviolet photoionization to unravel the synthesis of complex organic molecules in interstellar ices

    NASA Astrophysics Data System (ADS)

    Abplanalp, Matthew J.; Förstel, Marko; Kaiser, Ralf I.

    2016-01-01

    Complex organic molecules (COM) such as aldehydes, ketones, carboxylic acids, esters, and amides are ubiquitous in the interstellar medium, but traditional gas phase astrochemical models cannot explain their formation routes. By systematically exploiting on line and in situ vacuum ultraviolet photoionization coupled with reflectron time of flight mass spectrometry (PI-ReTOF-MS) and combining these data with infrared spectroscopy (FTIR), we reveal that complex organic molecules can be synthesized within interstellar ices that are condensed on interstellar grains via non-equilibrium reactions involving suprathermal hydrogen atoms at temperatures as low as 5 K. By probing for the first time specific structural isomers without their degradation (fragment-free), the incorporation of tunable vacuum ultraviolet photoionization allows for a much greater understanding of reaction mechanisms that exist in interstellar ices compared to traditional methods, thus eliminating the significant gap between observational and laboratory data that existed for the last decades. With the commission of the Atacama Large Millimeter/Submillimeter Array (ALMA), the number of detections of more complex organic molecules in space will continue to grow - including biorelevant molecules connected to the Origins of Life theme - and an understanding of these data will rely on future advances in sophisticated physical chemistry laboratory experiments.

  12. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    SciTech Connect

    Laity, George; Fierro, Andrew; Dickens, James; Neuber, Andreas; Frank, Klaus

    2014-03-28

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0 mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5 × 10{sup 17} cm{sup −3} and peak N atom densities of 9.9 × 10{sup 17} cm{sup −3} are observed within the first ∼1.0 mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0 nm band of the vacuum ultraviolet spectrum.

  13. Size-dependent emission efficiency and luminescence characteristics of YBO3:Tb3+ nanocrystals under vacuum ultraviolet excitations

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant K.; Dutta, Ranu K.; Pandey, Avinash C.

    2012-09-01

    The luminous efficiency and lifetime of plasma display panels (PDPs) are directly related to the performance of phosphors used in PDPs, thus higher efficiency, higher stability against high temperature processes, and a long lifetime along with good color chromaticity against vacuum-ultraviolet radiation are major concerns in selecting suitable phosphors for PDPs. In the same pursuit, well crystallized pure hexagonal phase YBO3:Tb3+ nanocrystals were prepared using co-precipitation method. The prepared YBO3:Tb3+ nanocrystals showed bright green luminescence, color chromaticity (0.21, 0.61), and could be assigned to 5D4→7Fj transitions (j = 2-6) due to electric dipole-dipole interaction of Tb3+ ions. The vacuum ultraviolet photoluminescence spectroscopy of the prepared YBO3:Tb3+ nanocrystals showed size dependent nonlinear luminescence enhancement with relatively shorter life time as compared to the commercial bulk YBO3:Tb3+ phosphor. The quenching concentration of Tb3+ doping for (5D4→7F5) transition was found significantly enhanced with the decrease in particle size suggesting it an ideal green phosphor for plasma display panels. The possible explanation for size-dependent emission efficiency and observed luminescence characteristics were proposed via charge transfer process and lowering of the structural symmetry.

  14. Surface Emitting, High Efficiency Near-Vacuum Ultraviolet Light Source with Aluminum Nitride Nanowires Monolithically Grown on Silicon.

    PubMed

    Zhao, S; Djavid, M; Mi, Z

    2015-10-14

    To date, it has remained challenging to realize electrically injected light sources in the vacuum ultraviolet wavelength range (∼200 nm or shorter), which are important for a broad range of applications, including sensing, surface treatment, and photochemical analysis. In this Letter, we have demonstrated such a light source with molecular beam epitaxially grown aluminum nitride (AlN) nanowires on low cost, large area Si substrate. Detailed angle dependent electroluminescence studies suggest that, albeit the light is TM polarized, the dominant light emission direction is from the nanowire top surface, that is, along the c axis, due to the strong light scattering effect. Such an efficient surface emitting device was not previously possible using conventional c-plane AlN planar structures. The AlN nanowire LEDs exhibit an extremely large electrical efficiency (>85%), which is nearly ten times higher than the previously reported AlN planar devices. Our detailed studies further suggest that the performance of AlN nanowire LEDs is predominantly limited by electron overflow. This study provides important insight on the fundamental emission characteristics of AlN nanowire LEDs and also offers a viable path to realize an efficient surface emitting near-vacuum ultraviolet light source through direct electrical injection. PMID:26375576

  15. INTRODUCTION: The 8th International Conference on Vacuum Ultraviolet Radiation Physics

    NASA Astrophysics Data System (ADS)

    Nilsson, Per Olof; Hedin, Lars

    1987-01-01

    The VUV conferences series The international conferences on vacuum ultraviolet radiation physics started in 1962, and are now being held every third year. VUV-8 took place at Lund University, August 4-8, 1986. VUV-9 will be arranged at the University of Hawaii, USA, August 14-18, 1989, with Prof. C S Fadley as conference chairman. Chairman of the international advisory board for the period 1986-89 is Prof. L Hedin. The theme of the series can be summarized as experimental and theoretical progress in research fields utilizing the interaction of VUV radiation with matter. The topics cover broad areas within atomic and molecular physics, solid state physics and VUV instrumentation. The conferences emphasize interdisciplinary aspects. To these belong common experimental techniques as, e.g., synchrotron radiation instrumentation, and common theoretical foundations for the description of photon interactions with matter. The VUV-8 conference The VUV-8 conference in Lund was attended by 300 participants from 26 countries. An address list of the participants is given at the end of this volume. There were 33 invited papers given as plenary or key-note talks. As many as 229 posters were presented; 49 of them were also given orally. These numbers are typical for the VUV conferences, except for the number of posters, which was unusually large. In the conference planning the poster sessions were stressed, and particular care was taken to provide a good atmosphere at these sessions. Thus the posters were kept up during the whole conference, coffee was served in the hail with the posters and there were convenient places to sit down close to the posters. Considering the wide scope of the conference it was necessary to emphasize a limited number of topics of high current interest and importance. Thus besides traditional topics, several rapidly expanding fields were discussed in special sessions. At VUV-8 there were the following sessions. Theory of atoms and molecules

  16. Generation of a vacuum ultraviolet to visible Raman frequency comb in H2-filled kagomé photonic crystal fiber.

    PubMed

    Mridha, M K; Novoa, D; Bauerschmidt, S T; Abdolvand, A; St J Russell, P

    2016-06-15

    We report on the generation of a purely vibrational Raman comb, extending from the vacuum ultraviolet (184 nm) to the visible (478 nm), in hydrogen-filled kagomé-style photonic crystal fiber pumped at 266 nm. Stimulated Raman scattering and molecular modulation processes are enhanced by higher Raman gain in the ultraviolet. Owing to the pressure-tunable normal dispersion landscape of the "fiber + gas" system in the ultraviolet, higher-order anti-Stokes bands are generated preferentially in higher-order fiber modes. The results pave the way toward tunable fiber-based sources of deep and vacuum ultraviolet light for applications in, e.g., spectroscopy and biomedicine. PMID:27304295

  17. Testing to determine the vacuum-ultraviolet degradation rate of thermal control coatings

    NASA Technical Reports Server (NTRS)

    Gilligan, J. E.

    1972-01-01

    Samples of S-13G that had been exposed to the salt air environment of Cape Kennedy, Florida were irradiated with simulated solar ultraviolet radiation after various cleaning treatments. In both of the the tests conducted two of the salt air exposed samples were not cleaned, two were lightly cleaned with water and detergent (i.e. rinsed), and two were vigorously scrubbed. Several other white thermal control coatings were also irradiated. The solar absorptance values of these coatings before and as a result of the ultraviolet irradiation are reported for exposure levels up to approximately 2000 ESH.

  18. Evaluation of miniature vacuum ultraviolet lamps for stability and operating characteristics, Lyman-Alpha task

    NASA Technical Reports Server (NTRS)

    Hurd, W. A.

    1985-01-01

    Modifications required to change the near ultraviolet source in the Optical Contamination Monitor to a source with output at or near the Lyman-Alpha hydrogen line are discussed. The effort consisted of selecting, acquiring and testing candidate miniature ultraviolet lamps with significant output in or near 121.6 nm. The effort also included selection of a miniature dc high-voltage power supply capable of operating the lamp. The power supply was required to operate from available primary power supplied by the Optical Effect Module (DEM) and it should be flight qualified or have the ability to be qualified by the user.

  19. Luminescent properties of Pr3+-sensitized LaPO4:Gd3+ ultraviolet-B phosphor under vacuum-ultraviolet light excitation

    NASA Astrophysics Data System (ADS)

    Okamoto, Shinji; Uchino, Rika; Kobayashi, Keisuke; Yamamoto, Hajime

    2009-07-01

    Luminescent properties of Pr3+-sensitized LaPO4:Gd3+ under vacuum-ultraviolet (vuv) light excitation have been investigated. The energy transfer probably occurs from the 5d levels in Pr3+ ions to Gd3+ ions under 172nm light excitation. LaPO4:Gd3+,Pr3+ shows efficient ultraviolet-B (uv-B) emission at 312nm, whose peak intensity reaches its maximum at Gd =35mol% and Pr =5mol%. (La0.65Gd0.35)0.95Pr0.05PO4 is about 1.6 times higher than a typical uv-B phosphor for vuv lamp, Y0.75Gd0.25Al3(BO3)4, in Gd3+-emission intensity under 172nm light excitation. This result implies that the Pr3+-sensitized LaPO4:Gd3+ is a candidate of uv-B phosphors for xenon-excimer discharge vuv lamps. In order to evaluate the effect of the narrow-band uv-B emission by LaPO4:Gd3+,Pr3+ phosphor, irradiation test on DNA was performed. The irradiation damage of pUC 18 DNA by the narrow-band uv-B light from the LaPO4:Gd3+,Pr3+ phosphor is in the same magnitude as that by uv-A light from a filtered Hg lamp, even though the uv-B lamp is higher than the uv-A lamp in power density and photon energy.

  20. Luminescent properties of Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} ultraviolet-B phosphor under vacuum-ultraviolet light excitation

    SciTech Connect

    Okamoto, Shinji; Uchino, Rika; Kobayashi, Keisuke; Yamamoto, Hajime

    2009-07-01

    Luminescent properties of Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} under vacuum-ultraviolet (vuv) light excitation have been investigated. The energy transfer probably occurs from the 5d levels in Pr{sup 3+} ions to Gd{sup 3+} ions under 172 nm light excitation. LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} shows efficient ultraviolet-B (uv-B) emission at 312 nm, whose peak intensity reaches its maximum at Gd=35 mol % and Pr=5 mol %. (La{sub 0.65}Gd{sub 0.35}){sub 0.95}Pr{sub 0.05}PO{sub 4} is about 1.6 times higher than a typical uv-B phosphor for vuv lamp, Y{sub 0.75}Gd{sub 0.25}Al{sub 3}(BO{sub 3}){sub 4}, in Gd{sup 3+}-emission intensity under 172 nm light excitation. This result implies that the Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} is a candidate of uv-B phosphors for xenon-excimer discharge vuv lamps. In order to evaluate the effect of the narrow-band uv-B emission by LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} phosphor, irradiation test on DNA was performed. The irradiation damage of pUC 18 DNA by the narrow-band uv-B light from the LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} phosphor is in the same magnitude as that by uv-A light from a filtered Hg lamp, even though the uv-B lamp is higher than the uv-A lamp in power density and photon energy.

  1. Vacuum ultraviolet photochemical selective area atomic layer deposition of Al{sub 2}O{sub 3} dielectrics

    SciTech Connect

    Chalker, P. R. Marshall, P. A.; Dawson, K.; Brunell, I. F.; Sutcliffe, C. J.; Potter, R. J.

    2015-01-15

    We report the photochemical atomic layer deposition of Al{sub 2}O{sub 3} thin films and the use of this process to achieve area-selective film deposition. A shuttered vacuum ultraviolet (VUV) light source is used to excite molecular oxygen and trimethyl aluminum to deposit films at 60°C. In-situ QCM and post-deposition ellipsometric measurements both show that the deposition rate is saturative as a function of irradiation time. Selective area deposition was achieved by projecting the VUV light through a metalized magnesium fluoride photolithographic mask and the selectivity of deposition on the illuminated and masked regions of the substrate is a logarithmic function of the UV exposure time. The Al{sub 2}O{sub 3} films exhibit dielectric constants of 8 – 10 at 1 MHz after forming gas annealing, similar to films deposited by conventional thermal ALD.

  2. Plasma and vacuum ultraviolet induced charging of SiO{sub 2} and HfO{sub 2} patterned structures

    SciTech Connect

    Lauer, J. L.; Upadhyaya, G. S.; Sinha, H.; Kruger, J. B.; Nishi, Y.; Shohet, J. L.

    2012-01-15

    The authors compare the effects of plasma charging and vacuum ultraviolet (VUV) irradiation on oxidized patterned Si structures with and without atomic-layer-deposited HfO{sub 2}. It was found that, unlike planar oxidized Si wafers, oxidized patterned Si wafers charge up significantly after exposure in an electron-cyclotron resonance plasma. The charging is dependent on the aspect ratio of the patterned structures. This is attributed to electron and/or ion shading during plasma exposure. The addition of a 10 nm thick HfO{sub 2} layer deposited on top of the oxidized silicon structures increases the photoemission yield during VUV irradiation, resulting in more trapped positive charge compared to patterns without the HfO{sub 2} dielectric.

  3. Compact optical cell system for vacuum ultraviolet absorption and circular dichroism spectroscopy and its application to aqueous solution sample.

    PubMed

    Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Kaneko, Fusae; Nakagawa, Kazumichi

    2008-09-01

    We have designed a compact optical cell for studying the absorption and circular dichroism (CD) of a solution sample in the vacuum ultraviolet (VUV) region using a temperature control unit. The cell size was 34 mm in diameter and 14 mm in length. Such compactness was obtained by coating the VUV scintillator onto the outside of the back window. Because this scintillator converts the transmitted VUV light to visible light, the outside of this cell is operated under atmospheric pressure. The temperature of the sample solution was maintained in the range of 5 degrees C to 80 degrees C using a temperature control unit with a Peltier thermoelectric element. Changes in the sample temperature were observed by monitoring the absorption intensity of water. Through the study of VUV-CD spectra of ammonium camphor-10-sulfonate aqueous solutions and the transmitted spectrum of an empty cell, it was concluded that this cell unit has sufficient performance for use in VUV spectroscopy. PMID:18473342

  4. Reflection polarizers for the vacuum ultraviolet using Al + MgF2 mirrors and an MgF2 plate

    NASA Technical Reports Server (NTRS)

    Hass, G.; Hunter, W. R.

    1978-01-01

    Consideration is given to the design and operation of a three-mirror reflecting polarizer where one of the reflecting surfaces is an MgF2 plate, the other surfaces are Al + MgF2 coatings, and one reflection occurs at or near the true Brewster angle. It is found that the polarizer is most efficient in the 1200-2000 A wavelength region, and that by optimum selection of the angle of incidence on the MgF2 plate, polarization values of 100 and over are yielded from 900 to 3000 A. The polarizer may be used at wavelengths as short as 500 A, although it is observed that at such wavelengths the polarization value decreases to about 10. It is noted that all reflecting polarizers operating in the vacuum ultraviolet wavelength may manifest changing characteristics as their mirrors become contaminated, and that polarization must therefore be occasionally remeasured.

  5. Fast luminescence in vacuum ultraviolet region in heavy-ion-irradiated α-Al2O3

    NASA Astrophysics Data System (ADS)

    Koshimizu, Masanori; Kimura, Kazuie; Fujimoto, Yutaka; Asai, Keisuke

    2015-12-01

    We analyzed the time-resolved luminescence properties of α-Al2O3 under heavy ion irradiations in the vacuum ultraviolet (VUV) wavelength region. A luminescence band at approximately 170 nm, at which a luminescence band was observed under VUV irradiation and was ascribed to self-shrunk excitons. The decay rate increased with the linear energy transfer (LET). The luminescence efficiency of the band increased sharply with the LET for the case of Xe irradiation, whose LET was estimated to be higher than the threshold LET for track formation. The fast decay rate and high luminescence intensity for Xe irradiation was explained according to the enhanced radiative rate caused by close interactions among excited states.

  6. Vacuum Ultraviolet (VUV) radiation-induced degradation of Fluorinated Ethylene Propylene (FEP) Teflon aboard the Long Duration Exposure Facility (LDEF)

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Stiegman, A. E.; Staszak, Paul R.; Laue, Eric G.; Liang, Ranty H.

    1992-01-01

    Examination of fluorinated ethylene propylene (FEP) copolymer specimens recovered from the Long Duration Exposure Facility (LDEF) provides evidence for degradation attributed to extended solar vacuum ultraviolet (VUV) irradiation. Scanning electron microscope (SEM) images of sheared FEP film edges reveal the presence of a highly embrittled layer on the exposed surface of specimens obtained from the trailing edge of the LDEF. Similar images obtained for leading edge and control FEP films do not exhibit evidence for such an embrittled layer. Laboratory VUV irradiation of FEP films is found to produce a damage layer similar to that witnessed in the LDEF trailing edge films. Spectroscopic analyses of irradiated films provide data to advance a photochemical mechanism for degradation.

  7. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    NASA Astrophysics Data System (ADS)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  8. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    SciTech Connect

    Jablonowski, H.; Hammer, M. U.; Reuter, S.; Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  9. Angular ion emission characteristics of a laser triggered tin vacuum arc as light source for extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Verbraak, Harald; Küpper, Felix; Jonkers, Jeroen; Bergmann, Klaus

    2010-11-01

    The angular resolved emission of tin ions from a laser triggered vacuum arc to be used as light source for extreme ultraviolet lithography is presented. Ion energies of more than 200 keV for emission angles up to 50° with respect to the optical axis are observed. The angular emission characteristic is strongly anisotropic with a pronounced peak for fast ions into a cone with an opening angle of roughly 10° at an angle of 35° with respect to the optical axis. These ions also exhibit a distinct energy distribution function compared to the more isotropic emitted bulk of ions, which can be referred to different mechanisms of production. Looking at the discharge current parameters, the production of the directed fast ions can be connected with a peaked increase in the impedance, which gives hint to a plasma instability as origin of those ions. The emission of isotropic emitted ions is in agreement with a model of plasma expansion into vacuum. The emission characteristic is also strongly dependent on the parameter of the trigger laser. It is shown that using a double trigger laser pulse the fast ion production can be suppressed by more than one order of magnitude.

  10. A simple electron time-of-flight spectrometer for ultrafast vacuum ultraviolet photoelectron spectroscopy of liquid solutions

    SciTech Connect

    Arrell, C. A. Ojeda, J.; Mourik, F. van; Chergui, M.; Sabbar, M.; Gallmann, L.; Keller, U.; Okell, W. A.; Witting, T.; Siegel, T.; Diveki, Z.; Hutchinson, S.; Tisch, J. W.G.; Marangos, J. P.; Chapman, R. T.; Cacho, C.; Rodrigues, N.; Turcu, I. C.E.; Springate, E.

    2014-10-01

    We present a simple electron time of flight spectrometer for time resolved photoelectron spectroscopy of liquid samples using a vacuum ultraviolet (VUV) source produced by high-harmonic generation. The field free spectrometer coupled with the time-preserving monochromator for the VUV at the Artemis facility of the Rutherford Appleton Laboratory achieves an energy resolution of 0.65 eV at 40 eV with a sub 100 fs temporal resolution. A key feature of the design is a differentially pumped drift tube allowing a microliquid jet to be aligned and started at ambient atmosphere while preserving a pressure of 10⁻¹ mbar at the micro channel plate detector. The pumping requirements for photoelectron (PE) spectroscopy in vacuum are presented, while the instrument performance is demonstrated with PE spectra of salt solutions in water. The capability of the instrument for time resolved measurements is demonstrated by observing the ultrafast (50 fs) vibrational excitation of water leading to temporary proton transfer.

  11. A simple electron time-of-flight spectrometer for ultrafast vacuum ultraviolet photoelectron spectroscopy of liquid solutions

    NASA Astrophysics Data System (ADS)

    Arrell, C. A.; Ojeda, J.; Sabbar, M.; Okell, W. A.; Witting, T.; Siegel, T.; Diveki, Z.; Hutchinson, S.; Gallmann, L.; Keller, U.; van Mourik, F.; Chapman, R. T.; Cacho, C.; Rodrigues, N.; Turcu, I. C. E.; Tisch, J. W. G.; Springate, E.; Marangos, J. P.; Chergui, M.

    2014-10-01

    We present a simple electron time of flight spectrometer for time resolved photoelectron spectroscopy of liquid samples using a vacuum ultraviolet (VUV) source produced by high-harmonic generation. The field free spectrometer coupled with the time-preserving monochromator for the VUV at the Artemis facility of the Rutherford Appleton Laboratory achieves an energy resolution of 0.65 eV at 40 eV with a sub 100 fs temporal resolution. A key feature of the design is a differentially pumped drift tube allowing a microliquid jet to be aligned and started at ambient atmosphere while preserving a pressure of 10-1 mbar at the micro channel plate detector. The pumping requirements for photoelectron (PE) spectroscopy in vacuum are presented, while the instrument performance is demonstrated with PE spectra of salt solutions in water. The capability of the instrument for time resolved measurements is demonstrated by observing the ultrafast (50 fs) vibrational excitation of water leading to temporary proton transfer.

  12. Vacuum upgrade and enhanced performances of the double imaging electron/ion coincidence end-station at the vacuum ultraviolet beamline DESIRS

    NASA Astrophysics Data System (ADS)

    Tang, Xiaofeng; Garcia, Gustavo A.; Gil, Jean-François; Nahon, Laurent

    2015-12-01

    We report here the recent upgrade of the SAPHIRS permanent photoionization end-station at the DESIRS vacuum ultraviolet beamline of synchrotron SOLEIL, whose performances have been enhanced by installing an additional double-skimmer differential chamber. The smaller molecular beam profile obtained at the interaction region has increased the mass resolution of the double imaging photoelectron photoion coincidence (i2PEPICO) spectrometer, DELICIOUS III, installed in the photoionization chamber of the SAPHIRS endstation, by a factor of two, to M/ΔM ˜ 1700 (FWHM). The electron kinetic energy resolution offered by the velocity map imaging (VMI) part of the spectrometer has been improved down to 2.8% (ΔE/E) as we show on the N2 photoionization case in the double skimmer configuration. As a representative example of the overall state-of-the-art i2PEPICO performances, experimental results of the dissociation of state-selected O2+ (B 2 ∑ g - , v+ = 0-6) molecular ions performed at the fixed photon energy of hν = 21.1 eV are presented.

  13. Vacuum upgrade and enhanced performances of the double imaging electron/ion coincidence end-station at the vacuum ultraviolet beamline DESIRS.

    PubMed

    Tang, Xiaofeng; Garcia, Gustavo A; Gil, Jean-François; Nahon, Laurent

    2015-12-01

    We report here the recent upgrade of the SAPHIRS permanent photoionization end-station at the DESIRS vacuum ultraviolet beamline of synchrotron SOLEIL, whose performances have been enhanced by installing an additional double-skimmer differential chamber. The smaller molecular beam profile obtained at the interaction region has increased the mass resolution of the double imaging photoelectron photoion coincidence (i(2)PEPICO) spectrometer, DELICIOUS III, installed in the photoionization chamber of the SAPHIRS endstation, by a factor of two, to M/ΔM ∼ 1700 (FWHM). The electron kinetic energy resolution offered by the velocity map imaging (VMI) part of the spectrometer has been improved down to 2.8% (ΔE/E) as we show on the N2 photoionization case in the double skimmer configuration. As a representative example of the overall state-of-the-art i(2)PEPICO performances, experimental results of the dissociation of state-selected O2(+)(B(2)∑(g)(-), v(+) = 0-6) molecular ions performed at the fixed photon energy of hν = 21.1 eV are presented. PMID:26724007

  14. Experimental station to study the interaction of intense femtosecond vacuum ultraviolet pulses with matter at TTF1 free electron laser

    NASA Astrophysics Data System (ADS)

    Sobierajski, R.; Krzywinski, J.; Andrejczuk, A.; Hahn, U.; Treusch, R.; Jurek, M.; Klinger, D.; Nietubyć, R.; Pełka, J. B.; Reniewicz, H.; Sikora, M.; Sobala, W.

    2005-01-01

    An experimental station to study the interaction of intense femtosecond vacuum ultraviolet pulses generated by the TTF1 free electron laser (FEL) (DESY, Germany) with solids was developed. The vacuum chamber, the sample holder and the detectors had been designed to fulfill strong constraints caused both by the unique properties of the interacting radiation and by TTF1 FEL innovative design. The applied mounting system allowed one to move and rotate the samples precisely with 4degrees of freedom and to heat them up to the maximal temperature of 1000K. In order to accomplish the in situ growth of thin metallic layers on the sample surfaces, evaporation cells had been installed in the vacuum chamber. A time-of-flight apparatus capable of recording both electrons and ions excited on the solid surfaces by the laser pulses had been included in the chamber design. A pulse energy monitor had been placed in the laser beam outside the experimental chamber. A second energy detector had been mounted inside the chamber on a rotational arm, permitting the angular resolved reflectivity measurements. The detectors placed in the chamber enabled a real-time study both of the ionized damage products and the reflected light from the interaction place on the sample surfaces. The measurements were made with respect to the primary beam incident angle and energy. Examples of the experimental results as well as an off-line analysis are presented. The usability of constructed experimental system to study of the interaction of intense, femtosecond pulses with solid matter is demonstrated.

  15. Breaking DNA strands by extreme-ultraviolet laser pulses in vacuum

    NASA Astrophysics Data System (ADS)

    Nováková, Eva; Vyšín, Luděk; Burian, Tomáš; Juha, Libor; Davídková, Marie; Múčka, Viliam; Čuba, Václav; Grisham, Michael E.; Heinbuch, Scott; Rocca, Jorge J.

    2015-04-01

    Ionizing radiation induces a variety of DNA damages including single-strand breaks (SSBs), double-strand breaks (DSBs), abasic sites, modified sugars, and bases. Most theoretical and experimental studies have been focused on DNA strand scissions, in particular production of DNA double-strand breaks. DSBs have been proven to be a key damage at a molecular level responsible for the formation of chromosomal aberrations, leading often to cell death. We have studied the nature of DNA damage induced directly by the pulsed 46.9-nm (26.5 eV) radiation provided by an extreme ultraviolet (XUV) capillary-discharge Ne-like Ar laser (CDL). Doses up to 45 kGy were delivered with a repetition rate of 3 Hz. We studied the dependence of the yield of SSBs and DSBs of a simple model of DNA molecule (pBR322) on the CDL pulse fluence. Agarose gel electrophoresis method was used for determination of both SSB and DSB yields. The action cross sections of the single- and double-strand breaks of pBR322 plasmid DNA in solid state were determined. We observed an increase in the efficiency of strand-break induction in the supercoiled DNA as a function of laser pulse fluence. Results are compared to those acquired at synchrotron radiation facilities and other sources of extreme-ultraviolet and soft x-ray radiation.

  16. Breaking DNA strands by extreme-ultraviolet laser pulses in vacuum.

    PubMed

    Nováková, Eva; Vyšín, Luděk; Burian, Tomáš; Juha, Libor; Davídková, Marie; Múčka, Viliam; Čuba, Václav; Grisham, Michael E; Heinbuch, Scott; Rocca, Jorge J

    2015-04-01

    Ionizing radiation induces a variety of DNA damages including single-strand breaks (SSBs), double-strand breaks (DSBs), abasic sites, modified sugars, and bases. Most theoretical and experimental studies have been focused on DNA strand scissions, in particular production of DNA double-strand breaks. DSBs have been proven to be a key damage at a molecular level responsible for the formation of chromosomal aberrations, leading often to cell death. We have studied the nature of DNA damage induced directly by the pulsed 46.9-nm (26.5 eV) radiation provided by an extreme ultraviolet (XUV) capillary-discharge Ne-like Ar laser (CDL). Doses up to 45 kGy were delivered with a repetition rate of 3 Hz. We studied the dependence of the yield of SSBs and DSBs of a simple model of DNA molecule (pBR322) on the CDL pulse fluence. Agarose gel electrophoresis method was used for determination of both SSB and DSB yields. The action cross sections of the single- and double-strand breaks of pBR322 plasmid DNA in solid state were determined. We observed an increase in the efficiency of strand-break induction in the supercoiled DNA as a function of laser pulse fluence. Results are compared to those acquired at synchrotron radiation facilities and other sources of extreme-ultraviolet and soft x-ray radiation. PMID:25974538

  17. Further studies on LiF-overcoated aluminum mirrors with highest reflectance in the vacuum ultraviolet.

    PubMed

    Cox, J T; Hass, G; Waylonis, J E

    1968-08-01

    Further studies have been made on the preparation of LiF-overcoated aluminum mirrors with highest reflectance at wavelengths down to 1000 A. Mirrors with 73% reflectance at lambda = 1026 A have been made. The extinction coefficient k of evaporated LiF films has been measured under various conditions of film preparation. Techniques for vacuum depositing LiF films with the smallest K and Al + LiF mirrors with the highest reflectance are described. Aging of LiF-coated Al mirrors under various conditions is discussed. PMID:20068835

  18. Vacuum Ultraviolet Photodissociation and Fourier Transform-Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry: Revisited.

    PubMed

    Shaw, Jared B; Robinson, Errol W; Paša-Tolić, Ljiljana

    2016-03-15

    We revisited the implementation of 193 nm ultraviolet photodissociation (UVPD) within the ion cyclotron resonance (ICR) cell of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. UVPD performance characteristics were examined in the context of recent developments in the understanding of UVPD and in-cell tandem mass spectrometry. Efficient UVPD and photo-ECD of a model peptide and proteins within the ICR cell of a FT-ICR mass spectrometer are accomplished through appropriate modulation of laser pulse timing, relative to ion magnetron motion and the potential applied to an ion optical element upon which photons impinge. It is shown that UVPD yields efficient and extensive fragmentation, resulting in excellent sequence coverage for model peptide and protein cations. PMID:26882021

  19. Optimization of northern analysis by vacuum-blotting, RNA-transfer visualization, and ultraviolet fixation

    SciTech Connect

    Kroczek, R.A.; Siebert, E. )

    1990-01-01

    We have optimized Northern analysis at several steps. Overnight electrophoresis was replaced by short gel runs and overnight capillary transfer by rapid vacuum-blotting adapted to Northern analysis. Short uv irradiation was used as a substitute for the usual RNA fixation by baking. Direct staining of RNA before electrophoresis made it possible to check RNA integrity and to evaluate the quality of the size separation immediately after electrophoresis. In this system, RNA transfer onto the membrane support could also be quickly assessed after the blotting step. The net result of all modifications was a doubling of the autoradiography signal compared with that obtained by modern Northern protocols. At the same time, the duration of the procedure was shortened drastically, allowing an autoradiography signal to be obtained within 24 h.

  20. Vacuum ultraviolet radiation/atomic oxygen synergism in fluorinated ethylene propylene Teflon erosion

    NASA Technical Reports Server (NTRS)

    Stiegman, A. E.; Brinza, David E.; Laue, Eric G.; Anderson, Mark S.; Liang, Ranty H.

    1992-01-01

    A micrographic investigation is reported of samples of the fluorinated ethylene propylene (FEP) Teflon thermal-blanketing materials recovered from the Long-Duration Exposure Facility (LDEF) satellite. The samples are taken from the trailing edge and row 8 which correspond to exposures to vacuum UV (VUV) and VUV + atomic O, respectively. Data are taken from SEM and IR-spectra observations, and the LDEF leading-edge FEP shows a high degree of erosion, roughening, and sharp peaks angled in the direction of the flow of atomic O. The trailing edge sample influenced primarily by VUV shows a hard brittle layer and some cracked mosaic patterns. Comparisons to a reference sample suggest that the brittle layer is related to exposure to VUV and is removed by atomic-O impingement. Polymers that are stable to VUV radiation appear to be more stable in terms of atomic oxygen.

  1. Vacuum ultraviolet radiation and thermal cycling effects on atomic oxygen protective photovoltaic array blanket materials

    NASA Technical Reports Server (NTRS)

    Brady, J.; Banks, B.

    1990-01-01

    The importance of synergistic environmental exposure is demonstrated through the evaluation of DuPont 93-1 in simulated LEO environment. Changes in optical properties, surface condition, and mass loss data are described. The qualitative results indicate the necessity for exposure of materials to a series of simulated LEO environments in order to properly determine synergistic effects and demonstrate the overall LEO durability of candidate materials. It is shown that synergistic effects may occur with vacuum thermal cycling combined with VUV radiation followed by atomic oxygen exposure. Testing the durability of candidate solar array blanket materials in a test sequence with necessary synergistic effects makes it possible to determine the appropriate material for providing structural support and maintaining the proper operating temperature for solar cells in the SSF Photovaltaic Power System.

  2. Radiometric calibration of the vacuum-ultraviolet spectrograph SUMER on the SOHO spacecraft with the B detector.

    PubMed

    Schühle, U; Curdt, W; Hollandt, J; Feldman, U; Lemaire, P; Wilhelm, K

    2000-01-20

    The Solar Ultraviolet Measurement of Emitted Radiation (SUMER) vacuum-ultraviolet spectrograph was calibrated in the laboratory before the integration of the instrument on the Solar and Heliospheric Observatory (SOHO) spacecraft in 1995. During the scientific operation of the SOHO it has been possible to track the radiometric calibration of the SUMER spectrograph since March 1996 by a strategy that employs various methods to update the calibration status and improve the coverage of the spectral calibration curve. The results for the A Detector were published previously [Appl. Opt. 36, 6416 (1997)]. During three years of operation in space, the B detector was used for two and one-half years. We describe the characteristics of the B detector and present results of the tracking and refinement of the spectral calibration curves with it. Observations of the spectra of the stars alpha and rho Leonis permit an extrapolation of the calibration curves in the range from 125 to 149.0 nm. Using a solar coronal spectrum observed above the solar disk, we can extrapolate the calibration curves by measuring emission line pairs with well-known intensity ratios. The sensitivity ratio of the two photocathode areas can be obtained by registration of many emission lines in the entire spectral range on both KBr-coated and bare parts of the detector's active surface. The results are found to be consistent with the published calibration performed in the laboratory in the wavelength range from 53 to 124 nm. We can extrapolate the calibration outside this range to 147 nm with a relative uncertainty of ?30% (1varsigma) for wavelengths longer than 125 nm and to 46.5 nm with 50% uncertainty for the short-wavelength range below 53 nm. PMID:18337910

  3. Absolute sensitivity calibration of vacuum and extreme ultraviolet spectrometer systems and Z(eff) measurement based on bremsstrahlung continuum in HL-2A tokamak.

    PubMed

    Zhou, Hangyu; Cui, Zhengying; Morita, Shigeru; Fu, Bingzhong; Goto, Motoshi; Sun, Ping; Dong, Chunfeng; Gao, Yadong; Xu, Yuan; Lu, Ping; Yang, Qingwei; Duan, Xuru

    2012-10-01

    A grazing-incidence flat-field extreme ultraviolet (EUV) spectrometer has been newly developed in HL-2A tokamak. Typical spectral lines are observed from intrinsic impurities of carbon, oxygen, iron, and extrinsic impurity of helium in the wavelength range of 20 Å-500 Å. Bremsstrahlung continuum is measured at different electron densities of HL-2A discharges to calibrate absolute sensitivity of the EUV spectrometer system and to measure effective ionic charge, Z(eff). The sensitivity of a vacuum ultraviolet (VUV) spectrometer system is also absolutely calibrated in overlapped wavelength range of 300 Å-500 Å by comparing the intensity between VUV and EUV line emissions. PMID:23126850

  4. Absolute sensitivity calibration of vacuum and extreme ultraviolet spectrometer systems and Z{sub eff} measurement based on bremsstrahlung continuum in HL-2A tokamak

    SciTech Connect

    Zhou Hangyu; Cui Zhengying; Fu Bingzhong; Sun Ping; Gao Yadong; Xu Yuan; Lu Ping; Yang Qingwei; Duan Xuru; Morita, Shigeru; Goto, Motoshi; Dong Chunfeng

    2012-10-15

    A grazing-incidence flat-field extreme ultraviolet (EUV) spectrometer has been newly developed in HL-2A tokamak. Typical spectral lines are observed from intrinsic impurities of carbon, oxygen, iron, and extrinsic impurity of helium in the wavelength range of 20 A-500 A. Bremsstrahlung continuum is measured at different electron densities of HL-2A discharges to calibrate absolute sensitivity of the EUV spectrometer system and to measure effective ionic charge, Z{sub eff}. The sensitivity of a vacuum ultraviolet (VUV) spectrometer system is also absolutely calibrated in overlapped wavelength range of 300 A-500 A by comparing the intensity between VUV and EUV line emissions.

  5. High-resolution, vacuum-ultraviolet absorption spectrum of boron trifluoride

    SciTech Connect

    Hughes, Patrick P.; Thompson, Alan K.; Vest, Robert E.; Sprague, Matthew K.; Irikura, Karl K.; Beasten, Amy; McComb, Jacob C.; Al-Sheikhly, Mohamad; Coplan, Michael A.; Clark, Charles W.

    2014-11-21

    In the course of investigations of thermal neutron detection based on mixtures of {sup 10}BF{sub 3} with other gases, knowledge was required of the photoabsorption cross sections of {sup 10}BF{sub 3} for wavelengths between 135 and 205 nm. Large discrepancies in the values reported in existing literature led to the absolute measurements reported in this communication. The measurements were made at the SURF III Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. The measured absorption cross sections vary from 10{sup −20} cm{sup 2} at 135 nm to less than 10{sup −21} cm{sup 2} in the region from 165 to 205 nm. Three previously unreported absorption features with resolvable structure were found in the regions 135–145 nm, 150–165 nm, and 190–205 nm. Quantum mechanical calculations, using the TD-B3LYP/aug-cc-pVDZ variant of time-dependent density functional theory implemented in Gaussian 09, suggest that the observed absorption features arise from symmetry-changing adiabatic transitions.

  6. Vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters

    SciTech Connect

    Ahmed, Musahid; Ahmed, Musahid; Wilson, Kevin R.; Belau, Leonid; Kostko, Oleg

    2008-05-12

    In this work we report on thevacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuumultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH + (n=1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH)n(H2O)H + (n=2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH +, (CH 3OH)2 +, (CH3OH)nH + (n=1-9), and (CH 3OH)n(H2O)H + (n=2-9 ) as a function of photon energy. With an increase in the water content in the molecular beam, there is an enhancement of photoionization intensity for methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations.

  7. Conformation of membrane-bound proteins revealed by vacuum-ultraviolet circular-dichroism and linear-dichroism spectroscopy.

    PubMed

    Matsuo, Koichi; Maki, Yasuyuki; Namatame, Hirofumi; Taniguchi, Masaki; Gekko, Kunihiko

    2016-03-01

    Knowledge of the conformations of a water-soluble protein bound to a membrane is important for understanding the membrane-interaction mechanisms and the membrane-mediated functions of the protein. In this study we applied vacuum-ultraviolet circular-dichroism (VUVCD) and linear-dichroism (LD) spectroscopy to analyze the conformations of α-lactalbumin (LA), thioredoxin (Trx), and β-lactoglobulin (LG) bound to phosphatidylglycerol liposomes. The VUVCD analysis coupled with a neural-network analysis showed that these three proteins have characteristic helix-rich conformations involving several helical segments, of which two amphiphilic or hydrophobic segments take part in interactions with the liposome. The LD analysis predicted the average orientations of these helix segments on the liposome: two amphiphilic helices parallel to the liposome surface for LA, two hydrophobic helices perpendicular to the liposome surface for Trx, and a hydrophobic helix perpendicular to and an amphiphilic helix parallel to the liposome surface for LG. This sequence-level information about the secondary structures and orientations was used to formulate interaction models of the three proteins at the membrane surface. This study demonstrates the validity of a combination of VUVCD and LD spectroscopy in conformational analyses of membrane-binding proteins, which are difficult targets for X-ray crystallography and nuclear magnetic resonance spectroscopy. PMID:26756612

  8. Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

    2016-01-01

    Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

  9. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    SciTech Connect

    Sorenson, Danny S.; Pazuchanics, Peter; Johnson, Randall P.; Malone, R. M.; Kaufman, M. I.; Tibbitts, A.; Tunnell, T.; Marks, D.; Capelle, G. A.; Grover, M.; Marshall, B.; Stevens, G. D.; Turley, W. D.; LaLone, B.

    2014-06-25

    An Ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic including the high-powered laser system and high-resolution optical relay system. In addition, the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles will also be described. Finally, results from six high-explosive (HE), shock-driven Sn ejecta experiments will be presented. Particle size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double pulsed experiment will be described.

  10. Rotationally Resolved Vacuum Ultraviolet Resonance-Enhanced Multiphoton Ionization (VUV REMPI) of Acetylene via the G̃ Rydberg State.

    PubMed

    Schmidt-May, Alice F; Grütter, Monika; Neugebohren, Jannis; Kitsopoulos, T N; Wodtke, Alec M; Harding, Dan J

    2016-07-14

    We present a 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme for acetylene via the linear G̃ 4sσ (1)Πu Rydberg state, offering partial rotational resolution and the possibility to detect excitation in both the cis- and trans-bending modes. The resonant transition to the G̃ state is driven by a vacuum ultraviolet (VUV) photon, generated by resonant four-wave mixing (FWM) in krypton. Ionization from the short-lived G̃ state then occurs quickly, driven by the high intensity of the residual light from the FWM process. We have observed nine bands in the region between 79 200 cm(-1) and 80 500 cm(-1) in C2H2 and C2D2. We compare our results with published spectra in this region and suggest alternative assignments for some of the Renner-Teller split bands. Similar REMPI schemes should be applicable to other small molecules with picosecond lifetime Rydberg states. PMID:27073931