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Sample records for high-resolution electron-energy-loss spectroscopy

  1. High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM

    NASA Technical Reports Server (NTRS)

    Sai, Z. R.; Bradley, J. P.; Erni, R.; Browning, N.

    2005-01-01

    A 200 keV FEI TF20 XT monochromated (scanning) transmission electron microscope funded by NASA's SRLIDAP program is undergoing installation at Lawrence Livermore National Laboratory. Instrument specifications in STEM mode are Cs =1.0 mm, Cc =1.2 mm, image resolution =0.18 nm, and in TEM mode Cs =1.3 mm, Cc =1.3 mm, information limit =0.14 nm. Key features of the instrument are a voltage-stabilized high tension (HT) supply, a monochromator, a high-resolution electron energy-loss spectrometer/energy filter, a high-resolution annular darkfield detector, and a solid-state x-ray energy-dispersive spectrometer. The high-tension tank contains additional sections for 60Hz and high frequency filtering, resulting in an operating voltage of 200 kV plus or minus 0.005V, a greater than 10-fold improvement over earlier systems. The monochromator is a single Wien filter design. The energy filter is a Gatan model 866 Tridiem-ERS high resolution GIF spec d for less than or equal to 0.15 eV energy resolution with 29 pA of current in a 2 nm diameter probe. 0.13 eV has already been achieved during early installation. The x-ray detector (EDAX/Genesis 4000) has a take-off angle of 20 degrees, an active area of 30 square millimeters, and a solid angle of 0.3 steradians. The higher solid angle is possible because the objective pole-piece allows the detector to be positioned as close as 9.47 mm from the specimen. The voltage-stabilized HT supply, monochromator and GIF enable high-resolution electron energy-loss spectroscopy (HREELS) with energy resolution comparable to synchrotron XANES, but with approximately 100X better spatial resolution. The region between 0 and 100 eV is called the low-loss or valence electron energy-loss spectroscopy (VEELS) region where features due to collective plasma oscillations and single electron transitions of valence electrons are observed. Most of the low-loss VEELS features we are detecting are being observed for the first time in IDPs. A major focus of

  2. High resolution electron energy loss spectroscopy with two-dimensional energy and momentum mapping.

    PubMed

    Zhu, Xuetao; Cao, Yanwei; Zhang, Shuyuan; Jia, Xun; Guo, Qinlin; Yang, Fang; Zhu, Linfan; Zhang, Jiandi; Plummer, E W; Guo, Jiandong

    2015-08-01

    High resolution electron energy loss spectroscopy (HREELS) is a powerful technique to probe vibrational and electronic excitations at surfaces. The dispersion relation of surface excitations, i.e., energy as a function of momentum, has in the past, been obtained by measuring the energy loss at a fixed angle (momentum) and then rotating sample, monochromator, or analyzer. Here, we introduce a new strategy for HREELS, utilizing a specially designed lens system with a double-cylindrical Ibach-type monochromator combined with a commercial VG Scienta hemispherical electron energy analyzer, which can simultaneously measure the energy and momentum of the scattered electrons. The new system possesses high angular resolution (<0.1°), detecting efficiency and sampling density. The capabilities of this system are demonstrated using Bi2Sr2CaCu2O(8+δ). The time required to obtain a complete dispersion spectrum is at least one order of magnitude shorter than conventional spectrometers, with improved momentum resolution and no loss in energy resolution.

  3. High resolution electron energy loss spectroscopy with two-dimensional energy and momentum mapping

    SciTech Connect

    Zhu, Xuetao; Cao, Yanwei; Zhang, Shuyuan; Jia, Xun; Guo, Qinlin; Yang, Fang; Zhu, Linfan; Zhang, Jiandi; Plummer, E. W.; Guo, Jiandong

    2015-08-15

    High resolution electron energy loss spectroscopy (HREELS) is a powerful technique to probe vibrational and electronic excitations at surfaces. The dispersion relation of surface excitations, i.e., energy as a function of momentum, has in the past, been obtained by measuring the energy loss at a fixed angle (momentum) and then rotating sample, monochromator, or analyzer. Here, we introduce a new strategy for HREELS, utilizing a specially designed lens system with a double-cylindrical Ibach-type monochromator combined with a commercial VG Scienta hemispherical electron energy analyzer, which can simultaneously measure the energy and momentum of the scattered electrons. The new system possesses high angular resolution (<0.1°), detecting efficiency and sampling density. The capabilities of this system are demonstrated using Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ}. The time required to obtain a complete dispersion spectrum is at least one order of magnitude shorter than conventional spectrometers, with improved momentum resolution and no loss in energy resolution.

  4. High-resolution electron microscopy and electron energy-loss spectroscopy of giant palladium clusters

    NASA Astrophysics Data System (ADS)

    Oleshko, V.; Volkov, V.; Gijbels, R.; Jacob, W.; Vargaftik, M.; Moiseev, I.; van Tendeloo, G.

    1995-12-01

    Combined structural and chemical characterization of cationic polynuclear palladium coordination compounds Pd561L60(OAc)180, where L=1,10-phenantroline or 2,2'-bipyridine has been carried out by high-resolution electron microscopy (HREM) and analytical electron microscopy methods including electron energy-loss spectroscopy (EELS), zero-loss electron spectroscopic imaging, and energy-dispersive X-ray spectroscopy (EDX). The cell structure of the cluster matter with almost completely uniform metal core size distributions centered around 2.3 ±0.5 nm was observed. Zero-loss energy filtering allowed to improve the image contrast and resolution. HREM images showed that most of the palladium clusters had a cubo-octahedral shape. Some of them had a distorted icosahedron structure exhibiting multiple twinning. The selected-area electron diffraction patterns confirmed the face centered cubic structure with lattice parameter close to that of metallic palladium. The energy-loss spectra of the populations of clusters contained several bands, which could be assigned to the delayed Pd M4, 5-edge at 362 eV, the Pd M3-edge at 533 eV and the Pd M2-edge at 561 eV, the NK-edge at about 400 eV, the O K-edge at 532 eV overlapping with the Pd M3-edge and the carbon C K-edge at 284 eV. Background subtraction was applied to reveal the exact positions and fine structure of low intensity elemental peaks. EELS evaluations have been confirmed by EDX. The recorded series of the Pd M-edges and the N K-edge in the spectra of the giant palladium clusters obviously were related to Pd-Pd- and Pd-ligand bonding.

  5. High-resolution monochromated electron energy-loss spectroscopy of organic photovoltaic materials.

    PubMed

    Alexander, Jessica A; Scheltens, Frank J; Drummy, Lawrence F; Durstock, Michael F; Hage, Fredrik S; Ramasse, Quentin M; McComb, David W

    2017-03-02

    Advances in electron monochromator technology are providing opportunities for high energy resolution (10 - 200meV) electron energy-loss spectroscopy (EELS) to be performed in the scanning transmission electron microscope (STEM). The energy-loss near-edge structure in core-loss spectroscopy is often limited by core-hole lifetimes rather than the energy spread of the incident illumination. However, in the valence-loss region, the reduced width of the zero loss peak makes it possible to resolve clearly and unambiguously spectral features at very low energy-losses (<3eV). In this contribution, high-resolution EELS was used to investigate four materials commonly used in organic photovoltaics (OPVs): poly(3-hexlythiophene) (P3HT), [6,6] phenyl-C61 butyric acid methyl ester (PCBM), copper phthalocyanine (CuPc), and fullerene (C60). Data was collected on two different monochromated instruments - a Nion UltraSTEM 100 MC 'HERMES' and a FEI Titan(3) 60-300 Image-Corrected S/TEM - using energy resolutions (as defined by the zero loss peak full-width at half-maximum) of 35meV and 175meV, respectively. The data was acquired to allow deconvolution of plural scattering, and Kramers-Kronig analysis was utilized to extract the complex dielectric functions. The real and imaginary parts of the complex dielectric functions obtained from the two instruments were compared to evaluate if the enhanced resolution in the Nion provides new opto-electronic information for these organic materials. The differences between the spectra are discussed, and the implications for STEM-EELS studies of advanced materials are considered.

  6. High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

    PubMed

    Patterson, C H

    2012-09-07

    Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

  7. High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles

    SciTech Connect

    Laffont, L.; Gibot, P.

    2010-11-15

    Manganese oxides particularly Mn{sub 3}O{sub 4} Hausmannite are currently used in many industrial applications such as catalysis, magnetism, electrochemistry or air contamination. The downsizing of the particle size of such material permits an improvement of its intrinsic properties and a consequent increase in its performances compared to a classical micron-sized material. Here, we report a novel synthesis of hydrophilic nano-sized Mn{sub 3}O{sub 4}, a bivalent oxide, for which a precise characterization is necessary and for which the determination of the valency proves to be essential. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and particularly High Resolution Electron Energy Loss Spectroscopy (HREELS) allow us to perform these measurements on the nanometer scale. Well crystallized 10-20 nm sized Mn{sub 3}O{sub 4} particles with sphere-shaped morphology were thus successfully synthesized. Meticulous EELS investigations allowed the determination of a Mn{sup 3+}/Mn{sup 2+} ratio of 1.5, i.e. slightly lower than the theoretical value of 2 for the bulk Hausmannite manganese oxide. This result emphasizes the presence of vacancies on the tetrahedral sites in the structure of the as-synthesized nanomaterial. - Research Highlights: {yields}Mn{sub 3}O{sub 4} bulk and nano were studied by XRD, TEM and EELS. {yields}XRD and TEM determine the degree of crystallinity and the narrow grain size. {yields}HREELS gave access to the Mn{sup 3+}/Mn{sup 2+} ratio. {yields}Mn{sub 3}O{sub 4} nano have vacancies on the tetrahedral sites.

  8. Identification of local phase of nanoscale BaTiO₃ powders by high-resolution electron energy loss spectroscopy.

    PubMed

    Moon, Sun-Min; Wang, Xiaohui; Cho, Nam-Hee

    2013-08-01

    The electron energy loss spectroscopy (EELS) technique was applied to investigate the local variation in the phase of barium titanate (BaTiO₃) ceramics. It was found that the fine structure of the titanium L₂,₃ edge and their satellite peaks were sensitively varied with the tetragonal-cubic phase transition. The peak splitting of Ti-L₃ edge of tetragonal-phased BaTiO₃ ceramics was widened because of the increased crystal field effect compared with that of cubic-phased BaTiO₃. In case of nanoscale BaTiO₃ powders, the L₃ edge splitting of the core region was found to be smaller than that of the shell region. The energy gap between peaks t₂g and eg varied from 2.36 to 1.94 eV with changing the probe position from 1 to 20 nm from the surface. These results suggest that the EELS technique can be used to identify the local phase of sintered BaTiO₃ ceramics.

  9. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

    SciTech Connect

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P. E-mail: michael.brunger@flinders.edu.au; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J. E-mail: michael.brunger@flinders.edu.au; and others

    2015-10-14

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

  10. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations.

    PubMed

    Ferreira da Silva, F; Lange, E; Limão-Vieira, P; Jones, N C; Hoffmann, S V; Hubin-Franskin, M-J; Delwiche, J; Brunger, M J; Neves, R F C; Lopes, M C A; de Oliveira, E M; da Costa, R F; Varella, M T do N; Bettega, M H F; Blanco, F; García, G; Lima, M A P; Jones, D B

    2015-10-14

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

  11. The use of high resolution electron-energy-loss spectroscopy for refining the infrared optical constants of GaS, GaSe, and InSe

    NASA Astrophysics Data System (ADS)

    Yu, Li-Ming; Thiry, P. A.; Degiovanni, A.; Conard, Th.; Leclerc, G.; Caudano, R.; Lambin, Ph.; Debever, J.-M.

    1994-06-01

    Cleaved surfaces of III-VI lamellar semiconducting compounds GaS, GaSe, and InSe have been studied by high resolution electron-energy-loss spectroscopy (HREELS). The infrared optical constants of the materials were retrieved by using the dielectric theory taking account of the resonance frequencies published from infrared reflectivity (IRS) data. The limitations of the HREELS and IRS measurements in the case of these materials are discussed in detail. However, it is shown that, by combining the informations from both spectroscopies, it is possible to refine some of the oscillator strengths of these materials.

  12. High-resolution electron-energy-loss spectroscopy and photoelectron-diffraction studies of the geometric structure of adsorbates on single-crystal metal surfaces

    SciTech Connect

    Rosenblatt, D.H.

    1982-11-01

    Two techniques which have made important contributions to the understanding of surface phenomena are high resolution electron energy loss spectroscopy (EELS) and photoelectron diffraction (PD). EELS is capable of directly measuring the vibrational modes of clean and adsorbate covered metal surfaces. In this work, the design, construction, and performance of a new EELS spectrometer are described. These results are discussed in terms of possible structures of the O-Cu(001) system. Recommendations for improvements in this EELS spectrometer and guidelines for future spectrometers are given. PD experiments provide accurate quantitative information about the geometry of atoms and molecules adsorbed on metal surfaces. The technique has advantages when used to study disordered overlayers, molecular overlayers, multiple site systems, and adsorbates which are weak electron scatterers. Four experiments were carried out which exploit these advantages.

  13. Hydrogen bonding configuration and thermal stability of ambient exposed and in situ hydrogenated polycrystalline diamond surfaces studied by high resolution electron energy loss spectroscopy.

    PubMed

    Michaelson, Sh; Akhvlediani, R; Hoffman, A

    2011-06-28

    In this work we report on an investigation of hydrogen bonding and thermal stability on the surface of poly-crystalline diamond by high resolution electron energy loss spectroscopy (HR-EELS). Diamond films were grown on silicon substrates from CH(4)/H(2) as well as from CD(4)/D(2) gas mixtures by hot filament chemical vapor deposition (HF-CVD). The impact of ex situ ambient exposure on hydrogen bonding and its thermal stability was examined for: (i) as deposited films from a CH(4)/H(2) gas mixture; (ii) the same sample treated ex situ in micro-wave activated hydrogen plasma; and (iii) as deposited films from a CD(4)/D(2) gas mixture. In order to clarify the changes in the hydrogen bonding configuration detected on the different surfaces as a function of thermal annealing in situ hydrogenation by thermally activated atomic hydrogen was performed and examined. This study provides direct evidence that the exposure to ambient conditions and low temperature vacuum annealing have a pronounced effect on the hydrogen-carbon bonding configuration onto the poly-crystalline diamond surfaces.

  14. Two bonding configurations of acetylene on Si(001)-(2 x 1): a combined high-resolution electron energy loss spectroscopy and density functional theory study.

    PubMed

    Mineva, T; Nathaniel, R; Kostov, K L; Widdra, W

    2006-11-21

    Two coexisting adsorption states of molecularly adsorbed acetylene on the Si(001)-(2 x 1) surface have been identified by a combined study based on the high-resolution electron energy loss spectroscopy and density functional computations. Seven possible adsorbate-substrate structures are considered theoretically including their full vibrational analysis. Based on a significantly enhanced experimental resolution, the assignment of 15 C2H2- and C2D2-derived vibrational modes identifies a dominant di-sigma bonded molecule adsorbed on top of a single Si-Si dimer. Additionally there is clear evidence for a second minority species which is di-sigma bonded between two Si-Si dimers within the same dimer row (end-bridge geometry). The possible symmetries of the adsorbate complexes are discussed based on the specular and off-specular vibrational measurements. They suggest lower than ideal C(2v) and C(s) symmetries for on-top and end-bridge species, respectively. At low coverages the symmetry reductions might be lifted.

  15. Probing optical band gaps at the nanoscale in NiFe₂O₄ and CoFe₂O₄ epitaxial films by high resolution electron energy loss spectroscopy

    SciTech Connect

    Dileep, K.; Loukya, B.; Datta, R.; Pachauri, N.; Gupta, A.

    2014-09-14

    Nanoscale optical band gap variations in epitaxial thin films of two different spinel ferrites, i.e., NiFe₂O₄ (NFO) and CoFe₂O₄ (CFO), have been investigated by spatially resolved high resolution electron energy loss spectroscopy. Experimentally, both NFO and CFO show indirect/direct band gaps around 1.52 eV/2.74 and 2.3 eV, and 1.3 eV/2.31 eV, respectively, for the ideal inverse spinel configuration with considerable standard deviation in the band gap values for CFO due to various levels of deviation from the ideal inverse spinel structure. Direct probing of the regions in both the systems with tetrahedral A site cation vacancy, which is distinct from the ideal inverse spinel configuration, shows significantly smaller band gap values. The experimental results are supported by the density functional theory based modified Becke-Johnson exchange correlation potential calculated band gap values for the different cation configurations.

  16. Image simulation for electron energy loss spectroscopy

    SciTech Connect

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations. Finally, the affect of the channelling of the electron probe within the sample is also discussed.

  17. Image simulation for electron energy loss spectroscopy

    DOE PAGES

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

  18. Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

    SciTech Connect

    Lazzari, Rémi Li, Jingfeng Jupille, Jacques

    2015-01-15

    A new spectral restoration algorithm of reflection electron energy loss spectra is proposed. It is based on the maximum likelihood principle as implemented in the iterative Lucy-Richardson approach. Resolution is enhanced and point spread function recovered in a semi-blind way by forcing cyclically the zero loss to converge towards a Dirac peak. Synthetic phonon spectra of TiO{sub 2} are used as a test bed to discuss resolution enhancement, convergence benefit, stability towards noise, and apparatus function recovery. Attention is focused on the interplay between spectral restoration and quasi-elastic broadening due to free carriers. A resolution enhancement by a factor up to 6 on the elastic peak width can be obtained on experimental spectra of TiO{sub 2}(110) and helps revealing mixed phonon/plasmon excitations.

  19. Direct band gap measurement of Cu(In,Ga)(Se,S){sub 2} thin films using high-resolution reflection electron energy loss spectroscopy

    SciTech Connect

    Heo, Sung; Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su; Song, Taewon; Lee, Dongho Nam, Junggyu; Kang, Hee Jae; Choi, Pyung-Ho; Choi, Byoung-Deog

    2015-06-29

    To investigate the band gap profile of Cu(In{sub 1−x},Ga{sub x})(Se{sub 1−y}S{sub y}){sub 2} of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.

  20. Probing battery chemistry with liquid cell electron energy loss spectroscopy

    DOE PAGES

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; ...

    2015-01-01

    Electron energy loss spectroscopy (EELS) was used to determine the chemistry and oxidation state of LiMn2O4 and Li4Ti5O12 thin film battery electrodes in liquid cells for in situ scanning/transmission electron microscopy (S/TEM). Using the L2,3 white line intensity ratio method we determine the oxidation state of Mn and Ti in a liquid electrolyte solvent and discuss experimental parameters that influence measurement sensitivity.

  1. Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy

    SciTech Connect

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Aguiar, Jeffery A.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren L.

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. The use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  2. Simulating electron energy loss spectroscopy with the MNPBEM toolbox

    NASA Astrophysics Data System (ADS)

    Hohenester, Ulrich

    2014-03-01

    Within the MNPBEM toolbox, we show how to simulate electron energy loss spectroscopy (EELS) of plasmonic nanoparticles using a boundary element method approach. The methodology underlying our approach closely follows the concepts developed by García de Abajo and coworkers (Garcia de Abajo, 2010). We introduce two classes eelsret and eelsstat that allow in combination with our recently developed MNPBEM toolbox for a simple, robust, and efficient computation of EEL spectra and maps. The classes are accompanied by a number of demo programs for EELS simulation of metallic nanospheres, nanodisks, and nanotriangles, and for electron trajectories passing by or penetrating through the metallic nanoparticles. We also discuss how to compute electric fields induced by the electron beam and cathodoluminescence. Catalogue identifier: AEKJ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKJ_v2_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 38886 No. of bytes in distributed program, including test data, etc.: 1222650 Distribution format: tar.gz Programming language: Matlab 7.11.0 (R2010b). Computer: Any which supports Matlab 7.11.0 (R2010b). Operating system: Any which supports Matlab 7.11.0 (R2010b). RAM:≥1 GB Classification: 18. Catalogue identifier of previous version: AEKJ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 183 (2012) 370 External routines: MESH2D available at www.mathworks.com Does the new version supersede the previous version?: Yes Nature of problem: Simulation of electron energy loss spectroscopy (EELS) for plasmonic nanoparticles. Solution method: Boundary element method using electromagnetic potentials. Reasons for new version: The new version of the toolbox includes two additional classes for the simulation of electron energy

  3. Probing battery chemistry with liquid cell electron energy loss spectroscopy

    SciTech Connect

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren Leslie; Aguiar, Jeffery A.

    2015-01-01

    Electron energy loss spectroscopy (EELS) was used to determine the chemistry and oxidation state of LiMn2O4 and Li4Ti5O12 thin film battery electrodes in liquid cells for in situ scanning/transmission electron microscopy (S/TEM). Using the L2,3 white line intensity ratio method we determine the oxidation state of Mn and Ti in a liquid electrolyte solvent and discuss experimental parameters that influence measurement sensitivity.

  4. Electron energy-loss spectroscopy of branched gap plasmon resonators

    PubMed Central

    Raza, Søren; Esfandyarpour, Majid; Koh, Ai Leen; Mortensen, N. Asger; Brongersma, Mark L.; Bozhevolnyi, Sergey I.

    2016-01-01

    The miniaturization of integrated optical circuits below the diffraction limit for high-speed manipulation of information is one of the cornerstones in plasmonics research. By coupling to surface plasmons supported on nanostructured metallic surfaces, light can be confined to the nanoscale, enabling the potential interface to electronic circuits. In particular, gap surface plasmons propagating in an air gap sandwiched between metal layers have shown extraordinary mode confinement with significant propagation length. In this work, we unveil the optical properties of gap surface plasmons in silver nanoslot structures with widths of only 25 nm. We fabricate linear, branched and cross-shaped nanoslot waveguide components, which all support resonances due to interference of counter-propagating gap plasmons. By exploiting the superior spatial resolution of a scanning transmission electron microscope combined with electron energy-loss spectroscopy, we experimentally show the propagation, bending and splitting of slot gap plasmons. PMID:27982030

  5. Electron energy-loss spectroscopy of branched gap plasmon resonators

    NASA Astrophysics Data System (ADS)

    Raza, Søren; Esfandyarpour, Majid; Koh, Ai Leen; Mortensen, N. Asger; Brongersma, Mark L.; Bozhevolnyi, Sergey I.

    2016-12-01

    The miniaturization of integrated optical circuits below the diffraction limit for high-speed manipulation of information is one of the cornerstones in plasmonics research. By coupling to surface plasmons supported on nanostructured metallic surfaces, light can be confined to the nanoscale, enabling the potential interface to electronic circuits. In particular, gap surface plasmons propagating in an air gap sandwiched between metal layers have shown extraordinary mode confinement with significant propagation length. In this work, we unveil the optical properties of gap surface plasmons in silver nanoslot structures with widths of only 25 nm. We fabricate linear, branched and cross-shaped nanoslot waveguide components, which all support resonances due to interference of counter-propagating gap plasmons. By exploiting the superior spatial resolution of a scanning transmission electron microscope combined with electron energy-loss spectroscopy, we experimentally show the propagation, bending and splitting of slot gap plasmons.

  6. Data processing for atomic resolution electron energy loss spectroscopy.

    PubMed

    Cueva, Paul; Hovden, Robert; Mundy, Julia A; Xin, Huolin L; Muller, David A

    2012-08-01

    The high beam current and subangstrom resolution of aberration-corrected scanning transmission electron microscopes has enabled electron energy loss spectroscopy (EELS) mapping with atomic resolution. These spectral maps are often dose limited and spatially oversampled, leading to low counts/channel and are thus highly sensitive to errors in background estimation. However, by taking advantage of redundancy in the dataset map, one can improve background estimation and increase chemical sensitivity. We consider two such approaches--linear combination of power laws and local background averaging--that reduce background error and improve signal extraction. Principal component analysis (PCA) can also be used to analyze spectrum images, but the poor peak-to-background ratio in EELS can lead to serious artifacts if raw EELS data are PCA filtered. We identify common artifacts and discuss alternative approaches. These algorithms are implemented within the Cornell Spectrum Imager, an open source software package for spectroscopic analysis.

  7. Uranium trioxide behavior during electron energy loss spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Degueldre, Claude; Alekseev, Evgeny V.

    2015-03-01

    A sample of uranium trioxide (UO3) was produced by focused ion beam (~10 μm×~10 μm×<0.5 μm) for transmission electron and electron energy loss (EEL) spectroscopy examinations in a transmission electron microscope (TEM). The EEL spectra were recorded as a function of the thickness for the P and O edges in the low energy range 0-350 eV and were compared to spectra of UO3 small grains attached to a TEM grid. The EEL spectrum was studied through a range of thicknesses going from ~60 to ~260 nm. The EEL spectra recorded for UO3 are compared with those recorded for UO2. The reduction of UO3 into U4O9 and/or UO2 is readily observed apparently during the TEM investigations and as confirmed by electron diffraction (eD). This redox effect is similar to that known for other redox sensitive oxides. Recommendations are suggested to avoid sample decomposition.

  8. Reflection Electron Energy Loss Spectroscopy of Iron Monosilicide

    NASA Astrophysics Data System (ADS)

    Parshin, A. S.; Igumenov, A. Yu.; Mikhlin, Yu. L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2017-02-01

    X-ray photoelectron spectra, reflection electron energy loss spectra, and inelastic electron scattering cross section spectra of iron monosilicide FeSi are investigated. It is shown that the spectra of inelastic electron scattering cross section have advantages over the reflection electron energy loss spectra in studying the processes of electron energy losses. An analysis of the fine structure of the inelastic electron scattering cross section spectra allows previously unresolved peaks to be identified and their energy, intensity, and nature to be determined. The difference between energies of fitting loss peaks in the spectra of inelastic electron scattering cross section of FeSi and pure Fe are more substantial than the chemical shifts in X-ray photoelectron spectra, which indicates the possibility of application of the fine structure of the spectra of inelastic electron scattering cross section for elemental analysis.

  9. Evidence for anisotropic dielectric properties of monoclinic hafnia using valence electron energy-loss spectroscopy in high-resolution transmission electron microscopy and ab initio time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Guedj, C.; Hung, L.; Zobelli, A.; Blaise, P.; Sottile, F.; Olevano, V.

    2014-12-01

    The effect of nanocrystal orientation on the energy loss spectra of monoclinic hafnia (m-HfO2) is measured by high resolution transmission electron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on high quality samples. For the same momentum-transfer directions, the dielectric properties are also calculated ab initio by time-dependent density-functional theory (TDDFT). Experiments and simulations evidence anisotropy in the dielectric properties of m-HfO2, most notably with the direction-dependent oscillator strength of the main bulk plasmon. The anisotropic nature of m-HfO2 may contribute to the differences among VEELS spectra reported in literature. The good agreement between the complex dielectric permittivity extracted from VEELS with nanometer spatial resolution, TDDFT modeling, and past literature demonstrates that the present HRTEM-VEELS device-oriented methodology is a possible solution to the difficult nanocharacterization challenges given in the International Technology Roadmap for Semiconductors.

  10. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-07

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

  11. Role of the kinematics of probing electrons in electron energy-loss spectroscopy of solid surfaces

    NASA Astrophysics Data System (ADS)

    Nazarov, V. U.; Silkin, V. M.; Krasovskii, E. E.

    2016-01-01

    Inelastic scattering of electrons incident on a solid surface is determined by two properties: (i) electronic response of the target system and (ii) the detailed quantum-mechanical motion of the projectile electron inside and in the vicinity of the target. We emphasize the equal importance of the second ingredient, pointing out the fundamental limitations of the conventionally used theoretical description of the electron energy-loss spectroscopy (EELS) in terms of the "energy-loss functions." Our approach encompasses the dipole and impact scattering as specific cases, with the emphasis on the quantum-mechanical treatment of the probe electron. Applied to the high-resolution EELS of Ag surface, our theory largely agrees with recent experiments, while some instructive exceptions are rationalized.

  12. Quantification of ordering at a solid-liquid interface using plasmon electron energy loss spectroscopy

    SciTech Connect

    Gandman, Maria; Kauffmann, Yaron; Kaplan, Wayne D.

    2015-02-02

    We present an in situ electron energy loss spectroscopy (EELS) study of ordering of liquid Al at various Al-Al{sub 2}O{sub 3} interfaces. This technique utilizes precise measurements of the shifts in bulk plasmon resonance and their sensitivity to the valence electron density. Plasmon EELS combined with high resolution transmission electron microscopy provides information regarding the chemical composition in liquid Al at Al-Al{sub 2}O{sub 3} interfaces. Preferential oxygen segregation to the (0006) Al{sub 2}O{sub 3} plane was verified, and the (101{sup ¯}2) Al{sub 2}O{sub 3} plane was found to contain the lowest amount of segregated species.

  13. Angular-resolved electron energy loss spectroscopy on a split-ring resonator

    NASA Astrophysics Data System (ADS)

    von Cube, F.; Niegemann, J.; Irsen, S.; Bell, D. C.; Linden, S.

    2014-03-01

    We investigate the plasmonic near field of a lithographically defined split-ring resonator with angular-resolved electron energy loss spectroscopy in a scanning transmission electron microscope. By tilting the sample, different electric field components of the plasmonic modes can be probed with the electron beam. The electron energy loss spectra recorded under oblique incidence can feature plasmonic resonances that are not observable under normal incidence. Our experimental findings are supported by full numerical calculations based on the discontinuous Galerkin time-domain method.

  14. Nanoscale mapping of optical band gaps using monochromated electron energy loss spectroscopy.

    PubMed

    Zhan, W; Granerød, C S; Venkatachalapathy, V; Johansen, K M H; Jensen, I J T; Kuznetsov, A Yu; Prytz, Ø

    2017-03-10

    Using monochromated electron energy loss spectroscopy in a probe-corrected scanning transmission electron microscope we demonstrate band gap mapping in ZnO/ZnCdO thin films with a spatial resolution below 10 nm and spectral precision of 20 meV.

  15. Nanoscale mapping of optical band gaps using monochromated electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhan, W.; Granerød, C. S.; Venkatachalapathy, V.; Johansen, K. M. H.; Jensen, I. J. T.; Kuznetsov, A. Yu; Prytz, Ø.

    2017-03-01

    Using monochromated electron energy loss spectroscopy in a probe-corrected scanning transmission electron microscope we demonstrate band gap mapping in ZnO/ZnCdO thin films with a spatial resolution below 10 nm and spectral precision of 20 meV.

  16. Chemical Analysis of Individual Aerosols Particles by Electron Energy-Loss Spectroscopy (EELS)

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Buseck, P. R.; Garvie, L. A.; Li, J.; Posfai, M.

    2001-12-01

    We use electron energy-loss spectroscopy (EELS) with a transmission electron microscope (TEM) to obtain chemical and bonding information on individual aerosol particles. EELS is ideally suited to this task because of its high spatial resolution and sensitivity to light elements such as C, N, and O. In addition, the spectral shapes provide information regarding bonding, atomic coordination and, for polyvalent elements, oxidation states. Our current focus is on carbonaceous aerosols both in the ambient air and emissions from biomass burning, with emphasis on the heterogeneous chemistry, particle structure, and chemical composition of soot particles. From the EELS spectra we were able to record for the first time, differences in composition between individual spherules within the same soot aggregate. We also found evidence of chemical variations even within individual soot spheres as small as 50 nm across. In the case of biomass burning, the most striking chemical differences are in the quantity of K, minor O and, in places, N. The quantity of elements associated with C decreases with the degree of graphitization of the soot spheres, as shown by the shapes of the C spectra and was corroborated by high-resolution TEM images of the analyzed particles. Knowledge of the degree of graphitization and quantity of associated elements is important for understanding and modeling their optical properties and in some case in source attributions.

  17. High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

    NASA Astrophysics Data System (ADS)

    Entringer, Anthony G.

    The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

  18. Real-space imaging of nanotip plasmons using electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Schröder, Benjamin; Weber, Thorsten; Yalunin, Sergey V.; Kiel, Thomas; Matyssek, Christian; Sivis, Murat; Schäfer, Sascha; von Cube, Felix; Irsen, Stephan; Busch, Kurt; Ropers, Claus; Linden, Stefan

    2015-08-01

    We report the spatial mapping of surface plasmons on conical gold nanotips by electron energy loss spectroscopy. We observe standing-wave patterns resulting from reflections of the fundamental surface-plasmon mode at the nanotip apex. The experimental results are in very good agreement with numerical calculations using the discontinuous Galerkin time-domain method and analytical computations based on a cylindrical mode expansion.

  19. The electronic properties of potassium doped copper-phthalocyanine studied by electron energy-loss spectroscopy.

    PubMed

    Flatz, K; Grobosch, M; Knupfer, M

    2007-06-07

    The authors have studied the electronic structure of potassium doped copper-phthalocyanine using electron energy-loss spectroscopy. The evolution of the loss function indicates the formation of distinct KxCuPc phases. Taking into account the C1s and K2p core level excitations and recent results by Giovanelli et al. [J. Chem. Phys. 126, 044709 (2007)], they conclude that these are K2CuPc and K4CuPc. They discuss the changes in the electronic excitations upon doping on the basis of the molecular electronic levels and the presence of electronic correlations.

  20. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    SciTech Connect

    Yedra, Ll.; Estradé, S.; Torruella, P.; Eljarrat, A.; Peiró, F.; Darbal, A. D.; Weiss, J. K.

    2014-08-04

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

  1. Investigation of the oxidation states of Cu additive in colored borosilicate glasses by electron energy loss spectroscopy

    SciTech Connect

    Yang, Guang Cheng, Shaodong; Li, Chao; Ma, Chuansheng; Zhong, Jiasong; Xiang, Weidong; Wang, Zhao

    2014-12-14

    Three optically transparent colorful (red, green, and blue) glasses were synthesized by the sol-gel method. Nano-sized precipitates were found in scanning electron microscopy images. The precipitates were analyzed by transmission electron microscopy (TEM) and high resolution TEM. The measured lattice parameters of these precipitates were found to fit the metallic copper in red glass but deviate from single valenced Cu oxides in green and blue glasses. The chemistry of these nano-sized particles was confirmed by electron energy loss spectroscopy (EELS). By fitting the EELS spectra obtained from the precipitates with the linear combination of reference spectra from Cu reference compounds, the oxidation states of Cu in the precipitates have been derived. First principle calculations suggested that the Cu nano-particles, which are in the similar oxidation states as our measurement, would show green color in the visible light range.

  2. Electron energy-loss spectroscopy of coupled plasmonic systems: beyond the standard electron perspective

    NASA Astrophysics Data System (ADS)

    Bernasconi, G. D.; Flauraud, V.; Alexander, D. T. L.; Brugger, J.; Martin, O. J. F.; Butet, J.

    2016-09-01

    Electron energy-loss spectroscopy (EELS) has become an experimental method of choice for the investigation of localized surface plasmon resonances, allowing the simultaneous mapping of the associated field distributions and their resonant energies with a nanoscale spatial resolution. The experimental observations have been well-supported by numerical models based on the computation of the Lorentz force acting on the impinging electrons by the scattered field. However, in this framework, the influence of the intrinsic properties of the plasmonic nanostructures studied with the electron energy-loss (EEL) measurements is somehow hidden in the global response. To overcome this limitation, we propose to go beyond this standard, and well-established, electron perspective and instead to interpret the EELS data using directly the intrinsic properties of the nanostructures, without regard to the force acting on the electron. The proposed method is particularly well-suited for the description of coupled plasmonic systems, because the role played by each individual nanoparticle in the observed EEL spectrum can be clearly disentangled, enabling a more subtle understanding of the underlying physical processes. As examples, we consider different plasmonic geometries in order to emphasize the benefits of this new conceptual approach for interpreting experimental EELS data. In particular, we use it to describe results from samples made by traditional thin film patterning and by arranging colloidal nanostructures.

  3. Toward 10 meV electron energy-loss spectroscopy resolution for plasmonics.

    PubMed

    Bellido, Edson P; Rossouw, David; Botton, Gianluigi A

    2014-06-01

    Energy resolution is one of the most important parameters in electron energy-loss spectroscopy. This is especially true for measurement of surface plasmon resonances, where high-energy resolution is crucial for resolving individual resonance peaks, in particular close to the zero-loss peak. In this work, we improve the energy resolution of electron energy-loss spectra of surface plasmon resonances, acquired with a monochromated beam in a scanning transmission electron microscope, by the use of the Richardson-Lucy deconvolution algorithm. We test the performance of the algorithm in a simulated spectrum and then apply it to experimental energy-loss spectra of a lithographically patterned silver nanorod. By reduction of the point spread function of the spectrum, we are able to identify low-energy surface plasmon peaks in spectra, more localized features, and higher contrast in surface plasmon energy-filtered maps. Thanks to the combination of a monochromated beam and the Richardson-Lucy algorithm, we improve the effective resolution down to 30 meV, and evidence of success up to 10 meV resolution for losses below 1 eV. We also propose, implement, and test two methods to limit the number of iterations in the algorithm. The first method is based on noise measurement and analysis, while in the second we monitor the change of slope in the deconvolved spectrum.

  4. High-resolution calcium mapping of the endoplasmic reticulum-Golgi-exocytic membrane system. Electron energy loss imaging analysis of quick frozen-freeze dried PC12 cells.

    PubMed

    Pezzati, R; Bossi, M; Podini, P; Meldolesi, J; Grohovaz, F

    1997-08-01

    The calcium pools segregated within the endoplasmic reticulum, Golgi complex, exocytic, and other organelles are believed to participate in the regulation of a variety of cell functions. Until now, however, the precise intracellular distribution of the element had not been established. Here, we report about the first high-resolution calcium mapping obtained in neurosecretory PC12 cells by the imaging mode of the electron energy loss spectroscopy technique. The preparation procedure used included quick freezing of cell monolayers, followed by freeze-drying, fixation with OSO4 vapors, resin embedding, and cutting of very thin sections. Conventional electron microscopy and high-resolution immunocytochemistry revealed a high degree of structural preservation, a condition in which inorganic elements are expected to maintain their native distribution. Within these cells, calcium signals of nucleus, cytosol, and most mitochondria remained below detection, whereas in other organelles specific patterns were identified. In the endoplasmic reticulum, the distribution was heterogeneous with strongly positive cisternae (more often the nuclear envelope and stacks of parallel elements that are frequent in quick frozen preparations) lying in the proximity of or even in direct continuity with other, apparently negative cisternae. The Golgi complexes were labeled strongly and uniformly in all cisternae and part of their vesicles, with no appreciable differences along the cis-trans axis. Weaker or negative signals were recorded from the trans-Golgi network elements and from scattered vesicles, whereas in contrast secretion granules were strongly positive for calcium. These results are discussed in relation to the existing knowledge about the mechanisms of calcium transport in the variations organelles, and about the processes and functions regulated by organelle lumenal calcium in eukaryotic cells.

  5. Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction

    NASA Technical Reports Server (NTRS)

    Daulton, Tyrone L.; Little, Brenda J.; Lowe, Kristine; Jones-Meehan, Joanne

    2002-01-01

    Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower.

  6. Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction.

    PubMed

    Daulton, Tyrone L; Little, Brenda J; Lowe, Kristine; Jones-Meehan, Joanne

    2002-06-01

    Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower.

  7. Transition metal d -band occupancy in skutterudites studied by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Prytz, Ø.; Taftø, J.; Ahn, C. C.; Fultz, B.

    2007-03-01

    The transition-metal 3d occupancy of a series of thermoelectric skutterudites is investigated using electron energy-loss spectroscopy. We find that bonding causes an emptying of the 3d states in the binary skutterudites CoP3 , CoAs3 , CoSb3 , and NiP3 , while compared to the pure Fe the 3d occupancy in LaFe4P12 is significantly increased, consistent with the idea that each interstitial La atom (rattler) donates three electrons to compensate for missing valence electron of Fe as compared to Co. These experimental results are in agreement with previous models suggesting a predominantly covalent bonding between transition metal and pnictogen atoms in skutterudites, and provide evidence of charge transfer from La to the Fe-P complex in LaFe4P12 .

  8. Electron energy loss spectroscopy study of Sr2-xGdxTiMnO6

    NASA Astrophysics Data System (ADS)

    Biskup, Nevenko; Alvarez-Serrano, Inmaculada; Veiga, Maria Luisa; Garcia-Hernandez, Mar; Lopez, Maria Luisa; Varela, Maria

    2012-02-01

    The newly synthesized double perovskite family Sr2-xGdxTiMnO6 (0electron energy loss spectroscopy. We find that, is spite of some precipitations of Mn and Ti rich regions that exist in 0.25<=x<=0.75, the manganese and titanium ions are generally well intermixed in both interior of the grains and on the grain boundaries. We discuss these results in the frame of highly non-linear electrical conductivity found in these materials.

  9. Electron Energy-Loss Spectroscopy Theory and Simulation Applied to Nanoparticle Plasmonics

    NASA Astrophysics Data System (ADS)

    Bigelow, Nicholas Walker

    In this dissertation, the capacity of electron energy-loss spectroscopy (EELS) to probe plasmons is examined in detail. EELS is shown to be able to detect both electric hot spots and Fano resonances in contrast to the prevailing knowledge prior to this work. The most detailed examination of magnetoplasmonic resonances in multi-ring structures to date and the utility of electron tomography to computational plasmonics is explored, and a new tomographic method for the reconstruction of a target is introduced. Since the observation of single-molecule surface-enhanced Raman scattering (SMSERS) in 1997, questions regarding the nature of the electromagnetic hot spots responsible for such observations still persist. A computational analysis of the electron- and photon-driven surface-plasmon resonances of monomer and dimer metal nanorods is presented to elucidate the differences and similarities between the two excitation mechanisms in a system with well understood optical properties. By correlating the nanostructure's simulated electron energy loss spectrum and loss-probability maps with its induced polarization and scattered electric field we discern how certain plasmon modes are selectively excited and how they funnel energy from the excitation source into the near- and far-field. Using a fully retarded electron-scattering theory capable of describing arbitrary three-dimensional nanoparticle geometries, aggregation schemes, and material compositions, we find that electron energy-loss spectroscopy (EELS) is able to indirectly probe the same electromagnetic hot spots that are generated by an optical excitation source. EELS is then employed in a scanning transmission electron microscope (STEM) to obtain maps of the localized surface plasmon modes of SMSERS-active nanostructures, which are resolved in both space and energy. Single-molecule character is confirmed by the bianalyte approach using two isotopologues of Rhodamine 6G. The origins of this observation are explored

  10. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    PubMed Central

    Cheng, Shaodong; Yang, Guang; Zhao, Yanqi; Peng, MingYing; Skibsted, Jørgen; Yue, Yuanzheng

    2015-01-01

    Transmission electron microscopy and related analytical techniques have been widely used to study the microstructure of different materials. However, few research works have been performed in the field of glasses, possibly due to the electron-beam irradiation damage. In this paper, we have developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which the fraction of BO4 tetrahedra can be obtained by fitting the experimental data with linear combinations of the reference spectra. The BO4 fractions (N4) obtained by EELS are consistent with those from 11B MAS NMR spectra, suggesting that EELS can be an alternative and convenient way to determine the N4 fraction in glasses. In addition, the boron speciation of a CeO2 doped potassium borosilicate glass has been analyzed by using the time-resolved EELS spectra. The results clearly demonstrate that the BO4 to BO3 transformation induced by the electron beam irradiation can be efficiently suppressed by doping CeO2 to the borosilicate glasses. PMID:26643370

  11. Mapping bright and dark modes in gold nanoparticle chains using electron energy loss spectroscopy.

    PubMed

    Barrow, Steven J; Rossouw, David; Funston, Alison M; Botton, Gianluigi A; Mulvaney, Paul

    2014-07-09

    We present a scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) investigation of gold nanosphere chains with lengths varying from 1 to 5 particles. We show localized EELS signals from the chains and identify energy-loss peaks arising due to l = 1, 2, 3, 4, and 5 plasmon modes through the use of EELS mapping. We also show the evolution of the energy of these modes as the length of a given chain increases, and we find that a chain containing N particles can accommodate at least N experimentally observable modes, in addition to the transverse mode. As the chain length is increased by the addition of one more gold particle to the chain, the new N + 1 mode becomes the highest energy mode, while the existing modes lower their energy and eventually asymptote as they delocalize along the chain. We also show that modes become increasingly difficult to detect with the EELS technique as l approaches N. The data are compared to numerical simulations.

  12. Band gap widening at random CIGS grain boundary detected by valence electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Keller, Debora; Buecheler, Stephan; Reinhard, Patrick; Pianezzi, Fabian; Bissig, Benjamin; Carron, Romain; Hage, Fredrik; Ramasse, Quentin; Erni, Rolf; Tiwari, Ayodhya N.

    2016-10-01

    Cu(In,Ga) Se2 (CIGS) thin film solar cells have demonstrated very high efficiencies, but still the role of nanoscale inhomogeneities in CIGS and their impact on the solar cell performance are not yet clearly understood. Due to the polycrystalline structure of CIGS, grain boundaries are very common structural defects that are also accompanied by compositional variations. In this work, we apply valence electron energy loss spectroscopy in scanning transmission electron microscopy to study the local band gap energy at a grain boundary in the CIGS absorber layer. Based on this example, we demonstrate the capabilities of a 2nd generation monochromator that provides a very high energy resolution and allows for directly relating the chemical composition and the band gap energy across the grain boundary. A band gap widening of about 20 meV is observed at the grain boundary. Furthermore, the compositional analysis by core-loss EELS reveals an enrichment of In together with a Cu, Ga and Se depletion at the same area. The experimentally obtained results can therefore be well explained by the presence of a valence band barrier at the grain boundary.

  13. The applications of in situ electron energy loss spectroscopy to the study of electron beam nanofabrication.

    PubMed

    Chen, Shiahn J; Howitt, David G; Gierhart, Brian C; Smith, Rosemary L; Collins, Scott D

    2009-06-01

    An in situ electron energy loss spectroscopy (EELS) technique has been developed to investigate the dynamic processes associated with electron-beam nanofabrication on thin membranes. In this article, practical applications germane to e-beam nanofabrication are illustrated with a case study of the drilling of nanometer-sized pores in silicon nitride membranes. This technique involves successive acquisitions of the plasmon-loss and the core-level ionization-loss spectra in real time, both of which provide the information regarding the hole-drilling kinetics, including two respective rates for total mass loss, individual nitrogen and silicon element depletion, and the change of the atomic bonding environment. In addition, the in situ EELS also provides an alternative method for endpoint detection with a potentially higher time resolution than by imaging. On the basis of the time evolution of in situ EELS spectra, a qualitative working model combining knock-on sputtering, irradiation-induced mass transport, and phase separation can be proposed.

  14. Valence electron energy-loss spectroscopy study of ZrSiO₄ and ZrO₂.

    PubMed

    Jiang, Nan; Spence, John C H

    2013-11-01

    ZrSiO4 (zircon) and m-ZrO2 (zirconia) are fundamental and industrially important materials. This work reports the detailed valence electron energy-loss spectroscopy (VEELS) studies of these compounds. The dielectric response functions, as well as single-electron interband transition spectra, are derived from VEELS data for both ZrSiO4 and m-ZrO2, in the range 5-50 eV using the Kramers-Kronig analysis method. Our interpretation of the interband transitions is given with the aid of ab initio calculations of density of states. The bandgap energies for both materials are also measured using VEELS. The surface and bulk plasmons are identified: the surface plasmon peaks locate at around 12 eV, and two bulk plasmon peaks are ∼15-16 eV and ∼25-27 eV, respectively. Although similarities in the VEELS exist between ZrSiO4 and m-ZrO2, two major differences are also noticed and explained in terms of composition and structure differences.

  15. Mode Coupling in Plasmonic Heterodimers Probed with Electron Energy Loss Spectroscopy.

    PubMed

    Flauraud, Valentin; Bernasconi, Gabriel D; Butet, Jérémy; Alexander, Duncan T L; Martin, Olivier J F; Brugger, Juergen

    2017-03-14

    While plasmonic antennas composed of building blocks made of the same material have been thoroughly studied, recent investigations have highlighted the unique opportunities enabled by making compositionally asymmetric plasmonic systems. So far, mainly heterostructures composed of nanospheres and nanodiscs have been investigated, revealing opportunities for the design of Fano resonant nanostructures, directional scattering, sensing and catalytic applications. In this article, an improved fabrication method is reported that enables precise tuning of the heterodimer geometry, with interparticle distances made down to a few nanometers between Au-Ag and Au-Al nanoparticles. A wide range of mode energy detuning and coupling conditions are observed by near field hyperspectral imaging performed with electron energy loss spectroscopy, supported by full wave analysis numerical simulations. These results provide direct insights into the mode hybridization of plasmonic heterodimers, pointing out the influence of each dimer constituent in the overall electromagnetic response. By relating the coupling of non-dipolar modes and plasmon-interband interaction with the dimer geometry, this work facilitates the development of plasmonic heterostructures with tailored responses, beyond the possibilities offered by homodimers.

  16. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities.

    PubMed

    Verhoeven, W; van Rens, J F M; van Ninhuijs, M A W; Toonen, W F; Kieft, E R; Mutsaers, P H A; Luiten, O J

    2016-09-01

    We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

  17. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

    PubMed Central

    Verhoeven, W.; van Rens, J. F. M.; van Ninhuijs, M. A. W.; Toonen, W. F.; Kieft, E. R.; Mutsaers, P. H. A.; Luiten, O. J.

    2016-01-01

    We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers. PMID:27704035

  18. Electron energy-loss spectroscopy of carbon in interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Bradley, John P.; Thomas, Kathie L.; Mckay, David S.

    1994-01-01

    The nature of the carbon-bearing phases in IDP's provides information regarding the chemical and physical processes involved in the formation and evolution of the early solar system. Several carbon-bearing materials have been observed in IDP's, but details of their nature, abundance, and distribution are still poorly known. A knowledge of the abundance and nature of carbon in IDP's is useful in constraining the sources of IDP's and for comparisons with other chondritic materials. Estimates of carbon abundance in anhydrous and hydrated IDP's indicate that most of these particles have significantly higher carbon than the carbonaceous chondrites. Mineralogical analyses show that carbonates are only a minor component of most hydrated IDP's, and so the high carbon abundances in this group of IDP's indicates that other carbon-bearing phases are present in significant concentrations. Using the technique of electron energy-loss spectroscopy (EELS), we have identified two forms of carbon in a hydrated IDP, oxidized carbon (carbonates), and amorphous elemental carbon.

  19. Quasinormal mode theory and modelling of electron energy loss spectroscopy for plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Ge, Rong-Chun; Hughes, Stephen

    2016-05-01

    Understanding light-matter interactions using localized surface plasmons (LSPs) is of fundamental interest in classical and quantum plasmonics and has a wide range of applications. In order to understand the spatial properties of LSPs, electron energy loss spectroscopy (EELS) is a common and powerful method of spatially resolving the extreme localized fields that can be obtained with metal resonators. However, modelling EELS for general shaped resonators presents a major challenge in computational electrodynamics, requiring the full photon Green function as a function of two space points and frequency. Here we present an intuitive and computationally simple method for computing EELS maps of plasmonic resonators using a quasinormal mode (QNM) expansion technique. By separating the contribution of the QNM and the bulk material, we give closed-form analytical formulas for the plasmonic QNM contribution to the EELS maps. We exemplify our technique for a split ring resonator, a gold nanorod, and a nanorod dimer structure. The method is accurate, intuitive, and gives orders of magnitude improvements over direct dipole simulations that numerically solve the full 3D Maxwell equations. We also show how the same QNM Green function can be used to obtain the Purcell factor (and projected local density of optical states) from quantum dipole emitters or two level atoms, and we demonstrate how the spectral features differ in general to the EELS spectrum.

  20. Electron energy loss spectroscopy of carbon in dissociated dislocations in tantalum carbide

    NASA Astrophysics Data System (ADS)

    Allison, Craig; Hoffman, Mark; Williams, Wendell S.

    1982-10-01

    The carbon concentration in individual stacking faults in dissociated dislocations in tantalum carbide (TaCx) was analyzed using electron energy loss spectroscopy. Although the faulted region is less than 10 nm wide, the small diameter electron beam (0.5 nm) of a dedicated scanning transmission electron microscope allowed the carbon K x-ray excitation edge from the faulted region to be distinguished from the corresponding signal from the unfaulted region. The 50-nm thick foil was prepared by grinding, polishing, and ion milling a specimen sawed from a single crystal of TaC0.78. The analysis showed a significantly lower value for the carbon concentration in the fault, in accordance with crystallographic and energy considerations. The stacking fault in NaCl-structure TaCx must exhibit hcp symmetry, but the appropriate hcp phase, Ta2C, contains less carbon. Hence diffusion of carbon away from the moving dislocation must accompany plastic deformation. However, in view of the high melting point and high activation energy for carbon migration, diffusion is slow below approximately 1600 °C. This temperature corresponds approximately with the brittle-ductile transition for TaC. The isomorphic compound TiC does not exhibit dissociated dislocations, and hence this form of Suzuki hardening should not occur. Indeed, gross plastic deformation in TiC can occur at temperatures as low as 800 °C.

  1. Practical spatial resolution of electron energy loss spectroscopy in aberration corrected scanning transmission electron microscopy.

    PubMed

    Shah, A B; Ramasse, Q M; Wen, J G; Bhattacharya, A; Zuo, J M

    2011-08-01

    The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using chemically modulated 2×(LaMnO(3))/2×(SrTiO(3)) and 2×(SrVO(3))/2×(SrTiO(3)) superlattices by measuring the full width at half maxima (FWHM) of integrated Ti M(2,3), Ti L(2,3), V L(2,3), Mn L(2,3), La N(4,5), La N(2,3) La M(4,5) and Sr L(3) edges over the superlattices. The EELS signals recorded using large collection angles are peaked at atomic columns. The FWHM of the EELS profile, obtained by curve-fitting, reveals a systematic trend with the energy loss for the Ti, V, and Mn edges. However, the experimental FWHM of the Sr and La edges deviates significantly from the observed experimental tendency.

  2. Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

    SciTech Connect

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-06-28

    We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

  3. The beta-SiC(100) surface studied by low energy electron diffraction, Auger electron spectroscopy, and electron energy loss spectra

    NASA Technical Reports Server (NTRS)

    Dayan, M.

    1986-01-01

    The beta-SiC(100) surface has been studied by low energy electron diffraction, Auger electron spectroscopy, high resolution electron energy loss spectra (HREELS), and core level excitation EELS. Two new Si-terminated phases have been discovered, one with (3 x 2) symmetry, and the other with (2 x 1) symmetry. Models are presented to describe these phases. New results, for the C-rich surface, are presented and discussed. In addition, core level excitation EELS results are given and compared with theory.

  4. Study of the Dielectric Function of Graphene from Spectroscopic Ellipsometry and Electron Energy Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nelson, Florence

    For more than 60 years, semiconductor research has been advancing up the periodic table. The first transistor was made from germanium. This later gave way to silicon-based devices due to the latter's ability to form an excellent interface with thermally-grown oxide. Now for the last ˜8 years, the focus has moved up one more row to carbon for post-CMOS devices in order to comply with the scaling limitations of Moore's law. However, for each of these, the measurements of film properties and dimensions have always been required for technological applications. These measurement methods often incorporate the use of light or electrons in order to take advantage of a wavelength that is on the order of, or smaller than, the feature sizes of interest. This thesis compares the dielectric function of graphene measured by an optical method to that obtained from an electron energy loss method in order to observe the effect of contamination and substrate on the optical properties of graphene exposed to the environment. Whether viewed in terms of how light affects a material (dielectric function) or how a material affects light (refractive index), the optical response is a quantity that may be used to obtain information about a film's thickness, energy structure, and the types of excitations that are responsible for energy loss. The three main experimental methods used in this thesis work are spectroscopic ellipsometry (SE), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). SE is commonly used in clean-room environments for optical measurement over the energy range of ˜0-5 eV. This method is used to study graphene's dielectric function from the ultraviolet (UV) through infrared (IR) regions through use of an oscillator dispersion model. A nearly constant absorbance over the IR and into the visible region is observed due to vertical transitions between graphene's linearly dispersed pi-bands at the Dirac points. An exciton

  5. Observation of Odd Symmetry Surface Phonon Modes on NICKEL(100) and SILVER(100) Surfaces Using the New Multichannel High Resolution Electron Energy Loss Spectrometer

    NASA Astrophysics Data System (ADS)

    Jeong, Eue-Jin

    A multichannel detection high resolution electron analyzer has been constructed and tested. The capabilities of achieving out-of-plane scattering geometry, high resolution and high sensitivity has made it possible to detect for the first time the odd-symmetry surface phonon modes on Ni(100) and Ag(100) surfaces. Initial tests were performed to verify the performance of the spectrometer. The best instrumental resolution obtained was 3.5 meV and analyzer count rate could be maintained at 1000 Hz in large angle scattering geometry. This represents an improvement in performance of a factor of at least 50 compared to the existing conventional single channel spectrometers. Odd symmetry surface phonon modes found on Ag(100) surfaces have been measured to be 3.2 meV which agrees closely with available calculations. An additional interesting feature found to be interesting is that the background width of odd symmetry modes appear to be narrower than that of the even symmetry mode scattering data. This effect has not been predicted or explained by theory. As it stands now, the large angle high-resolution electron energy loss cross sections are not completely characterized by theory.

  6. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

    PubMed

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  7. Probing the bonding and electronic structure of single atom dopants in graphene with electron energy loss spectroscopy.

    PubMed

    Ramasse, Quentin M; Seabourne, Che R; Kepaptsoglou, Despoina-Maria; Zan, Recep; Bangert, Ursel; Scott, Andrew J

    2013-10-09

    A combination of scanning transmission electron microscopy, electron energy loss spectroscopy, and ab initio calculations reveal striking electronic structure differences between two distinct single substitutional Si defect geometries in graphene. Optimised acquisition conditions allow for exceptional signal-to-noise levels in the spectroscopic data. The near-edge fine structure can be compared with great accuracy to simulations and reveal either an sp(3)-like configuration for a trivalent Si or a more complicated hybridized structure for a tetravalent Si impurity.

  8. Implementation of subcellular water mapping by electron energy loss spectroscopy in a medium-voltage scanning transmission electron microscope.

    PubMed

    Terryn, C; Michel, J; Thomas, X; Laurent-Maquin, D; Balossier, G

    2004-07-01

    The water concentration in biological cells plays a predominant role in cellular life. Using electron energy loss spectroscopy, the feasibility to measure the water content in cells has already been demonstrated. In this paper, we present an upgrade of water measurement in hydrated cryosections by spectrum imaging mode in a medium-voltage scanning transmission electron microscope. The electron energy loss spectra are recorded in spectrum imaging mode in a 2(n)x2(n) pixels array. Each spectrum is processed in order to determine the water mass content in the corresponding pixel. Then a parametric image is obtained in which grey levels are related to water concentration. In this image, it is possible to recognize the different subcellular compartments. By averaging the water concentration over the relevant pixels, we can determine the water mass content in the concerned subcellular compartment. As an example, we present water mass content measurement at subcellular level in rat hepatocytes.

  9. Combined study of the ground and unoccupied electronic states of graphite by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Löffler, Stefan; Eder, Franz; Meyer, Jannik C.; Su, Dangsheng; Schattschneider, Peter

    2013-11-14

    Both the unoccupied and ground electronic states of graphite have been studied by electron energy-loss spectroscopy in a transmission electron microscope. Electron energy-loss near-edge structures of the K-edge of carbon have been investigated in detail for scattering angles from 0 to 2.8 mrad. The π{sup *} and σ{sup *} components were separated. The angular and energy dependences of the π{sup *} and σ{sup *} structures were in fair agreement with theory. Electron energy loss Compton spectra of graphite were recorded at scattering angles from 45 to 68 mrad. One Compton scattering spectrum was obtained in 1 min compared with several hours or days using photons. The contributions of core electrons were calculated by the exact Hartree-Slater method in the Compton scattering region. The electron Compton profile for graphite is in good agreement with other conventional Compton profile measurements, as well as with theory, thus establishing the validity of the technique.

  10. Electron energy-loss spectroscopy of excited states of the pyridine molecules

    NASA Astrophysics Data System (ADS)

    Linert, Ireneusz; Zubek, Mariusz

    2016-04-01

    Electron energy-loss spectra of the pyridine, C5H5N, molecules in the gas phase have been measured to investigate electronic excitation in the energy range 3.5-10 eV. The applied wide range of residual electron energy and the scattering angle range from 10° to 180° enabled to differentiate between optically-allowed and -forbidden transitions. These measurements have allowed vertical excitation energies of the triplet excited states of pyridine to be determined and tentative assignments of these states to be proposed. Some of these states have not been identified in the previous works. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  11. Microstructure of highly strained BiFeO{sub 3} thin films: Transmission electron microscopy and electron-energy loss spectroscopy studies

    SciTech Connect

    Heon Kim, Young; Bhatnagar, Akash; Pippel, Eckhard; Hesse, Dietrich; Alexe, Marin

    2014-01-28

    Microstructure and electronic structure of highly strained bismuth ferrite (BiFeO{sub 3}) thin films grown on lanthanum aluminate substrates are studied using high-resolution transmission and scanning transmission electron microscopies and electron energy loss spectroscopy (EELS). Monoclinic and tetragonal phases were observed in films grown at different temperatures, and a mix of both phases was detected in a film grown at intermediate temperature. In this film, a smooth transition of the microstructure was found between the monoclinic and the tetragonal phases. A considerable increase in the c-axis parameters was observed in both phases compared with the rhombohedral bulk phase. The off-center displacement of iron (Fe) ions was increased in the monoclinic phase as compared with the tetragonal phase. EEL spectra show different electronic structures in the monoclinic and the tetragonal phases. These experimental observations are well consistent with the results of theoretical first-principle calculations performed.

  12. Microstructure of highly strained BiFeO3 thin films: Transmission electron microscopy and electron-energy loss spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Heon Kim, Young; Bhatnagar, Akash; Pippel, Eckhard; Alexe, Marin; Hesse, Dietrich

    2014-01-01

    Microstructure and electronic structure of highly strained bismuth ferrite (BiFeO3) thin films grown on lanthanum aluminate substrates are studied using high-resolution transmission and scanning transmission electron microscopies and electron energy loss spectroscopy (EELS). Monoclinic and tetragonal phases were observed in films grown at different temperatures, and a mix of both phases was detected in a film grown at intermediate temperature. In this film, a smooth transition of the microstructure was found between the monoclinic and the tetragonal phases. A considerable increase in the c-axis parameters was observed in both phases compared with the rhombohedral bulk phase. The off-center displacement of iron (Fe) ions was increased in the monoclinic phase as compared with the tetragonal phase. EEL spectra show different electronic structures in the monoclinic and the tetragonal phases. These experimental observations are well consistent with the results of theoretical first-principle calculations performed.

  13. A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu.

    PubMed

    Ewels, Philip; Sikora, Thierry; Serin, Virginie; Ewels, Chris P; Lajaunie, Luc

    2016-06-01

    The electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra.

  14. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

    SciTech Connect

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; Lee, Jaekwang; Prange, Micah P.; Pennycook, Stephen J.; Idrobo Tapia, Juan Carlos; Pantelides, Sokrates T.

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with a theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.

  15. Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

    DOE PAGES

    Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; ...

    2015-09-25

    Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with amore » theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.« less

  16. π-plasmon dispersion in free-standing graphene by momentum-resolved electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Liou, S. C.; Shie, C.-S.; Chen, C. H.; Breitwieser, R.; Pai, W. W.; Guo, G. Y.; Chu, M.-W.

    2015-01-01

    The π-plasmon dispersion in graphene was scrutinized by momentum-resolved electron energy-loss spectroscopy with an improved momentum q resolution and was found to display the square root of the q dispersion characteristic of the collective excitation of two-dimensional electron systems, in contrast to previous experimental and theoretical studies which reported a linear q dispersion. Our theoretical elaborations on the q -dependent spectra affirm this square root of q relation and further unveil an in-plane electronic anisotropy. The physical property of the π plasmon is thoroughly compared to that of the two-dimensional plasmon due to carriers of the Dirac fermions. A clear distinction between the π plasmon and the two-dimensional Dirac plasmon is demonstrated, clarifying the common notion about correlating the linearly dispersed Dirac cones with the linear dispersion of the π plasmon previously reported.

  17. π-Plasmon Dispersion in Free-Standing Monolayer Graphene Investigated by Momentum-Resolved Electron Energy-Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liou, S. C.; Breitwieser, R.; Chen, C. H.; Pai, W. W.; Guo, G. Y.; Chu, M. W.

    2014-08-01

    The {\\pi}-plasmon dispersion in graphene was scrutinized by momentum(q)-resolved electron energy-loss spectroscopy with an improved q resolution and found to display the square root of q dispersion characteristic of the collective excitation of two-dimensional electron systems, in contrast with previous experimental and theoretical studies which reported a linear q dispersion. Our theoretical elaborations on the q-dependent spectra affirm this square root of q relation and further unveil an in-plane electronic anisotropy. The physical property of the {\\pi} plasmon is thoroughly compared to that of the two-dimensional plasmon due to carriers of the Dirac fermions. A clear distinction between the {\\pi} plasmon and the two-dimensional Dirac plasmon was demonstrated, clarifying the common notion on correlating the linearly-dispersed Dirac cones to the linear dispersion of the {\\pi} plasmon previously reported.

  18. Si(111)(\\sqrt{3}× \\sqrt{3})-Al Surface Studied by Angle-Resolved Electron-Energy-Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Sung-Te; Hasegawa, Shigehiko; Nakamura, Shogo; Nakashima, Hisao

    1991-09-01

    The surface electronic structures of Si(111)(\\sqrt{3}× \\sqrt{3})-Al are investigated with the use of angle-resolved electron-energy-loss spectroscopy. Three new surface one-electron transitions (in specular reflection) are found at 1.8, 7.2, and 13.1 eV. Compared with the surface state band structures calculated by Northrup and STM results by Hamers and Demuth, the loss peak at 1.8 eV is ascribed to the one-electron transition between the occupied and unoccupied surface state bands which originate from the Al adatoms. The other two peaks are considered to be due to the Si-Si strained back bonds.

  19. Surface plasmon excitations in metal spheres: Direct comparison of light scattering and electron energy-loss spectroscopy by modal decomposition

    NASA Astrophysics Data System (ADS)

    Collins, Sean M.; Midgley, Paul A.

    2013-06-01

    In previous publications, qualitative agreement between studies of surface plasmon excitations in nanoparticles by near-field light scattering and electron energy-loss spectroscopy (EELS) has been found for experiments and simulations. Here, we present a quantitative method for the comparison of light scattering and EELS for surface plasmons in metal spheres. Defining the Fourier transform of the modal component of the scattered electric field along the equivalent electron trajectory enables a direct evaluation of the relative weighting factor for light- and electron-excited surface plasmon modes. This common quantity for light scattering and EELS is examined for size, composition, and trajectory dependencies, facilitating the analysis of key differences between light and electron excitation. A single functional dependence on Drude model plasmon energies is identified to explain the relative modal weighting factors for light scattering and EELS. This method represents an important step toward the complete spectral and spatial reconstruction of EELS maps from near-field light scattering calculations.

  20. High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy.

    PubMed

    Krivanek, Ondrej L; Ursin, Jonathan P; Bacon, Neil J; Corbin, George J; Dellby, Niklas; Hrncirik, Petr; Murfitt, Matthew F; Own, Christopher S; Szilagyi, Zoltan S

    2009-09-28

    An all-magnetic monochromator/spectrometer system for sub-30 meV energy-resolution electron energy-loss spectroscopy in the scanning transmission electron microscope is described. It will link the energy being selected by the monochromator to the energy being analysed by the spectrometer, without resorting to decelerating the electron beam. This will allow it to attain spectral energy stability comparable to systems using monochromators and spectrometers that are raised to near the high voltage of the instrument. It will also be able to correct the chromatic aberration of the probe-forming column. It should be able to provide variable energy resolution down to approximately 10 meV and spatial resolution less than 1 A.

  1. Comparison of theoretical and experimental dielectric functions: Electron energy-loss spectroscopy and density-functional calculations on skutterudites

    NASA Astrophysics Data System (ADS)

    Prytz, Ø.; Løvvik, O. M.; Taftø, J.

    2006-12-01

    We explore the possibility of combining density functional theory (DFT) and electron energy loss spectroscopy (EELS) to determine the dielectric function of materials. As model systems we use the skutterudites CoP3 , CoAs3 , and CoSb3 which are prototypes for thermoelectric materials. We achieve qualitative agreement between the theoretically and experimentally obtained low energy-loss spectra and dielectric function. Some of the remaining discrepancies may be caused by the challenge of refining the experimental spectra before Kramers-Kronig analysis. However, contrary to what is the case for some crystals with less complicated electronic structure, the DFT calculated plasmon energies deviate significantly from the experimental values. The great accuracy with which the plasmon energy can be determined by EELS, suggests that this technique may provide valuable inputs in further efforts to improve DFT calculations. The use of EELS as the experimental technique may become particularly powerful in studies of small volumes of materials.

  2. High resolution hypernuclear spectroscopy

    SciTech Connect

    F. Garibaldi

    2005-02-01

    Hypernuclear spectroscopy provides fundamental information for understanding the effective ?-Nucleon interaction. Jefferson Laboratory experiment E94-107 was designed to perform high resolution hypernuclear spectroscopy by electroproduction of strangeness in four 1p-shell nuclei: 12C, 9Be, 16O, and 7Li. The first part of the experiment on 12C and 9Be has been performed in January and April-May 2004 in Hall A at Jefferson Lab. Significant modifications were made to the standard Hall A apparatus for this challenging experiment: two septum magnets and a RICH detector have been added to get reasonable counting rates and excellent particle identification, as required for the experiment. A description of the apparatus and the preliminary analysis results are presented here.

  3. High Resolution Electron Energy Loss Spectroscopy Studies of Chemisorbed Species on Metal Surfaces

    DTIC Science & Technology

    1990-03-31

    vibrational modes at crystal surfaces, the first detection of projected bulk phonon modes by surface electron scattering and elucidation of novel properties associated with hydrogen interaction at Niobium surfaces. (jg)

  4. Signatures of distinct impurity configurations in atomic-resolution valence electron-energy-loss spectroscopy: Application to graphene

    NASA Astrophysics Data System (ADS)

    Kapetanakis, Myron D.; Oxley, Mark P.; Zhou, Wu; Pennycook, Stephen J.; Idrobo, Juan-Carlos; Pantelides, Sokrates T.

    2016-10-01

    The detection and identification of impurities and other point defects in materials is a challenging task. Signatures for point defects are typically obtained using spectroscopies without spatial resolution. Here we demonstrate the power of valence electron-energy-loss spectroscopy (VEELS) in an aberration-corrected scanning transmission-electron microscope (STEM) to provide energy-resolved and atomically resolved maps of electronic excitations of individual impurities which, combined with theoretical simulations, yield unique signatures of distinct bonding configurations of impurities. We report VEELS maps for isolated Si impurities in graphene, which are known to exist in two distinct configurations. We also report simulations of the maps, based on density functional theory and dynamical scattering theory, which agree with and provide direct interpretation of observed features. We show that theoretical VEELS maps exhibit distinct and unambiguous signatures for the threefold- and fourfold-coordinated configurations of Si impurities in different energy-loss windows, corresponding to impurity-induced bound states, resonances, and antiresonances. With the advent of new monochromators and detectors with high energy resolution and low signal-to-noise ratio, the present work ushers an atomically resolved STEM-based spectroscopy of individual impurities as an alternative to conventional spectroscopies for probing impurities and defects.

  5. High Resolution Laboratory Spectroscopy

    NASA Astrophysics Data System (ADS)

    Brünken, S.; Schlemmer, S.

    2016-05-01

    In this short review we will highlight some of the recent advancements in the field of high-resolution laboratory spectroscopy that meet the needs dictated by the advent of highly sensitive and broadband telescopes like ALMA and SOFIA. Among these is the development of broadband techniques for the study of complex organic molecules, like fast scanning conventional absorption spectroscopy based on multiplier chains, chirped pulse instrumentation, or the use of synchrotron facilities. Of similar importance is the extension of the accessible frequency range to THz frequencies, where many light hydrides have their ground state rotational transitions. Another key experimental challenge is the production of sufficiently high number densities of refractory and transient species in the laboratory, where discharges have proven to be efficient sources that can also be coupled to molecular jets. For ionic molecular species sensitive action spectroscopic schemes have recently been developed to overcome some of the limitations of conventional absorption spectroscopy. Throughout this review examples demonstrating the strong interplay between laboratory and observational studies will be given.

  6. Signatures of Fano interferences in the electron energy loss spectroscopy and cathodoluminescence of symmetry-broken nanorod dimers.

    PubMed

    Bigelow, Nicholas W; Vaschillo, Alex; Camden, Jon P; Masiello, David J

    2013-05-28

    Through numerical simulation, we predict the existence of the Fano interference effect in the electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) of symmetry-broken nanorod dimers that are heterogeneous in material composition and asymmetric in length. The differing selection rules of the electron probe in comparison to the photon of a plane wave allow for the simultaneous excitation of both optically bright and dark plasmons of each monomer unit, suggesting that Fano resonances will not arise in EELS and CL. Yet, interferences are manifested in the dimer's scattered near- and far-fields and are evident in EELS and CL due to the rapid π-phase offset in the polarizations between super-radiant and subradiant hybridized plasmon modes of the dimer as a function of the energy loss suffered by the impinging electron. Depending upon the location of the electron beam, we demonstrate the conditions under which Fano interferences will be present in both optical and electron spectroscopies (EELS and CL) as well as a new class of Fano interferences that are uniquely electron-driven and are absent in the optical response. Among other things, the knowledge gained from this work bears impact upon the design of some of the world's most sensitive sensors, which are currently based upon Fano resonances.

  7. Optical Dark-Field and Electron Energy Loss Imaging and Spectroscopy of Symmetry-Forbidden Modes in Loaded Nanogap Antennas.

    PubMed

    Brintlinger, Todd; Herzing, Andrew A; Long, James P; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, B S

    2015-06-23

    We have produced large numbers of hybrid metal-semiconductor nanogap antennas using a scalable electrochemical approach and systematically characterized the spectral and spatial character of their plasmonic modes with optical dark-field scattering, electron energy loss spectroscopy with principal component analysis, and full wave simulations. The coordination of these techniques reveal that these nanostructures support degenerate transverse modes which split due to substrate interactions, a longitudinal mode which scales with antenna length, and a symmetry-forbidden gap-localized transverse mode. This gap-localized transverse mode arises from mode splitting of transverse resonances supported on both antenna arms and is confined to the gap load enabling (i) delivery of substantial energy to the gap material and (ii) the possibility of tuning the antenna resonance via active modulation of the gap material's optical properties. The resonant position of this symmetry-forbidden mode is sensitive to gap size, dielectric strength of the gap material, and is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multifunctional components many seek.

  8. Verifying the presence of low levels of neptunium in a uranium matrix with electron energy-loss spectroscopy.

    PubMed

    Buck, Edgar C; Douglas, Matt; Wittman, Rick S

    2010-01-01

    This paper examines the problems associated with analysis of low levels of neptunium in a uranium matrix with electron energy-loss spectroscopy (EELS) on the transmission electron microscope (TEM). The detection of neptunium in a matrix of uranium can be impeded by the occurrence of a plural scattering event from uranium (U-M(5)+U-O(4,5)) that results in severe overlap on the Np-M(5) edge at 3665 eV. Low levels of Np (1600-6300 ppm) can be detected in a uranium solid, uranophane [Ca(UO(2))(2)(SiO(3)OH)(2)(H(2)O)(5)], by confirming that the energy gap between the Np-M(5) and Np-M(4) edges is at 184 eV and showing that the M(4)/M(5) ratio for the neptunium is smaller than that for uranium. The Richardson-Lucy deconvolution method was applied to energy-loss spectral images and was shown to increase the signal to noise ratio.

  9. Band gap and defect states of MgO thin films investigated using reflection electron energy loss spectroscopy

    SciTech Connect

    Heo, Sung; Cho, Eunseog; Lee, Hyung-Ik; Park, Gyeong Su; Kang, Hee Jae; Nagatomi, T.; Choi, Pyungho; Choi, Byoung-Deog

    2015-07-15

    The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS) and high-energy resolution REELS (HR-REELS). HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS) energy was located at approximately 4.2 eV above the valence band maximum (VBM) and the surface band gap width (E{sub g}{sup S}) was approximately 6.3 eV. The bulk F center (F{sub B}) energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were F{sub S} and F{sub B}, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (γ) for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies.

  10. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    NASA Astrophysics Data System (ADS)

    Da, B.; Sun, Y.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.; Ding, Z. J.

    2013-06-01

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO2 in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  11. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    SciTech Connect

    Da, B.; Sun, Y.; Ding, Z. J.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.

    2013-06-07

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO{sub 2} in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  12. Verifying the Presence of Low Levels of Neptunium in a Uranium Matrix with Electron Energy-Loss Spectroscopy

    SciTech Connect

    Buck, Edgar C.; Douglas, Matthew; Wittman, Richard S.

    2010-01-01

    This paper examines the problems associated with the analysis of low levels of neptunium (Np) in a uranium (U) matrix with electron energy-loss spectroscopy (EELS) on the transmission electron microscope (TEM). The detection of Np in a matrix of uranium (U) can be impeded by the occurrence of a plural scattering event from U (U-M5 + U-O4,5) that results in severe overlap on the Np-M5 edge at 3665 eV. Low levels (1600 - 6300 ppm) of Np can be detected in U solids by confirming the energy gap between the Np-M5 and Np-M4 edges is at 184 eV and showing that the M4/M5 ratio for the Np is smaller than that for U. The Richardson-Lucy deconvolution method was applied to energy-loss spectral images and was shown to increase the signal to noise. This method also improves the limits of detection for Np in a U matrix.

  13. Comprehensive studies of the electronic structure of pristine and potassium doped chrysene investigated by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Roth, Friedrich; Mahns, Benjamin; Schönfelder, Ronny; Hampel, Silke; Nohr, Markus; Büchner, Bernd; Knupfer, Martin

    2012-09-01

    We have performed electron energy-loss spectroscopy studies in order to investigate the electronic properties of chrysene molecular solids. The valence band electronic excitation spectra and the C 1s core level excitations have been measured for pristine and potassium doped chrysene. The core level studies show a fine structure which signals the presence of four close lying conduction bands close to the Fermi level. Upon potassium doping, these bands are filled with electrons, and we have reached a doping level of about K2.7chrysene. Furthermore, undoped chrysene is characterized by an optical gap of about 3.3 eV and five, relatively weak, excitonic features following the excitation onset. Doping induces major changes in the electronic excitation spectra, with a new, prominent low energy excitation at about 1.3 eV. The results of a Kramers-Kronig analysis indicate that this new feature can be assigned to a charge carrier plasmon in the doped material, and momentum dependent studies reveal a negative plasmon dispersion.

  14. Electron Energy-Loss Spectroscopy (EELS)Calculation in Finite-Difference Time-Domain (FDTD) Package: EELS-FDTD

    NASA Astrophysics Data System (ADS)

    Large, Nicolas; Cao, Yang; Manjavacas, Alejandro; Nordlander, Peter

    2015-03-01

    Electron energy-loss spectroscopy (EELS) is a unique tool that is extensively used to investigate the plasmonic response of metallic nanostructures since the early works in the '50s. To be able to interpret and theoretically investigate EELS results, a myriad of different numerical techniques have been developed for EELS simulations (BEM, DDA, FEM, GDTD, Green dyadic functions). Although these techniques are able to predict and reproduce experimental results, they possess significant drawbacks and are often limited to highly symmetrical geometries, non-penetrating trajectories, small nanostructures, and free standing nanostructures. We present here a novel approach for EELS calculations using the Finite-difference time-domain (FDTD) method: EELS-FDTD. We benchmark our approach by direct comparison with results from the well-established boundary element method (BEM) and published experimental results. In particular, we compute EELS spectra for spherical nanoparticles, nanoparticle dimers, nanodisks supported by various substrates, and gold bowtie antennas on a silicon nitride substrate. Our EELS-FDTD implementation can be easily extended to more complex geometries and configurations and can be directly implemented within other numerical methods. Work funded by the Welch Foundation (C-1222, L-C-004), and the NSF (CNS-0821727, OCI-0959097).

  15. Measurement of vibrational spectrum of liquid using monochromated scanning transmission electron microscopy-electron energy loss spectroscopy.

    PubMed

    Miyata, Tomohiro; Fukuyama, Mao; Hibara, Akihide; Okunishi, Eiji; Mukai, Masaki; Mizoguchi, Teruyasu

    2014-10-01

    Investigations on the dynamic behavior of molecules in liquids at high spatial resolution are greatly desired because localized regions, such as solid-liquid interfaces or sites of reacting molecules, have assumed increasing importance with respect to improving material performance. In application to liquids, electron energy loss spectroscopy (EELS) observed with transmission electron microscopy (TEM) is a promising analytical technique with the appropriate resolutions. In this study, we obtained EELS spectra from an ionic liquid, 1-ethyl-3-methylimidazolium bis (trifluoromethyl-sulfonyl) imide (C2mim-TFSI), chosen as the sampled liquid, using monochromated scanning TEM (STEM). The molecular vibrational spectrum and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of the liquid were investigated. The HOMO-LUMO gap measurement coincided with that obtained from the ultraviolet-visible spectrum. A shoulder in the spectrum observed ∼0.4 eV is believed to originate from the molecular vibration. From a separately performed infrared observation and first-principles calculations, we found that this shoulder coincided with the vibrational peak attributed to the C-H stretching vibration of the [C2mim(+)] cation. This study demonstrates that a vibrational peak for a liquid can be observed using monochromated STEM-EELS, and leads one to expect observations of chemical reactions or aids in the analysis of the dynamic behavior of molecules in liquid.

  16. Electron energy loss spectroscopy of the L2,3 edge of phosphorus skutterudites and electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Sæterli, Ragnhild; Flage-Larsen, Espen; Prytz, Øystein; Taftø, Johan; Marthinsen, Knut; Holmestad, Randi

    2009-08-01

    In this study we report the results of experiments and theoretical calculations on the phosphorus L2,3 edges of the skutterudites CoP3 , LaFe4P12 , NiP3 , RhP3 , and IrP3 . Phosphorus s and d density of states above the Fermi level was studied by transmission electron energy loss spectroscopy while theoretical calculations were performed using both a real-space multiple-scattering procedure and density-functional theory. Generally, there are good agreements between both types of calculations and the experimental results. The near-edge structure of all the examined compounds shows the same overall features, including the metallic NiP3 and the metallic filled skutterudite LaFeP12 , and is well explained by comparison to phosphorus density of states. We also discuss the similarities to previously reported results on SiL2,3 edges and interpret the differences of the various skutterudites in terms of the electronegativities of the involved atom species.

  17. Detection of local chemical states of lithium and their spatial mapping by scanning transmission electron microscopy, electron energy-loss spectroscopy and hyperspectral image analysis.

    PubMed

    Muto, Shunsuke; Tatsumi, Kazuyoshi

    2017-02-08

    Advancements in the field of renewable energy resources have led to a growing demand for the analysis of light elements at the nanometer scale. Detection of lithium is one of the key issues to be resolved for providing guiding principles for the synthesis of cathode active materials, and degradation analysis after repeated use of those materials. We have reviewed the different techniques currently used for the characterization of light elements such as high-resolution transmission electron microscopy, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). In the present study, we have introduced a methodology to detect lithium in solid materials, particularly for cathode active materials used in lithium-ion battery. The chemical states of lithium were isolated and analyzed from the overlapping multiple spectral profiles, using a suite of STEM, EELS and hyperspectral image analysis. The method was successfully applied in the chemical state analyses of hetero-phases near the surface and grain boundary regions of the active material particles formed by chemical reactions between the electrolyte and the active materials.

  18. Using Plasmon Peaks in Electron Energy-Loss Spectroscopy to Determine the Physical and Mechanical Properties of Nanoscale Materials

    SciTech Connect

    Howe, James M.

    2013-05-09

    In this program, we developed new theoretical and experimental insights into understanding the relationships among fundamental universality and scaling phenomena, the solid-state physical and mechanical properties of materials, and the volume plasmon energy as measured by electron energy-loss spectroscopy (EELS). Particular achievements in these areas are summarized as follows: (i) Using a previously proposed physical model based on the universal binding-energy relation (UBER), we established close phenomenological connections regarding the influence of the valence electrons in materials on the longitudinal plasma oscillations (plasmons) and various solid-state properties such as the optical constants (including absorption and dispersion), elastic constants, cohesive energy, etc. (ii) We found that carbon materials, e.g., diamond, graphite, diamond-like carbons, hydrogenated and amorphous carbon films, exhibit strong correlations in density vs. Ep (or maximum of the volume plasmon peak) and density vs. hardness, both from available experimental data and ab initio DFT calculations. This allowed us to derive a three-dimensional relationship between hardness and the plasmon energy, that can be used to determine experimentally both hardness and density of carbon materials based on measurements of the plasmon peak position. (iii) As major experimental accomplishments, we demonstrated the possibility of in-situ monitoring of changes in the physical properties of materials with conditions, e.g., temperature, and we also applied a new plasmon ratio-imaging technique to map multiple physical properties of materials, such as the elastic moduli, cohesive energy and bonding electron density, with a sub-nanometer lateral resolution. This presents new capability for understanding material behavior. (iv) Lastly, we demonstrated a new physical phenomenon - electron-beam trapping, or electron tweezers - of a solid metal nanoparticle inside a liquid metal. This phenomenon is

  19. Reflection electron energy loss spectroscopy as efficient technique for the determination of optical properties of polystyrene intermixed with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Deris, Jamileh; Hajati, Shaaker

    2017-01-01

    The electronic properties (electron inelastic cross section, energy loss function) of a nano-metalized polystyrene obtained by reflection electron energy loss spectroscopy (REELS) in a previous study [J. Deris, S. Hajati, S. Tougaard, V. Zaporojtchenko, Appl. Surf. Sci. 377 (2016) 44-47], which relies on the Yubero-Tougaard method, were used in the complementary application of Kramers-Kronig transformation to determine its optical properties such as the real part (ε1) and imaginary part (ε2) of the dielectric function (ε), refractive index (n), coefficients of extinction (k), reflection (R) and absorption (μ). The degree of intermixing of polystyrene thin film and gold nanoparticles of sizes 5.5 nm was controlled by annealing the sample to achieve a morphology in which the nanoparticles were homogeneously distributed within polystyrene. It is worth noting that no data are available on the optical properties of metalized polymers such as gold nanoparticles intermixed with polystyrene. Therefore, this work is of high importance in terms of both the sample studied here and the method applied. The advantage of the method applied here is that no information on the lateral distribution of the nanocomposite sample is required. This means that the REELS technique has been presented here to suitably, efficiently and easily obtain the optical properties of such nano-metalized polymer in which the metal nanoparticles have been vertically well distributed (homogeneous in depth). Therefore, for vertically homogeneous and laterally inhomogeneous samples, it is possible to make REELS imaging by scanning the sample and thus to make an image of their optical properties.

  20. Successful application of spatial difference technique to electron energy-loss spectroscopy studies of Mo/SrTiO3 interfaces.

    PubMed

    Gao, M; Scheu, C; Tchernychova, E; Rühle, M

    2003-04-01

    The electron energy-loss near-edge structure (ELNES) of Mo/SrTiO3 interfaces has been studied using high spatial resolution electron energy-loss spectroscopy (EELS) in a dedicated scanning transmission electron microscope. Thin films of Mo with a thickness of 50 nm were grown on (001)-orientated SrTiO3 surfaces by molecular beam epitaxy at 600 degrees C. High-resolution transmission electron microscopy revealed that the interfaces were atomically abrupt with the (110)Mo plane parallel to the substrate surface. Ti-L2,3 ( approximately 460 eV), O-K ( approximately 530 eV), Sr-L2,3 ( approximately 1950 eV) and Mo-L2,3 ( approximately 2500 eV) absorption edges were acquired by using the Gatan Enfina parallel EELS system with a CCD detector. The interface-specific components of the ELNES were extracted by employing the spatial difference method. The interfacial Ti-L2,3 edge shifted to lower energy values and the splitting due to crystal field became less pronounced compared to bulk SrTiO3, which indicated that the Ti atoms at the interface were in a reduced oxidation state and that the symmetry of the TiO6 octahedra was disturbed. No interfacial Sr-L2,3 edge was observed, which may demonstrate that Sr atoms do not participate in the interfacial bonding. An evident interface-specific O-K edge was found, which differs from that of the bulk in both position (0.8 +/- 0.2 eV positive shift) and shape. In addition, a positive shift (0.9 +/- 0.3 eV) occurred for the interfacial Mo-L2,3, revealing an oxidized state of Mo at the interface. Our results indicated that at the interface SrTiO3 was terminated with TiO2. The validity of the spatial difference technique is discussed and examined by introducing subchannel drift intentionally.

  1. Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope

    SciTech Connect

    Kundmann, M.K.

    1988-11-01

    Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs.

  2. Microwave fixation and localization of calcium in synaptic terminals using x-ray microanalysis and electron energy loss spectroscopy imaging.

    PubMed

    Mizuhira, V; Hasegawa, H

    1997-01-01

    The distribution of calcium ions is demonstrated in synaptic terminals by means of a two-step chemical precipitation of calcium ions in the rat brain. K-oxalate/K-antimonate chemical replacement with simultaneous computerized microwave irradiation was used. This precipitate in nerve cell structures was investigated by computerized electron probe x-ray microanalysis (EDX) and electron energy loss spectroscopic (EELS) imaging. The values obtained by EDX agreed with those of the standard sample and theoretical values of Ca-antimonate. Typical EELS spectra of Ca:L, O:K, and Sb:M were obtained from nerve terminals in the same tissue block as that used for EDX analysis. Excellent net Ca:L and Sb:M EELS digital images were obtained after their background images were subtracted. Calcium ions were distributed in the nerve terminals, synaptic vesicles, mitochondria, and synaptic membranes.

  3. Blue and red shifts of interband transition energy in supported Au nanoclusters on SiO2 and HOPG investigated by reflection electron energy-loss spectroscopy.

    PubMed

    Borisyuk, P V; Troyan, V I; Pushkin, M A; Borman, V D; Tronin, V N

    2012-11-01

    Gold nanoclusters supported on SiO2 and HOPG are experimentally investigated by the reflection electron energy-loss spectroscopy. Two different trends in the size-dependence of the position of the energy-loss peak corresponding to the interband Au 5d --> 6s6p transition is observed: a blue shift for Au clusters on SiO2 and a red shift for Au clusters on HOPG. The different behaviors are qualitatively explained by the influence of the substrate on the spectrum of electronic states in Au nanoclusters.

  4. Study of the evolution of the atomic composition of thin NbN films under irradiation with mixed ion beams by methods of electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Dement'eva, M. M.; Prikhod'ko, K. E.; Gurovich, B. A.; Kutuzov, L. V.; Komarov, D. A.

    2016-11-01

    The variation in the atomic composition of ultrathin NbN films under irradiation by mixed ion beams to a doze of 4 dpa (for nitrogen) is experimentally studied by methods of electron energy loss spectroscopy with a transmission electron microscope in the transmission scan mode on cross-cut samples. The behavior of the substitution of nitrogen atoms by oxygen atoms has been established; it is characterized by changing the composition of the conducting part of the film from NbN to NbNO.

  5. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-01

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  6. Doubly excited states of water as studied by electron energy loss spectroscopy in coincidence with detecting Lyman-α photons

    NASA Astrophysics Data System (ADS)

    Tsuchida, Toshinori; Odagiri, Takeshi; Ishikawa, Lisa; Yachi, Kazufumi; Shigemura, Keisuke; Ohno, Naruhito; Hosaka, Kouichi; Kitajima, Masashi; Kouchi, Noriyuki

    2011-09-01

    The electron energy loss spectrum of H2O in coincidence with detecting Lyman-α photons (CoEELS) has been measured at the incident electron energy of 100 eV and electron scattering angle of 8° in the inner valence range in order to investigate the formation and decay of the doubly excited states. The present CoEELS has been compared with that at the infinite incident electron energy and 0° electron scattering angle, which was derived from the density of the dipole oscillator strength of H2O for the emission of the Lyman-α photons against the incident photon energy (Nakano et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 215206). It is remarkable that there exists a large difference in shape between these CoEELSs. This difference has turned out to be attributed to the noticeable contribution of the forbidden doubly excited states at 100 eV incident electron energy and 8° scattering angle. They lie at 25.0 and 27.4 eV and have been found out in this study. The differential cross sections for the excitation to the superexcited states resulting in H(2p) formation have been obtained at 100 eV and 8° and compared with those at the infinite energy and 0°. The electron collisions at 100 eV and 8° enhance the dissociative double excitation against the dissociative single excitation as compared with the electron collision at the infinite energy and 0°.

  7. Martensitic transformation of Ni2FeGa ferromagnetic shape-memory alloy studied via transmission electron microscopy and electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, H. R.; Ma, C.; Tian, H. F.; Wu, G. H.; Li, J. Q.

    2008-06-01

    The structural properties of Ni2FeGa Heusler alloy synthesized by melt-spinning technique have been systematically studied by means of in situ heating and cooling transmission electron microscopy. It was found that the Ni2FeGa alloy was annealed into a well-defined L21 structure at around 980 K, and complex microstructural domains appeared along with lowering temperature. At room temperature (293 K), a rich variety of micromodulated domains were observed. The domain structures were aligned along the ⟨110⟩ or ⟨100⟩ directions resulting to complex tweed structures. Below martensitic transformation (MT) temperature (Ms,˜142K) , the cubic parent phase transformed into unmodulated martensitic variants and modulated martensitic variants. The variants were alternated along the ⟨100⟩ direction with various arrangements and steplike incommensurate boundaries. The modulated martensitic variants were composed of lamellar structures that have predominately a 5M modulation structure along the ⟨110⟩ directions. The electron energy-loss spectroscopy analysis of the low-loss region and the electron energy-loss near-edge fine structure revealed a visible change of the electronic structure along with MT, which can be well interpreted by means of intra-atomic or intraband charge redistribution due to spd orbital hybridization among the Ni-Fe-Ga atoms.

  8. Observability of localized magnetoplasmons in quantum dots: Scrutinizing the eligibility of far-infrared, Raman, and electron-energy-loss spectroscopies

    NASA Astrophysics Data System (ADS)

    Kushwaha, Manvir S.

    2016-03-01

    We investigate a one-component, quasi-zero dimensional, quantum plasma exposed to a parabolic potential and an applied magnetic field in the symmetric gauge. If the size of such a system as can be realized in the semiconducting quantum dots is on the order of the de-Broglie wavelength, the electronic and optical properties become highly tunable. Then the quantum size effects challenge the observation of many-particle phenomena such as the magneto-optical absorption, Raman intensity, and electron energy-loss spectrum. An exact analytical solution of the problem leads us to infer that these many-particle phenomena are, in fact, dictated by the generalized Kohn's theorem (GKT) in the long-wavelength limit. Maneuvering the confinement and/or the magnetic field furnishes the resonance energies capable of being explored with the FIR, Raman, and/or electron-energy-loss spectroscopy. This implies that either of these probes is competent in observing the localized magnetoplasmons in the system. As an application of the rigorous analytical diagnosis of the system, we have presented various pertinent single-particle, such as Fock-Darwin spectrum, Fermi energy, zigzag excitation spectrum, and magneto-optical transitions, and the many-particle phenomena, such as magneto-optical absorption, Raman intensity, and electron energy-loss probability. In the latter, the energy position of the resonance peaks is observed to be independent of the electron-electron interactions and hence of the number of electrons in the quantum dot in compliance with the GKT. It is found that both confinement potential and magnetic field play a decisive role in influencing the aforementioned many-particle phenomena. Specifically, increasing (decreasing) the strength of the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots and results into a blue (red) shift in the respective spectra. Intensifying the magnetic field has two-fold effects in the resonance

  9. Iron sources used by the nonpathogenic lactic acid bacterium Lactobacillus sakei as revealed by electron energy loss spectroscopy and secondary-ion mass spectrometry.

    PubMed

    Duhutrel, Philippe; Bordat, Christian; Wu, Ting-Di; Zagorec, Monique; Guerquin-Kern, Jean-Luc; Champomier-Vergès, Marie-Christine

    2010-01-01

    Lactobacillus sakei is a lactic acid bacterium naturally found on meat. Although it is generally acknowledged that lactic acid bacteria are rare species in the microbial world which do not have iron requirements, the genome sequence of L. sakei 23K has revealed quite complete genetic equipment dedicated to transport and use of this metal. Here, we aimed to investigate which iron sources could be used by this species as well as their role in the bacterium's physiology. Therefore, we developed a microscopy approach based on electron energy loss spectroscopy (EELS) analysis and nano-scale secondary-ion mass spectrometry (SIMS) in order to analyze the iron content of L. sakei cells. This revealed that L. sakei can use iron sources found in its natural ecosystem, myoglobin, hemoglobin, hematin, and transferrin, to ensure long-term survival during stationary phase. This study reveals that analytical image methods (EELS and SIMS) are powerful complementary tools for investigation of metal utilization by bacteria.

  10. Probing the chemical structure in diamond-based materials using combined low-loss and core-loss electron energy-loss spectroscopy.

    PubMed

    Longo, Paolo; Twesten, Ray D; Olivier, Jaco

    2014-06-01

    We report the analysis of the changes in local carbon structure and chemistry caused by the self-implantation of carbon into diamond via electron energy-loss spectroscopy (EELS) plasmon energy shifts and core-edge fine structure fingerprinting. These two very different EELS energy and intensity ranges of the spectrum can be acquired under identical experimental conditions and nearly simultaneously using specially designed deflectors and energy offset devices known as "DualEELS." In this way, it is possible to take full advantage of the unique and complementary information that is present in the low- and core-loss regions of the EELS spectrum. We find that self-implanted carbon under the implantation conditions used for the material investigated in this paper creates an amorphous region with significant sp 2 content that varies across the interface.

  11. Distributions of hafnia and titania cores in EUV metal resists evaluated by scanning transmission electron microscopy and electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Toriumi, Minoru; Sato, Yuta; Koshino, Masanori; Suenaga, Kazu; Itani, Toshiro

    2016-11-01

    The morphologies of hafnia (HfO x ) and titania (TiO x ) cores and their distributions in metal resists for EUV lithography were characterized at the atomic level by scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The HfO x cores show a higher affinity to organic components, such as methacrylic acid and benzoic acid, than the TiO x cores, and the same core-shell state as in a solution is almost completely maintained in the HfO x resist film. Furthermore, it was found that the surface modification of the TiO x cores by silylation is effective for preventing their aggregation and improves the postcoating delay (PCD) of the resist.

  12. In Situ Environmental Cell-Transmission Electron Microscopy Study of Microbial Reduction of Chromium(VI) Using Electron Energy Loss Spectroscopy.

    PubMed

    Daulton, Tyrone L.; Little, Brenda J.; Lowe, Kristine; Jones-Meehan, Joanne

    2001-11-01

    Reduction of Cr(VI) by the bacterium, Shewanella oneidensis (previously classified Shewanella putrefaciens strain MR-1), was studied by absorption spectrophotometry and in situ, environmental cell-transmission electron microscopy (EC-TEM) coupled with electron energy loss spectroscopy (EELS). Bacteria from rinsed cultures were placed directly in the environmental cell of the transmission electron microscope and examined under 100 Torr pressure. Bright field EC-TEM images show two distinct populations of S. oneidensis in incubated cultures containing Cr(VI)O2- 4: those that exhibit low image contrast and heavily precipitate-encrusted cells exhibiting high image contrast. Several EELS techniques were applied to determine the oxidation state of Cr associated with encrusted cells. The encrusted cells are shown to contain a reduced form of Cr in oxidation state +3 or lower. These results demonstrate the capability to determine the chemistry and valence state of reduction products associated with unfixed, hydrated bacteria in an environmental cell transmission electron microscope.

  13. Combination of electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy to determine indium concentration in InGaN thin film structures

    NASA Astrophysics Data System (ADS)

    Wang, X.; Chauvat, M. P.; Ruterana, P.; Walther, T.

    2015-11-01

    We demonstrate a method to determine the indium concentration, x, of In x Ga1-x N thin films by combining plasmon excitation studies in electron energy-loss spectroscopy (EELS) with a novel way of quantification of the intensity of x-ray lines in energy-dispersive x-ray spectroscopy (EDXS). The plasmon peak in EELS of InGaN is relatively broad. We fitted a Lorentz function to the main plasmon peak to suppress noise and the influence from the neighboring Ga 3d transition in the spectrum, which improves the precision in the evaluation of the plasmon peak position. As the indium concentration of InGaN is difficult to control during high temperature growth due to partial In desorption, the nominal indium concentrations provided by the growers were not considered reliable. The indium concentration obtained from EDXS quantification using Oxford Instrument ISIS 300 x-ray standard quantification software often did not agree with the nominal indium concentration, and quantification using K and L lines was inconsistent. We therefore developed a self-consistent iterative procedure to determine the In content from thickness-dependent k-factors, as described in recent work submitted to Journal of Microscopy. When the plasmon peak position is plotted versus the indium concentration from EDXS we obtain a linear relationship over the whole compositional range, and the standard error from linear least-squares fitting shows that the indium concentration can be determined from the plasmon peak position to within Δx = ± 0.037 standard deviation.

  14. Isolated energy level in the band gap of Yb2Si2O7 identified by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Ogawa, Takafumi; Kobayashi, Shunsuke; Wada, Masashi; Fisher, Craig A. J.; Kuwabara, Akihide; Kato, Takeharu; Yoshiya, Masato; Kitaoka, Satoshi; Moriwake, Hiroki

    2016-05-01

    We report the detection of an isolated energy level in the band gap of crystalline Yb2Si2O7 in the low-energy-loss region of its electron energy-loss (EEL) spectrum, obtained using a monochromated scanning transmission electron microscope. The experimental results are corroborated by first-principles calculations of the theoretical EEL spectrum. The calculations reveal that unoccupied Yb 4 f orbitals constitute an isolated energy level about 1 eV below the conduction band minimum (CBM), resulting in a terrace about 1 eV wide at the band edge of the EEL spectrum. In the case of Yb2O3 , no band edge terrace is present because the unoccupied f level lies just below the CBM. We also examined optical absorption properties of Yb2Si2O7 using UV-vis diffuse reflectance spectroscopy, which shows that the isolated energy level could not be detected in the band edge of the obtained absorbance spectrum. These findings demonstrate the utility of low-loss EEL spectroscopy with high energy resolution for probing semilocalized electronic features.

  15. High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of bulk and nanoparticle LaB6 in the near-infrared region.

    PubMed

    Sato, Yohei; Terauchi, Masami; Mukai, Masaki; Kaneyama, Toshikatsu; Adachi, Kenji

    2011-07-01

    The dielectric properties of LaB(6) crystals and the plasmonic behavior of LaB(6) nanoparticles, which have been applied to solar heat-shielding filters, were studied by high energy-resolution electron energy-loss spectroscopy (HR-EELS). An EELS spectrum of a LaB(6) crystal showed a peak at 2.0 eV, which was attributed to volume plasmon excitation of carrier electrons. EELS spectra of single LaB(6) nanoparticles showed peaks at 1.1-1.4 eV depending on the dielectric effect from the substrates. The peaks were assigned to dipole oscillation excitations. These peak energies almost coincided with the peak energy of optical absorption of a heat-shielding filter with LaB(6) nanoparticles. On the other hand, those energies were a smaller than a dipole oscillation energy predicted using the dielectric function of bulk LaB(6) crystal. It is suggested that the lower energy than expected is due to an excitation at 1.2 eV, which was observed for oxidized LaB(6) area.

  16. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

    PubMed

    Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

    2015-06-28

    The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.

  17. Assessing electron beam sensitivity for SrTiO3 and La0.7Sr0.3MnO3 using electron energy loss spectroscopy.

    PubMed

    Nord, Magnus; Vullum, Per Erik; Hallsteinsen, Ingrid; Tybell, Thomas; Holmestad, Randi

    2016-10-01

    Thresholds for beam damage have been assessed for La0.7Sr0.3MnO3 and SrTiO3 as a function of electron probe current and exposure time at 80 and 200kV acceleration voltage. The materials were exposed to an intense electron probe by aberration corrected scanning transmission electron microscopy (STEM) with simultaneous acquisition of electron energy loss spectroscopy (EELS) data. Electron beam damage was identified by changes of the core loss fine structure after quantification by a refined and improved model based approach. At 200kV acceleration voltage, damage in SrTiO3 was identified by changes both in the EEL fine structure and by contrast changes in the STEM images. However, the changes in the STEM image contrast as introduced by minor damage can be difficult to detect under several common experimental conditions. No damage was observed in SrTiO3 at 80kV acceleration voltage, independent of probe current and exposure time. In La0.7Sr0.3MnO3, beam damage was observed at both 80 and 200kV acceleration voltages. This damage was observed by large changes in the EEL fine structure, but not by any detectable changes in the STEM images. The typical method to validate if damage has been introduced during acquisitions is to compare STEM images prior to and after spectroscopy. Quantifications in this work show that this method possibly can result in misinterpretation of beam damage as changes of material properties.

  18. Electronic structure of metastable bcc Cu-Cr alloy thin films: Comparison of electron energy-loss spectroscopy and first-principles calculations.

    PubMed

    Liebscher, C H; Freysoldt, C; Dennenwaldt, T; Harzer, T P; Dehm, G

    2016-07-12

    Metastable Cu-Cr alloy thin films with nominal thickness of 300nm and composition of Cu67Cr33 (at%) are obtained by co-evaporation using molecular beam epitaxy. The microstructure, chemical phase separation and electronic structure are investigated by transmission electron microscopy (TEM). The thin film adopts the body-centered cubic crystal structure and consists of columnar grains with ~50nm diameter. Aberration-corrected scanning TEM in combination with energy dispersive X-ray spectroscopy confirms compositional fluctuations within the grains. Cu- and Cr-rich domains with composition of Cu85Cr15 (at%) and Cu42Cr58 (at%) and domain size of 1-5nm are observed. The alignment of the interface between the Cu- and Cr-rich domains shows a preference for {110}-type habit plane. The electronic structure of the Cu-Cr thin films is investigated by electron energy loss spectroscopy (EELS) and is contrasted to an fcc-Cu reference sample. The experimental EEL spectra are compared to spectra computed by density functional theory. The main differences between bcc-and fcc-Cu are related to differences in van Hove singularities in the electron density of states. In Cu-Cr solid solutions with bcc crystal structure a single peak after the L3-edge, corresponding to a van Hove singularity at the N-point of the first Brillouin zone is observed. Spectra computed for pure bcc-Cu and random Cu-Cr solid solutions with 10at% Cr confirm the experimental observations. The calculated spectrum for a perfect Cu50Cr50 (at%) random structure shows a shift in the van Hove singularity towards higher energy by developing a Cu-Cr d-band that lies between the delocalized d-bands of Cu and Cr.

  19. Dynamical observation of lithium insertion/extraction reaction during charge-discharge processes in Li-ion batteries by in situ spatially resolved electron energy-loss spectroscopy.

    PubMed

    Shimoyamada, Atsushi; Yamamoto, Kazuo; Yoshida, Ryuji; Kato, Takehisa; Iriyama, Yasutoshi; Hirayama, Tsukasa

    2015-12-01

    All-solid-state Li-ion batteries (LIBs) with solid electrolytes are expected to be the next generation devices to overcome serious issues facing conventional LIBs with liquid electrolytes. However, the large Li-ion transfer resistance at the electrode/solid-electrolyte interfaces causes low power density and prevents practical use. In-situ-formed negative electrodes prepared by decomposing the solid electrolyte Li(1+x+3z)Alx(Ti,Ge)(2-x)Si(3z)P(3-z)O12 (LASGTP) with an excess Li-ion insertion reaction are effective electrodes providing low Li-ion transfer resistance at the interfaces. Prior to our work, however, it had still been unclear how the negative electrodes were formed in the parent solid electrolytes. Here, we succeeded in dynamically visualizing the formation by in situ spatially resolved electron energy-loss spectroscopy in a transmission electron microscope mode (SR-TEM-EELS). The Li-ions were gradually inserted into the solid electrolyte region around 400 nm from the negative current-collector/solid-electrolyte interface in the charge process. Some of the ions were then extracted in the discharge process, and the rest were diffused such that the distribution was almost flat, resulting in the negative electrodes. The redox reaction of Ti(4+)/Ti(3+) in the solid electrolyte was also observed in situ during the Li insertion/extraction processes. The in situ SR-TEM-EELS revealed the mechanism of the electrochemical reaction in solid-state batteries.

  20. Spatially resolved chemical mapping of dry and hydrated polymer morphology by electron energy-loss spectroscopy in the scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Sousa, Alioscka A. C. A.

    Electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) is a technique that allows compositional analysis to be performed at high spatial resolution in thin TEM specimens, and here we implement and apply this technique to quantitatively study the morphology of unstained dry and frozen-hydrated polymer films. While water can play a controlling role that determines many of the important properties of polymers, there has not yet been much experimental work performed to correlate water spatial distribution with variations in underlying polymer morphology. We show how a quantitative map of the nanoscale spatial distribution of water can be generated from frozen-hydrated polymer thin films using EELS in the STEM. We find that hydrated polymers are very sensitive to the incident electron irradiation, and there is a trade off between the spatial resolution that a compositional map can display and its signal-to-noise ratio. The identification of minor fluctuations in composition within small regions across a given water map is therefore challenging because one must distinguish the fluctuations that are significant from those within noise. We implement a methodology using scatter diagrams in combination with noise simulations to threshold water maps and separate real pixel-by-pixel compositional fluctuations from noise. We study a model system comprised of hydrophilic poly(vinyl pyrrolidone) and hydrophobic poly(styrene), and we show that the thresholding approach enables us to quantitatively identify statistically significant single-pixel fluctuations in water content. We also apply EELS in the STEM to characterize the morphology of a dry, solvent-cast thin-film biopolymer blend comprised of poly(caprolactone) and poly(DTE carbonate). We quantitatively show the effect that solvent evaporation rate has on the morphology development of this blend and how the underlying morphology can dramatically influence the spatial distribution of

  1. New insights into the chemical structure of Y2Ti2O7-δ nanoparticles in oxide dispersion-strengthened steels designed for sodium fast reactors by electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Badjeck, V.; Walls, M. G.; Chaffron, L.; Malaplate, J.; March, K.

    2015-01-01

    In this paper we study by high resolution scanning transmission electron microscopy coupled with electron energy-loss spectroscopy (STEM-EELS) an oxide dispersion-strengthened (ODS) steel with the nominal composition Fe-14Cr-1W-0.3TiH2-0.3Y2O3 (wt.%) designed to withstand the extreme conditions met in Gen. IV nuclear reactors. After denoising via principal component analysis (PCA) the data are analyzed using independent component analysis (ICA) which is useful in the investigation of the physical properties and chemical structure of the material by separating the individual spectral responses. The Y-Ti-O nanoparticles are found to be homogeneously distributed in the ferritic matrix, sized from 1 to 20 nm and match a non-stoichiometric pyrochlore-Y2Ti2O7-δ structure for sizes greater than 5 nm. We show that they adopt a (Y-Ti-O)-Cr core-shell structure and that Cr also segregates at the matrix grain boundaries, which may slightly modify the corrosion properties of the steel. Using Ti-L2,3 and O-K fine structure (ELNES) the Ti oxidation state is shown to vary from the center of the nanoparticles to their periphery, from Ti4+ in distorted Oh symmetry to a valency often lower than 3+. The sensitivity of the Ti "white lines" ELNES to local symmetry distortions is also shown to be useful when investigating the strain induced in the nanoparticles by the surrounding matrix. The Cr-shell and the variation of the Ti valence state highlight a complex nanoparticle-matrix interface.

  2. The electronic states of buta-1,3-diene studied by ab initio configuration interaction and DFT methods, and electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    H., Michael; | Isobel C., Palmer; Walker

    2010-08-01

    The electronic vertical excitation energies for singlet and triplet valence, and Rydberg states of trans-buta-1,3-diene have been computed using ab initio multi-reference multi-root CI procedures with a [4s3p3d3f] set of Rydberg functions. Close numerical agreement between theory and experiment was found for a number of low-lying electronic states. The present CI and CASSCF [8MO,8e] calculations suggest that both the vertical and adiabatic order of the valence (ππ∗) states is: A˜1Aelectron energy-loss spectrum, reported here, in which the incident electrons have near-threshold energies, supports this order. Adiabatic excitation energies and structures were obtained for several singlet and triplet states using CASSCF and B3LYP procedures; the results from these methods are generally in good agreement with each other. The C 1C 2 to C 2C 3 bond length ratio in the excited states varies widely, and is discussed.

  3. The electronic states of oxazole studied by VUV absorption and electron energy-loss (EEL) spectroscopies, and ab initio configuration interaction methods

    NASA Astrophysics Data System (ADS)

    Palmer, Michael H.; Ganzenmüller, Georg; Walker, Isobel C.

    2007-04-01

    The oxazole VUV absorption spectrum over the range 5-12 eV shows intense bands centred near 6.3, 7.5, 8.3, 9.6 and 10.8 eV. The electron energy-loss (EEL) spectrum shows additional structure with a strong peak (˜1.4 eV) arising from resonant vibrational excitation of the molecule via a shape resonance, and a spin-forbidden 3ππ ∗ state at 4.6 eV. Electronic excitation energies for valence and Rydberg-type states have been computed using ab initio multi-reference multi-root CI methods. The CI studies used a triple zeta + polarisation basis set, augmented by diffuse (Rydberg) orbitals, to generate the theoretical singlet and triplet energy manifolds. The correlation of theory and experiment shows the nature of the more intense Rydberg state types, and identification of the main valence and Rydberg bands. Calculated energies for low-lying Rydberg states are relatively close (SD 0.38) to those expected, and there is generally a good correlation between the theoretical and experimental envelopes. Two of the three lowest electronic states arise from ππ ∗ excitation of the outer (3a″ and 2a″) π-orbitals, with one state (LP Nπ ∗) originating from the lone pair on nitrogen (15a') between them.

  4. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  5. High-resolution electron spectroscopy of different adsorption states of ethylene on Pd(1 1 1)

    NASA Astrophysics Data System (ADS)

    Sock, M.; Eichler, A.; Surnev, S.; Andersen, J. N.; Klötzer, B.; Hayek, K.; Ramsey, M. G.; Netzer, F. P.

    2003-11-01

    The adsorption of ethylene at 100 K on clean and oxygen precovered Pd(1 1 1) surfaces and the thermal evolution of the ethylene adsorbate layers have been investigated experimentally by high-resolution electron energy loss spectroscopy (HREELS), high-resolution X-ray photoelectron spectroscopy with synchrotron radiation, thermal desorption spectroscopy and theoretically by ab initio density functional theory (DFT) calculations. On the clean Pd(1 1 1) surface at 100 K ethylene is adsorbed in a di-σ bonding state, whereas on the oxygen precovered Pd(1 1 1)2 × 2-O surface the π-bonded configuration is more stable; this has been established both experimentally and theoretically. Upon adsorption at room temperature ethylidyne adspecies are formed on both surfaces, but neither di-σ nor π-bonded ethylene transform into ethylidyne on heating from low temperature up to 450 K. Complete molecular desorption of ethylene is observed in both cases, with no signs of dehydrogenation. The spectroscopic data recorded during the thermal evolution of the low temperature adsorbate phase have been analysed with the help of DFT and indicate that π-bonded ethylene adsorption states may become populated upon heating the low temperature adlayer to 350 K.

  6. Nano-scale simultaneous observation of Li-concentration profile and Ti-, O electronic structure changes in an all-solid-state Li-ion battery by spatially-resolved electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuo; Yoshida, Ryuji; Sato, Takeshi; Matsumoto, Hiroaki; Kurobe, Hisanori; Hamanaka, Tadashi; Kato, Takehisa; Iriyama, Yasutoshi; Hirayama, Tsukasa

    2014-11-01

    All-solid-state Li-ion batteries having incombustible solid electrolytes are expected to be promising candidates for safe next-generation energy storage devices that have a long lifetime and high energy density. However, it is essential to address the large resistance of Li-ion transfer at the electrode/solid-electrolyte interfaces. A new concept electrode that is formed in situ from the Li2O-Al2O3-TiO2-P2O5-based glass-ceramic solid electrolytes with Si and Ge doping (LASGTP) produces atomic scale connection at the interfaces, which provides extremely low interfacial resistance. However, the formation mechanism and the reason for the low resistance are still unclear. Here we applied spatially-resolved electron energy-loss spectroscopy in a transmission electron microscope mode (SR-TEM-EELS) to visualize the nanometer-scale Li distribution and its effects on the electronic structures of other important elements (Ti and O). Local electron diffraction showed that the in situ formed electrode was an amorphous phase caused by the Li insertion. Picometer-scale expansion of O-O distance due to the Li insertion was also visualized in the electrode. These electronic and crystal changes and gradual Li distribution contribute to the low resistance and stable battery cycles.

  7. Electron energy-loss spectra in molecular fluorine

    NASA Technical Reports Server (NTRS)

    Nishimura, H.; Cartwright, D. C.; Trajmar, S.

    1979-01-01

    Electron energy-loss spectra in molecular fluorine, for energy losses from 0 to 17.0 eV, have been taken at incident electron energies of 30, 50, and 90 eV and scattering angles from 5 to 140 deg. Features in the spectra above 11.5 eV energy loss agree well with the assignments recently made from optical spectroscopy. Excitations of many of the eleven repulsive valence excited electronic states are observed and their location correlates reasonably well with recent theoretical results. Several of these excitations have been observed for the first time and four features, for which there are no identifications, appear in the spectra.

  8. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Benner, D. Chris; Venkataraman, Malathy Devi

    2000-01-01

    The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as carbon dioxide, water vapor, ozone, methane, and carbon monoxide, to name a few. Measurements were made using the NASA Langley Tunable Diode Laser Spectrometer System (TDL) and several Fourier Transform Spectrometer Systems (FTS) around the globe. The results from these studies made remarkable improvements in the line positions and intensities for several molecules, particularly ozone and carbon dioxide in the 2 to 17-micrometer spectral region. Measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced line shift coefficients for infrared transitions of ozone, methane, and water vapor were also performed. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon-and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields.

  9. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Benner, D. Chris; Venkataraman, Malathy Devi

    2000-01-01

    The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as carbon dioxide, water vapor, ozone, methane, and carbon monoxide, to name a few. Measurements were made using the NASA Langley Tunable Diode Laser Spectrometer System (TDL) and several Fourier Transform Spectrometer Systems (FTS) around the globe. The results from these studies made remarkable improvements in the line positions and intensities for several molecules, particularly ozone and carbon dioxide in the 2 to 17-micrometer spectral region. Measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced line shift coefficients for infrared transitions of ozone, methane, and water vapor were also performed. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon- and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields.

  10. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Venkataraman, Malathy Devi

    2003-01-01

    Spectroscopic parameters (such as line position, intensity, broadening and shifting coefficients and their temperature dependences, line mixing coefficients etc.) for various molecular species of atmospheric interest are determined. In order to achieve these results, infrared spectra of several molecular bands are obtained using high-resolution recording instruments such as tunable diode laser spectrometer and Fourier transform spectrometers. Using sophisticated analysis routines (Multispectrum nonlinear least squares technique) these high-resolution infrared spectra are processed to determine the various spectral line parameters that are cited above. Spectra were taken using the McMath-Pierce Fourier transform spectrometer (FTS) at the National Solar Observatory on Kitt Peak, Arizona as well as the Bruker FTS at the Pacific Northwest National Laboratory (PNNL) at Richland, Washington. Most of the spectra are acquired not only at room temperature, but also at several different cold temperatures. This procedure is necessary to study the variation of the spectral line parameters as a function of temperature in order to simulate the Earth's and other planetary atmospheric environments. Depending upon the strength or weakness of the various bands recorded and analyzed, the length(s) of the absorption cells in which the gas samples under study are kept varied from a few centimeters up to several meters and the sample temperatures varied from approximately +30 C to -63 C. Research on several infrared bands of various molecular species and their isotopomers are undertaken. Those studies are briefly described.

  11. High Resolution Laser Spectroscopy of Rhenium Carbide

    NASA Astrophysics Data System (ADS)

    Adam, Allan G.; Hall, Ryan M.; Linton, Colan; Tokaryk, Dennis

    2014-06-01

    The first spectroscopic study of rhenium carbide, ReC, has been performed using both low and high resolution techniques to collect rotationally resolved electronic spectra from 420 to 500nm. Laser-induced fluorescence (LIF), and dispersed fluorescence (DF) techniques were employed. ReC was formed in our laser ablation molecular jet apparatus by ablating a rhenium target rod in the presence of 1% methane in helium. The low resolution spectrum identified four bands of an electronic system belonging to ReC, three of which have been studied so far. Extensive hyperfine structure composed of six hyperfine components was observed in the high resolution spectrum, as well as a clear distinction between the 187ReC and 185ReC isotopologues. The data seems consistent with a ^4Π - ^4Σ- transition, as was predicted before experimentation. Dispersed fluorescence spectra allowed us to determine the ground state vibrational frequency (ωe"=994.4 ± 0.3 wn), and to identify a low-lying electronically excited state at Te"=1118.4 ± 0.4 wn with a vibrational frequency of ωe"=984 ± 2 wn. Personal communication, F. Grein, University of New Brunswick

  12. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Venkataraman, Malathy Devi

    2006-01-01

    The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as H2O (water vapor), O3 (ozone), HCN (hydrogen cyanide), CH4 (methane), NO2 (nitrogen dioxide) and CO (carbon monoxide). The data required for the analyses were obtained from two different Fourier Transform Spectrometers (FTS); one of which is located at the National Solar Observatory (NSO) on Kitt Peak, Arizona and the other instrument is located at the Pacific Northwest National Laboratories (PNNL) at Richland, Washington. The data were analyzed using a modified multispectrum nonlinear least squares fitting algorithm developed by Dr. D. Chris Benner of the College of William and Mary. The results from these studies made significant improvements in the line positons and intensities for these molecules. The measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced shift coefficients for hundreds of infrared transitions of HCN, CO3 CH4 and H2O were also performed during this period. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research Satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon- and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields. The research conducted during the period 2003-2006 has resulted in publications given in this paper. In addition to Journal publications, several oral and poster presentations were given at various Scientific conferences within the United States

  13. High-resolution flurescence spectroscopy in immunoanalysis

    SciTech Connect

    Grubor, Nenad M.

    2005-01-01

    The work presented in this dissertation combines highly sensitive and selective fluorescence line-narrowing spectroscopy (FLNS) detection with various modes of immunoanalytical techniques. It has been shown that FLNS is capable of directly probing molecules immunocomplexed with antibodies, eliminating analytical ambiguities that may arise from interferences that accompany traditional immunochemical techniques. Moreover, the utilization of highly cross-reactive antibodies for highly specific analyte determination has been demonstrated. Finally, they demonstrate the first example of the spectral resolution of diastereomeric analytes based on their interaction with a cross-reactive antibody.

  14. High resolution gamma spectroscopy well logging system

    SciTech Connect

    Giles, J.R.; Dooley, K.J.

    1997-05-01

    A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. The absolute counting efficiencies of the GSLS detectors were determined using cylindrical reference sources. More complex borehole geometries were modeled using commercially available shielding software and correction factors were developed based on relative gamma-ray fluence rates. Examination of varying porosity and moisture content showed that as porosity increases, and as the formation saturation ratio decreases, relative gamma-ray fluence rates increase linearly for all energies. Correction factors for iron and water cylindrical shields were found to agree well with correction factors determined during previous studies allowing for the development of correction factors for type-304 stainless steel and low-carbon steel casings. Regression analyses of correction factor data produced equations for determining correction factors applicable to spectral gamma-ray well logs acquired under non-standard borehole conditions.

  15. High resolution electron microscopy and spectroscopy of ferritin in thin window liquid cells

    NASA Astrophysics Data System (ADS)

    Wang, Canhui; Qiao, Qiao; Shokuhfar, Tolou; Klie, Robert

    2014-03-01

    In-situ transmission electron microscopy (TEM) has seen a dramatic increase in interest in recent years with the commercial development of liquid and gas stages. High-resolution TEM characterization of samples in a liquid environment remains limited by radiation damage and loss of resolution due to the thick window-layers required by the in-situ stages. We introduce thin-window static-liquid cells that enable sample imaging with atomic resolution and electron energy-loss (EEL) spectroscopy with 1.3 nm resolution. Using this approach, atomic and electronic structures of biological samples such as ferritin is studied via in-situ transmission electron microscopy experiments. Ferritin in solution is encapsulated using the static liquid cells with reduced window thickness. The integrity of the thin window liquid cell is maintained by controlling the electron dose rate. Radiation damage of samples, such as liquid water and protein, is quantitatively studied to allow precision control of radiation damage level within the liquid cells. Biochemical reactions, such as valence change of the iron in a functioning ferritin, is observed and will be quantified. Relevant biochemical activity: the release and uptake of Fe atoms through the channels of ferritin protein shell is also imaged at atomic resolution. This work is funded by Michigan Technological University. The UIC JEOL JEM-ARM200CF is supported by an MRI-R2 grant from the National Science Foundation (Grant No. DMR-0959470).

  16. Defect engineering in GaAs using high energy light ion irradiation: Role of electronic energy loss

    SciTech Connect

    Kabiraj, D.; Ghosh, Subhasis

    2011-02-01

    We report on the application of high energy light ions (Li and O) irradiation for modification of defects, in particular, for annihilation of point defects using electronic energy loss in GaAs to minimize the defects produced by nuclear collisions. The high resolution x-ray diffraction and micro-Raman spectroscopy have been used to monitor that no lattice damage or amorphization take place due to irradiating ions. The effects of irradiation on defects and their energy levels have been studied using thermally stimulated current spectroscopy. It has been observed that till an optimum irradiation fluence of 10{sup 13} ions/cm{sup 2} there is annihilation of native defects but further increase in irradiation fluence results in accumulation of defects, which scales with the nuclear energy loss process, indicating that the rate of defects produced by the binary collision process exceeds rate of defect annihilation. Defect annihilation due to electronic energy loss has been discussed on the basis of breaking of bonds and enhanced diffusivity of ionized native defects.

  17. Application of spectral phase shaping to high resolution CARS spectroscopy.

    PubMed

    Postma, S; van Rhijn, A C W; Korterik, J P; Gross, P; Herek, J L; Offerhaus, H L

    2008-05-26

    By spectral phase shaping of both the pump and probe pulses in coherent anti-Stokes Raman scattering (CARS) spectroscopy we demonstrate the extraction of the frequencies, bandwidths and relative cross sections of vibrational lines. We employ a tunable broadband Ti:Sapphire laser synchronized to a ps-Nd:YVO mode locked laser. A high resolution spectral phase shaper allows for spectroscopy with a precision better than 1 cm(-1) in the high frequency region around 3000 cm(-1). We also demonstrate how new spectral phase shaping strategies can amplify the resonant features of isolated vibrations to such an extent that spectroscopy and microscopy can be done at high resolution, on the integrated spectral response without the need for a spectrograph.

  18. The electron energy loss rate due to radiative recombination

    NASA Astrophysics Data System (ADS)

    Mao, Junjie; Kaastra, Jelle; Badnell, N. R.

    2017-02-01

    Context. For photoionized plasmas, electron energy loss rates due to radiative recombination (RR) are required for thermal equilibrium calculations, which assume a local balance between the energy gain and loss. While many calculations of total and/or partial RR rates are available from the literature, specific calculations of associated RR electron energy loss rates are lacking. Aims: Here we focus on electron energy loss rates due to radiative recombination of H-like to Ne-like ions for all the elements up to and including zinc (Z = 30), over a wide temperature range. Methods: We used the AUTOSTRUCTURE code to calculate the level-resolved photoionization cross section and modify the ADASRR code so that we can simultaneously obtain level-resolved RR rate coefficients and associated RR electron energy loss rate coefficients. We compared the total RR rates and electron energy loss rates of H i and He i with those found in the literature. Furthermore, we utilized and parameterized the weighted electron energy loss factors (dimensionless) to characterize total electron energy loss rates due to RR. Results: The RR electron energy loss data are archived according to the Atomic Data and Analysis Structure (ADAS) data class adf48. The RR electron energy loss data are also incorporated into the SPEX code for detailed modeling of photoionized plamsas. Full Tables 1 and 2 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A10

  19. An Introduction to High Resolution Coherent Multidimensional Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Wells, Thresa A.; House, Zuri R.; Strangfeld, Benjamin R.

    2013-06-01

    High resolution coherent multidimensional spectroscopy is a technique that can be used to analyze and assign peaks for molecules that have resisted spectral analysis. Molecules that yield heavily congested and seemingly patternless spectra using conventional methods can yield 2D spectra that have recognizable patterns. The off-diagonal region of the coherent 2D plot shows only cross-peaks that are related by rotational selection rules. The resulting patterns facilitate peak assignment if they are sufficiently resolved. For systems that are not well-resolved, coherent 3D spectra may be generated to further improve resolution and provide selectivity. This presentation will provide an introduction to high resolution coherent 2D and 3D spectroscopies.

  20. Adaptive optics high resolution spectroscopy: present status and future direction

    SciTech Connect

    Alcock, C; Angel, R; Ciarlo, D; Fugate, R O; Ge, J; Kuzmenko, P; Lloyd-Hart, M; Macintosh, B; Najita, J; Woolf, N

    1999-07-27

    High resolution spectroscopy experiments with visible adaptive optics (AO) telescopes at Starfire Optical Range and Mt. Wilson have demonstrated that spectral resolution can be routinely improved by a factor of - 10 over the seeing-limited case with no extra light losses at visible wavelengths. With large CCDs now available, a very wide wavelength range can be covered in a single exposure. In the near future, most large ground-based telescopes will be equipped with powerful A0 systems. Most of these systems are aimed primarily at diffraction-limited operation in the near IR. An exciting new opportunity will thus open up for high resolution IR spectroscopy. Immersion echelle gratings with much coarser grooves being developed by us at LLNL will play a critical role in achieving high spectral resolution with a compact and low cost IR cryogenically cooled spectrograph and simultaneous large wavelength coverage on relatively small IR detectors. We have constructed a new A0 optimized spectrograph at Steward Observatory to provide R = 200,000 in the optical, which is being commissioned at the Starfire Optical Range 3.5m telescope. We have completed the optical design of the LLNL IR Immersion Spectrograph (LISPEC) to take advantage of improved silicon etching technology. Key words: adaptive optics, spectroscopy, high resolution, immersion gratings

  1. High Resolution Coherent 3d Spectroscopy of Bromine

    NASA Astrophysics Data System (ADS)

    Strangfeld, Benjamin R.; Wells, Thresa A.; House, Zuri R.; Chen, Peter C.

    2013-06-01

    The high resolution gas phase electronic spectrum of bromine is rather congested due to many overlapping vibrational and rotational transitions with similar transition frequencies, and also due to isotopomeric effects. Expansion into the second dimension will remove some of this congestion; however through the implementation of High Resolution Coherent 3D Spectroscopy, the density of peaks is further reduced by at least two orders of magnitude. This allows for the selective examination of a small number of spatially resolved multidimensional bands, separated by vibrational quantum number and by isotopomer, which facilitates the fitting of many rovibrational peaks in bromine. The ability to derive information about the molecular constants for the electronic states involved will be discussed.

  2. High-resolution threshold photoelectron spectroscopy by electron attachment

    NASA Technical Reports Server (NTRS)

    Ajello, J. M.; Chutjian, A.

    1976-01-01

    A new technique for measuring high-resolution threshold photoelectron spectra of atoms, molecules, and radicals is described. It involves photoionization of a gaseous species, attachment of the threshold, or nearly zero electron to some trapping molecule (here SF6 or CFCl3), and mass detection of the attachment product (SF6/-/ or Cl/-/ respectively). This technique of threshold photoelectron spectroscopy by electron attachment was used to measure the spectra of argon and xenon at 11 meV (FWHM) resolution, and was also applied to CFCl3.

  3. Reconfigurable Pointing Control for High Resolution Space Spectroscopy

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Kia, Tooraj; Van Cleve, Jeffrey

    1997-01-01

    In this paper, a pointing control performance criteria is established to suppport high resolution space spectroscopy. Results indicate that these pointing control requirements are very stringent, and would typically be difficult to meet using standard 3-axis spacecraft control. To resolve this difficulty, it is shown that performance can be significantly improved using a reconfigurable control architecture that switches among a small bankof detuned Kalman filters. The effectiveness of the control reconfiguration approach is demonstrated by example on the Space Infra-Red Telescope Facility (SIRTF) pointing system, in support of the InfraRed Spectrograph (IRS) payload.

  4. Reconfigurable Pointing Control for High Resolution Space Spectroscopy

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Kia, Tooraj; vanCleve, Jeffrey

    1997-01-01

    In this paper, a pointing control performance criteria is established to support high resolution space spectroscopy. Results indicate that these pointing requirements are very stringent, and would typically be difficult to meet using standard 3-axis spacecraft control. To resolve this difficulty, it is shown that performance can be significantly improved using a reconfigurable control architecture that switches among a small bank of detuned Kalman filters. The effectiveness of the control reconfiguration approach is demonstrated by example on the Space Infra, Red Telescope Facility (SIRTF) pointing system, in support of the Infrared Spectrograph (IRS) payload.

  5. Quantum electrodynamics, high-resolution spectroscopy and fundamental constants

    NASA Astrophysics Data System (ADS)

    Karshenboim, Savely G.; Ivanov, Vladimir G.

    2017-01-01

    Recent progress in high-resolution spectroscopy has delivered us a variety of accurate optical results, which can be used for the determination of the atomic fundamental constants and for constraining their possible time variation. We present a brief overview of the results discussing in particular, the determination of the Rydberg constant, the relative atomic weight of the electron and proton, their mass ratio and the fine structure constant. Many individual results on those constants are obtained with use of quantum electrodynamics, and we discuss which sectors of QED are involved. We derive constraints on a possible time variation of the fine structure constants and me/mp.

  6. High resolution ultrasonic spectroscopy system for nondestructive evaluation

    NASA Technical Reports Server (NTRS)

    Chen, C. H.

    1991-01-01

    With increased demand for high resolution ultrasonic evaluation, computer based systems or work stations become essential. The ultrasonic spectroscopy method of nondestructive evaluation (NDE) was used to develop a high resolution ultrasonic inspection system supported by modern signal processing, pattern recognition, and neural network technologies. The basic system which was completed consists of a 386/20 MHz PC (IBM AT compatible), a pulser/receiver, a digital oscilloscope with serial and parallel communications to the computer, an immersion tank with motor control of X-Y axis movement, and the supporting software package, IUNDE, for interactive ultrasonic evaluation. Although the hardware components are commercially available, the software development is entirely original. By integrating signal processing, pattern recognition, maximum entropy spectral analysis, and artificial neural network functions into the system, many NDE tasks can be performed. The high resolution graphics capability provides visualization of complex NDE problems. The phase 3 efforts involve intensive marketing of the software package and collaborative work with industrial sectors.

  7. Metallicity determination of M dwarfs. High-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Lindgren, Sara; Heiter, Ulrike; Seifahrt, Andreas

    2016-02-01

    Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance analysis, standard methods established for warmer solar-like stars, i.e. model-dependent methods using fitting of synthetic spectra, still need to be used. Aims: In this work we continue the reliability confirmation and development of metallicity determinations of M dwarfs using high-resolution infrared spectra. The reliability was confirmed through analysis of M dwarfs in four binary systems with FGK dwarf companions and by comparison with previous optical studies of the FGK dwarfs. Methods: The metallicity determination was based on spectra taken in the J band (1.1-1.4 μm) with the CRIRES spectrograph. In this part of the infrared, the density of stellar molecular lines is limited, reducing the amount of blends with atomic lines enabling an accurate continuum placement. Lines of several atomic species were used to determine the stellar metallicity. Results: All binaries show excellent agreement between the derived metallicity of the M dwarf and its binary companion. Our results are also in good agreement with values found in the literature. Furthermore, we propose an alternative way to determine the effective temperature of M dwarfs of spectral types later than M2 through synthetic spectral fitting of the FeH lines in our observed spectra. Conclusions: We have confirmed that a reliable metallicity determination of M dwarfs can be achieved using high-resolution infrared spectroscopy. We also note that metallicites obtained with photometric metallicity calibrations available for M dwarfs only partly agree with the results we obtain from high-resolution spectroscopy. Based on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID 082.D-0838(A) and 084.D-1042(A).

  8. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

    NASA Astrophysics Data System (ADS)

    Tait, E. W.; Ratcliff, L. E.; Payne, M. C.; Haynes, P. D.; Hine, N. D. M.

    2016-05-01

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable.

  9. The molecular and electronic states of 1,2,4,5-tetrazine studied by VUV absorption, near-threshold electron energy-loss spectroscopy and ab initio multi-reference configuration interaction studies

    NASA Astrophysics Data System (ADS)

    Palmer, Michael H.; McNab, Hamish; Reed, David; Pollacchi, Anne; Walker, Isobel C.; Guest, Martyn F.; Siggel, Michele R. F.

    1997-01-01

    The VUV electronic absorption spectrum of 1,2,4,5-tetrazine has been re-investigated, and together with electron energy-loss spectra has led to identification of a number of new excited states. The valence and Rydberg excited states have been studied by multi-reference multi-root configuration interaction studies using MRDCI techniques. Initial studies with the RPA and TDA methods gave almost identical results for the excitation energies, but there is a substantial energy-lowering in the MRDCI calculations, which improves agreement with experiment substantially; these differences are a result of the double, triple and quadruple excited reference configurations included in the reference set of the latter method. The 1ππ ∗ excitations are calculated rather higher than experiment, except for the lowest-lying (weak) 1B 2u state at 5.0 eV. The calculated order for the next three ππ ∗ states is 1B 1u (weak) followed by 1B 2u (strong) and 1B 1u (strong), the last two bands being responsible for the dominant absorption near 7.5 and 8.5 eV. All of this group of four bands involve excitations from the pair of MOs 1b 2g and 1b 1g into the 1a u∗ and 4b 3u∗ VMOs. The sequence of nπ ∗ stakes are in a similar order to the ππ ∗ excitations, with respect to the upper state, and the two lowest singlet states, 1B 3u and 1A u are reasonably well determined. The triplet states follow a similar order to the singlets, and again the dominance of the effect of the two lowest VMOs is demonstrated, but considerable differences between the weighting of leading configurations occurs between singlet and triplet manifolds. The non-diagonal TDA method has been used to reconsider the UV-photoelectron spectrum. The ionisation potentials for tetrazine are reinterpreted with the first three bands being regrouped into 1, 2, 2 ionisations respectively. The ground state properties of tetrazine suggest that the NQR spectrum will show a principal axis 14N quadrupole coupling constant

  10. Two simple image slicers for high resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Tala, M.; Vanzi, L.; Avila, G.; Guirao, C.; Pecchioli, E.; Zapata, A.; Pieralli, F.

    2017-01-01

    We present the design, manufacturing, test and performance of two image slicers for high resolution spectroscopy. Based on the classical Bowen-Walraven concept, our slicers allow to make two slices of the image of the input fibre. We introduce the idea of a second fibre that can be cropped in half to reach the same width of the science target fibre and that can be used for simultaneous wavelength reference. The slicers presented are mirror and prism based, respectively. Both devices work within expectation, showing differences mainly in their efficiency. The prism based slicer is the solution that was adopted for the FIDEOS spectrograph, an instrument built by the AIUC for the ESO 1m telescope of La Silla. Test spectra obtained with this instrument are included as examples of a real application of the device.

  11. Two simple image slicers for high resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Tala, M.; Vanzi, L.; Avila, G.; Guirao, C.; Pecchioli, E.; Zapata, A.; Pieralli, F.

    2017-04-01

    We present the design, manufacturing, test and performance of two image slicers for high resolution spectroscopy. Based on the classical Bowen-Walraven concept, our slicers allow to make two slices of the image of the input fibre. We introduce the idea of a second fibre that can be cropped in half to reach the same width of the science target fibre and that can be used for simultaneous wavelength reference. The slicers presented are mirror and prism based, respectively. Both devices work within expectation, showing differences mainly in their efficiency. The prism based slicer is the solution that was adopted for the FIDEOS spectrograph, an instrument built by the AIUC for the ESO 1m telescope of La Silla. Test spectra obtained with this instrument are included as examples of a real application of the device.

  12. Recent Results in Quantum Chemical Kinetics from High Resolution Spectroscopy

    SciTech Connect

    Quack, Martin

    2007-12-26

    We outline the approach of our group to derive intramolecular kinetic primary processes from high resolution spectroscopy. We then review recent results on intramolecular vibrational redistribution (IVR) and on tunneling processes. Examples are the quantum dynamics of the C-H-chromophore in organic molecules, hydrogen bond dynamics in (HF){sub 2} and stereomutation dynamics in H{sub 2}O{sub 2} and related chiral molecules. We finally discuss the time scales for these and further processes which range from 10 fs to more than seconds in terms of successive symmetry breakings, leading to the question of nuclear spin symmetry and parity violation as well as the question of CPT symmetry.

  13. Using High Resolution Force Spectroscopy to Study Haemocompatibility

    NASA Astrophysics Data System (ADS)

    Rixman, Monica; Macias, Celia; Dean, Delphine; Ortiz, Christine

    2003-03-01

    A critical determinant of the biocompatibility of implanted blood-contacting devices is the initial noncovalent adsorption of blood plasma proteins onto the biomaterial surface. Using high resolution force spectroscopy, we have measured the intermolecular interaction forces between a probe tip covalently bound with human serum albumin (HSA), the most abundant blood plasma protein in the human body, and various chemically modified surfaces that either already are, or may potentially be, used as biomaterial surface coatings. Statistical analysis and theoretical modeling enable us to interpret our experimental results in terms of electrostatic interactions, hydrogen bonding, and steric forces. We have expanded our initial studies on surfaces of poly(ethylene oxide) to explore a variety of experimental conditions, and then utilized our results in identifying and studying various oligosaccharides, which we hope may be useful in the discovery of novel materials for future biomaterial applications.

  14. High Resolution Absorption Spectroscopy using Externally Dispersed Interferometry

    SciTech Connect

    Edelstein, J; Erskine, D J

    2005-07-06

    We describe the use of Externally Dispersed Interferometry (EDI) for high-resolution absorption spectroscopy. By adding a small fixed-delay interferometer to a dispersive spectrograph, a precise fiducial grid in wavelength is created over the entire spectrograph bandwidth. The fiducial grid interacts with narrow spectral features in the input spectrum to create a moire pattern. EDI uses the moire pattern to obtain new information about the spectra that is otherwise unavailable, thereby improving spectrograph performance. We describe the theory and practice of EDI instruments and demonstrate improvements in the spectral resolution of conventional spectrographs by a factor of 2 to 6. The improvement of spectral resolution offered by EDI can benefit space instruments by reducing spectrograph size or increasing instantaneous bandwidth.

  15. High-Resolution Imaging and Spectroscopy at High Pressure: A Novel Liquid Cell for the TEM

    PubMed Central

    Tanase, Mihaela; Winterstein, Jonathan; Sharma, Renu; Aksyuk, Vladimir; Holland, Glenn; Liddle, J. Alexander

    2016-01-01

    We demonstrate quantitative core-loss electron energy-loss spectroscopy of iron oxide nanoparticles and imaging resolution of Ag nanoparticles in liquid down to 0.24 nm, in both transmission and scanning-transmission modes, in a novel, monolithic liquid cell developed for the transmission electron microscope (TEM). At typical SiN membrane thicknesses of 50 nm the liquid layer thickness has a maximum change of only 30 nm for the entire TEM viewing area of 200 μm × 200 μm. PMID:26650072

  16. High-resolution two-field nuclear magnetic resonance spectroscopy.

    PubMed

    Cousin, Samuel F; Charlier, Cyril; Kadeřávek, Pavel; Marquardsen, Thorsten; Tyburn, Jean-Max; Bovier, Pierre-Alain; Ulzega, Simone; Speck, Thomas; Wilhelm, Dirk; Engelke, Frank; Maas, Werner; Sakellariou, Dimitrios; Bodenhausen, Geoffrey; Pelupessy, Philippe; Ferrage, Fabien

    2016-12-07

    Nuclear magnetic resonance (NMR) is a ubiquitous branch of spectroscopy that can explore matter at the scale of an atom. Significant improvements in sensitivity and resolution have been driven by a steady increase of static magnetic field strengths. However, some properties of nuclei may be more favourable at low magnetic fields. For example, transverse relaxation due to chemical shift anisotropy increases sharply at higher magnetic fields leading to line-broadening and inefficient coherence transfers. Here, we present a two-field NMR spectrometer that permits the application of rf-pulses and acquisition of NMR signals in two magnetic centres. Our prototype operates at 14.1 T and 0.33 T. The main features of this system are demonstrated by novel NMR experiments, in particular a proof-of-concept correlation between zero-quantum coherences at low magnetic field and single quantum coherences at high magnetic field, so that high resolution can be achieved in both dimensions, despite a ca. 10 ppm inhomogeneity of the low-field centre. Two-field NMR spectroscopy offers the possibility to circumvent the limits of high magnetic fields, while benefiting from their exceptional sensitivity and resolution. This approach opens new avenues for NMR above 1 GHz.

  17. High Resolution Rotational Spectroscopy of a Flexible Cyclic Ether

    NASA Astrophysics Data System (ADS)

    Gámez, F.; Martínez-Haya, B.; Blanco, S.; López, J. C.; Alonso, J. L.

    2011-06-01

    Crown ethers stand as one cornerstone molecular class inhost-guest Supramolecular Chemistry and constitute building blocks for a broad range of modern materials. We report here the first high resolution rotational study of a crown ether: 1,4,7,10,13-pentaoxacyclopentadecane (15-crown-5 ether,15c5). Molecular beam Fourier transform microwave spectroscopy has been employed. The liquid sample of 15c5 has been vaporized using heating methods. The considerable size of 15c5 and the broad range of conformations allowed by the flexibility of its backbone pose important challenges to spectroscopy approaches. In fact, the ab-initio computational study for isolated 15c5, yields at least six stable conformers with relative free energies within 2 kJ Mol-1 (167 Cm-1). Nevertheless, in this investigation it has been possible to identify and characterize in detail one stable rotamer of the 15c5 molecule and to challenge different quantum methods for the accurate description of this system. The results pave the ground for an extensive description of the conformational landscape of 15c5 and related cyclic ethers in the near term. J. L. Alonso, F. J. Lorenzo, J. C. López, A. Lesarri, S. Mata and H. Dreizler, Chem. Phys., 218, 267 (1997) S. Blanco, J.C López, J.L. Alonso, P. Ottaviani, W. Caminati, J. Chem. Phys. 119, 880 (2003) S.E. Hill, D. Feller, Int. J. Mass Spectrom. 201, 41 (2000)

  18. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Yu, Xiaoqi; Yang, Tao

    2005-12-01

    A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension position-sensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out (FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown.

  19. Theoretical interpretation of electron energy-loss spectroscopic images

    DOE PAGES

    Allen, L. J.; D'Alfonso, Adrian J.; Findlay, Scott D.; ...

    2008-04-10

    In this paper, we discuss the theory of electron energy-loss spectroscopic images in scanning transmission electron microscopy. Three case studies are presented which have as common themes issues of inelastic scattering, coherence and image interpretation. The first is a state-by-state inelastic transitions analysis of a spectroscopic image which does not admit direct visual interpretation. The second compares theory and experiment for two-dimensional mapping. Finally, the third considers imaging in three dimensions via depth sectioning.

  20. High resolution spectroscopy from ground and space: Introduction

    NASA Astrophysics Data System (ADS)

    Ward, William E.

    In contrast to the broad brush approach often used for the sounding of atmospheric constituents, high resolution spectroscopy is a refined, efficient and often elegant tool which uses small spectral regions to probe specific phenomena. Application areas range from wind and temperature measurements in terrestrial and planetary atmospheres, to magnetic field measurements on the sun. In most cases, subtle changes in line shape or line position are used with a priori information to generate the geophysical information of interest. Use of this technique for space applications started in the 1960's and was a natural extension of the spectroscopic heritage which was started by Fabry and Perot and Michelson over 100 year ago. This field has evolved over the past 50 years in response to refinements in detector technologies, manufacturing techniques and the development of active techniques using lasers. This session will trace the evolution of these techniques over the past half-century and showcase the state-of-the-art today. Within Canada, Gordon Shepherd has played a hand in many of the developments in this technique. This introduction will briefly summarize this field and provide a short historical sketch of Shepherd's contributions as a lead into his keynote review of this topic.

  1. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    SciTech Connect

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  2. High-Resolution Spectroscopy of the Lunar Sodium Exosphere

    NASA Technical Reports Server (NTRS)

    Mierkiewicz, E. J.; Oliversen, R. J.; Roesler, F. L.; Lupie, O. L.

    2014-01-01

    We have applied high-resolution Fabry-Perot spectroscopy to the study of the lunar sodium exosphere for the study of exospheric effective temperature and velocity variations. Observing from the National Solar Observatory McMath-Pierce Telescope, we used a dual-etalon Fabry-Perot spectrometer with a resolving power of 180,000 to measure line widths and Doppler shifts of the sodium D2 (5889.95 Å) emission line. Our field of view was 360 km, and measurements were made in equatorial and polar regions from 500 km to 3500 km off the limb. Data were obtained from full moon to 3 days following full moon (waning phase) in March 2009. Measured Doppler line widths within 1100 km of the sunlit east and south lunar limbs for observations between 5 and 40 deg lunar phase imply effective temperatures ranging between 3260 +/- 190 and 1000 +/- 135 K. Preliminary line center analysis indicates velocity displacements between different locations off the lunar limb ranging between 100 and 600 m/s from the lunar rest velocity with a precision of +/-20 to +/-50 m/s depending on brightness. Based on the success of these exploratory observations, an extensive program has been initiated that is expected to constrain lunar atmospheric and surface-process modeling and help quantify source and escape mechanisms.

  3. Improvement of sensitivity in high-resolution Rutherford backscattering spectroscopy

    SciTech Connect

    Hashimoto, H.; Nakajima, K.; Suzuki, M.; Kimura, K.; Sasakawa, K.

    2011-06-15

    The sensitivity (limit of detection) of high-resolution Rutherford backscattering spectroscopy (HRBS) is mainly determined by the background noise of the spectrometer. There are two major origins of the background noise in HRBS, one is the stray ions scattered from the inner wall of the vacuum chamber of the spectrometer and the other is the dark noise of the microchannel plate (MCP) detector which is commonly used as a focal plane detector of the spectrometer in HRBS. In order to reject the stray ions, several barriers are installed inside the spectrometer and a thin Mylar foil is mounted in front of the detector. The dark noise of the MCP detector is rejected by the coincidence measurement with the secondary electrons emitted from the Mylar foil upon the ion passage. After these improvements, the background noise is reduced by a factor of 200 at a maximum. The detection limit can be improved down to 10 ppm for As in Si at a measurement time of 1 h under ideal conditions.

  4. High-resolution ground-based spectroscopy: where and how ?

    NASA Astrophysics Data System (ADS)

    Pallavicini, R.

    2002-07-01

    An overview is presented of high-resolution optical spectrographs in operation or under development at large telescopes, with emphasis on those facilities best suited for the study of late-type stars and stellar surface inhomogeneities. Plans for the development of new high-resolution spectroscopic instruments are discussed with emphasis on the ICE spectrograph for the PEPSI spectropolarimeter at the LBT.

  5. Immersion Gratings for Infrared High-resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sarugaku, Yuki; Ikeda, Yuji; Kobayashi, Naoto; Kaji, Sayumi; Sukegawa, Takashi; Sugiyama, Shigeru; Nakagawa, Takao; Arasaki, Takayuki; Kondo, Sohei; Nakanishi, Kenshi; Yasui, Chikako; Kawakita, Hideyo

    2016-10-01

    High-resolution spectroscopy in the infrared wavelength range is essential for observations of minor isotopologues, such as HDO for water, and prebiotic organic molecules like hydrocarbons/P-bearing molecules because numerous vibrational molecular bands (including non-polar molecules) are located in this wavelength range. High spectral resolution enables us to detect weak lines without spectral line confusion. This technique has been widely used in planetary sciences, e.g., cometary coma (H2O, CO, and organic molecules), the martian atmosphere (CH4, CO2, H2O and HDO), and the upper atmosphere of gas giants (H3+ and organic molecules such as C2H6). Spectrographs with higher resolution (and higher sensitivity) still have a potential to provide a plenty of findings. However, because the size of spectrographs scales with the spectral resolution, it is difficult to realize it.Immersion grating (IG), which is a diffraction grating wherein the diffraction surface is immersed in a material with a high refractive index (n > 2), provides n times higher spectral resolution compared to a reflective grating of the same size. Because IG reduces the size of spectrograph to 1/n compared to the spectrograph with the same spectral resolution using a conventional reflective grating, it is widely acknowledged as a key optical device to realize compact spectrographs with high spectral resolution.Recently, we succeeded in fabricating a CdZnTe immersion grating with the theoretically predicted diffraction efficiency by machining process using an ultrahigh-precision five-axis processing machine developed by Canon Inc. Using the same technique, we completed a practical germanium (Ge) immersion grating with both a reflection coating on the grating surface and the an AR coating on the entrance surface. It is noteworthy that the wide wavelength range from 2 to 20 um can be covered by the two immersion gratings.In this paper, we present the performances and the applications of the immersion

  6. Direct frequency comb spectroscopy and high-resolution coherent control

    NASA Astrophysics Data System (ADS)

    Stowe, Matthew C.

    We present the first experiments demonstrating absolute frequency measurements of one- and two-photon transitions using direct frequency comb spectroscopy (DFCS). In particular we phase stabilized the inter-pulse period and optical phases of the pulses emitted from a mode-locked Ti:Sapphire laser, creating a broad-bandwidth optical frequency comb. By referencing the optical comb directly to the cesium microwave frequency standard, we were able to measure absolute transition frequencies over greater than a 50 nm bandwidth, utilizing the phase coherence between wavelengths spanning from 741 nm to 795 nm. As an initial demonstration of DFCS we studied transitions from the 5S to 5P, 5D, and 7S states in Rb. To reduce Doppler broadening the atoms were laser cooled in a magneto-optical trap. We present an overview of several systematic error sources that perturb the natural transition frequencies, magnitudes, and linewidths. These include radiation pressure from the probe beam, AC-Stark shifts, Zeeman shifts, power-broadening, and incoherent optical pumping. After careful study and suppression of these systematic error sources, we measured transition linewidths as narrow as 1.1 MHz FWHM and 10 kHz linecenter uncertainties. Our measurements of the 5S to 7S two-photon transition frequency demonstrated the ability to determine the comb mode order numbers when the initial transition frequency is not known to better than the comb mode frequency spacing. By modifying the spectral phase of the pulses we demonstrated high-resolution coherent control. Our first coherent control experiment utilized a grating based pulse stretcher/compressor to apply a large chirp to the pulses. We measured the two-photon transition rate as a function of linear frequency chirp. The results illustrate the differences between similar classic coherent experiments done with a single femtosecond pulse and ours conducted with multiple pulses. Furthermore, we show that it is possible to reduce the two

  7. Electron energy-loss spectroscopic tomography of FexCo(3-x)O4 impregnated Co3O4 mesoporous particles: unraveling the chemical information in three dimensions.

    PubMed

    Yedra, L; Eljarrat, A; Arenal, R; López-Conesa, L; Pellicer, E; López-Ortega, A; Estrader, M; Sort, J; Baró, M D; Estradé, S; Peiró, F

    2016-08-02

    Electron energy-loss spectroscopy-spectrum image (EELS-SI) tomography is a powerful tool to investigate the three dimensional chemical configuration in nanostructures. Here, we demonstrate, for the first time, the possibility to characterize the spatial distribution of Fe and Co cations in a complex FexCo(3-x)O4/Co3O4 ordered mesoporous system. This hybrid material is relevant because of the ferrimagnetic/antiferromagnetic coupling and high surface area. We unambiguously prove that the EELS-SI tomography shows a sufficiently high resolution to simultaneously unravel the pore structure and the chemical signal.

  8. Multiple scattering calculations of relativistic electron energy loss spectra

    NASA Astrophysics Data System (ADS)

    Jorissen, K.; Rehr, J. J.; Verbeeck, J.

    2010-04-01

    A generalization of the real-space Green’s-function approach is presented for ab initio calculations of relativistic electron energy loss spectra (EELS) which are particularly important in anisotropic materials. The approach incorporates relativistic effects in terms of the transition tensor within the dipole-selection rule. In particular, the method accounts for relativistic corrections to the magic angle in orientation resolved EELS experiments. The approach is validated by a study of the graphite CK edge, for which we present an accurate magic angle measurement consistent with the predicted value.

  9. An electron energy-loss study of picene and chrysene based charge transfer salts

    SciTech Connect

    Müller, Eric; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2015-05-14

    The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F{sub 4}TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.

  10. High Resolution Coherent Three-Dimensional Spectroscopy of Iodine

    NASA Astrophysics Data System (ADS)

    House, Zuri R.; Wells, Thresa A.; Chen, Peter C.; Strangfeld, Benjamin R.

    2013-06-01

    The heavy congestion found in many one-dimensional spectra can make it difficult to study many transitions. A new coherent three-dimensional spectroscopic technique has been developed to eliminate the kind of congestion commonly seen in high resolution electronic spectra. The molecule used for this test was Iodine. A well-characterized transition (X to B) was used to determine which four wave mixing process or processes were responsible for the peaks in the resulting multidimensional spectrum. The resolution of several peaks that overlap in a coherent 2D spectrum can be accomplished by using a higher dimensional (3D) spectroscopic method. This talk will discuss strategies for finding spectroscopic constants using this high resolution coherent 3D spectroscopic method.

  11. Microcoil high-resolution magic angle spinning NMR spectroscopy.

    PubMed

    Janssen, Hans; Brinkmann, Andreas; van Eck, Ernst R H; van Bentum, P Jan M; Kentgens, Arno P M

    2006-07-12

    We report the construction of a dual-channel microcoil nuclear magnetic resonance probehead allowing magic-angle spinning for mass-limited samples. With coils down to 235 mum inner diameter, this allows high-resolution solid-state NMR spectra to be obtained for amounts of materials of a few nanoliters. This is demonstrated by the carbon-13 spectrum of a tripeptide and a single silk rod, prepared from the silk gland of the Bombyx mori silkworm. Furthermore, the microcoil allows for radio frequency field strengths well beyond current probe technology, aiding in getting the highest possible resolution by efficiently decoupling the observed nuclei from the abundantly present proton nuclei.

  12. High-Resolution Infrared Spectroscopy of Ge_2C_3

    NASA Astrophysics Data System (ADS)

    Thorwirth, S.; Lutter, V.; Schlemmer, S.; Giesen, T. F.; Gauss, J.

    2013-06-01

    Carbon-rich systems are of great importance in diverse areas of research like material science as well as astro- and structural chemistry. Despite this relevance, our knowledge of smaller cluster units is still fragmentary, particularly with respect to investigations at high-spectral resolution in the gas phase. Unequivocal assignment of spectral features to their molecular carriers is critically dependent on predictions from high-level quantum-chemical calculations. In turn, high-resolution studies provide useful information to assess the predictive power of quantum-chemical methods. This is particularly interesting for cluster systems harboring heavy elements for which so far relatively little is known from experiment. With this contribution, we would like to present a recent gas-phase study of a polyatomic germanium-carbon cluster, linear Ge_2C_3 (Ge=C=C=C=Ge), which was previously studied in an Ar matrix. The cluster was produced through laser ablation of germanium-graphite sample rods and observed in a free jet at wavelengths around 5μm. Additionally, quantum-chemical calculations of Ge_2C_3 were performed at the CCSD(T) level of theory. The production and observation of Ge_2C_3 suggests that many more binary clusters should be amenable to high-resolution spectroscopic techniques not only in the infrared but also in the microwave region. D. L. Robbins, C. M. L. Rittby, and W. R. M. Graham, J. Chem. Phys. 114, 3570 (2001).

  13. High resolution spectroscopy from low altitude satellites. [gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Nakano, G. H.; Imhof, W. L.

    1978-01-01

    The P 78 1 satellite to be placed in a synchronous polar orbit at an altitude of 550-660 km will carry two identical high resolution spectrometers each consisting of a single (approximately 85 cc) intrinsic germanium IGE detector. The payload also includes a pair of phoswitch scintillators, an array of CdTe detectors and several particle detectors, all of which are mounted on the wheel of the satellite. The intrinsic high purity IGE detectors receive cooling from two Stirling cycle refrigerators and facilitate the assembly of large and complex detector arrays planned for the next generation of high sensitivity instruments such as those planned for the gamma ray observatory. The major subsystems of the spectrometer are discussed as well as its capabilities.

  14. CARMENES science preparation. High-resolution spectroscopy of M dwarfs

    NASA Astrophysics Data System (ADS)

    Montes, D.; Caballero, J. A.; Jeffers, S.; Alonso-Floriano, F. J.; Mundt, R.; CARMENES Consortium

    2015-05-01

    To ensure an efficient use of CARMENES observing time, and the highest chances of success, it is necessary first to select the most promising targets. To achieve this, we are observing 500 M dwarfs at high-resolution (R = 30,000-48,000), from which we determine the projected rotational velocity vsin{i} with an accuracy better than 0.5-0.2 km/s and radial-velocity stability better than 0.2-0.1 km/s. Our aim is to have at least two spectra at different epochs of the final 300 CARMENES targets. Our observations with FEROS at ESO/MPG 2.2 m La Silla, CAFE at 2.2 m Calar Alto and HRS at Hobby Eberly Telescope allow us to identify single- and double-line spectroscopic binaries and, especially, fast rotators, which should be discarded from the target list for exoplanet searches. Here we present preliminary results.

  15. High-resolution spectroscopy of a giant solar filament

    NASA Astrophysics Data System (ADS)

    Kuckein, Christoph; Denker, Carsten; Verma, Meetu

    2014-01-01

    High-resolution spectra of a giant solar quiescent filament were taken with the Echelle spectrograph at the Vacuum Tower Telescope (VTT; Tenerife, Spain). A mosaic of various spectroheliograms (Hα, Hα+/-0.5 Å and Na D2) were chosen to examine the filament at different heights in the solar atmosphere. In addition, full-disk images (He i 10830 Å and Ca ii K) of the Chromspheric Telescope and full-disk magnetograms of the Helioseismic and Magnetic Imager were used to complement the spectra. Preliminary results are shown of this filament, which had extremely large linear dimensions (~740'') and was observed in November 2011 while it traversed the northern solar hemisphere.

  16. Quadrature phase interferometer for high resolution force spectroscopy

    SciTech Connect

    Paolino, Pierdomenico; Aguilar Sandoval, Felipe A.; Bellon, Ludovic

    2013-09-15

    In this article, we present a deflection measurement setup for Atomic Force Microscopy (AFM). It is based on a quadrature phase differential interferometer: we measure the optical path difference between a laser beam reflecting above the cantilever tip and a reference beam reflecting on the static base of the sensor. A design with very low environmental susceptibility and another allowing calibrated measurements on a wide spectral range are described. Both enable a very high resolution (down to 2.5×10{sup −15} m/√(Hz)), illustrated by thermal noise measurements on AFM cantilevers. They present an excellent long-term stability and a constant sensitivity independent of the optical phase of the interferometer. A quick review shows that our precision is equaling or out-performing the best results reported in the literature, but for a much larger deflection range, up to a few μm.

  17. High-Resolution Absorption Spectroscopy of NO2

    DTIC Science & Technology

    1987-08-31

    identify by block number) FIELD GROUP SUB-GROUP Atmospheric propagation, Laser spectroscopy, Nitrogen dioxide , Spectroscopy 19. RACT (Continue on reverse if...pulsed dye laser having a 0.05-A"-bandwidth (FWHM). This represents an improvement of at least a factor of three over the resolution employed in...concise interpretation of the observed features has yet to be made. Actual state-to-state assignments in the visible and near UV have been possible only

  18. Understanding reconstructed Dante spectra using high resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    May, M. J.; Weaver, J.; Widmann, K.; Kemp, G. E.; Thorn, D.; Colvin, J. D.; Schneider, M. B.; Moore, A.; Blue, B. E.

    2016-11-01

    The Dante is an 18 channel filtered diode array used at the National Ignition Facility (NIF) to measure the spectrally and temporally resolved radiation flux between 50 eV and 20 keV from various targets. The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and a reconstruction algorithm applied to the recorded voltages from each channel. The reconstructed spectra are very low resolution with features consistent with the instrument response and are not necessarily consistent with the spectral emission features from the plasma. Errors may exist between the reconstructed spectra and the actual emission features due to assumptions in the algorithm. Recently, a high resolution convex crystal spectrometer, VIRGIL, has been installed at NIF with the same line of sight as the Dante. Spectra from L-shell Ag and Xe have been recorded by both VIRGIL and Dante. Comparisons of these two spectroscopic measurements yield insights into the accuracy of the Dante reconstructions.

  19. High Resolution γ-Ray Spectroscopy: the First 85 Years

    PubMed Central

    Deslattes, Richard D.

    2000-01-01

    This opening review attempts to follow the main trends in crystal diffraction spectrometry of nuclear γ rays from its 1914 beginning in Rutherford’s laboratory to the ultra-high resolution instrumentation realized in the current generation of spectrometers at the Institute Laue Langeven (ILL). My perspective is that of an instrumentalist hoping to convey a sense of our intellectual debt to a number of predecessors, each of whom realized a certain elegance in making the tools that have enabled much good science, including that to which the remainder of this workshop is dedicated. This overview follows some of the main ideas along a trajectory toward higher resolution at higher energies, thereby enabling not only the disentangling of dense spectra, but also allowing detailed study of aspects of spectral profiles sensitive to excited state lifetimes and inter-atomic potentials. The parallel evolution toward increasing efficiency while preserving needed resolution is also an interesting story of artful compromise that should not be neglected. Finally, it is the robustness of the measurement chain connecting γ-ray wavelengths with optical wavelengths associated with the Rydberg constant that only recently has allowed γ-ray data to contribute to determination of particle masses and fundamental constants, as will be described in more detail in other papers from this workshop. PMID:27551582

  20. High Resolution FIR and IR Spectroscopy of Methanol Isotopologues

    SciTech Connect

    Lees, R. M.; Xu, Li-Hong; Appadoo, D. R. T.; Billinghurst, B.

    2010-02-03

    New astronomical facilities such as HIFI on the Herschel Space Observatory, the SOFIA airborne IR telescope and the ALMA sub-mm telescope array will yield spectra from interstellar and protostellar sources with vastly increased sensitivity and frequency coverage. This creates the need for major enhancements to laboratory databases for the more prominent interstellar 'weed' species in order to model and account for their lines in observed spectra in the search for new and more exotic interstellar molecular 'flowers'. With its large-amplitude internal torsional motion, methanol has particularly rich spectra throughout the FIR and IR regions and, being very widely distributed throughout the galaxy, is perhaps the most notorious interstellar weed. Thus, we have recorded new spectra for a variety of methanol isotopic species on the high-resolution FTIR spectrometer on the CLS FIR beamline. The aim is to extend quantum number coverage of the data, improve our understanding of the energy level structure, and provide the astronomical community with better databases and models of the spectral patterns with greater predictive power for a range of astrophysical conditions.

  1. Understanding reconstructed Dante spectra using high resolution spectroscopy.

    PubMed

    May, M J; Weaver, J; Widmann, K; Kemp, G E; Thorn, D; Colvin, J D; Schneider, M B; Moore, A; Blue, B E

    2016-11-01

    The Dante is an 18 channel filtered diode array used at the National Ignition Facility (NIF) to measure the spectrally and temporally resolved radiation flux between 50 eV and 20 keV from various targets. The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and a reconstruction algorithm applied to the recorded voltages from each channel. The reconstructed spectra are very low resolution with features consistent with the instrument response and are not necessarily consistent with the spectral emission features from the plasma. Errors may exist between the reconstructed spectra and the actual emission features due to assumptions in the algorithm. Recently, a high resolution convex crystal spectrometer, VIRGIL, has been installed at NIF with the same line of sight as the Dante. Spectra from L-shell Ag and Xe have been recorded by both VIRGIL and Dante. Comparisons of these two spectroscopic measurements yield insights into the accuracy of the Dante reconstructions.

  2. High resolution infrared spectroscopy of [1.1.1]propellane

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Robynne; Masiello, Tony; Jariyasopit, Narumol; Weber, Alfons; Nibler, Joseph W.; Maki, Arthur; Blake, Thomas A.; Hubler, Timothy

    2008-04-01

    The infrared spectrum of [1.1.1]propellane has been recorded at high resolution (0.002 cm -1) with individual rovibrational lines resolved for the first time. This initial report presents the ground state constants for this molecule determined from the analysis of five of the eight infrared-allowed fundamentals ν9(e'), ν10(e'), ν12(e'), ν14(a2″),ν15(a2″), as well as of several combination bands. In nearly all cases it was found that the upper states of the transitions exhibit some degree of perturbation but, by use of the combination difference method, the assigned frequencies provided over 4000 consistent ground state difference values. Analysis of these gave for the parameters of the ground state the following values, in cm -1: B0 = 0.28755833(14), DJ = 1.1313(5) × 10 -7, DJK = -1.2633(7) × 10 -7, HJ = 0.72(4) × 10 -13, HJK = -2.24(13) × 10 -13, and HKJ = 2.25(15) × 10 -13, where the numbers in parentheses indicate twice the uncertainties in the last quoted digit(s) of the parameters. Gaussian ab initio calculations, especially with the computed anharmonic corrections to some of the spectroscopic parameters, assisted in the assignments of the bands and also provided information on the electron distribution in the bridge-head carbon-carbon bond.

  3. High-Resolution Laser Spectroscopy on the Negative Osmium Ion

    SciTech Connect

    Warring, U.; Amoretti, M.; Canali, C.; Fischer, A.; Heyne, R.; Meier, J. O.; Morhard, Ch.; Kellerbauer, A.

    2009-01-30

    We have applied a combination of laser excitation and electric-field detachment to negative atomic ions for the first time, resulting in an enhancement of the excited-state detection efficiency for spectroscopy by at least 2 orders of magnitude. Applying the new method, a measurement of the bound-bound electric-dipole transition frequency in {sup 192}Os{sup -} was performed using collinear spectroscopy with a narrow-bandwidth cw laser. The transition frequency was found to be 257.831 190(35) THz [wavelength 1162.747 06(16) nm, wave number 8600.3227(12) cm{sup -1}], in agreement with the only prior measurement, but with more than 100-fold higher precision.

  4. Giant quiescent solar filament observed with high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Kuckein, C.; Verma, M.; Denker, C.

    2016-05-01

    Aims: An extremely large filament was studied in various layers of the solar atmosphere. The inferred physical parameters and the morphological aspects are compared with smaller quiescent filaments. Methods: A giant quiet-Sun filament was observed with the high-resolution Echelle spectrograph at the Vacuum Tower Telescope at Observatorio del Teide, Tenerife, Spain, on 2011 November 15. A mosaic of spectra (ten maps of 100″ × 182″) was recorded simultaneously in the chromospheric absorption lines Hα and Na i D2. Physical parameters of the filament plasma were derived using cloud model (CM) inversions and line core fits. The spectra were complemented with full-disk filtergrams (He i λ10830 Å, Hα, and Ca ii K) of the Chromospheric Telescope (ChroTel) and full-disk magnetograms of the Helioseismic and Magnetic Imager (HMI). Results: The filament had extremely large linear dimensions (~817 arcsec), which corresponds to about 658 Mm along a great circle on the solar surface. A total amount of 175119 Hα contrast profiles were inverted using the CM approach. The inferred mean line-of-sight (LOS) velocity, Doppler width, and source function were similar to previous works of smaller quiescent filaments. However, the derived optical thickness was higher. LOS velocity trends inferred from the Hα line core fits were in accord but weaker than those obtained with CM inversions. Signatures of counter-streaming flows were detected in the filament. The largest brightening conglomerates in the line core of Na i D2 coincided well with small-scale magnetic fields as seen by HMI. Mixed magnetic polarities were detected close to the ends of barbs. The computation of photospheric horizontal flows based on HMI magnetograms revealed flow kernels with a size of 5-8 Mm and velocities of 0.30-0.45 km s-1 at the ends of the filament. Conclusions: The physical properties of extremely large filaments are similar to their smaller counterparts, except for the optical thickness, which in

  5. High-resolution spectroscopy with a femtosecond laser frequency comb.

    PubMed

    Gerginov, V; Tanner, C E; Diddams, S A; Bartels, A; Hollberg, L

    2005-07-01

    The output of a mode-locked femtosecond laser is used for precision single-photon spectroscopy of 133Cs in an atomic beam. By changing the laser's repetition rate, the cesium D1 (6s 2S(1/2)-->6p 2P(1/2)) and D2 (6s 2S(1/2)-->6p 2P(3/2)) transitions are detected and the optical frequencies are measured with accuracy similar to that obtained with a cw laser. Control of the femtosecond laser repetition rate by use of the atomic fluorescence is also implemented, thus realizing a simple cesium optical clock.

  6. Molecular Chirality: Enantiomer Differentiation by High-Resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hirota, Eizi

    2014-06-01

    I have demonstrated that triple resonance performed on a three-rotational-level system of a chiral molecule of C1 symmetry exhibits signals opposite in phase for different enantiomers, thereby making enantiomer differentiation possible by microwave spectroscopy This prediction was realized by Patterson et al. on 1,2-propanediol and 1,3-butanediol. We thus now add a powerful method: microwave spectroscopy to the study of chiral molecules, for which hitherto only the measurement of optical rotation has been employed. Although microwave spectroscopy is applied to molecules in the gaseous phase, it is unprecedentedly superior to the traditional method: polarimeter in resolution, accuracy, sensitivity, and so on, and I anticipate a new fascinating research area to be opened in the field of molecular chirality. More versatile and efficient systems should be invented and developed for microwave spectroscopy, in order to cope well with new applications expected for this method For C2 and Cn (n ≥ 3)chiral molecules, the three-rotational-level systems treated above for C1 molecules are no more available within one vibronic state. It should, however, be pointed out that, if we take into account an excited vibronic state in addition to the ground state, for example, we may encounter many three-level systems. Namely, either one rotational transition in the ground state is combined with two vibronic transitions, or such a rotational transition in an excited state may be connected through two vibronic transitions to a rotational level in the ground state manifold. The racemization obviously plays a crucial role in the study of molecular chirality. However, like many other terms employed in chemistry, this important process has been "defined" only in a vague way, in other words, it includes many kinds of processes, which are not well classified on a molecular basis. I shall mention an attempt to obviate these shortcomings in the definition of racemization and also to clarify the

  7. High-resolution waveguide THz spectroscopy of biological molecules.

    PubMed

    Laman, N; Harsha, S Sree; Grischkowsky, D; Melinger, Joseph S

    2008-02-01

    Low-frequency vibrational modes of biological molecules consist of intramolecular modes, which are dependent on the molecule as a whole, as well as intermolecular modes, which arise from hydrogen-bonding interactions and van der Waals forces. Vibrational modes thus contain important information about conformation dynamics of biological molecules, and can also be used for identification purposes. However, conventional Fourier transform infrared spectroscopy and terahertz time-domain spectroscopy (THz-TDS) often result in broad, overlapping features that are difficult to distinguish. The technique of waveguide THz-TDS has been recently developed, resulting in sharper features. For this technique, an ordered polycrystalline film of the molecule is formed on a metal sample plate. This plate is incorporated into a metal parallel-plate waveguide and probed via waveguide THz-TDS. The planar order of the film reduces the inhomogeneous broadening, and cooling of the samples to 77K reduces the homogenous broadening. This combination results in the line-narrowing of THz vibrational modes, in some cases to an unprecedented degree. Here, this technique has been demonstrated with seven small biological molecules, thymine, deoxycytidine, adenosine, D-glucose, tryptophan, glycine, and L-alanine. The successful demonstration of this technique shows the possibilities and promise for future studies of internal vibrational modes of large biological molecules.

  8. High resolution ion Doppler spectroscopy at Prairie View Rotamak

    SciTech Connect

    Houshmandyar, Saeid; Yang Xiaokang; Magee, Richard

    2012-10-15

    A fast ion Doppler spectroscopy (IDS) diagnostic system is installed on the Prairie View Rotamak to measure ion temperature and plasma flow. The diagnostic employs a single channel photomultiplier tube and a Jarrell-Ash 50 monochromator with a diffraction grating line density of 1180 lines/mm, which allows for first order spectra of 200-600 nm. The motorized gear of the monochromator allows spectral resolution of 0.01 nm. Equal IDS measurements are observed for various impurity emission lines of which carbon lines exhibit stronger intensities. Furthermore, the diagnostics is examined in an experiment where plasma experiences sudden disruption and quick recovery. In this case, the IDS measurements show {approx}130% increase in ion temperature. Flow measurements are shown to be consistent with plasma rotation.

  9. High resolution charge spectroscopy of heavy ions with FNTD technology

    NASA Astrophysics Data System (ADS)

    Bartz, J. A.; Kodaira, S.; Kurano, M.; Yasuda, N.; Akselrod, M. S.

    2014-09-01

    This paper is focused on the improvement of the heavy charge particle charge resolution of Fluorescent Nuclear Track Detector (FNTD) technology. Fluorescent intensity of individual heavy charge particle tracks is used to construct the spectrum. Sources of spectroscopic line broadening were investigated and several fluorescent intensity correction procedures were introduced to improve the charge resolution down to δZ = 0.25 c.u. and enable FNTD technology to distinguish between all projectile fragments of 290 MeV carbon ions. The benefits of using FNTD technology for fragmentation study include large dynamic range and wide angular acceptance. While we describe these developments in the context of fragmentation studies, the same techniques are readily extended to FNTD LET spectroscopy in general.

  10. High resolution spectroscopy reveals fibrillation inhibition pathways of insulin

    NASA Astrophysics Data System (ADS)

    Deckert-Gaudig, Tanja; Deckert, Volker

    2016-12-01

    Fibril formation implies the conversion of a protein’s native secondary structure and is associated with several neurodegenerative diseases. A better understanding of fibrillation inhibition and fibril dissection requires nanoscale molecular characterization of amyloid structures involved. Tip-enhanced Raman scattering (TERS) has already been used to chemically analyze amyloid fibrils on a sub-protein unit basis. Here, TERS in combination with atomic force microscopy (AFM), and conventional Raman spectroscopy characterizes insulin assemblies generated during inhibition and dissection experiments in the presence of benzonitrile, dimethylsulfoxide, quercetin, and β-carotene. The AFM topography indicates formation of filamentous or bead-like insulin self-assemblies. Information on the secondary structure of bulk samples and of single aggregates is obtained from standard Raman and TERS measurements. In particular the high spatial resolution of TERS reveals the surface conformations associated with the specific agents. The insulin aggregates formed under different inhibition and dissection conditions can show a similar morphology but differ in their β-sheet structure content. This suggests different aggregation pathways where the prevention of the β-sheet stacking of the peptide chains plays a major role. The presented approach is not limited to amyloid-related reasearch but can be readily applied to systems requiring extremely surface-sensitive characterization without the need of labels.

  11. High resolution spectroscopy reveals fibrillation inhibition pathways of insulin

    PubMed Central

    Deckert-Gaudig, Tanja; Deckert, Volker

    2016-01-01

    Fibril formation implies the conversion of a protein’s native secondary structure and is associated with several neurodegenerative diseases. A better understanding of fibrillation inhibition and fibril dissection requires nanoscale molecular characterization of amyloid structures involved. Tip-enhanced Raman scattering (TERS) has already been used to chemically analyze amyloid fibrils on a sub-protein unit basis. Here, TERS in combination with atomic force microscopy (AFM), and conventional Raman spectroscopy characterizes insulin assemblies generated during inhibition and dissection experiments in the presence of benzonitrile, dimethylsulfoxide, quercetin, and β-carotene. The AFM topography indicates formation of filamentous or bead-like insulin self-assemblies. Information on the secondary structure of bulk samples and of single aggregates is obtained from standard Raman and TERS measurements. In particular the high spatial resolution of TERS reveals the surface conformations associated with the specific agents. The insulin aggregates formed under different inhibition and dissection conditions can show a similar morphology but differ in their β-sheet structure content. This suggests different aggregation pathways where the prevention of the β-sheet stacking of the peptide chains plays a major role. The presented approach is not limited to amyloid-related reasearch but can be readily applied to systems requiring extremely surface-sensitive characterization without the need of labels. PMID:28008970

  12. High resolution FTIR spectroscopy of the ClO radical

    NASA Technical Reports Server (NTRS)

    Lang, Valerie; Sander, Stanley P.; Friedl, Randy

    1988-01-01

    The chlorine monoxide radical, ClO, plays a significant role in the catalytic destruction of ozone in the Earth's stratosphere. Because of its atmospheric importance, ClO has been the subject of numerous observational attempts. In order to deduce ClO concentrations from stratospheric infrared measurements, the infrared spectroscopy of ClO must be well characterized. Approximately 830 individual lines were measured form ClO imfrared spectra with the ClO concentration between 1 x 10 to the 13th power and 6 x 10 to the 13th power molecules per cu cu. The lines were then averaged and fit to a function of m (where m = O, -J or J+1 for the Q,P and R branches respectively) to obtain the band strength, S sub v and the first Herman-Wallis coefficient, alpha. The total S sub v for the two main isotopmers was 13.11 plus or minus 1 cm(-2) atm(-1) while alpha was 0.00412 plus or minus .00062.

  13. Ultra high resolution molecular beam cars spectroscopy with application to planetary atmospheric molecules

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1982-01-01

    The measurement of high resolution pulsed and continuous wave (CW) coherent anti-Stokes Raman spectroscopy (CARS) measurements in pulsed and steady state supersonic expansions were demonstrated. Pulsed molecular beam sources were characterized, and saturation of a Raman transition and, for the first time, the Raman spectrum of a complex molecular cluster were observed. The observation of CW CARS spectra in a molecular expansion and the effects of transit time broadening is described. Supersonic expansion is established as a viable technique for high resolution Raman spectroscopy of cold molecules with resolutions of 100 MH2.

  14. High-Resolution Solid-State NMR Spectroscopy: Characterization of Polymorphism in Cimetidine, a Pharmaceutical Compound

    ERIC Educational Resources Information Center

    Pacilio, Julia E.; Tokarski, John T.; Quiñones, Rosalynn; Iuliucci, Robbie J.

    2014-01-01

    High-resolution solid-state NMR (SSNMR) spectroscopy has many advantages as a tool to characterize solid-phase material that finds applications in polymer chemistry, nanotechnology, materials science, biomolecular structure determination, and others, including the pharmaceutical industry. The technology associated with achieving high resolution…

  15. High-resolution mirror temperature mapping in GaN-based diode lasers by thermoreflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Pierścińska, Dorota; Marona, Łucja; Pierściński, Kamil; Wiśniewski, Przemysław; Perlin, Piotr; Bugajski, Maciej

    2017-02-01

    In this paper accurate measurements of temperature distribution on the facet of GaN-based diode lasers are presented as well as development of the instrumentation for high-resolution thermal imaging based on thermoreflectance. It is shown that thermoreflectance can be successfully applied to provide information on heat dissipation in these devices. We demonstrate the quantitative measurements of the temperature profiles and high-resolution temperature maps on the front facet of nitride lasers and prove that thermoreflectance spectroscopy can be considered as the accurate and fast nondestructive tool for investigation of thermally induced degradation modes of GaN lasers.

  16. Very high resolution UV and X-ray spectroscopy and imagery of solar active regions

    NASA Technical Reports Server (NTRS)

    Bruner, M.; Brown, W. A.; Haisch, B. M.

    1987-01-01

    A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft X-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the X-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical X-ray observations using this new technique.

  17. Experimental setup for high resolution x-ray spectroscopy of solids and liquid samples

    NASA Astrophysics Data System (ADS)

    Yin, Zhong; Rajković, Ivan; Raiser, Dirk; Scholz, Mirko; Techert, Simone

    2013-09-01

    Here we present a next-generation experimental setup for high-resolution X-ray spectroscopy of solid and liquid samples in the soft X-ray region to elucidate the complex molecular structures of (bio)chemical systems. The setup consists of a main target chamber, a target holder for either solid samples or a liquid jet delivery system, and a high-resolution soft X-ray grating spectrometer. This setup is in commissioning at PETRA III, presently one of the most brilliant storage ring based X-ray radiation sources in the world. The newly designed grazing incidence grating spectrometer is utilized for high-resolution measurement in the XUV range from 1 nm up to 6 nm.

  18. High-resolution inverse Raman and resonant-wave-mixing spectroscopy

    SciTech Connect

    Rahn, L.A.

    1993-12-01

    These research activities consist of high-resolution inverse Raman spectroscopy (IRS) and resonant wave-mixing spectroscopy to support the development of nonlinear-optical techniques for temperature and concentration measurements in combustion research. Objectives of this work include development of spectral models of important molecular species needed to perform coherent anti-Stokes Raman spectroscopy (CARS) measurements and the investigation of new nonlinear-optical processes as potential diagnostic techniques. Some of the techniques being investigated include frequency-degenerate and nearly frequency-degenerate resonant four-wave-mixing (DFWM and NDFWM), and resonant multi-wave mixing (RMWM).

  19. The role of electronic energy loss in ion beam modification of materials

    DOE PAGES

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; ...

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less

  20. The role of electronic energy loss in ion beam modification of materials

    SciTech Connect

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.

  1. Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

    SciTech Connect

    Hall,G.E.; Sears, T.J.

    2009-04-03

    This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. High-resolution spectroscopy, augmented by theoretical and computational methods, is used to investigate the structure and collision dynamics of chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry. Applications and methods development are equally important experimental components of this work.

  2. High-resolution extreme-ultraviolet spectroscopy of potassium using anti-Stokes radiation

    NASA Technical Reports Server (NTRS)

    Rothenberg, J. E.; Young, J. F.; Harris, S. E.

    1981-01-01

    The use of a new extreme-ultraviolet radiation source based on spontaneous anti-Stokes scattering for high-resolution absorption spectroscopy of transition originating from the 3p6 shell of potassium is reported. The region from 546.6 to 536.8 A is scanned at a resolution of about 1.2 Kayser. Within this region, four previously unreported lines are observed.

  3. Update of High Resolution (e,e'K^+) Hypernuclear Spectroscopy at Jefferson Lab's Hall A

    SciTech Connect

    Cusanno, F; Bydzovsky, P; Chang, C C; Cisbani, E; De Jager, C W; De Leo, R; Frullani, S; Garibaldi, F; Higinbotham, D W; Iodice, M; LeRose, J J; Markowitz, P; Marrone, S; Sotona, M; Urciuoli, G M

    2010-03-01

    Updated results of the experiment E94-107 hypernuclear spectroscopy in Hall A of the Thomas Jefferson National Accelerator Facility (Jefferson Lab), are presented. The experiment provides high resolution spectra of excitation energy for 12B_\\Lambda, 16N_\\Lambda, and 9Li_\\Lambda hypernuclei obtained by electroproduction of strangeness. A new theoretical calculation for 12B_\\Lambda, final results for 16N_\\Lambda, and discussion of the preliminary results of 9Li_\\Lambda are reported.

  4. High resolution optical spectroscopy of air-induced electrical instabilities in n-type polymer semiconductors.

    PubMed

    Di Pietro, Riccardo; Sirringhaus, Henning

    2012-07-03

    We use high-resolution charge-accumulation optical spectroscopy to measure charge accumulation in the channel of an n-type organic field-effect transistor. We monitor the degradation of device performance in air, correlate the onset voltage shift with the reduction of charge accumulated in the polymer semiconductor, and explain the results in view of the redox reaction between the polymer, water and oxygen in the accumulation layer.

  5. Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

    SciTech Connect

    Hall, G.E.

    2011-05-31

    This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection with theory, as well as specific molecular properties.

  6. Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

    SciTech Connect

    Hall G. E.; Goncharov, V.

    2012-05-29

    This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection with theory, as well as specific molecular properties.

  7. Elimination of the Vacuum Pump Requirement for High-Resolution Rotational Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Holt, Jennifer; Daly, Ryan W.; Neese, Christopher F.; De Lucia, Frank C.

    2015-06-01

    It has been observed that with the advances being driven by the wireless communications industry, the microwave components for submillimeter wave spectrometers and sensors will become almost "free". Moreover, these electronic components will require little power. However, neither of these attributes applies to the vacuum requirements for high-resolution rotational spectroscopy. We will report on the design, construction, and operation of a simple spectroscopic cell that overcomes these problems.

  8. Beamline 9.0.1 - a high-resolution undulator beamline for gas-phase spectroscopy

    SciTech Connect

    Bozek, J.D.; Heimann, P.A.; Mossessian, D.

    1997-04-01

    Beamline 9.0.1 at the Advanced Light Source is an undulator beamline with a Spherical Grating Monochromator (SGM) which provides very high resolution and flux over the photon energy range 20-320eV. The beamline has been used primarily by the atomic and molecular science community to conduct spectroscopy experiments using electron, ion and fluorescence photon detection. A description of the beamline and its performance will be provided in this abstract.

  9. High Resolution Velocity Map Imaging Photoelectron Spectroscopy of the Beryllium Oxide Anion, BeO-

    NASA Astrophysics Data System (ADS)

    Dermer, Amanda Reed; Mascaritolo, Kyle; Heaven, Michael

    2016-06-01

    The photodetachment spectrum of BeO- has been studied using high resolution velocity map imaging photoelectron spectroscopy. The vibrational contours were imaged and compared with Franck-Condon simulations for the ground and excited states of the neutral. The electron affinity of BeO was measured for the first time, and anisotropies of several transitions were determined. Experimental findings are compared to high level ab initio calculations.

  10. Elemental electron energy loss mapping of a precipitate in a multi-component aluminium alloy.

    PubMed

    Mørtsell, Eva A; Wenner, Sigurd; Longo, Paolo; Andersen, Sigmund J; Marioara, Calin D; Holmestad, Randi

    2016-07-01

    The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). A correlative analysis of the EELS data is connected to the results and discussed in detail. The energy loss maps for all relevant elements were recorded simultaneously. The good spatial resolution allows elemental distribution to be evaluated, such as by correlation functions, in addition to being compared with the HAADF image. The fcc-Al lattice and the hexagonal Si-network within the precipitates were resolved by EELS. The combination of EELS and HAADF-STEM demonstrated that some atomic columns consist of mixed elements, a result that would be very uncertain based on one of the techniques alone. EELS elemental mapping combined with a correlative analysis have great potential for identification and quantification of small amounts of elements at the atomic scale.

  11. High-resolution monochromator for iron nuclear resonance vibrational spectroscopy of biological samples

    NASA Astrophysics Data System (ADS)

    Yoda, Yoshitaka; Okada, Kyoko; Wang, Hongxin; Cramer, Stephen P.; Seto, Makoto

    2016-12-01

    A new high-resolution monochromator for 14.4-keV X-rays has been designed and developed for the Fe nuclear resonance vibrational spectroscopy of biological samples. In addition to high resolution, higher flux and stability are especially important for measuring biological samples, because of the very weak signals produced due to the low concentrations of Fe-57. A 24% increase in flux while maintaining a high resolution better than 0.9 meV is achieved in the calculation by adopting an asymmetric reflection of Ge, which is used as the first crystal of the three-bounce high-resolution monochromator. A 20% increase of the exit beam size is acceptable to our biological applications. The higher throughput of the new design has been experimentally verified. A fine rotation mechanics that combines a weak-link hinge with a piezoelectric actuator was used for controlling the photon energy of the monochromatic beam. The resulting stability is sufficient to preserve the intrinsic resolution.

  12. High-resolution heteronuclear multi-dimensional NMR spectroscopy in magnetic fields with unknown spatial variations.

    PubMed

    Zhang, Zhiyong; Huang, Yuqing; Smith, Pieter E S; Wang, Kaiyu; Cai, Shuhui; Chen, Zhong

    2014-05-01

    Heteronuclear NMR spectroscopy is an extremely powerful tool for determining the structures of organic molecules and is of particular significance in the structural analysis of proteins. In order to leverage the method's potential for structural investigations, obtaining high-resolution NMR spectra is essential and this is generally accomplished by using very homogeneous magnetic fields. However, there are several situations where magnetic field distortions and thus line broadening is unavoidable, for example, the samples under investigation may be inherently heterogeneous, and the magnet's homogeneity may be poor. This line broadening can hinder resonance assignment or even render it impossible. We put forth a new class of pulse sequences for obtaining high-resolution heteronuclear spectra in magnetic fields with unknown spatial variations based on distant dipolar field modulations. This strategy's capabilities are demonstrated with the acquisition of high-resolution 2D gHSQC and gHMBC spectra. These sequences' performances are evaluated on the basis of their sensitivities and acquisition efficiencies. Moreover, we show that by encoding and decoding NMR observables spatially, as is done in ultrafast NMR, an extra dimension containing J-coupling information can be obtained without increasing the time necessary to acquire a heteronuclear correlation spectrum. Since the new sequences relax magnetic field homogeneity constraints imposed upon high-resolution NMR, they may be applied in portable NMR sensors and studies of heterogeneous chemical and biological materials.

  13. High resolution transmission spectroscopy as a diagnostic for Jovian exoplanet atmospheres: constraints from theoretical models

    SciTech Connect

    Kempton, Eliza M.-R.; Perna, Rosalba; Heng, Kevin

    2014-11-01

    We present high resolution transmission spectra of giant planet atmospheres from a coupled three-dimensional (3D) atmospheric dynamics and transmission spectrum model that includes Doppler shifts which arise from winds and planetary motion. We model Jovian planets covering more than two orders of magnitude in incident flux, corresponding to planets with 0.9-55 day orbital periods around solar-type stars. The results of our 3D dynamical models reveal certain aspects of high resolution transmission spectra that are not present in simple one-dimensional (1D) models. We find that the hottest planets experience strong substellar to anti-stellar (SSAS) winds, resulting in transmission spectra with net blueshifts of up to 3 km s{sup –1}, whereas less irradiated planets show almost no net Doppler shifts. We find only minor differences between transmission spectra for atmospheres with temperature inversions and those without. Compared to 1D models, peak line strengths are significantly reduced for the hottest atmospheres owing to Doppler broadening from a combination of rotation (which is faster for close-in planets under the assumption of tidal locking) and atmospheric winds. Finally, high resolution transmission spectra may be useful in studying the atmospheres of exoplanets with optically thick clouds since line cores for very strong transitions should remain optically thick to very high altitude. High resolution transmission spectra are an excellent observational test for the validity of 3D atmospheric dynamics models, because they provide a direct probe of wind structures and heat circulation. Ground-based exoplanet spectroscopy is currently on the verge of being able to verify some of our modeling predictions, most notably the dependence of SSAS winds on insolation. We caution that interpretation of high resolution transmission spectra based on 1D atmospheric models may be inadequate, as 3D atmospheric motions can produce a noticeable effect on the absorption

  14. High Resolution Infrared Spectroscopy of Molecules of Terrestrial and Planetary Interest

    NASA Technical Reports Server (NTRS)

    Freedman, Richard S.

    2001-01-01

    In collaboration with the laboratory spectroscopy group of the Ames Atmospheric Physics Research Branch (SGP), high resolution infrared spectra of molecules that are of importance for the dynamics of the earth's and other planets' atmospheres were acquired using the SGP high resolution Fourier transform spectrometer and gas handling apparatus. That data, along with data acquired using similar instrumentation at the Kitt Peak National Observatory was analyzed to determine the spectral parameters for each of the rotationally resolved transitions for each molecule. Those parameters were incorporated into existing international databases (e.g. HITRANS and GEISA) so that field measurements could be converted into quantitative information regarding the physical and chemical structures of earth and planetary atmospheres.

  15. Performance of the AILES THz-Infrared beamline at SOLEIL for High resolution spectroscopy

    SciTech Connect

    Brubach, Jean-Blaise; Rouzieres, Mathieu; Roy, Pascale; Manceron, Laurent; Pirali, Olivier; Balcon, Didier; Tchana, Fridolin Kwabia; Boudon, Vincent; Tudorie, M.; Huet, Therese; Cuisset, Arnaud

    2010-02-03

    The new THz beamline (AILES) located at the third generation Synchrotron Radiation source SOLEIL is now operating for applications in a wide variety of research themes. In particular, this source with its adapted optics allows high resolution spectroscopic measurements of molecules in the entire infrared and THz range. This presentation focuses on the performances concerning flux, spectral range and stability for molecular spectroscopy. Thanks to these performances, the coupling of synchrotron radiation from a highly stable third generation source with high resolution FTIR spectrometer and with a long path cell (150 m or more) can be particularly advantageous. This fact is related to the optics of the beamline permitting the entire source to be used without aperture stop (entrance iris), even for measurements at highest-resolution of approx0.1 mueV (10{sup -3} cm{sup -1}).

  16. Fast acquisition of high-resolution 2D NMR spectroscopy in inhomogeneous magnetic fields

    NASA Astrophysics Data System (ADS)

    Lin, Liangjie; Wei, Zhiliang; Zeng, Qing; Yang, Jian; Lin, Yanqin; Chen, Zhong

    2016-05-01

    High-resolution nuclear magnetic resonance (NMR) spectroscopy plays an important role in chemical and biological analyses. In this study, we combine the J-coupling coherence transfer module with the echo-train acquisition technique for fast acquisition of high-resolution 2D NMR spectra in magnetic fields with unknown spatial variations. The proposed method shows satisfactory performance on a 5 mM ethyl 3-bromopropionate sample, under a 5-kHz (10 ppm at 11.7 T) B0 inhomogeneous field, as well as under varying degrees of pulse-flip-angle deviations. Moreover, a simulative ex situ NMR measurement is also conducted to show the effectiveness of the proposed pulse sequence.

  17. High resolution coherent three dimensional spectroscopy of NO{sub 2}

    SciTech Connect

    Wells, Thresa A.; Muthike, Angelar K.; Robinson, Jessica E.; Chen, Peter C.

    2015-06-07

    Expansion from coherent 2D spectroscopy to coherent 3D spectroscopy can provide significant advantages when studying molecules that have heavily perturbed energy levels. This paper illustrates such advantages by demonstrating how high resolution coherent 3D (HRC3D) spectroscopy can be used to study a portion of the visible spectrum of nitrogen dioxide. High resolution coherent 2D spectra usually contain rotational and vibrational patterns that are easy to analyze, but severe congestion and complexity preclude its effective use for many parts of the NO{sub 2} spectrum. HRC3D spectroscopy appears to be much more effective; multidimensional rotational and vibrational patterns produced by this new technique are easy to identify even in the presence of strong perturbations. A method for assigning peaks, which is based upon analyzing the resulting multidimensional patterns, has been developed. The higher level of multidimensionality is useful for reducing uncertainty in peak assignments, improving spectral resolution, providing simultaneous information on multiple levels and states, and predicting, verifying, and categorizing peaks.

  18. High-resolution pulsed-field ionization photoelectron spectroscopy using multi-bunch synchrotron radiation

    SciTech Connect

    Hsu, C.W.; Evans, M.; Ng, C.Y.; Heimann, P.

    1997-04-01

    BL9.0.2.2 is the newly constructed experimental End Station 2 at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source (ALS). It is dedicated to the high resolution photoionization study of molecules of interest to atmospheric and combustion chemistry. This End Station is equipped with a high resolution scanning monochromator, which has been demonstrated to have a world record resolution of E/{delta}E=70,000. Taking the advantage of the high resolution ALS light, the authors have improved the energy resolution in threshold photoelectron spectroscopy (TPES) to 0.8 meV. The TPES is a popular technique for photoionization experiments at all synchrotron radiation facilities due to its high energy resolution as compared to that of traditional photoelectron spectroscopy (PES). TPES achieves higher energy resolution by preferentially detecting near zero kinetic energy photoelectrons resulting from threshold photoionization. However, the spectra obtained from the TPES technique generally are complicated by the simultaneous detection of electrons with nonzero kinetic energy, which are not fully discriminated against. On the other hand, the spectra obtained from pulsed field ionization photoelectron spectroscopy (PFI-PES) are completely free of the contamination from kinetic electrons. The PFI-PE technique basically involves the detection of the photoelectrons from field ionization of the very high-n Rydberg states, a few cm{sup {minus}1} below the ionization energy (IE), by applying a delayed pulsed electric field. Within a delay of a few microseconds, all the prompt electrons formed from direct ionization will escape from the photoionization region and will not be collected. The authors have recently overcome problems with energy resolution of an electron time-of-flight technique, and incorporated the PFI-PE technique with multi-bunch VUV synchrotron radiation.

  19. High resolution energy loss research: Si compound ceramics and composites. [1990 annual progress report

    SciTech Connect

    Carpenter, R W; Lin, S H

    1990-12-31

    This report discusses proposed work on silicon compound ceramics and composites. High resolution composition and structure analysis of interfaces in ceramic and metal matrix composites and certain grain boundaries in silicon and its interfaces with oxides and nitrides is proposed. Composition and bonding analysis will be done with high spatial resolution (20 Angstroms or better) parallel electron energy loss spectroscopy using a field emission analytical electron microscope. Structural analysis will be done at the 1.8 Angstrom resolution level at 200kV by HREM. Theoretical electron energy loss cross section computations will be used to interpret electronic structure of these materials. Both self-consistent field MO and multiple scattering computational methods are being done and evaluated.

  20. High-Resolution Spectroscopy with the Chandra X-ray Observatory

    ScienceCinema

    Canizares, Claude R. [MIT, Cambridge, Massachusetts, United States

    2016-07-12

    The capabilities of the Chandra X-ray Observatory and XMM-Newton for high-resolution spectroscopy have brought tradition plasma diagnostic techniques to the study of cosmic plasma. Observations have probed nearly every class of astronomical object, from young proto-starts through massive O starts and black hole binaries, supernova remnants, active galactic nuclei, and the intergalactic medium. Many of these sources show remarkable rich spectra that reveal new physical information, such as emission measure distributions, elemental abundances, accretion disk and wind signatures, and time variability. This talk will present an overview of the Chandra instrumentaton and selected examples of spectral observations of astrophysical and cosmological importance.

  1. Negative electron energy loss and second-harmonic emission of nonlinear nanoparticles.

    PubMed

    Xu, Jinying; Zhang, Xiangdong

    2011-11-07

    A fast and general technique to investigation the interaction between a fast electron and nonlinear materials consisting of centrosymmetric spheres is presented by means of multiple scattering of electromagnetic multipole fields. Two kinds of new effect, the negative electron energy loss caused by the second-harmonic field and the second-harmonic Smith-Purcell radiation using finite chain of nonlinear spheres, are predicted for the first time. It is shown that these new effects can be probed by the electron energy loss spectrum, suggesting their possible applications in tunable light sources for the second-harmonic generation.

  2. Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

    SciTech Connect

    Limão-Vieira, P.; Ferreira da Silva, F.; Almeida, D.; Hoshino, M.; Tanaka, H.; Mogi, D.; Tanioka, T.; Mason, N. J.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.

    2015-02-14

    The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ({sup 1}Δ←{sup 1}Σ{sup +}) transition, with a new weak transition assigned to ({sup 1}Σ{sup −}←{sup 1}Σ{sup +}) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to {sup 1}Σ{sup +} and {sup 1}Π transitions. Based on our recent measurements of differential cross sections for the optically allowed ({sup 1}Σ{sup +} and {sup 1}Π) transitions of COS by electron impact, the optical oscillator strength f{sub 0} value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km)

  3. Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV.

    PubMed

    Limão-Vieira, P; Ferreira da Silva, F; Almeida, D; Hoshino, M; Tanaka, H; Mogi, D; Tanioka, T; Mason, N J; Hoffmann, S V; Hubin-Franskin, M-J; Delwiche, J

    2015-02-14

    The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0-10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ((1)Δ←(1)Σ(+)) transition, with a new weak transition assigned to ((1)Σ(-)←(1)Σ(+)) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to (1)Σ(+) and (1)Π transitions. Based on our recent measurements of differential cross sections for the optically allowed ((1)Σ(+) and (1)Π) transitions of COS by electron impact, the optical oscillator strength f0 value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20-50 km).

  4. A Framework to Combine Low- and High-resolution Spectroscopy for the Atmospheres of Transiting Exoplanets

    NASA Astrophysics Data System (ADS)

    Brogi, M.; Line, M.; Bean, J.; Désert, J.-M.; Schwarz, H.

    2017-04-01

    Current observations of the atmospheres of close-in exoplanets are predominantly obtained with two techniques: low-resolution spectroscopy with space telescopes and high-resolution spectroscopy from the ground. Although the observables delivered by the two methods are in principle highly complementary, no attempt has ever been made to combine them, perhaps due to the different modeling approaches that are typically used in their interpretation. Here, we present the first combined analysis of previously published dayside spectra of the exoplanet HD 209458 b obtained at low resolution with HST/Wide Field Camera 3 (WFC3) and Spitzer/IRAC and at high resolution with VLT/CRIRES. By utilizing a novel retrieval algorithm capable of computing the joint probability distribution of low- and high-resolution spectra, we obtain tight constraints on the chemical composition of the planet’s atmosphere. In contrast to the WFC3 data, we do not confidently detect H2O at high spectral resolution. The retrieved water abundance from the combined analysis deviates by 1.9σ from the expectations for a solar-composition atmosphere in chemical equilibrium. Measured relative molecular abundances of CO and H2O strongly favor an oxygen-rich atmosphere (C/O < 1 at 3.5σ ) for the planet when compared to equilibrium calculations including O rainout. From the abundances of the seven molecular species included in this study we constrain the planet metallicity to 0.1–1.0× the stellar value (1σ). This study opens the way to coordinated exoplanet surveys between the flagship ground- and space-based facilities, which ultimately will be crucial for characterizing potentially habitable planets.

  5. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    SciTech Connect

    Niu, B.

    1992-09-01

    High resolution He I[alpha] photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a soft'' mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  6. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    SciTech Connect

    Niu, B.

    1992-09-01

    High resolution He I{alpha} photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a ``soft`` mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  7. Photodissociation of ozone at 276nm by photofragment imaging and high resolution photofragment translational spectroscopy

    SciTech Connect

    Blunt, D.A.; Suits, A.G.

    1996-11-01

    The photodissociation of ozone at 276 nm is investigated using both state resolved ion imaging and high-resolution photofragment translational spectroscopy. Ion images from both [3+1] and [2+1] resonance enhanced multiphoton ionization of the O({sup 1}D) photofragment are reported. All images show strong evidence of O({sup 1}D) orbital alignment. Photofragment translation spectroscopy time-of-flight spectra are reported for the O{sub 2} ({sup 1}{Delta}{sub g}) photofragment. Total kinetic energy release distributions determined form these spectra are generally consistent with those distributions determined from imaging data. Observed angular distributions are reported for both detection methods, pointing to some unresolved questions for ozone dissociation in this wavelength region.

  8. High-resolution multi-heterodyne spectroscopy based on Fabry-Perot quantum cascade lasers

    SciTech Connect

    Wang, Yin; Wang, Wen; Wysocki, Gerard; Soskind, Michael G.

    2014-01-20

    In this Letter, we present a method of performing broadband mid-infrared spectroscopy with conventional, free-running, continuous wave Fabry-Perot quantum cascade lasers (FP-QCLs). The measurement method is based on multi-heterodyne down-conversion of optical signals. The sample transmission spectrum probed by one multi-mode FP-QCL is down-converted to the radio-frequency domain through an optical multi-heterodyne process using a second FP-QCL as the local oscillator. Both a broadband multi-mode spectral measurement as well as high-resolution (∼15 MHz) spectroscopy of molecular absorption are demonstrated and show great potential for development of high performance FP-laser-based spectrometers for chemical sensing.

  9. Automatic pole-zero/zero-pole digital compensator for high-resolution spectroscopy: Design and experiments

    SciTech Connect

    Geraci, A.; Pullia, A.; Ripamonti, G.

    1999-08-01

    In a high-resolution spectroscopy system the relatively long exponential decay due to the charge preamplifier is customarily canceled in an analogue fashion by means of a PZ (Pole-Zero) stage. The accurateness of such a compensation has a big impact on the energy resolution because it strongly affects the baseline-stability problems. The authors have automatically and on-line performed such a compensation in a digital way, while maintaining a spectroscopy performance and keeping at minimum both the ADC sampling frequency (thus power consumption) and its resolution (thus cost). This is done through an IIR filter, implemented within a FPGA by a DSP. The so-compensated waveform has, in excellent approximation, an all-pole shape. Starting from such a signal, the minimum-noise filters for energy and/or time measurements are then promptly synthesized and implemented for real time operation through the same DSP.

  10. High resolution Halpha spectroscopy and R-band photometry of Swift J1357.2-0933

    NASA Astrophysics Data System (ADS)

    Casares, Jorge; Torres, Manuel A. P.; Negueruela, Ignacio; Gonzalez-Fernandez, Carlos; Corral-Santana, Jesus M.; Zurita, Cristina; Llano, Sergio Rodriguez

    2011-03-01

    We report on high resolution Halpha spectroscopy and time-resolved photometry of the optical counterpart to the X-ray transient Swift J1357.2-0933 in outburst (Krimm et al. ATEL #3138). SPECTROSCOPY: Six 30-33 min spectra were obtained on the nights of 2011 Feb 25-27 using the IDS Spectrograph on the 2.5m Isaac Newton Telescope (INT) at the Observatorio del Roque de Los Muchachos. The observations were performed with the H1800V grating and a slit width 1.6 arcsec to yield a spectral coverage of 6270-7000 Angs with a 30 km/s FWHM spectral resolution at Halpha..

  11. High-resolution structure of the photosynthetic Mn4Ca catalyst from X-ray spectroscopy.

    PubMed

    Yano, Junko; Kern, Jan; Pushkar, Yulia; Sauer, Kenneth; Glatzel, Pieter; Bergmann, Uwe; Messinger, Johannes; Zouni, Athina; Yachandra, Vittal K

    2008-03-27

    The application of high-resolution X-ray spectroscopy methods to study the photosynthetic water oxidizing complex, which contains a unique hetero-nuclear catalytic Mn4Ca cluster, is described. Issues of X-ray damage, especially at the metal sites in the Mn4Ca cluster, are discussed. The structure of the Mn4Ca catalyst at high resolution, which has so far eluded attempts of determination by X-ray diffraction, X-ray absorption fine structure (EXAFS) and other spectroscopic techniques, has been addressed using polarized EXAFS techniques applied to oriented photosystem II (PSII) membrane preparations and PSII single crystals. A review of how the resolution of traditional EXAFS techniques can be improved, using methods such as range-extended EXAFS, is presented, and the changes that occur in the structure of the cluster as it advances through the catalytic cycle are described. X-ray absorption and emission techniques (XANES and Kbeta emission) have been used earlier to determine the oxidation states of the Mn4Ca cluster, and in this report we review the use of X-ray resonant Raman spectroscopy to understand the electronic structure of the Mn4Ca cluster as it cycles through the intermediate S-states.

  12. High-Resolution Structure of the Photosynthetic Mn4Ca Catalyst from X-ray Spectroscopy

    SciTech Connect

    Yachandra, Vittal; Yano, Junko; Kern, Jan; Pushkar, Yulia; Sauer, Kenneth; Glatzel, Pieter; Bergmann, Uwe; Messinger, Johannes; Zouni, Athina; Yachandra, Vittal K.

    2007-08-01

    The application of high-resolution X-ray spectroscopy methods to study the photosynthetic water oxidizing complex, which contains a unique hetero-nuclear catalytic Mn4Ca cluster, are described. Issues of X-ray damage especially at the metal sites in the Mn4Ca cluster are discussed. The structure of the Mn4Ca catalyst at high-resolution which has so far eluded attempts of determination by X-ray diffraction, EXAFS and other spectroscopic techniques has been addressed using polarized EXAFS techniques applied to oriented PS II membrane preparations and PS II single crystals. A review of how the resolution of traditional EXAFS techniques can be improved, using methods such as range-extended EXAFS is presented, and the changes that occur in the structure of the cluster as it advances through the catalytic cycle are described. X-ray absorption and emission techniques (XANES and K? emission) have been used earlier to determine the oxidation states of the Mn4Ca cluster, and in this report we review the use of X-ray resonant Raman spectroscopy to understand the electronic structure of the Mn4Ca cluster as it cycles through the intermediate S-states.

  13. High-resolution laser spectroscopy with the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN-ISOLDE

    NASA Astrophysics Data System (ADS)

    Cocolios, T. E.; de Groote, R. P.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Day Goodacre, T.; Farooq-Smith, G. J.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heylen, H.; Kron, T.; Li, R.; Lynch, K. M.; Marsh, B. A.; Neyens, G.; Rossel, R. E.; Rothe, S.; Smith, A. J.; Stroke, H. H.; Wendt, K. D. A.; Wilkins, S. G.; Yang, X.

    2016-06-01

    The Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN has achieved high-resolution resonance ionisation laser spectroscopy with a full width at half maximum linewidth of 20(1) MHz for 219,221 Fr, and has measured isotopes as short lived as 5 ms with 214 Fr. This development allows for greater precision in the study of hyperfine structures and isotope shifts, as well as a higher selectivity of single-isotope, even single-isomer, beams. These achievements are linked with the development of a new laser laboratory and new data-acquisition systems.

  14. Transfer-printing of single DNA molecule arrays on graphene for high resolution electron imaging and analysis

    PubMed Central

    Cerf, Aline; Alava, Thomas; Barton, Robert A.; Craighead, Harold G.

    2011-01-01

    Graphene represents the ultimate substrate for high-resolution transmission electron microscopy, but the deposition of biological samples on this highly hydrophobic material has until now been a challenge. We present a reliable method for depositing ordered arrays of individual elongated DNA molecules on single-layer graphene substrates for high resolution electron beam imaging and electron energy loss spectroscopy analysis. This method is a necessary step towards the observation of single elongated DNA molecules with single base spatial resolution to directly read genetic and epigenetic information. PMID:21919532

  15. A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate

    DOE PAGES

    Liu, Peng; Zhang, Yanwen; Xue, Haizhou; ...

    2016-01-09

    Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss, themore » velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.« less

  16. A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate

    SciTech Connect

    Liu, Peng; Zhang, Yanwen; Xue, Haizhou; Jin, Ke; Crespillo, Miguel L.; Wang, Xuelin; Weber, William J.

    2016-01-09

    Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss, the velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.

  17. Diamond-machined ZnSe immersion grating for NIR high-resolution spectroscopy

    SciTech Connect

    Ikeda, Y; Kobayashi, N; Kuzmenko, P J; Little, S L; Yasui, C; Kondo, S; Minami, A; Motohara, K

    2008-07-25

    ZnSe immersion gratings (n {approx} 2.45) provide the possibility of high-resolution spectroscopy for the near-infrared (NIR) region. Since ZnSe has a lower internal attenuation than other NIR materials, it is most suitable for immersion grating, particularly in short NIR region (0.8-1.4 {micro}m). We are developing an extremely high-resolution spectrograph with {lambda}/{Delta}{lambda} = 100,000, WINERED, customized for the short NIR region, using ZnSe (or ZnS) immersion grating. However, it had been very difficult to make fine grooves on ZnSe substrate with a small pitch of less than 50 {micro}m because ZnSe is a soft/brittle material. We have overcome this problem and successfully machined sharp grooves with fine pitch on ZnSe substrates by nano precision fly-cutting technique at LLNL. The optical testing of the sample grating with HeNe laser shows an excellent performance: the relative efficiency more than 87.4 % at 0.633 {micro}m for a classical grating configuration. The diffraction efficiency when used as an immersion grating is estimated to be more than 65 % at 1 {micro}m. Following this progress, we are about to start machining a grating on a large ZnSe prism with an entrance aperture of 23mm x 50mm and the blaze angle of 70{sup o}.

  18. High-resolution absorptive intermolecular multiple-quantum coherence NMR spectroscopy under inhomogeneous fields

    NASA Astrophysics Data System (ADS)

    Lin, Meijin; Lin, Yanqin; Chen, Xi; Cai, Shuhui; Chen, Zhong

    2012-01-01

    Intermolecular multiple-quantum coherence (iMQC) is capable of improving NMR spectral resolution using a 2D shearing manipulation method. A pulse sequence termed CT-iDH, which combines intermolecular double-quantum filter (iDQF) with a modified constant-time (CT) scheme, is designed to achieve fast acquisition of high-resolution intermolecular zero-quantum coherences (iZQCs) and intermolecular double-quantum coherences (iDQCs) spectra without strong coupling artifacts. Furthermore, double-absorption lineshapes are first realized in 2D intermolecular multi-quantum coherences (iMQCs) spectra under inhomogeneous fields through a combination of iZQC and iDQC signals to double the resolution without loss of sensitivity. Theoretically the spectral linewidth can be further reduced by half compared to original iMQC high-resolution spectra. Several experiments were performed to test the feasibility of the new method and the improvements are evaluated quantitatively. The study suggests potential applications for in vivo spectroscopy.

  19. High resolution spin- and angle-resolved photoelectron spectroscopy for 3D spin vectorial analysis

    NASA Astrophysics Data System (ADS)

    Okuda, Taichi; Miyamoto, Koji; Kimura, Akio; Namatame, Hirofumi; Taniguchi, Masaki

    2013-03-01

    Spin- and angle-resolved photoelectron spectroscopy (SARPES) is the excellent tool which can directly observe the band structure of crystals with separating spin-up and -down states. Recent findings of new class of materials possessing strong spin orbit interaction such as Rashba spin splitting systems or topological insulators stimulate to develop new SARPES apparatuses and many sophisticated techniques have been reported recently. Here we report our newly developed a SARPES apparatus for spin vectorial analysis with high precision at Hiroshima Synchrotron Radiation Center. Highly efficient spin polarimeter utilizing very low energy electron diffraction (VLEED) makes high resolution (ΔE < 10 meV, Δθ ~ +/- 0.2 °) compatible with the SARPES measurement. By placing two VLEED spin detectors orthogonally we have realized the polarization measurement of all spin components (x, y and z) with the high resolution. Some examples of the three-dimensional spin observation will be presented. This work is supported by KAKENHI (23244066), Grant-in-Aid for Scientific Research (A) of Japan Society for the Promotion of Science.

  20. Fragmentation and conformation study of ephedrine by low- and high-resolution mass selective UV spectroscopy

    NASA Astrophysics Data System (ADS)

    Chervenkov, S.; Wang, P. Q.; Braun, J. E.; Neusser, H. J.

    2004-10-01

    The neurotransmitter molecule, ephedrine, has been studied by mass-selective low- and high-resolution UV resonance enhanced two-photon ionization spectroscopy. Under all experimental conditions we observed an efficient fragmentation upon ionization. The detected vibronic peaks in the spectrum are classified according to the efficiency of the fragmentation, which leads to the conclusion that there exist three different species in the molecular beam: ephedrine-water cluster and two distinct conformers. The two-color two-photon ionization experiment with a decreased energy of the second photon leads to an upper limit of 8.3 eV for the ionization energy of ephedrine. The high-resolution (70 MHz) spectrum of the strongest vibronic peak in the spectrum measured at the fragment (m/z=58) mass channel displays a pronounced and rich rotational structure. Its analysis by the use of a specially designed computer-aided rotational fit process yields accurate rotational constants for the S0 and S1 states and the transition moment ratio, providing information on the respective conformational structure.

  1. High-resolution optical spectroscopy in a hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Perrella, C.; Light, P. S.; Stace, T. M.; Benabid, F.; Luiten, A. N.

    2012-01-01

    In this paper, we present detailed high-resolution spectroscopy of rubidium (Rb) vapor confined within a hollow-core photonic crystal fiber (HC-PCF). We find a very low level of additional frequency broadening associated with this confinement, with spectral features being only 1 MHz broader than the natural linewidth of the excited state. We show that this additional broadening is consistent solely with the atoms' transit across the fiber's optical mode. This low level of decoherence opens the door to a wide variety of applications including compact frequency standards and new types of quantum optical devices based on alkali-metal-loaded HC-PCFs. We highlight the low level of decoherence through observation of electromagnetically induced transparency in the confined vapor.

  2. Low energy nuclear spin excitations in Ho metal investigated by high resolution neutron spectroscopy.

    PubMed

    Chatterji, Tapan; Jalarvo, Niina

    2013-04-17

    We have investigated the low energy excitations in metallic Ho by high resolution neutron spectroscopy. We found at T = 3 K clear inelastic peaks in the energy loss and energy gain sides, along with the central elastic peak. The energy of this low energy excitation, which is 26.59 ± 0.02 μeV at T = 3 K, decreased continuously and became zero at TN ≈ 130 K. By fitting the data in the temperature range 100-127.5 K with a power law we obtained the power-law exponent β = 0.37 ± 0.02, which agrees with the expected value β = 0.367 for a three-dimensional Heisenberg model. Thus the energy of the low energy excitations can be associated with the order parameter.

  3. Application of a continuously tunable, cw optical parametric oscillator for high-resolution spectroscopy.

    PubMed

    Gibson, G M; Dunn, M H; Padgett, M J

    1998-01-01

    We report the use of a smoothly tunable, single-frequency continuous-wave optical parametric oscillator (OPO) for high-resolution spectroscopy. The OPO is based on potassium titanyl phosphate and is resonant for both signal and idler fields, resulting in a device with a very low pump power threshold of 30 mW. The frequency-selective nature of the doubly resonant oscillator ensures that the signal and idler modes can be tuned across the entire phase-match bandwidth without the need for additional intracavity frequency-selective components. Smooth frequency tuning of the output of the OPO is obtained by tuning of the pump laser. To demonstrate the practicality of our OPO we recorded the absorption spectrum of cesium vapor in the 1-microm spectral region.

  4. Continuous-wave whispering-gallery optical parametric oscillator for high-resolution spectroscopy.

    PubMed

    Werner, Christoph S; Buse, Karsten; Breunig, Ingo

    2015-03-01

    We achieve a continuous operation of a whispering gallery optical parametric oscillator by stabilizing the resonator temperature T on the mK level and simultaneously locking the pump frequency to a cavity resonance using the Pound-Drever-Hall technique. The millimeter-sized device converts several mW of a pump wave at 1040 nm wavelength to signal and idler waves around 2000 nm wavelength with more than 50% efficiency. Over 1 h, power and frequency of the signal wave vary by <±1% and by <±25  MHz, respectively. The latter can be tuned over 480 MHz without a mode hop by changing T over 120 mK. In order to prove the suitability for high-resolution spectroscopy, we scan the signal frequency across the resonance of a Fabry-Perot interferometer resolving nicely its 10 MHz linewidth.

  5. Multiple Populations in M31 Globular Clusters: Clues from Infrared High Resolution Integrated Light Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sakari, Charli; APOGEE Team

    2017-01-01

    Abundance variations are a common feature of Milky Way globular clusters. The globular clusters in M31 are too distant for detailed abundance studies of their individual stars; however, cluster abundances can be determined through high resolution, integrated light (IL) spectroscopy. In this talk, I discuss how IL abundances can be interpreted in the context of multiple populations. In particular, I will present new infrared abudances of 25 M31 globular clusters, derived from IL spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). These H band spectra allow determinations of C, N, and O from molecular features, and Fe, Na, Mg, Al, Si, Ca, Ti, and K from atomic features. The integrated abundance ratios are then investigated with cluster [Fe/H] and mass.

  6. A Study of the Conformational Isomerism of 1-Iodobutane by High Resolution Rotational Spectroscopy

    DOE PAGES

    Arsenault, Eric A.; Obenchain, Daniel A.; Blake, Thomas A.; ...

    2017-03-24

    The first microwave study of 1-iodobutane, performed by Steinmetz et al. in 1977, led to the determination of the B+C parameter for the anti-anti- and gauche-anti-conformers. Nearly 40 years later, in this paper this reinvestigation of 1-iodobutane, by high-resolution microwave spectroscopy, led to the determination of rotational constants, centrifugal distortion constants, nuclear quadrupole coupling constants (NQCCs), and nuclear-spin rotation constants belonging to both of the two previously mentioned conformers, in addition to the gauche-gauche-conformer, which was observed in this frequency regime for the first time. Finally, comparisons between the three conformers of 1-iodobutane and other iodo- and bromoalkanes are made,more » specifically through an analysis of the nuclear quadrupole coupling constants belonging to the iodine and bromine atoms in the respective chemical environments.« less

  7. High resolution spectroscopy of comet C/2002 C1 Ikeya-Zhang with SARG at TNG

    NASA Astrophysics Data System (ADS)

    Capria, M. T.; Cremonese, G.; Boattini, A.; de Sanctis, M. C.; D'Abramo, G.; Buzzoni, A.

    2002-11-01

    A program of high resolution spectroscopy of comets is being conducted at TNG in Canary Islands using the echelle spectrograph SARG. The aim of the program is to catalogue known and unknown emission lines, compare them with the lines already listed in existing catalogues and possibly identify unknown lines. In the visible range of the spectrum emission lines of daughter molecules and ions can be found, and many of them are still unidentified. The comet C/2002 C1 Ikeya-Zhang was observed with SARG during the night 19-20 of April and spectra with two different setups were taken. In the first case a narrow band filter was used to isolate the sodium emissions with a long slit and R = 43000. The data show very interesting cometary sodium emissions in the coma. The second setup used a short slit covering the spectral range of 4620-7920 Å with R = 57000.

  8. High-Resolution Spectroscopy and Optical Photometry of MWC 349A and MWC 349B

    NASA Astrophysics Data System (ADS)

    Manset, N.; Miroshnichenko, A. S.; Zharikov, S. V.; Kusakin, A. V.

    2017-02-01

    MWC 349A is a V ˜ 13 mag object with the B[e] phenomenon, a very strong optical emission-line spectrum, maser and laser line emission, and a radio-bright bipolar nebula, attenuated by ˜10 mag of interstellar extinction. MWC 349B is a visual companion of MWC 349A with no previously reported signs of emission. The physical connection of the pair has been the subject of debates toward revealing the evolutionary state of MWC 349A. Only low-resolution spectra reported for MWC 349B resulted in estimating its parameters with a large uncertainty. We report the results of high-resolution optical spectroscopy of both objects as well as their optical photometry.

  9. High-resolution vibrational and rotational spectroscopy of CD2H+ in a cryogenic ion trap

    NASA Astrophysics Data System (ADS)

    Jusko, Pavol; Stoffels, Alexander; Thorwirth, Sven; Brünken, Sandra; Schlemmer, Stephan; Asvany, Oskar

    2017-02-01

    The low-lying rotational states (J = 0, … , 5) of CD2H+ have been probed by high-resolution ro-vibrational and pure rotational spectroscopy, applying several action spectroscopic methods in a cryogenic 22-pole ion trap. For this, the ν1 ro-vibrational band has been revisited, detecting 108 transitions, among which 36 are new. The use of a frequency comb system allowed us to measure the ro-vibrational transitions with high precision and accuracy, typically better than 1 MHz. The high precision has been confirmed by comparing equal combination differences in the ground and excited state. Moreover, precise predictions of pure rotational transitions were possible for the ground state. Twenty-five rotational transitions have been detected directly by a novel IR-mm-wave double resonance method, giving rise to highly accurate ground state spectroscopic parameters.

  10. High-resolution photoelectron spectroscopy analysis of sulfidation of brass at the rubber/brass interface

    NASA Astrophysics Data System (ADS)

    Ozawa, Kenichi; Kakubo, Takashi; Shimizu, Katsunori; Amino, Naoya; Mase, Kazuhiko; Komatsu, Takayuki

    2013-01-01

    High resolution photoelectron spectroscopy is utilized to investigate the chemical composition at the rubber/brass interface to elucidate the origin of strong adhesion as well as the degradation between rubber and brass. Special attention has been given to copper sulfides formed at the interface during the vulcanization reaction at 170 °C. At least five sulfur-containing species are identified in the adhesive interlayer including crystalline CuS and amorphous CuxS (x ≃ 2). These copper sulfide species are not uniformly distributed within the layer, but there exits the concentration gradation; the concentration of CuxS is high in the region on the rubber side and is diminished in the deeper region, while vice versa for that of CuS. Degradation of the interface adhesive strength by prolonged vulcanization arises from the decrease in the CuxS/CuS ratio accompanying desulfurization of the adhesive layer.

  11. High resolution laser induced fluorescence Doppler velocimetry utilizing saturated absorption spectroscopy

    SciTech Connect

    Aramaki, Mitsutoshi; Ogiwara, Kohei; Etoh, Shuzo; Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2009-05-15

    A high resolution laser induced fluorescence (LIF) system has been developed to measure the flow velocity field of neutral particles in an electron-cyclotron-resonance argon plasma. The flow velocity has been determined by the Doppler shift of the LIF spectrum, which is proportional to the velocity distribution function. Very high accuracy in velocity determination has been achieved by installing a saturated absorption spectroscopy unit into the LIF system, where the absolute value and scale of laser wavelength are determined by using the Lamb dip and the fringes of a Fabry-Perot interferometer. The minimum detectable flow velocity of a newly developed LIF system is {+-}2 m/s, and this performance remains unchanged in a long-time experiment. From the radial measurements of LIF spectra of argon metastable atoms, it is found that there exists an inward flow of neutral particles associated with neutral depletion.

  12. High Resolution Spectroscopy of Naphthalene Calibrated by AN Optical Frequency Comb

    NASA Astrophysics Data System (ADS)

    Nishiyama, Akiko; Nakashima, Kazuki; Matsuba, Ayumi; Misono, Masatoshi

    2015-06-01

    In high-resolution molecular spectroscopy, the precise measure of the optical frequency is crucial to evaluate minute shifts and splittings of the energy levels. On the other hand, in such spectroscopy, thousands of spectral lines distributed over several wavenumbers have to be measured by a continuously scanning cw laser. Therefore, the continuously changing optical frequency of the scanning laser has to be determined with enough precision. To satisfy these contradictory requirements, we have been developed two types of high-resolution spectroscopic systems employing an optical frequency comb. One of the systems employs RF band-pass filters to generate equally spaced frequency markers for optical frequency calibration, and is appropriate for wide wavelength-range measurement with relatively high scanning rate.^a In the other system, the beat frequency between the optical frequency comb and the scanning laser is controlled by an acousto-optic frequency shifter. This system is suitable for more precise measurement, and enables detailed analyses of frequency characteristics of scanning laser.^b In the present study, we observe Doppler-free two-photon absorption spectra of A^1B1u (v_4 = 1) ← X^1A_g (v = 0) transition of naphthalene around 298 nm. The spectral lines are rotationally resolved and the resolution is about 100 kHz. For ^qQ transition, the rotational lines are assigned, and molecular constants in the excited state are determined. In addition, we analyze the origin of the measured linewidth and Coriolis interactions between energy levels. To determine molecular constants more precisely, we proceed to measure and analyze spectra of other transitions, such as ^sS transitions. ^a A. Nishiyama, D. Ishikawa, and M. Misono, J. Opt. Soc. Am. B 30, 2107 (2013). ^b A. Nishiyama, A. Matsuba, and M. Misono, Opt. Lett. 39, 4923 (2014).

  13. High-resolution laser spectroscopy of long-lived plutonium isotopes

    NASA Astrophysics Data System (ADS)

    Voss, A.; Sonnenschein, V.; Campbell, P.; Cheal, B.; Kron, T.; Moore, I. D.; Pohjalainen, I.; Raeder, S.; Trautmann, N.; Wendt, K.

    2017-03-01

    Long-lived isotopes of plutonium were studied using two complementary techniques, high-resolution resonance ionization spectroscopy (HR-RIS) and collinear laser spectroscopy (CLS). Isotope shifts have been measured on the 5 f67 s27F0→5 f56 d27 s (J =1 ) and 5 f67 s27F1→5 f67 s 7 p (J =2 ) atomic transitions using the HR-RIS method and the hyperfine factors have been extracted for the odd mass nuclei Pu,241239. CLS was performed on the 5 f67 s 8F1 /2→J =1 /2 (27 523.61 cm-1) ionic transition with the hyperfine A factors measured for 239Pu. Changes in mean-squared charge radii have been extracted and show a good agreement with previous nonoptical methods, with an uncertainty improvement by approximately one order of magnitude. Plutonium represents the heaviest element studied to date using collinear laser spectroscopy.

  14. High Resolution Rovibrational Spectroscopy of Large Molecules Using Infrared Frequency Combs and Buffer Gas Cooling

    NASA Astrophysics Data System (ADS)

    Changala, Bryan; Spaun, Ben; Patterson, David; Bjork, Bryce J.; Heckl, Oliver H.; Doyle, John M.; Ye, Jun

    2016-06-01

    We have recently demonstrated the integration of cavity-enhanced direct frequency comb spectroscopy with buffer gas cooling to acquire high resolution infrared spectra of translationally and rotationally cold (˜10 K) gas-phase molecules. Here, we extend this method to significantly larger systems, including naphthalene (C10H_8), a prototypical polyaromatic hydrocarbon, and adamantane (C10H_{16}), the fundamental building block of diamonoids. To the authors' knowledge, the latter molecule represents the largest system for which rotationally resolved spectra in the CH stretch region (3 μm) have been obtained. In addition to the measured spectra, we present several details of our experimental methods. These include introducing non-volatile species into the cold buffer gas cell and obtaining broadband spectra with single comb mode resolution. We also discuss recent modifications to the apparatus to improve its absorption sensitivity and time resolution, which facilitate the study of both larger molecular systems and cold chemical dynamics. B. Spaun, et al. Probing buffer-gas cooled molecules with direct frequency comb spectroscopy in the mid-infrared, WF02, 70th International Symposium on Molecular Spectroscopy, Champaign-Urbana, IL, 2015.

  15. Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study

    SciTech Connect

    Roth, Friedrich

    2015-10-21

    We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping.

  16. Far Infrared High Resolution Synchrotron FTIR Spectroscopy of the Low Frequency Bending Modes of Dmso

    NASA Astrophysics Data System (ADS)

    Cuisset, Arnaud; Smirnova, Irina; Bocquet, Robin; Hindle, Francis; Mouret, Gael; Sadovskii, Dmitrii A.; Pirali, Olivier; Roy, Pascale

    2010-06-01

    In addition to its importance for industrial and environmental studies, the monitoring of DiMethylSulfOxyde (DMSO, (CH_3)_2SO) concentrations is of considerable interest for civil protection. The existing high resolution gas phase spectroscopic data of DMSO only concerned the pure rotational transitions in the ground state. In the Far-IR domain, the low-frequency rovibrational transitions have never previously resolved. The high brightness of the AILES beamline of the synchrotron SOLEIL and the instrumental sensitivity provided by the multipass cell allowed to measure for the first time these transitions. 1581 A-type and C-type transitions in the ν11 band have been assigned and 25 molecular constants of Watson's s-form hamiltonian developed to degree 8 have been fitted within the experimental accuracy. The use of then synchrotron radiation has opened many possibilities for new spectroscopic studies. Together with several other recent studies, our successful measurement and analysis of DMSO convincingly demonstrates the potential of the AILES beamline for high resolution FIR spectroscopy. Thus our present work is just at the beginning of unraveling the rovibrational structure of low frequency bending and torsional vibrational states of DMSO and yielding important comprehensive structural and spectroscopic information on this molecule. L. Margules, R. A. Motienko, E. A. Alekseev, J. Demaison, J. Molec. Spectrosc., 260(23),2009 V. Typke, M. Dakkouri, J. Molec. Struct., 599(177),2001 A. Cuisset, L. Nanobashvili, I. Smirnova, R. Bocquet, F. Hindle, G. Mouret, O. Pirali, P. Roy, D. Sadovskii, Chem. Phys. Lett., accepted for publication

  17. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  18. VizieR Online Data Catalog: Radiative recombination electron energy loss data (Mao+, 2017)

    NASA Astrophysics Data System (ADS)

    Mao, J.; Kaastra, J.; Badnell, N. R.

    2016-11-01

    The weighted electron energy loss factors (dimensionless) are defined by weighting the electron energy loss rate coefficients (per ion) with respect to the total radiative recombination rates. Both the unparameterized and parameterized weighted electron energy-loss factors for H-like to Ne-like ions from H (z=1) up to and including Zn (z=30), in a wide temperature range, are available here. For the unparameterized data set, the temperatures are set to the conventional ADAS temperature grid, i.e. c2*(10,20,50,100,200,...,2*106,5*106,107)K, where c is the ionic charge of the recombined ion. For the fitting parameters, the temperature should be in units of eV. We refer to the recombined ion when we speak of the radiative recombination of a certain ion, for example, for a bare oxygen ion capturing a free electron via radiative recombination to form H-like oxygen (O VIII, s=1, z=8). The fitting accuracies are better than 4%. (2 data files).

  19. What can we Expect of High-Resolution Spectroscopies on Carbohydrates?

    NASA Astrophysics Data System (ADS)

    Cocinero, Emilio J.; Ecija, Patricia; Uriarte, Iciar; Usabiaga, Imanol; Fernández, José A.; Basterretxea, Francisco J.; Lesarri, Alberto; Davis, Benjamin G.

    2015-06-01

    Carbohydrates are one of the most multifaceted building blocks, performing numerous roles in living organisms. We present several structural investigations on carbohydrates exploiting an experimental strategy which combines microwave (MW) and laser spectroscopies in high-resolution. Laser spectroscopy offers high sensitivity coupled to mass and conformer selectivity, making it ideal for polysaccharides studies. On the other hand, microwave spectroscopy provides much higher resolution and direct access to molecular structure of monosaccharides. This combined approach provides not only accurate chemical insight on conformation, structure and molecular properties, but also benchmarking standards guiding the development of theoretical calculations. In order to illustrate the possibilities of a combined MW-laser approach we present results on the conformational landscape and structural properties of several monosaccharides and oligosaccharides including microsolvation and molecular recognition processes of carbohydrates. E.J. Cocinero, A. Lesarri, P. écija, F.J. Basterretxea, J.-U. Grabow, J.A. Fernández and F. Casta {n}o Angew. Chem. Int. Ed. 51, 3119-3124, 2012. E.J. Cocinero, A. Lesarri, P. écija, Á. Cimas, B.G. Davis, F.J. Basterretxea, J.A. Fernández and F. Casta {n}o J. Am. Chem. Soc. 135, 2845-2852, 2013. E.J. Cocinero, P. Çarçabal, T.D. Vaden, J.P. Simons and B.G. Davis Nature 469, 76-80, 2011. C.S. Barry, E.J. Cocinero, P. Çarçabal, D.P. Gamblin, E.C. Stanca-Kaposta, S. M. Fernández-Alonso, S. Rudić, J.P. Simons and B.G. Davis J. Am. Chem. Soc. 135, 16895-16903, 2013.

  20. High-Resolution Spectroscopy of Mars: Recent Results and Implications for Atmospheric Evolution

    NASA Technical Reports Server (NTRS)

    Krasnopolsky, V. A.; Owen, T. C.; Maillard, J. P.

    1999-01-01

    It is believed that Earth, Venus, and Mars were formed by the same rocky and icy planetesimals, which resembled meteorites and comets in their composition, respectively. These planets are thus expected to have initially had the same chemical and isotope composition. Scaling the mass of the terrestrial ocean by the planetary mass ratio, the expected initial H2O abundance on Mars is a layer of about 1 km thick. Scaling the abundance of CO2 on Venus, the expected initial CO2 abundance on Mars is 15 bars. Evidently, significant parts of the initial H2O and CO2 abundances have been lost. Intense meteorite impact erosion and hydrodynamic escape of hydrogen (which could drag to escape more heavy species) were dominant loss processes in the first 0.8 Byr. Later, atmospheric sputtering by O+ ions resulted in the dissociation of CO2 and massive losses of O, C, and H. Formation of carbonates also reduced CO2 to its present abundance which currently exists in the atmosphere, on the polar caps, and is absorbed by regolith. Water loss is currently due to thermal escape of H and nonthermal escape of O, both formed by photodissociation of H2O. All loss processes resulted in fractionation of the H, O, and C isotopes. Therefore, the current isotope ratios in H2O and CO2 are clues to the history of volatiles on Mars. There are three tools to study H2O and CO2 isotopes in the martian atmosphere: (i) mass spectrometry from landing probes, (ii) analyses of Mars' gases trapped in the SNC meteorites which were ejected from Mars, and (iii) high-resolution spectroscopy of the H2O andCO2 bands. Method (i) is the best but is the most expensive. Mass spectrometers to be used should be designed for high-precision isotope measurements. Method (ii) makes it possible to reach an uncertainty +/- 0.1%. However, the obtained results are affected by some uncontrolled interactions: isotope fractionations of (1) trapped gases and (2) those released in pyrolysis, (3) contribution of the impactor, isotope

  1. High Resolution Spectroscopy of 1,2-Difluoroethane in a Molecular Beam: A Case Study of Vibrational Mode-Coupling

    DTIC Science & Technology

    1992-05-29

    Spectroscopy of 1,2- Difluoroethane in a Molecular Beam: A Case Study of Vibrational Mode-Coupling by Steven W. Mork, C. Cameron Miller, and Laura A...and sale; its distribution is unlimited. 92-14657 l9lll l l l , II a HIGH RESOLUTION SPECTROSCOPY OF 1,2- DIFLUOROETHANE IN A MOLECULAR BEAM: A CASE...14853-1301 Abstract The high resolution infrared spectrum of 1,2- difluoroethane (DFE) in a molecular beam has been obtained over the 2978-2996 cm-1

  2. Effect of the van der Waals interaction on the electron energy-loss near edge structure theoretical calculation.

    PubMed

    Katsukura, Hirotaka; Miyata, Tomohiro; Tomita, Kota; Mizoguchi, Teruyasu

    2016-07-21

    The effect of the van der Waals (vdW) interaction on the simulation of the electron energy-loss near edge structure (ELNES) by a first-principles band-structure calculation is reported. The effect of the vdW interaction is considered by the Tkatchenko-Scheffler scheme, and the change of the spectrum profile and the energy shift are discussed. We perform calculations on systems in the solid, liquid and gaseous states. The transition energy shifts to lower energy by approximately 0.1eV in the condensed (solid and liquid) systems by introducing the vdW effect into the calculation, whereas the energy shift in the gaseous models is negligible owing to the long intermolecular distance. We reveal that the vdW interaction exhibits a larger effect on the excited state than the ground state owing to the presence of an excited electron in the unoccupied band. Moreover, the vdW effect is found to depend on the local electron density and the molecular coordination. In addition, this study suggests that the detection of the vdW interactions exhibited within materials is possible by a very stable and high resolution observation.

  3. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    SciTech Connect

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; Watkins, S. P.

    2016-01-01

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar to other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.

  4. Hitomi X-ray Astronomy Satellite: Power of High-Resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Odaka, Hirokazu; Aff001

    2017-01-01

    Hitomi (ASTRO-H) is an X-ray observatory developed by an international collaboration led by JAXA. An X-ray microcalorimeter onboard this satellite has opened a new window of high-resolution spectroscopy with an unprecedented energy resolution of 5 eV (FWHM) at 6 keV. The spacecraft was launched on February 17, 2016 from Tanegashima Island, Japan, and we completed initial operations including deployment of the hard X-ray imagers on the extensible optical bench. All scientific instruments had successfully worked until the sudden loss of the mission on March 26. We have obtained a spectrum showing fully resolved emission lines through the first-light observation of the Perseus Cluster. The line-of-sight velocity dispersion of 164 +/- 10 km s-1 reveals the quiescent environment of intracluster medium at the cluster core, implying that measured cluster mass requires little correction for the turbulent pressure. We also discuss observations to the Galactic Center which could be performed with Hitomi.

  5. Triplet states in isotopically mixed anthracene crystals: High resolution optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Port, H.; Rund, D.; Wolf, H. C.

    1981-08-01

    The triplet O,O transitions of guest and host in isotopically mixed anthracene crystals of various compositions (A- h10, 13C-monosubstituted A- h10, A- d1h9, A- d2hg in A- d10 and A- d10 in A- h10) have been investigated using high resolution laser excitation spectroscopy. The guest aggregate spectra have been studied in polarized light as a function of guest concentration up to 15%. The analyses allow us to identify the monomer, dimer and trimer lines. From the dimer splittings the dominant resonance pair interactions are dedu The comparison of different mixed crystal systems with guest levels below and above the host exciton band reveals that quasiresonance and superexchange corrections are of minor importance. The experimental resonance pair interactions are used to calculate the triplet exciton band structure of anthracen and the observed guest polarization behaviour is interpreted quantitatively by the Rashba effect. Finally, the lower Davydov component of the host is s and broadened with increasing guest concentration. The shift is discussed using a theoretical model of Lifshitz.

  6. HIGH-RESOLUTION SPECTROSCOPY OF [Ne II] EMISSION FROM AA Tau AND GM Aur

    SciTech Connect

    Najita, Joan R.; Doppmann, Greg W.; Bitner, Martin A.; Richter, Matthew J.; Lacy, John H.; Jaffe, Daniel T.; Carr, John S.; Meijerink, Rowin; Blake, Geoffrey A.; Herczeg, Gregory J.; Glassgold, Alfred E.

    2009-05-20

    We present high-resolution (R = 80,000) spectroscopy of [Ne II] emission from two young stars, GM Aur and AA Tau, which have moderate to high inclinations. The emission from both sources appears centered near the stellar velocity and is broader than the [Ne II] emission measured previously for the face-on disk system TW Hya. These properties are consistent with a disk origin for the [Ne II] emission we detect, with disk rotation (rather than photoevaporation or turbulence in a hot disk atmosphere) playing the dominant role in the origin of the line width. In the non-face-on systems, the [Ne II] emission is narrower than the CO fundamental emission from the same sources. If the widths of both diagnostics are dominated by Keplerian rotation, this suggests that the [Ne II] emission arises from larger disk radii on average than does the CO emission. The equivalent width of the [Ne II] emission we detect is less than that of the spectrally unresolved [Ne II] feature in the Spitzer spectra of the same sources. Variability in the [Ne II] emission or the mid-infrared continuum, a spatially extended [Ne II] component, or a very (spectrally) broad [Ne II] component might account for the difference in the equivalent widths.

  7. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    DOE PAGES

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; ...

    2016-01-01

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar tomore » other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.« less

  8. Tracing Supernova Enrichment of the Nearest Young Star Forming Complex with High Resolution Stellar Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bubar, Eric Joseph; Mamajek, Eric E.; Pecaut, Mark

    2010-02-01

    The chemical evolution of the galaxy can be examined on a small scale locally by searching for evidence of enrichment by core collapse (type II) supernova explosions among stars belonging to the same star- forming complex. We propose to obtain high resolution spectroscopy of a sample of slowly rotating members of nearby, young stellar groups associated with the nearest star-forming complex: Scorpius-Centaurus. These spectra will be used to perform a precise spectroscopic abundance analysis to test for enrichment of the ~5 Myr-old Upper Scorpius region and neighboring regions by supernova explosions in the neighboring ~ 15 Myr-old Upper Centaurus Lupus and Lower Centaurus Crux subgroups. Enrichment by core-collapse supernovae can be traced by enhancements in oxygen and other alpha- element abundances compared to Fe-peak elements. These abundances can also be used for constraining the chemical homogeneity of members of Upper-Sco. This study will allow us to explore the processes of Galactic chemical evolution and SN enrichment on a small scale (< 0.1 kpc, <10-20 SN) in a complex with a relatively well constrained star formation history and high mass stellar membership.

  9. High resolution 4-D spectroscopy with sparse concentric shell sampling and FFT-CLEAN.

    PubMed

    Coggins, Brian E; Zhou, Pei

    2008-12-01

    Recent efforts to reduce the measurement time for multidimensional NMR experiments have fostered the development of a variety of new procedures for sampling and data processing. We recently described concentric ring sampling for 3-D NMR experiments, which is superior to radial sampling as input for processing by a multidimensional discrete Fourier transform. Here, we report the extension of this approach to 4-D spectroscopy as Randomized Concentric Shell Sampling (RCSS), where sampling points for the indirect dimensions are positioned on concentric shells, and where random rotations in the angular space are used to avoid coherent artifacts. With simulations, we show that RCSS produces a very low level of artifacts, even with a very limited number of sampling points. The RCSS sampling patterns can be adapted to fine rectangular grids to permit use of the Fast Fourier Transform in data processing, without an apparent increase in the artifact level. These artifacts can be further reduced to the noise level using the iterative CLEAN algorithm developed in radioastronomy. We demonstrate these methods on the high resolution 4-D HCCH-TOCSY spectrum of protein G's B1 domain, using only 1.2% of the sampling that would be needed conventionally for this resolution. The use of a multidimensional FFT instead of the slow DFT for initial data processing and for subsequent CLEAN significantly reduces the calculation time, yielding an artifact level that is on par with the level of the true spectral noise.

  10. High-resolution x-ray absorption spectroscopy studies of metal compounds in neurodegenerative brain tissue

    NASA Astrophysics Data System (ADS)

    Collingwood, J. F.; Mikhaylova, A.; Davidson, M. R.; Batich, C.; Streit, W. J.; Eskin, T.; Terry, J.; Barrea, R.; Underhill, R. S.; Dobson, J.

    2005-01-01

    Fluorescence mapping and microfocus X-ray absorption spectroscopy are used to detect, locate and identify iron biominerals and other inorganic metal accumulations in neurodegenerative brain tissue at sub-cellular resolution (<5 microns). Recent progress in developing the technique is reviewed. Synchrotron X-rays are used to map tissue sections for metals of interest, and XANES and XAFS are used to characterise anomalous concentrations of the metals in-situ so that they can be correlated with tissue structures and disease pathology. Iron anomalies associated with biogenic magnetite, ferritin and haemoglobin are located and identified in an avian tissue model with a pixel resolution ~5 microns. Subsequent studies include brain tissue sections from transgenic Huntington's mice, and the first high-resolution mapping and identification of iron biominerals in human Alzheimer's and control autopsy brain tissue. Technical developments include use of microfocus diffraction to obtain structural information about biominerals in-situ, and depositing sample location grids by lithography for the location of anomalies by conventional microscopy. The combined techniques provide a breakthrough in the study of both intra- and extra-cellular iron compounds and related metals in tissue. The information to be gained from this approach has implications for future diagnosis and treatment of neurodegeneration, and for our understanding of the mechanisms involved.

  11. High-resolution x-ray absorption spectroscopy studies of metal compounds in neurodegenerative brain tissue

    SciTech Connect

    Collingwood, J.F.; Mikhaylova, A.; Davidson, M.R.; Batich, C.; Streit, W.J.; Eskin, T.; Terry, J.; Barrea, R.; Underhill, R.S.; Dobson, J.

    2008-06-16

    Fluorescence mapping and microfocus X-ray absorption spectroscopy are used to detect, locate and identify iron biominerals and other inorganic metal accumulations in neurodegenerative brain tissue at sub-cellular resolution (< 5 microns). Recent progress in developing the technique is reviewed. Synchrotron X-rays are used to map tissue sections for metals of interest, and XANES and XAFS are used to characterize anomalous concentrations of the metals in-situ so that they can be correlated with tissue structures and disease pathology. Iron anomalies associated with biogenic magnetite, ferritin and haemoglobin are located and identified in an avian tissue model with a pixel resolution {approx} 5 microns. Subsequent studies include brain tissue sections from transgenic Huntington's mice, and the first high-resolution mapping and identification of iron biominerals in human Alzheimer's and control autopsy brain tissue. Technical developments include use of microfocus diffraction to obtain structural information about biominerals in-situ, and depositing sample location grids by lithography for the location of anomalies by conventional microscopy. The combined techniques provide a breakthrough in the study of both intra- and extra-cellular iron compounds and related metals in tissue. The information to be gained from this approach has implications for future diagnosis and treatment of neurodegeneration, and for our understanding of the mechanisms involved.

  12. Surface structure of an ionic liquid with high-resolution Rutherford backscattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, K.; Ohno, A.; Suzuki, M.; Kimura, K.

    2009-02-01

    The surface of an ionic liquid, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide ([TMPA] [TFSI]), is observed by high-resolution Rutherford backscattering spectroscopy (HRBS). The composition depth profiles are derived from the observed HRBS spectra through spectrum simulation. The observed composition is in good agreement with the stoichiometric composition at depths larger than ∼1 nm. The observed composition profiles, however, show pronounced structures at the surface. Fluorine profile has a sharp peak at ∼0.1 nm and a broad peak at ∼1.0 nm. The sulfur profile also has a peak at ∼0.35 nm. These results indicate that the molecules show preferred orientations at the surface. From the observed profiles, it was concluded that the C1 conformer of the [TFSI] anion is dominant over the C2 conformer at the surface in contrast to bulk, where the C2 conformer is known to be dominant. It was also found that C1 conformers are oriented with their CF3 groups pointing toward the vacuum in the outermost molecular layer.

  13. High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

    NASA Astrophysics Data System (ADS)

    Riley, M. A.; Simpson, J.; Paul, E. S.

    2016-12-01

    In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’. High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum-excitation energy plane that continue to surprise and fascinate scientists.

  14. High-contrast imaging and high-resolution spectroscopy observation of exoplanets

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Mawet, Dimitri; Hu, Renyu; Benneke, Björn

    2016-08-01

    Detection and characterization of exoplanets faces challenges of smaller angular separation and high contrast between exoplanets and their host stars. High contrast imaging (HCI) instruments equipped with coronagraphs are built to meet these challenges, providing a way of spatially suppressing and separating stellar flux from that of a planet. Another way of separating stellar flux can be achieved by high-resolution spectroscopy (HRS), exploiting the fact that spectral features are different between a star and a planet. Observing exoplanets with HCI+HRS will achieve a higher contrast than the spatial or the spectroscopic method alone, improving the sensitivity to planet detection and enabling the study of the physical and chemical processes. Here, we simulate the performance of a HCI+HRS instrument (i.e., the upgrade Keck NIRSPEC and the fiber injection unit) to study its potential in detecting and characterizing currently known directly imaged planets. The simulation considers the spectral information content of an exoplanet, telescope and instrument specifications and realistic noise sources. The result of the simulation helps to set system requirement and informs designs at system-level. We also perform a trade study for a HCI+HRS instrument for a space mission to study an Earth-like planet orbiting a Sun-like star at 10 pc.

  15. High-Resolution K-Band Spectroscopy of MWC 480 and V1331 Cyg

    NASA Astrophysics Data System (ADS)

    Najita, Joan R.; Doppmann, Greg W.; Carr, John S.; Graham, James R.; Eisner, J. A.

    2009-01-01

    We present high-resolution (R = 25,000-35,000) K-band spectroscopy of two young stars, MWC 480 and V1331 Cyg. Earlier spectrally dispersed (R = 230) interferometric observations of MWC 480 indicated the presence of an excess continuum emission interior to the dust sublimation radius, with a spectral shape that was interpreted as evidence for hot water emission from the inner disk of MWC 480. Our spectrum of V1331 Cyg reveals strong emission from CO and hot water vapor, likely arising in a circumstellar disk. In comparison, our spectrum of MWC 480 appears mostly featureless. We discuss possible ways in which strong water emission from MWC 480 might go undetected in our data. If strong water emission is in fact absent from the inner disk, as our data suggest, the continuum excess interior to the dust sublimation radius that is detected in the interferometric data must have another origin. We discuss possible physical origins for the continuum excess. The data presented herein were obtained at the W. M. Keck Observatory, in part from telescope time allocated to NASA through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  16. High-resolution Spectroscopy and Spectropolarimetry of Selected δ-Sct Pulsating Variables

    NASA Astrophysics Data System (ADS)

    Joshi, Santosh; Semenko, Eugene; Moiseeva, A.; Sharma, Kaushal; Joshi, Y. C.; Sachkov, M.; Singh, Harinder P.; Kumar, Yerra Bharat

    2017-01-01

    The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay with stellar atmosphere and circumstellar environment. The prime objective of the present study is to determine the atmospheric parameters of a set of Am stars to understand their evolutionary status. Atmospheric abundances and basic parameters are determined using full spectrum fitting technique by comparing the high-resolution spectra to the synthetic spectra. To know the evolutionary status we derive the effective temperature and luminosity from different methods and compare them with the literature. The location of these stars in the H-R diagram demonstrate that all the sample stars are evolved from the Zero-Age-Main-Sequence towards Terminal-Age-Main-Sequence and occupy the region of δ Sct instability strip. The abundance analysis shows that the light elements e.g. Ca and Sc are underabundant while iron peak elements such as Ba, Ce etc. are overabundant and these chemical properties are typical for Am stars. The results obtained from the spectropolarimetric analysis shows that the longitudinal magnetic fields in all the studied stars are negligible that gives further support their Am class of peculiarity.

  17. Differentiating brown and white adipose tissues by high-resolution diffusion NMR spectroscopy.

    PubMed

    Verma, Sanjay Kumar; Nagashima, Kaz; Yaligar, Jadegoud; Michael, Navin; Lee, Swee Shean; Xianfeng, Tian; Gopalan, Venkatesh; Sadananthan, Suresh Anand; Anantharaj, Rengaraj; Velan, S Sendhil

    2017-01-01

    There are two types of fat tissues, white adipose tissue (WAT) and brown adipose tissue (BAT), which essentially perform opposite functions in whole body energy metabolism. There is a large interest in identifying novel biophysical properties of WAT and BAT by a quantitative and easy-to-run technique. In this work, we used high-resolution pulsed field gradient diffusion NMR spectroscopy to study the apparent diffusion coefficient (ADC) of fat molecules in rat BAT and WAT samples. The ADC of fat in BAT and WAT from rats fed with a chow diet was compared with that of rats fed with a high-fat diet to monitor how the diffusion properties change due to obesity-associated parameters such as lipid droplet size, fatty acid chain length, and saturation. Feeding a high-fat diet resulted in increased saturation, increased chain lengths, and reduced ADC of fat in WAT. The ADC of fat was lower in BAT relative to WAT in rats fed both chow and high-fat diets. Diffusion of fat was restricted in BAT due to the presence of small multilocular lipid droplets. Our findings indicate that in vivo diffusion might be a potential way for better delineation of BAT and WAT in both lean and obese states.

  18. Spectral characteristics of chlorites and Mg-serpentines using high- resolution reflectance spectroscopy

    USGS Publications Warehouse

    King, T.V.V.; Clark, R.N.

    1989-01-01

    The present laboratory study using high-resolution reflectance spectroscopy (0.25-2.7 ??m) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end-members of the Mg-rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a function of Fe/Mg ratio (~8-38 wt% Fe). The position and relative strength of the 1.4-??m absorption feature in the trioctahedral chlorites appear to be correlated to the total iron content and/or the Mg/Si ratio and the loss on ignition values of the sample. Spectral differences in the 2.3-??m wavelength region can be attributed to differences in lattice environments and are characteristic for specific trioctahedral chlorites. The 1.4-??m feature in the isochemical Mg-rich serpentines (total iron content ~1.5-7.0 wt%) show marked spectral differences, apparently due to structural differences. -Authors

  19. Quantitative neuropathology by high resolution magic angle spinning proton magnetic resonance spectroscopy

    PubMed Central

    Cheng, L. L.; Ma, M. J.; Becerra, L.; Ptak, T.; Tracey, I.; Lackner, A.; González, R. G.

    1997-01-01

    We describe a method that directly relates tissue neuropathological analysis to medical imaging. Presently, only indirect and often tenuous relationships are made between imaging (such as MRI or x-ray computed tomography) and neuropathology. We present a biochemistry-based, quantitative neuropathological method that can help to precisely quantify information provided by in vivo proton magnetic resonance spectroscopy (1HMRS), an emerging medical imaging technique. This method, high resolution magic angle spinning (HRMAS) 1HMRS, is rapid and requires only small amounts of unprocessed samples. Unlike chemical extraction or other forms of tissue processing, this method analyzes tissue directly, thus minimizing artifacts. We demonstrate the utility of this method by assessing neuronal damage using multiple tissue samples from differently affected brain regions in a case of Pick disease, a human neurodegenerative disorder. Among different regions, we found an excellent correlation between neuronal loss shown by traditional neurohistopathology and decrease of the neuronal marker N-acetylaspartate measured by HRMAS 1HMRS. This result demonstrates for the first time, to our knowledge, a direct, quantitative link between a decrease in N-acetylaspartate and neuronal loss in a human neurodegenerative disease. As a quantitative method, HRMAS 1HMRS has potential applications in experimental and clinical neuropathologic investigations. It should also provide a rational basis for the interpretation of in vivo 1HMRS studies of human neurological disorders. PMID:9177231

  20. High-efficiency blazed transmission gratings for high-resolution soft x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alexander R.; Schattenburg, Mark L.

    2015-09-01

    High-resolution spectroscopy of astrophysical sources is the key to gaining a quantitative understanding of the history, dynamics, and current conditions of the cosmos. A large-area (> 1,000 cm2), high resolving power (R = λ/Δλ> 3000) soft x-ray grating spectrometer (XGS) that covers the lines of C, N, O, Ne and Fe ions is the ideal tool to address a number of high-priority science questions from the 2010 Decadal Survey, such as the connection between super-massive black holes and large-scale structure via cosmic feedback, the evolution of large- scale structure, the behavior of matter at high densities, and the conditions close to black holes. While no grating missions or instruments are currently approved, an XGS aboard a potential future X-ray Surveyor could easily surpass the above performance metrics. To improve the chances for future soft x-ray grating spectroscopy missions or instruments, grating technology has to progress and advance to higher Technology Readiness Levels (TRLs). To that end we have developed Critical-Angle Transmission (CAT) gratings that combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, high transparency at higher energies). A CAT grating-based spectrometer can provide performance 1-2 orders of magnitude better than current grating instruments on Chandra and Newton-XMM with minimal resource requirements. At present we have fabricated large-area freestanding CAT gratings with narrow integrated support structures from silicon-on- insulator wafers using advanced lithography and a combination of deep reactive-ion and wet etching. Our latest x-ray test results show record high absolute diffraction efficiencies in blazed orders in excess of 30% with room for improvement.

  1. Metabolomic Analysis of Rat Brain by High Resolution Nuclear Magnetic Resonance Spectroscopy of Tissue Extracts

    PubMed Central

    Lutz, Norbert W.; Béraud, Evelyne; Cozzone, Patrick J.

    2014-01-01

    Studies of gene expression on the RNA and protein levels have long been used to explore biological processes underlying disease. More recently, genomics and proteomics have been complemented by comprehensive quantitative analysis of the metabolite pool present in biological systems. This strategy, termed metabolomics, strives to provide a global characterization of the small-molecule complement involved in metabolism. While the genome and the proteome define the tasks cells can perform, the metabolome is part of the actual phenotype. Among the methods currently used in metabolomics, spectroscopic techniques are of special interest because they allow one to simultaneously analyze a large number of metabolites without prior selection for specific biochemical pathways, thus enabling a broad unbiased approach. Here, an optimized experimental protocol for metabolomic analysis by high-resolution NMR spectroscopy is presented, which is the method of choice for efficient quantification of tissue metabolites. Important strengths of this method are (i) the use of crude extracts, without the need to purify the sample and/or separate metabolites; (ii) the intrinsically quantitative nature of NMR, permitting quantitation of all metabolites represented by an NMR spectrum with one reference compound only; and (iii) the nondestructive nature of NMR enabling repeated use of the same sample for multiple measurements. The dynamic range of metabolite concentrations that can be covered is considerable due to the linear response of NMR signals, although metabolites occurring at extremely low concentrations may be difficult to detect. For the least abundant compounds, the highly sensitive mass spectrometry method may be advantageous although this technique requires more intricate sample preparation and quantification procedures than NMR spectroscopy. We present here an NMR protocol adjusted to rat brain analysis; however, the same protocol can be applied to other tissues with minor

  2. Effects of inverse degree on electronic structure and electron energy-loss spectrum in zinc ferrites

    NASA Astrophysics Data System (ADS)

    Sun, D.; Wang, M. X.; Zhang, Z. H.; Tao, H. L.; He, M.; Song, B.; Li, Q.

    2015-12-01

    First-principles calculations were performed to study the effects of inverse degree in zinc ferrite on electronic structure and properties. The electron energy-loss near-edge fine structure (ELNES) were simulated, and the splitting of peak and intensities of the oxygen K-edges can be used to identify the inversion of zinc ferrite. More Fe3+ transferring from the octahedral sites to the tetrahedral sites lead to the changing of the ligand shells surrounding the absorbing atom, accounting for the observed changing in ELNES. The standard criterion for determining the reversal extent of the cations in zinc ferrite by ELNES was given.

  3. Vanishing Electronic Energy Loss of Very Slow Light Ions in Insulators with Large Band Gaps

    SciTech Connect

    Markin, S. N.; Primetzhofer, D.; Bauer, P.

    2009-09-11

    Electronic energy loss of light ions in nanometer films of materials with large band gaps has been studied for very low velocities. For LiF, a threshold velocity is observed at 0.1 a.u. (250 eV/u), below which the ions move without transferring energy to the electronic system. For KCl, a lower (extrapolated) threshold velocity is found, identical for H and He ions. For SiO{sub 2}, no clear velocity threshold is observed for He particles. For protons and deuterons, electronic stopping is found to perfectly fulfill velocity scaling, as expected for binary ion-electron interaction.

  4. Synergistic effects of nuclear and electronic energy loss in KTaO3 under ion irradiation

    DOE PAGES

    Zarkadoula, Eva; Jin, Ke; Zhang, Yanwen; ...

    2017-01-09

    In this paper, we use the inelastic thermal spike model for insulators and molecular dynamic simulations to investigate the effects of pre-existing damage on the energy dissipation and structural alterations in KTaO3 under irradiation with 21 MeV Ni ions. Our results reveal a synergy between the pre-existing defects and the electronic energy loss, indicating that the defects play an important role on the energy deposition in the system. Our findings highlight the need for better understanding on the role of defects in electronic energy dissipation and the coupling of the electronic and atomic subsystems.

  5. The relation between the electron energy loss spectra of hafnia and its dielectric function

    NASA Astrophysics Data System (ADS)

    Vos, Maarten; Grande, Pedro Luis

    2014-12-01

    Recently two papers have been published deriving the dielectric function from hafnia from electron energy loss data (Jin et al. Applied Physics Letters 100 083713 (2006), Behar et al. Phys. Rev A. 80 062901 (2009)). The obtained dielectric functions are compared in their optical limit and differ considerably. Here we try to clarify the situation by presenting new experimental data and review the analysis procedure used in the earlier work. We conclude that the discrepancy is most likely caused by a shortcoming in the way that the momentum-dependence of the dielectric function is modelled.

  6. Electronic energy loss spectra from mono-layer to few layers of phosphorene

    NASA Astrophysics Data System (ADS)

    Mohan, Brij; Thakur, Rajesh; Ahluwalia, P. K.

    2016-05-01

    Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

  7. IGRINS Near-IR High-resolution Spectroscopy of Multiple Jets around LkHα 234

    NASA Astrophysics Data System (ADS)

    Oh, Heeyoung; Pyo, Tae-Soo; Yuk, In-Soo; Park, Byeong-Gon; Park, Chan; Chun, Moo-Young; Pak, Soojong; Kim, Kang-Min; Sok Oh, Jae; Jeong, Ueejeong; Yu, Young Sam; Lee, Jae-Joon; Kim, Hwihyun; Hwang, Narae; Kaplan, Kyle; Pavel, Michael; Mace, Gregory; Lee, Hye-In; Nguyen Le, Huynh Anh; Lee, Sungho; Jaffe, Daniel T.

    2016-02-01

    We present the results of high-resolution near-IR spectroscopy toward the multiple outflows around the Herbig Be star LkHα 234 using the Immersion Grating Infrared Spectrograph. Previous studies indicate that the region around LkHα 234 is complex, with several embedded young stellar objects and the outflows associated with them. In simultaneous H- and K-band spectra from HH 167, we detected 5 [Fe ii] and 14 H2 emission lines. We revealed a new [Fe ii] jet driven by radio continuum source VLA 3B. Position-velocity diagrams of the H2 1-0 S(1) λ2.122 μm line show multiple velocity peaks. The kinematics may be explained by a geometrical bow shock model. We detected a component of H2 emission at the systemic velocity (VLSR = -10.2 km s-1) along the whole slit in all slit positions, which may arise from the ambient photodissociation region. Low-velocity gas dominates the molecular hydrogen emission from knots A and B in HH 167, which is close to the systemic velocity; [Fe ii] emission lines are detected farther from the systemic velocity, at VLSR = -100--130 km s-1. We infer that the H2 emission arises from shocked gas entrained by a high-velocity outflow. Population diagrams of H2 lines imply that the gas is thermalized at a temperature of 2500-3000 K and the emission results from shock excitation. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

  8. IGRINS NEAR-IR HIGH-RESOLUTION SPECTROSCOPY OF MULTIPLE JETS AROUND LkHα 234

    SciTech Connect

    Oh, Heeyoung; Yuk, In-Soo; Park, Byeong-Gon; Park, Chan; Chun, Moo-Young; Kim, Kang-Min; Oh, Jae Sok; Jeong, Ueejeong; Yu, Young Sam; Lee, Jae-Joon; Kim, Hwihyun; Hwang, Narae; Lee, Sungho; Pyo, Tae-Soo; Pak, Soojong; Lee, Hye-In; Le, Huynh Anh Nguyen; Kaplan, Kyle; Pavel, Michael; Mace, Gregory; and others

    2016-02-01

    We present the results of high-resolution near-IR spectroscopy toward the multiple outflows around the Herbig Be star LkHα 234 using the Immersion Grating Infrared Spectrograph. Previous studies indicate that the region around LkHα 234 is complex, with several embedded young stellar objects and the outflows associated with them. In simultaneous H- and K-band spectra from HH 167, we detected 5 [Fe ii] and 14 H{sub 2} emission lines. We revealed a new [Fe ii] jet driven by radio continuum source VLA 3B. Position–velocity diagrams of the H{sub 2} 1−0 S(1) λ2.122 μm line show multiple velocity peaks. The kinematics may be explained by a geometrical bow shock model. We detected a component of H{sub 2} emission at the systemic velocity (V{sub LSR} = −10.2 km s{sup −1}) along the whole slit in all slit positions, which may arise from the ambient photodissociation region. Low-velocity gas dominates the molecular hydrogen emission from knots A and B in HH 167, which is close to the systemic velocity; [Fe ii] emission lines are detected farther from the systemic velocity, at V{sub LSR} = −100–−130 km s{sup −1}. We infer that the H{sub 2} emission arises from shocked gas entrained by a high-velocity outflow. Population diagrams of H{sub 2} lines imply that the gas is thermalized at a temperature of 2500–3000 K and the emission results from shock excitation.

  9. Imaging and high-resolution spectroscopy of the Planetary Nebula NGC 3242

    NASA Astrophysics Data System (ADS)

    Gómez-Muñoz, Marco Antonio; Wendolyn Blanco Cárdenas, Mónica; Vázquez, Roberto; Zavala, Saúl A.; Guillén, Pedro F.; Ayala, Sandra A.

    2015-08-01

    We present a high-resolution imaging and high-dispersion spectroscopy study of the complex morphological and kinematical structure of the planetary nebula NGC 3242. We analyze narrowband Hα, [O III] and [N II] images, addressing important morphological features: in the [O III] image we found one knot oriented to PA=-4°, in the [N II] image, three knots oriented at PA1=155°, PA2=+157°, and PA3=-45.5°, and in the Hα image, two bubbles in the internal region, one of them oriented toward SE and the other toward NW. Additionally we used the unsharp-masking technique and found faint structures in the halo that have not been studied before. These structures are presented in two pairs of arcs, one pair oriented toward PA=-35° and the other toward PA=140°. NGC 3242 is a morphologically rich PN with bubbles, asymmetrical outflows, and some knots in a double-shell nebular structure. Ground-based long-slit echelle spectra were obtained crossing NGC 3242 at twelve different positions to precisely determine kinematical features in the structure of the nebula. We obtain a systemic velocity of VLSR=-6.6 km/s. We have used the software SHAPE (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to reconstruct a 3D model of NGC 3242 which fits all our observational data. Preliminary results (deprojected velocities and kinematical ages) of all these structures will be presented.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  10. High-Resolution Spectroscopy of Stratospheric Ethane Following the Jupiter Impact of 2009

    NASA Technical Reports Server (NTRS)

    Fast, Kelly; Kostiuk, Theodor; Livengood, Timothy A.; Hewagama, Tilak; Amen, John

    2010-01-01

    We report on high-resolution infrared spectroscopy of ethane (C2H6) performed at the latitude of an impact site on Jupiter discovered on 19 July 2009 by A. Wesley from a location in Murrumbateman, Australia. The observations used the NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind and Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. HIPWAC is a mid-infrared (9-12 microns) heterodyne spectrometer operating at the highest limit of spectral resolving power (lambda\\Delta\\lambda > l06), providing information on atmospheric constituent abundance and temperature through fully resolved tine shapes. Ethane is a stable trace product of methane photochemistry that is nearly uniformly mixed in Jupiter's stratosphere, providing an effective probe of that altitude region. Ethane emission line profiles near 11,74 microns in the Ug band were measured in Jupiter's stratosphere at 25 MHz (11.00083/cm) resolution. A sequence of spectra of ethane acquired over a range of longitude at the impact latitude (56S planetocentric) probes constituent abundance and temperature profile, both on and off the impact region. Near the site of the impact, ethane emission increased above levels measured well outside the impact region. Radiative transfer analysis indicates increased ethane mole fraction (30% greater). Variation in the measured continuum level and line intensities within 75deg of the impact longitude indicate the presence of an opacity source (haze) at altitudes near and above the tropopause and as high as the 10-mbar level near the impact site. The indication of possible haze opacity up to the 10-mbar level in the atmosphere is consistent with measurements made by HIPWAC's predecessor as part of the IRTF Shoemaker Levy-9 campaign in 1994.

  11. Development of an Apparatus for High-Resolution Auger Photoelectron Coincidence Spectroscopy (APECS) and Electron Ion Coincidence (EICO) Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kakiuchi, Takuhiro; Hashimoto, Shogo; Fujita, Narihiko; Mase, Kazuhiko; Tanaka, Masatoshi; Okusawa, Makoto

    We have developed an electron electron ion coincidence (EEICO) apparatus for high-resolution Auger photoelectron coincidence spectroscopy (APECS) and electron ion coincidence (EICO) spectroscopy. It consists of a coaxially symmetric mirror electron energy analyzer (ASMA), a miniature double-pass cylindrical mirror electron energy analyzer (DP-CMA), a miniature time-of-flight ion mass spectrometer (TOF-MS), a magnetic shield, an xyz stage, a tilt-adjustment mechanism, and a conflat flange with an outer diameter of 203 mm. A sample surface was irradiated by synchrotron radiation, and emitted electrons were energy-analyzed and detected by the ASMA and the DP-CMA, while desorbed ions were mass-analyzed and detected by the TOF-MS. The performance of the new EEICO analyzer was evaluated by measuring Si 2p photoelectron spectra of clean Si(001)-2×1 and Si(111)-7×7, and by measuring Si-L23VV-Si-2p Auger photoelectron coincidence spectra (Si-L23VV-Si-2p APECS) of clean Si(001)-2×1.

  12. Probing Chemical Dynamics with High Resolution Spectroscopy: Chirped-Pulse Fourier-Transform Microwave Spectroscopy Coupled with a Hyperthermal Source

    NASA Astrophysics Data System (ADS)

    Kidwell, Nathanael M.; Vara, Vanesa Vaquero; Mehta-Hurt, Deepali N.; Korn, Joseph A.; Dian, Brian C.; Zwier, Timothy S.

    2013-06-01

    Chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy has proven to be a well-suited technique for the rapid study and spectral identification of molecular species due to its ultra-broadband capability and excellent specificity to molecular structure from high-resolution rotational transitions. This talk will describe initial results from combining CP-FTMW detection with a hyperthermal nozzle source. This source has the advantage of producing traditionally high thermal product densities in a pulsed supersonic expansion with a short contact time compared to conventional pyrolysis. Used in tandem, CP-FTMW spectroscopy and the hyperthermal nozzle in a supersonic expansion is a powerful method that can produce and detect changes in conformation and isomer populations, and characterize important intermediates on the reaction surface of a precursor. In particular, we show its utility to provide insight into the unimolecular decomposition pathways of model lignin compounds and alternative biofuels. Preliminary results will be discussed including spectroscopic evidence for formation of cyclopentadienone in the pyrolysis of a lignin derivative guaiacol (o-methoxyphenol).

  13. Exploiting high resolution Fourier transform spectroscopy to inform the development of a quantum cascade laser based explosives detection systems

    NASA Astrophysics Data System (ADS)

    Carlysle, Felicity; Nic Daeid, Niamh; Normand, Erwan; McCulloch, Michael

    2012-10-01

    Fourier Transform infrared spectroscopy (FTIR) is regularly used in forensic analysis, however the application of high resolution Fourier Transform infrared spectroscopy for the detection of explosive materials and explosive precursors has not been fully explored. This project aimed to develop systematically a protocol for the analysis of explosives and precursors using Fourier Transform infrared spectroscopy and basic data analysis to enable the further development of a quantum cascade laser (QCL) based airport detection system. This paper details the development of the protocol and results of the initial analysis of compounds of interest.

  14. Valence electron energy loss study of Fe-doped SrTiO3 and a sigma13 boundary: electronic structure and dispersion forces.

    PubMed

    van Benthem, K; French, R H; Sigle, W; Elsässer, C; Rühle, M

    2001-02-01

    Valence electron energy loss spectroscopy in a dedicated scanning transmission electron microscope has been used to obtain the interband transition strength of a sigma13 tilt grain boundary in SrTiO3. In a first step the electronic structure of bulk SrTiO3 has been analysed quantitatively by comparing VEELS spectra with vacuum ultraviolet spectra and with ab initio density of states calculations. The electronic structure of a near sigma13 grain boundary and the corresponding dispersion forces were then determined by spatially resolved VEELS. Also the effects of delocalization of the inelastic scattering processes were estimated and compared with results from the literature.

  15. Emerging Trends on the Volatile Chemistry in Comets as Measured with High-Resolution Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dello Russo, Neil; Kawakita, Hideyo; Vervack, Ronald J., Jr.; Weaver, Harold A.

    2016-10-01

    A systematic analysis of the mixing ratios with respect to H2O for eight species (CH3OH, HCN, NH3, H2CO, C2H2, C2H6, CH4, and CO) measured with high-resolution infrared spectroscopy is presented. Some trends are beginning to emerge when mixing ratios in individual comets are compared to average mixing ratios obtained for all species within the population. The variation in mixing ratios for all measured species is at least an order of magnitude. Overall, Jupiter-family comets are depleted in volatile species with respect to H2O compared to long-period Oort cloud comets, with the most volatile species showing the greatest relative depletion. There is a high positive correlation between the mixing ratios of HCN, C2H6, and CH4, whereas NH3, H2CO, and C2H2 are moderately correlated with each other but generally uncorrelated or show only weak correlation with other species. CO is generally uncorrelated with the other measured species possibly because it has the highest volatility and is therefore more susceptible to thermal evolutionary effects. Molecular mixing ratios for CH3OH, HCN, C2H6, and CH4 show an expected behavior with heliocentric distance suggesting a dominant ice source, whereas there is emerging evidence that the mixing ratios of NH3, H2CO, and C2H2 may increase at small heliocentric distances, suggesting the possibility of additional sources related to the thermal decomposition of organic dust. Although this provides information on the composition of the most volatile grains in comets, it presents an additional difficulty in classifying comet chemistry because most comets within this dataset were only observed over a limited range of heliocentric distance. Optical and infrared comparisons indicate that mixing ratios of daughter species and potential parents from cometary ices are sometimes but not always consistent with one another. This suggests that in many comets there are significant sources of C2 and/or CN from grains, and that the importance of these

  16. A search for inversion layers in hot Jupiters with high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Hood, Callie; Birkby, Jayne; Lopez-Morales, Mercedes

    2017-01-01

    At present, the existence of thermal inversion layers in hot Jupiter atmospheres is uncertain due to conflicting results on their detection. However, understanding the thermal structure of exoplanet atmospheres is crucial to measuring their chemical compositions because the two quantities are highly interdependent. Here, we present high-resolution infrared spectroscopy of a hot Jupiter taken at 3.5 μm with CRIRES (R~100,000) on the Very Large Telescope. We directly detect the spectrum of the planet by tracing the radial-velocity shift of water features in its atmosphere during approximately one tenth of its orbit. We removed telluric contamination effects and the lines of the host star from our observed combined light spectra using singular value decomposition, then cross-correlated these processed spectra with a grid of high spectral resolution molecular templates containing features from water, methane, and carbon dioxide. The templates included atmospheric profiles with and without thermal inversion i.e. emission and absorption lines, respectively. We find evidence of water emission features in the planet’s dayside spectrum at a signal-to-noise of 4.7, indicative of a thermal inversion in the planet's atmosphere within the pressures ranges probed by our observations. The direct detection of emission lines at high spectral resolution in the planet spectrum make it one of the most unambiguous detections of a thermal inversion layer in an exoplanet atmosphere to date. However, we are carrying out further data analysis to ensure the robustness of the signal. Future observations of other molecules that could cause inversion layers, e.g. titanium oxide, would provide strong additional evidence of the inversion and help further our understanding of the behavior of highly irradiated giant planet atmospheres.The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. 1262851, and by the

  17. High Resolution Photoelectron Spectroscopy of Au_2^- and Au_4^- by Photoelectron Imaging

    NASA Astrophysics Data System (ADS)

    Leon, Iker; Yang, Zheng; Wang, Lai-Sheng

    2013-06-01

    We report high resolution photoelectron spectra of Au_2^- and Au_4^- obtained with a newly-built photoelectron imaging apparatus. Gold anions are produced by laser vaporization and the desired specie is mass selected and focused into the collinear velocity-map imaging (VMI) lens assembly. The design of the imaging lens has allowed us to obtain less than 0.9% energy resolution for high kinetic energy electrons ( > 1eV) while maintaining wavenumber resolution for low kinetic energy electrons. Although gold dimer and tetramer have been studied in the past, we present spectroscopic results under high resolution. For Au_2^-, we report high resolution spectra with an accurate determination of the electron affinity together with a complete vibrational assignment, for both the anion and neutral ground states, while for Au_4^-, we are able to resolve a low frequency mode and obtain accurately the adiabatic detachment energy.

  18. Magnetic dynamics studied by high-resolution electron spectroscopy and time-resolved electron microscopy

    NASA Astrophysics Data System (ADS)

    Jayaraman, Rajeswari

    Future information technology requires an increased magnetically encoded data density and novel electromagnetic modes of data transfer. While to date magnetic properties are observed and characterized mostly statically, the need emerges to monitor and capture their fast dynamics. In this talk, I will focus on the spin dynamics i.e. spin wave excitations and the dynamics of a new topological distribution of spins termed ``skyrmions''. Wave packets of spin waves offer the unique capability to transport a quantum bit, the spin, without the transport of charge or mass. Here, large wave-vector spin waves are of particular interest as they admit spin localization within a few nanometers. By using our recently developed electron energy loss spectrometer, we could study such spin waves in ultrathin films with an unprecedented energy resolution of 4 meV. By virtue of the finite penetration depth of low energy electrons, spin waves localized at interfaces between a substrate and a thin capping layer can be been studied yielding information about the exchange coupling between atoms at the interface. The quantization of spin waves with wave vectors perpendicular to the film gives rise to standing modes to which EELS has likewise access. Such studies when carried out as function of the film thickness again yield information on the layer dependence of the exchange coupling. Magnetic skyrmions are promising candidates as information carriers in logic or storage devices. Currently, little is known about the influence of disorder, defects, or external stimuli on the spatial distribution and temporal evolution of the skyrmion lattice. In this talk, I will describe the dynamical role of disorder in a large and flat thin film of Cu2OSeO3, exhibiting a skyrmion phase in an insulating material. We image up to 70,000 skyrmions by means of cryo-Lorentz Transmission Electron Microscopy as a function of the applied magnetic field. In the skyrmion phase, dislocations are shown to cause the

  19. High-Resolution Vibration-Rotation Spectroscopy of CO[subscript 2]: Understanding the Boltzmann Distribution

    ERIC Educational Resources Information Center

    Castle, Karen J.

    2007-01-01

    In this undergraduate physical chemistry laboratory experiment, students acquire a high-resolution infrared absorption spectrum of carbon dioxide and use their data to show that the rotational-vibrational state populations follow a Boltzmann distribution. Data are acquired with a mid-infrared laser source and infrared detector. Appropriate…

  20. Tunneling and tunneling switching dynamics in phenol and its isotopomers from high-resolution FTIR spectroscopy with synchrotron radiation.

    PubMed

    Albert, Sieghard; Lerch, Philippe; Prentner, Robert; Quack, Martin

    2013-01-02

    Tunneling and chemical reactions by tunneling switching are reported for phenol and ortho-deuterophenol on the basis of high-resolution FTIR spectroscopy. Tunneling splittings are measured for the torsional motion in the ground and several vibrationally excited states of phenol. Tunneling times range from 10 ns to 1 ps, depending on excitation. For more-highly excited torsional levels in ortho-deuterophenol, delocalization and chemical reaction by tunneling switching is found.

  1. Coordination defects in bismuth-modified arsenic selenide glasses: High-resolution x-ray photoelectron spectroscopy measurements

    SciTech Connect

    Golovchak, Roman; Shpotyuk, Oleh

    2008-05-01

    The possibility of coordination defects formation in Bi-modified chalcogenide glasses is examined by high-resolution x-ray photoelectron spectroscopy. The results provide evidence for the formation of positively charged fourfold coordinated defects on As and Bi sites in glasses with low Bi concentration. At high Bi concentration, mixed As{sub 2}Se{sub 3}-Bi{sub 2}Se{sub 3} nanocrystallites are formed in the investigated Se-rich As-Se glasses.

  2. Synchrotron-based rotationally resolved high-resolution FTIR spectroscopy of azulene and the unidentified infrared bands of astronomy.

    PubMed

    Albert, Sieghard; Lerch, Philippe; Quack, Martin

    2013-10-07

    Chasing the unidentified IR bands: The first rotationally resolved high-resolution infrared spectrum of azulene is reported using synchrotron Fourier transform infrared spectroscopy including a rovibrational analysis of the out-of-plane fundamental ν44. Comparison of azulene, naphthalene, indole, and biphenyl infrared bands leads to coincidences with UIR bands at 12.8 μm with naphthalene and at 13.55 and 14.6 μm with biphenyl bands, but excluding azulene as a strong absorber.

  3. Quantitative analysis of electron energy loss spectra and modelling of optical properties of multilayer systems for extreme ultraviolet radiation regime

    SciTech Connect

    Gusenleitner, S.; Hauschild, D.; Reinert, F.; Handick, E.

    2014-03-28

    Ruthenium capped multilayer coatings for use in the extreme ultraviolet (EUV) radiation regime have manifold applications in science and industry. Although the Ru cap shall protect the reflecting multilayers, the surface of the heterostructures suffers from contamination issues and surface degradation. In order to get a better understanding of the effects of these impurities on the optical parameters, reflection electron energy loss spectroscopy (REELS) measurements of contaminated and H cleaned Ru multilayer coatings were taken at various primary electron beam energies. Experiments conducted at low primary beam energies between 100 eV and 1000 eV are very surface sensitive due to the short inelastic mean free path of the electrons in this energy range. Therefore, influences of the surface condition on the above mentioned characteristics can be appraised. In this paper, it can be shown that carbon and oxide impurities on the mirror surface decrease the transmission of the Ru cap by about 0.75% and the overall reflectance of the device is impaired as the main share of the non-transmitted EUV light is absorbed in the contamination layer.

  4. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  5. Reflection electron energy loss spectrum of single layer graphene measured on a graphite substrate

    NASA Astrophysics Data System (ADS)

    Werner, Wolfgang S. M.; Bellissimo, Alessandra; Leber, Roland; Ashraf, Afshan; Segui, Silvina

    2015-05-01

    Reflection electron energy loss spectra (REELS) have been measured on a highly oriented pyrolytic graphite (HOPG) sample. Two spectra were measured for different energies, 1600 eV, being more sensitive to the bulk and 500 eV being more sensitive to the surface. The energy loss distributions for a single surface and bulk excitation were extracted from the two spectra using a simple decomposition procedure. These single scattering loss distributions correspond to electron trajectories with significantly different penetration depths and agree with energy loss spectra measured on free standing single layer graphene and multilayer graphene (i.e. graphite). This result implies that for a layered electron gas (LEG) material, the number of layers which responds in a correlated fashion to an external perturbation is determined by the depth range penetrated by the external perturbation, and not by the number of layers actually present in the specimen.

  6. Comparison between Monte Carlo and experimental aluminum and silicon electron energy loss spectra

    NASA Astrophysics Data System (ADS)

    Dapor, Maurizio; Calliari, Lucia; Scarduelli, Giorgina

    2011-07-01

    A Monte Carlo (MC) simulation is described and used to calculate the energy distribution spectra of backscattered electrons from Al and Si. For the simulations, elastic scattering cross sections are calculated by numerically solving the Dirac equation in a central field. Inelastic scattering cross sections are computed within the dielectric response theory developed by Ritchie, and by Tung et al. Extension from the optical case to non-zero momentum transfer is done according to Ritchie and Howie. To evaluate surface and bulk contributions to the spectra, the Monte Carlo model treats the surface excitations according to the Werner differential surface and volume excitation probability theory. The Monte Carlo calculations are compared with the experimental reflection electron energy loss (REEL) spectra acquired in our laboratory.

  7. The effect of electronic energy loss on irradiation-induced grain growth in nanocrystalline oxides.

    PubMed

    Zhang, Yanwen; Aidhy, Dilpuneet S; Varga, Tamas; Moll, Sandra; Edmondson, Philip D; Namavar, Fereydoon; Jin, Ke; Ostrouchov, Christopher N; Weber, William J

    2014-05-07

    Grain growth of nanocrystalline materials is generally thermally activated, but can also be driven by irradiation at much lower temperature. In nanocrystalline ceria and zirconia, energetic ions deposit their energy to both atomic nuclei and electrons. Our experimental results have shown that irradiation-induced grain growth is dependent on the total energy deposited, where electronic energy loss and elastic collisions between atomic nuclei both contribute to the production of disorder and grain growth. Our atomistic simulations reveal that a high density of disorder near grain boundaries leads to locally rapid grain movement. The additive effect from both electronic excitation and atomic collision cascades on grain growth demonstrated in this work opens up new possibilities for controlling grain sizes to improve functionality of nanocrystalline materials.

  8. Single particle plasmon spectroscopy of silver nanowires and gold nanorods.

    PubMed

    N'Gom, Moussa; Ringnalda, Jan; Mansfield, John F; Agarwal, Ashish; Kotov, Nicholas; Zaluzec, Nestor J; Norris, Theodore B

    2008-10-01

    The excitation of surface plasmons in individual silver nanowires and gold nanorods is investigated by means of high-resolution electron energy loss spectroscopy in a transmission electron microscope. The transverse and longitudinal modes of these nanostructures are resolved, and the size variation of the plasmon peaks is studied. The effect of electromagnetic coupling between closely spaced nanoparticles is also observed. Finally, the relation between energy-loss measurements and optical spectroscopy of nanoparticle plasmon modes is discussed.

  9. High-resolution optical spectroscopy of RS Ophiuchi during 2008-2009

    NASA Astrophysics Data System (ADS)

    Somero, A.; Hakala, P.; Wynn, G. A.

    2017-01-01

    RS Ophiuchi (RS Oph) is a symbiotic variable and a recurrent nova (RN). We have monitored it with the Nordic Optical Telescope and obtained 30 high-resolution (R = 46 000) optical spectra over one orbital cycle during quiescence. To our knowledge, this is the best-sampled high-resolution spectroscopic data set of RS Oph over one orbital period. We do not detect any direct signatures of an accretion disc such as double peaked emission lines, but many line profiles are complex consisting of superimposed emission and absorption components. We measure the spin of the red giant and conclude that it is tidally locked to the binary orbit. We observe Na I absorption features, probably arising from the circumbinary medium, that has been shaped by previous RN outbursts. We do not detect any intrinsic polarization in the optical wavelengths.

  10. Detector arrays for high resolution spectroscopy from 5-28 microns (Contributed)

    NASA Astrophysics Data System (ADS)

    Wiedemann, G.; Jennings, D. E.; Moseley, S. H.; Lamb, G.

    A linear Si:As BIB detector array (Rockwell International) is being implemented in a postdispersion detection system for ground based Fourier transform spectrometers. The array version can be used as a multichannel narrow band filter for extended spectral coverage or for imaging with a narrow bandpass. A Si:As solid state photomultiplier array (Rockwell) is evaluated for use in high resolution infrared spectrometers. Test results and applications are discussed.

  11. Chemical effects of lanthanides and actinides in glasses determined with electron energy loss spectroscopy

    SciTech Connect

    Fortner, J.A.; Buck, E.C.; Ellison, A.J.G.; Bates, J.K.

    1996-07-01

    Chemical and structural environments of f-electron elements in glasses are the origin of many of the important properties of materials with these elements; thus oxidation state and chemical coordination of lanthanides and actinides in host materials is an important design consideration in optically active glasses, magnetic materials, perovskite superconductors, and nuclear waste materials. We have made use of the line shapes of Ce to determine its oxidation state in alkali borosilicate glasses being developed for immobilization of Pu. Examination of several prototype waste glass compositions with EELS shows that the redox state of Ce doped to 7 wt% could be varied by suitable choice of alkali elements. EELS for a Pu-doped glass illustrate the small actinide N{sub 4}/N{sub 5} intensity ratio and show that the Pu-N{sub 4,5} white line cross section is comparable to that of Gd M{sub 4,5}.

  12. Electron Energy-Loss Spectroscopy (EELS) of Fe-bearing Sheet Silicates in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Buseck, Peter R.

    2003-01-01

    The primitive character and hydrated mineralogy of the CM chondrites offers insight into some of the earliest reactions between solids and water. Such reactions profoundly affected the matrices and fine-grained rims (FGRs) [1-4], two of the most significant components of these meteorites [5]. We are using EELS combined with a transmission electron microscope (TEM) to investigate the compositions of Fe-bearing minerals, with emphasis on determining oxidation states and quantification of oxidation-state ratios. Iron is among the most abundant elements in the solar system and it can occur naturally in three oxidation states: Fe0, Fe2+, and Fe3+. Determination of oxidation- state ratios is useful because they can be used to infer the redox conditions under which the minerals formed or were last equilibrated [6, 7]. We are particularly interested in understanding how the oxidation state of Fe was affected by the aqueous reactions of the CM chondrites.

  13. Use of a Continuous Wave Laser and Pockels Cell for Sensitive High-Resolution Collinear Resonance Ionization Spectroscopy.

    PubMed

    de Groote, R P; Budinčević, I; Billowes, J; Bissell, M L; Cocolios, T E; Farooq-Smith, G J; Fedosseev, V N; Flanagan, K T; Franchoo, S; Garcia Ruiz, R F; Heylen, H; Li, R; Lynch, K M; Marsh, B A; Neyens, G; Rossel, R E; Rothe, S; Stroke, H H; Wendt, K D A; Wilkins, S G; Yang, X

    2015-09-25

    New technical developments have led to a 2 orders of magnitude improvement of the resolution of the collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing the high efficiency of the CRIS technique. Experimental linewidths of 20(1) MHz were obtained on radioactive beams of francium, allowing us for the first time to determine the electric quadrupole moment of the short lived [t_{1/2}=22.0(5) ms] ^{219}Fr Q_{s}=-1.21(2) eb, which would not have been possible without the advantages offered by the new method. This method relies on a continuous-wave laser and an external Pockels cell to produce narrow-band light pulses, required to reach the high resolution in two-step resonance ionization. Exotic nuclei produced at rates of a few hundred ions/s can now be studied with high resolution, allowing detailed studies of the anchor points for nuclear theories.

  14. Use of a Continuous Wave Laser and Pockels Cell for Sensitive High-Resolution Collinear Resonance Ionization Spectroscopy

    NASA Astrophysics Data System (ADS)

    de Groote, R. P.; Budinčević, I.; Billowes, J.; Bissell, M. L.; Cocolios, T. E.; Farooq-Smith, G. J.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Li, R.; Lynch, K. M.; Marsh, B. A.; Neyens, G.; Rossel, R. E.; Rothe, S.; Stroke, H. H.; Wendt, K. D. A.; Wilkins, S. G.; Yang, X.

    2015-09-01

    New technical developments have led to a 2 orders of magnitude improvement of the resolution of the collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing the high efficiency of the CRIS technique. Experimental linewidths of 20(1) MHz were obtained on radioactive beams of francium, allowing us for the first time to determine the electric quadrupole moment of the short lived [t1 /2=22.0 (5 ) ms ] 219Fr Qs=-1.21 (2 ) eb , which would not have been possible without the advantages offered by the new method. This method relies on a continuous-wave laser and an external Pockels cell to produce narrow-band light pulses, required to reach the high resolution in two-step resonance ionization. Exotic nuclei produced at rates of a few hundred ions/s can now be studied with high resolution, allowing detailed studies of the anchor points for nuclear theories.

  15. Coherent Vibrational Dynamics and High-Resolution Nonlinear Spectroscopy: A Comparison with the Air/DMSO Liquid Interface

    SciTech Connect

    Velarde Ruiz Esparza, Luis A.; Lu, Zhou; Wang, Hongfei

    2013-12-27

    In this report we present a comparative study on the C-H stretching vibrations at air/DMSO (dimethyl sulfoxide) interface with both the free-induction decay (FID) coherent vibrational dynamics and sub-wavenumber high resolution sum-frequency generation vibrational spectroscopy measurements. In principle the frequency-domain and time-domain spectroscopic measurements should generate identical information for a given molecular system. However, when the molecular systems are with several coupled or overlapping vibrational modes, to obtain detailed spectroscopic and coherent dynamics information is not as straightforward and rather difficult from either the time-domain or the frequency domain measurements. For the case of air/DMSO interface that is with moderately complex vibrational spectra, we show that the frequency-domain measurement with sub-wavenumber high-resolution SFGVS is probably more advantageous than the time-domain measurement in obtaining quantitative understanding of the structure and coherent dynamics of the molecular interface.

  16. High Resolution Infrared Spectroscopy of Slit-Jet Cooled Radicals and Ions

    NASA Astrophysics Data System (ADS)

    Roberts, Melanie A.

    This thesis presents high-resolution spectra of supersonically-cooled organic radicals in the mid-infrared, the details and design of the instruments necessary to obtain the spectra, and the theory to understand the spectra and the larger context of the results. Specifically, four organic radicals are studied: singly-deuterated methyl radical (CH2D), phenyl radical (C6H5), hydroxymethyl radical (CH2OH), and ethynyl radical (C2H). All of the spectroscopic studies presented use an existing mid-infrared high-resolution spectrometer with a frequency precision of better than 10 MHz. The radicals are generated using a discharge to dissociate a neutral precursor and form the radicals. The discharge is localized at the orifice of a slit supersonic expansion, which cools the radicals to around 20 K and allows for sub-Doppler spectral resolution. In addition to the description of the existing spectrometer, the design, construction, and successful testing of a new, automated mid-infrared spectrometer is presented. The new spectrometer is based upon difference frequency generation of a scanning Ti:Sapphire laser and a single-frequency Nd:YAG laser to create high-resolution mid-infrared radiation. The new system speeds up data-taking by fully automating the scanning process. The four radicals studied in this thesis are all intermediates in combustion processes of hydrocarbon fuels. First, the out-of-phase symmetric stretch of phenyl radical is presented. As the first high-resolution infrared study of phenyl, it paves the way for future studies of this and other aromatic radicals. Second, the two fundamental CH stretches in CH2D are studied with full rotational resolution. The narrow linewidth of the transitions reveals resolved fine structure and partially resolved hyperfine structure. This resolution yields additional information regarding the distribution of electrons in the radical. With this study of CH2D, a nearly complete set of vibrational frequencies is present in the

  17. HIGH-RESOLUTION XMM-NEWTON SPECTROSCOPY OF THE COOLING FLOW CLUSTER A3112

    SciTech Connect

    Bulbul, G. Esra; Smith, Randall K.; Foster, Adam; Cottam, Jean; Loewenstein, Michael; Mushotzky, Richard; Shafer, Richard

    2012-03-01

    We examine high signal-to-noise XMM-Newton European Photon Imaging Camera (EPIC) and Reflection Grating Spectrometer (RGS) observations to determine the physical characteristics of the gas in the cool core and outskirts of the nearby rich cluster A3112. The XMM-Newton Extended Source Analysis Software data reduction and background modeling methods were used to analyze the XMM-Newton EPIC data. From the EPIC data, we find that the iron and silicon abundance gradients show significant increase toward the center of the cluster while the oxygen abundance profile is centrally peaked but has a shallower distribution than that of iron. The X-ray mass modeling is based on the temperature and deprojected density distributions of the intracluster medium determined from EPIC observations. The total mass of A3112 obeys the M-T scaling relations found using XMM-Newton and Chandra observations of massive clusters at r{sub 500}. The gas mass fraction f{sub gas} = 0.149{sup +0.036}{sub -0.032} at r{sub 500} is consistent with the seven-year Wilkinson Microwave Anisotropy Probe results. The comparisons of line fluxes and flux limits on the Fe XVII and Fe XVIII lines obtained from high-resolution RGS spectra indicate that there is no spectral evidence for cooler gas associated with the cluster with temperature below 1.0 keV in the central <38'' ({approx}52 kpc) region of A3112. High-resolution RGS spectra also yield an upper limit to the turbulent motions in the compact core of A3112 (206 km s{sup -1}). We find that the contribution of turbulence to total energy is less than 6%. This upper limit is consistent with the energy contribution measured in recent high-resolution simulations of relaxed galaxy clusters.

  18. Extended electron energy loss fine structure simulation of the local boron environment in sodium aluminoborosilicate glasses containing gadolinium

    SciTech Connect

    Qian, Morris; Li, Hong; Li, Liyu ); Strachan, Denis M. )

    2003-12-01

    Phase separation in sodium-aluminoborosilicate glasses was systematically studied as a function of Gd2O3 concentration with transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) methods. Gadolinium-induced phase separation in the three systems can be consistently explained by proposing that Gd cations partition to the borate-rich environments and subsequent agglomeration of the Gd-borate moieties, or short-range ordered structural groups, in the glass. Agglomeration of the Gd-borate rich environments is further discussed within the context of excess metal oxides,[Na2O]ex or[Al2O3]ex=|Na2O - Al2O3|, and excess B2O3,[B2O3]ex, available for incorporating Gd cations. Results showed that agglomeration of the Gd-borate rich environments occurred at a much lower Gd2O3 concentration in the glass without[Na2O]ex or[Al2O3]ex and at a significantly higher Gd2O3 concentration in the glass with either[Na2O]ex or[Al2O3]ex. Assuming 1BO4 : 1Gd : 2BO3 (based on literature-reported Gd-metaborate structure) as a local Gd-borate environment in glass, we introduced the saturation index of boron, SI[B]= Gd2O3/(1/3[B2O3]ex), to examine the glass susceptibility to Gd-induced phase separation for all three alkali-aluminoborosilicate systems. While our results have provided some insight to the glass structure, they also provide insight to the mechanism by which the metal oxide is dissolved into the melt. This appears to occur predominantly through boron complexation of the metal oxide.

  19. High-resolution FTIR spectroscopy of the ν3 band of methyl acetylene-d

    NASA Astrophysics Data System (ADS)

    Pal, Ayan Kumar; Kshirsagar, R. J.

    2014-04-01

    The high-resolution Fourier transform spectrum of methyl acetylene-d1 (CH3CCD) at room temperature has been recorded in the region of the ν3 band (1980-2035 cm-1) at an apodized resolution of 0.004 cm-1. About 600 vibration-rotation transitions have been assigned, with J upto 36 and K upto 6. The spectrum shows the presence of several perturbations. The observed minus calculated deviation of the fit for K = 4 subband is much more than the expected, shows the presence of Fermi resonance with the nearby vibrational state.

  20. From BASIS to MIRACLES: Benchmarking and perspectives for high-resolution neutron spectroscopy at the ESS

    NASA Astrophysics Data System (ADS)

    Tsapatsaris, Nikolaos; Willendrup, Peter K.; Lechner, Ruep E.; Bordallo, Heloisa N.

    2015-01-01

    Results based on virtual instrument models for the first high-flux, high-resolution, spallation based, backscattering spectrometer, BASIS are presented in this paper. These were verified using the Monte Carlo instrument simulation packages McStas and VITESS. Excellent agreement of the neutron count rate at the sample position between the virtual instrument simulation and experiments was found, in both time and energy distributions. This achievement was only possible after a new component for a bent single crystal analyser in McStas, using a Gaussian approximation, was developed. These findings are pivotal to the conceptual design of the next generation backscattering spectrometer, MIRACLES at the European Spallation Source.

  1. High Resolution UV Emission Spectroscopy of Molecules Excited by Electron Impact

    NASA Technical Reports Server (NTRS)

    James, G. K.; Ajello, J. M.; Beegle, L.; Ciocca, M.; Dziczek, D.; Kanik, I.; Noren, C.; Jonin, C.; Hansen, D.

    1999-01-01

    Photodissociation via discrete line absorption into predissociating Rydberg and valence states is the dominant destruction mechanism of CO and other molecules in the interstellar medium and molecular clouds. Accurate values for the rovibronic oscillator strengths of these transitions and predissociation yields of the excited states are required for input into the photochemical models that attempt to reproduce observed abundances. We report here on our latest experimental results of the electron collisional properties of CO and N2 obtained using the 3-meter high resolution single-scattering spectroscopic facility at JPL.

  2. Holmium iron borate: high-resolution spectroscopy and crystal-field parameters

    NASA Astrophysics Data System (ADS)

    Erofeev, D. A.; Chukalina, E. P.; Popova, M. N.; Malkin, B. Z.; Bezmaternykh, L. N.; Gudim, I. A.

    2016-12-01

    High-resolution transmission spectra of HoFe3(BO3)4 single crystals were measured in broad spectral (5000-23000 cm-1) and temperature (1.7-300 K) ranges. Crystal-field energies of the Ho3+ ions were determined for a paramagnetic and easy-axis antiferromagnetic phases of the compound. On the basis of these data and of preliminary crystal-field calculations in the frame of the exchange-charge model, crystal-field parameters were found. A parameter of the isotropic Ho-Fe exchange interaction was estimated.

  3. High Resolution Spectroscopy of C_2 and CN in the Cygnus OB2 Association

    NASA Astrophysics Data System (ADS)

    McCall, Benjamin J.; Oka, Takeshi

    2000-08-01

    The unexpected detection of a large column density of hhh along the lines of sight to Cygnus OB2 #12 and Cygnus OB2 #5 cannot be explained by the standard models of diffuse cloud chemistry, which imply unreasonably long absorption path lengths (hundreds of parsecs). In order to gather more information about the physical condition of the diffuse gas in these lines of sight, we propose to obtain high resolution (R 120 000) visible spectra of several stars in the Cygnus OB2 association, including #12 and #5. The observed rotational distribution of the diatomics çand CN will enable us to estimate the kinetic temperature and number density of the molecular gas. In addition, the high resolution of the HRS at HET will allow us to study the velocity distribution of both the atomic (K I) and molecular (çand CN) gas along these lines of sight. Together with our previous observations of hhh, the temperatures, number densities, and velocity distributions from the proposed observations will seriously constrain theoretical models of these sightlines, such as that recently proposed by Cecchi-Pestellini and Dalgarno.

  4. Sample-Induced RF Perturbations in High-Field, High-Resolution NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Crozier, Stuart; Brereton, Ian M.; Zelaya, Fernando O.; Roffmann, Wolfgang U.; Doddrell, David M.

    1997-05-01

    Conducting dielectric samples are often used in high-resolution experiments at high field. It is shown that significant amplitude and phase distortions of the RF magnetic field may result from perturbations caused by such samples. Theoretical analyses demonstrate the spatial variation of the RF field amplitude and phase across the sample, and comparisons of the effect are made for a variety of sample properties and operating field strengths. Although the effect is highly nonlinear, it tends to increase with increasing field strength, permittivity, conductivity, and sample size. There are cases, however, in which increasing the conductivity of the sample improves the homogeneity of the amplitude of the RF field across the sample at the expense of distorted RF phase. It is important that the perturbation effects be calculated for the experimental conditions used, as they have the potential to reduce the signal-to-noise ratio of NMR experiments and may increase the generation of spurious coherences. The effect of RF-coil geometry on the coherences is also modeled, with the use of homogeneous resonators such as the birdcage design being preferred. Recommendations are made concerning methods of reducing sample-induced perturbations. Experimental high-field imaging and high-resolution studies demonstrate the effect.

  5. Synthesis, High-Resolution Infrared Spectroscopy, and Vibrational Structure of Cubane, C8H8.

    PubMed

    Boudon, V; Lamy, M; Dugue-Boyé, F; Pirali, O; Gruet, S; D'Accolti, L; Fusco, C; Annese, C; Alikhani, M E

    2016-06-30

    Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family ( Pirali , O. ; et al. J. Chem. Phys. 2012 , 136 , 024310 ). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp(3) hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm(-1) region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented.

  6. High-resolution subtyping of Staphylococcus aureus strains by means of Fourier-transform infrared spectroscopy.

    PubMed

    Johler, Sophia; Stephan, Roger; Althaus, Denise; Ehling-Schulz, Monika; Grunert, Tom

    2016-05-01

    Staphylococcus aureus causes a variety of serious illnesses in humans and animals. Subtyping of S. aureus isolates plays a crucial role in epidemiological investigations. Metabolic fingerprinting by Fourier-transform infrared (FTIR) spectroscopy is commonly used to identify microbes at species as well as subspecies level. In this study, we aimed to assess the suitability of FTIR spectroscopy as a tool for S. aureus subtyping. To this end, we compared the subtyping performance of FTIR spectroscopy to other subtyping methods such as pulsed field gel electrophoresis (PFGE) and spa typing in a blinded experimental setup and investigated the ability of FTIR spectroscopy for identifying S. aureus clonal complexes (CC). A total of 70 S. aureus strains from human, animal, and food sources were selected, for which clonal complexes and a unique virulence and resistance gene pattern had been determined by DNA microarray analysis. FTIR spectral analysis resulted in high discriminatory power similar as obtained by spa typing and PFGE. High directional concordance was found between FTIR spectroscopy based subtypes and capsular polysaccharide expression detected by FTIR spectroscopy and the cap specific locus, reflecting strain specific expression of capsular polysaccharides and/or other surface glycopolymers, such as wall teichoic acid, peptidoglycane, and lipoteichoic acid. Supervised chemometrics showed only limited possibilities for differentiation of S. aureus CC by FTIR spectroscopy with the exception of CC45 and CC705. In conclusion, FTIR spectroscopy represents a valuable tool for S. aureus subtyping, which complements current molecular and proteomic strain typing.

  7. High resolution infrared spectroscopy: Some new approaches and applications to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.

    1978-01-01

    The principles of spectral line formation and of techniques for retrieval of atmospheric temperature and constituent profiles are discussed. Applications to the atmospheres of Earth, Mars, Venus, and Jupiter are illustrated by results obtained with Fourier transform and infrared heterodyne spectrometers at resolving powers (lambda/delta hyperon lambda of approximately 10,000 and approximately 10 to the seventh power), respectively, showing the high complementarity of spectroscopy at these two widely different resolving powers. The principles of heterodyne spectroscopy are presented and its applications to atmospheric probing and to laboratory spectroscopy are discussed. Direct absorption spectroscopy with tuneable semiconductor lasers is discussed in terms of precision frequency-and line strength-measurements, showing substantial advances in laboratory infrared spectroscopy.

  8. High-Resolution Infrared Spectroscopy of Cubane, C_8H_8

    NASA Astrophysics Data System (ADS)

    Boudon, Vincent; Pirali, Olivier; Gruet, Sébastien; D'accolti, Lucia; Fusco, Caterina; Annese, Cosimo

    2014-06-01

    Carbon-cage molecules have generated a considerable interest from both experimental and theoretical point of views. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family. There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called Platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C_8H_8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp^3 hybridized form of carbon. This generates a considerable strain in the molecule. Cubane itself has the highest density of all hydrocarbons (1.29 g/cm^3). This makes it able to store larges amounts of energy, although the molecule is fully stable. Up to now, only one high-resolution study of cubane has been performed on a few bands [2]. We report here a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature [3]; its {}1H and 13C NMR, FTIR, and mass spectrometry agreed with reported data [4]. Several spectra have been recorded at the AILES beamline of the SOLEIL French synchrotron facility. They cover the 800 to 3100 cm-1 region. Besides the three infrared-active fundamentals (ν10, ν11 and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensrorial formalism developed in the Dijon group [5]. [1] O. Pirali, V. Boudon, J. Oomens, M. Vervloet, J. Chem. Phys., 136, 024310 (2012). [2] A. S. Pine, A. G. Maki, A. G. Robiette, B. J. Krohn, J. K. G. Watson, Th. Urbanek, J. Am. Chem. Soc., 106, 891-897 (1984). [3] P. E. Eaton, N. Nordari, J. Tsanaktsidis, P. S. Upadhyaya, Synthesis, 1, 501, (1995). [4] E

  9. High resolution far-infrared Fourier transform spectroscopy of radicals at the AILES beamline of SOLEIL synchrotron facility.

    PubMed

    Martin-Drumel, M A; Pirali, O; Balcon, D; Bréchignac, Ph; Roy, P; Vervloet, M

    2011-11-01

    Experimental far-infrared (FIR) spectroscopy of transient species (unstable molecules, free radicals, and ions) has been limited so far in both emission and absorption (mainly by the low probability of spontaneous emission in that spectral range and the low brightness of continuum sources used for absorption measurements, respectively). Nevertheless, the FIR spectral range recently became of high astrophysical relevance thanks to several new observational platforms (HERSCHEL, ALMA...) dedicated to the study of this region suitable for the detection of the emission from cold objects of the interstellar medium. In order to complete the experimental dataset concerning transient species, three discharge experiments dedicated to the recording of high resolution FIR spectra of radicals have been developed at the Advanced Infrared Line Exploited for Spectroscopy (AILES) which extracts the bright FIR synchrotron continuum of the synchrotron facility SOLEIL. These experiments make use of a high resolution (R = 0.001 cm(-1)) Bruker IFS125 Fourier transform (FT) spectrometer. An emission setup (allowing to record spectra of radicals excited at high rotational and vibrational temperatures) and two absorption setups (exploiting the bright synchrotron source at the highest resolution available on the FT) are alternatively connected to the FT. The advantages and limitations of these techniques are discussed on the basis of the recent results obtained on OH and CH radicals. These results constitute the first FIR spectra of radicals using synchrotron radiation, and the first FIR spectrum of a C-bearing radical using FT-spectroscopy.

  10. Observation of molecular ordering at the surface of trimethylpropylammonium bis(trifluoromethanesulfonyl)imide using high-resolution rutherford backscattering spectroscopy.

    PubMed

    Nakajima, Kaoru; Ohno, Atsushi; Suzuki, Motofumi; Kimura, Kenji

    2008-05-06

    The surface structure of trimethylpropylammonium bis(trifluoromethanesulfonyl)imide ([TMPA] [TFSI]) is studied by high-resolution Rutherford backscattering spectroscopy at room temperature. The results provide direct evidence of the molecular ordering at the surface. The C1 conformer of the [TFSI] anion is dominant among two stable conformers, and the anions are oriented with their CF3 groups pointing toward the vacuum in the outermost molecular layer. The anions in the second molecular layer also show preferred orientation although it is rather weak.

  11. High Resolution Far Infrared Spectroscopy of HFC-134a at Cold Temperatures

    NASA Astrophysics Data System (ADS)

    Wong, Andy; Medcraft, Chris; Thompson, Christopher; Robertson, Evan Gary; Appadoo, Dominique; McNaughton, Don

    2016-06-01

    Since the signing of the Montreal protocol, long-lived chlorofluorocarbons have been banned due to their high ozone depleting potential. In order to minimise the effect of such molecules, hydrofluorocarbons (HFCs) were synthesized as replacement molecules to be used as refrigerants and foam blowing agents. HFC-134a, or 1,1,1,2-tetrafluoroethane, is one of these molecules. Although HFCs do not cause ozone depletion, they are typically strong absorbers within the 10 micron atmospheric window, which lead to high global warming potentials. A high resolution FT-IR analysis of the νb{8} band (near 665 wn) of HFC-134a has been performed to help understand the intermode coupling between the νb{8} vibrational state and unobserved dark states.

  12. CARMENES at PPVI. High-Resolution Spectroscopy of M Dwarfs with FEROS, CAFE and HRS

    NASA Astrophysics Data System (ADS)

    Alonso-Floriano, F. J.; Montes, D.; Jeffers, S.; Caballero, J. A.; Zechmeister, M.; Mundt, R.; Reiners, A.; Amado, P. J.; Casal, E.; Cortés-Contreras, M.; Modroño, Z.; Ribas, I.; Rodríguez-López, C.; Quirrenbach, A.

    2013-07-01

    To ensure an efficient use of CARMENES observing time, and the highest chances of success, it is necessary first to select the most promising targets. To achieve this, we are observing ~500 M dwarfs at high-resolution (R = 30,000-48,000), from which we determine the projected rotational velocity vsini with an accuracy better than 0.5-0.2 km/s and radial-velocity stability better than 0.2-0.1 km/s. Our aim is to have at least two spectra at different epochs of the final 300 CARMENES targets. Our observations with FEROS at ESO/MPG 2.2m La Silla , CAFE at 2.2m Calar Alto and HRS at Hobby Eberly Telescope allow us to identify single- and double-line spectroscopic binaries and, especially, fast rotators, which should be discarded from the target list for exoplanet searches. Here we present preliminary results.

  13. High resolution spectroscopy and spectral simulation of C2 using degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Lloyd, G. M.; Ewart, P.

    1999-01-01

    Degenerate four-wave mixing in the sub-Doppler phase conjugate geometry was used to record high resolution spectra of the d 3Πg-a3Πu (0-0) Swan band of C2 produced in an oxy-acetylene flame. The line positions of isolated transitions were measured to an accuracy of ˜3×10-3 cm-1 and calibrated using a Fizeau interferometer system. The data obtained from these spectra was used to calculate rotational constants and lambda doubling parameters for the 3Π states from which the line positions for the whole band were calculated. Noticeable improvements between experimental and calculated line positions are seen when compared to previously published values. The effect of inaccuracies in line positions on the simulation of degenerate four-wave mixing spectra is discussed and some examples of the improvement in simulation using the newly calculated line positions are presented.

  14. High-resolution spectroscopy and mode identification in non-radially pulsating stars

    NASA Astrophysics Data System (ADS)

    Pollard, K. R.; Wright, D. J.; Zima, W.; Cottrell, P. L.; De Cat, P.

    2008-12-01

    We have obtained high-resolution spectroscopic data of a sample of non-radially pulsating stars with the HERCULES spectrograph on the 1.0-m telescope at the Mt John University Observatory in New Zealand. We have developed and used a new technique which cross- correlates stellar spectra with scaled delta function templates to obtain high signal-to-noise representative spectral line profiles for further analysis. Using these profiles, and employing the Fourier Parameter Fit method, we have been able to place constraints on the degree, ℓ, and azimuthal order, m, of the non-radial pulsation modes in one β Cephei star, V2052 Oph and two γ Doradus stars, QW Pup and HD 139095.

  15. High-resolution spectroscopy of jet-cooled CH{sub 5}{sup +}: Progress

    SciTech Connect

    Savage, C.; Dong, F.; Nesbitt, D. J.

    2015-01-22

    Protonated methane (CH{sub 5}{sup +}) is thought to be a highly abundant molecular ion in interstellar medium, as well as a potentially bright μwave- mm wave emitter that could serve as a tracer for methane. This paper describes progress and first successful efforts to obtain a high resolution, supersonically cooled spectrum of CH{sub 5}{sup +} in the 2900-3100 cm{sup −1} region, formed in a slit supersonic discharge at low jet temperatures and with sub-Doppler resolution. Short term precision in frequency measurement (< 5 MHz on an hour time scale) is obtained from a thermally controlled optical transfer cavity servoloop locked onto a frequency stabilized HeNe laser. Long term precision (< 20 MHz day-to-day) due to pressure, temperature and humidity dependent index of refraction effects in the optical transfer cavity is also present and discussed.

  16. High Resolution Near-IR Spectroscopy of Protostars With Large Telescopes

    NASA Technical Reports Server (NTRS)

    Greene, Tom; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    It is now possible to measure absorption spectra of Class I protostars using D greater than or = 8m telescopes equipped with sensitive cryogenic IR spectrographs. Our latest high-resolution (R approx. 20,000) Keck data reveal that Class I protostars are indeed low-mass stars with dwarf-like features. However, they differ from T Tauri stars in that Class I protostars have much higher IR veilings (tau(sub k) greater than or = 1 - 3+) and they are rotating quickly, v sin i greater than 20 km/s. Interestingly, the vast majority of protostellar absorption spectra show stellar - not disk - absorption features. A preliminary H-R diagram suggests that protostellar photospheres may have different physical structures than T Tauri stars, perhaps due to their higher accretion rates.

  17. High-resolution spectroscopy used to measure inertial confinement fusion neutron spectra on Omega (invited)

    SciTech Connect

    Forrest, C. J.; Radha, P. B.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Pruyne, A.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J. III; Stoeckl, C.; Casey, D. T.; Gatu-Johnson, M.; Gardner, S.

    2012-10-15

    The areal density ({rho}R) of cryogenic DT implosions on Omega is inferred by measuring the spectrum of neutrons that elastically scatter off the dense deuterium (D) and tritium (T) fuel. Neutron time-of-flight (nTOF) techniques are used to measure the energy spectrum with high resolution. High signal-to-background data has been recorded on cryogenic DT implosions using a well-collimated 13.4-m line of sight and an nTOF detector with an advanced liquid scintillator compound. An innovative method to analyze the elastically scattered neutron spectra was developed using well-known cross sections of the DT nuclear reactions. The estimated areal densities are consistent with alternative {rho}R measurements and 1-D simulations.

  18. Tissue differentiation by means of high resolution optical emission spectroscopy during electrosurgical intervention

    NASA Astrophysics Data System (ADS)

    Bürger, Ines; Scharpf, Marcus; Hennenlotter, Jörg; Nüßle, Daniela; Spether, Dominik; Neugebauer, Alexander; Bibinov, Nikita; Stenzl, Arnulf; Fend, Falko; Enderle, Markus; Awakowicz, Peter

    2017-01-01

    Electrosurgery is the use of radio-frequency electric current for the cutting of biological tissue e.g. for resection of tumour tissue. In this work, the optical emission of plasma being generated during the electrosurgical procedure is investigated with a high resolution echelle spectrometer to find differences between tumour tissue and normal renal tissue in a pre-clinical ex vivo study. Trace elements like zinc, iron, copper and cadmium are present in the tissue spectra as well as the electrolytes magnesium, calcium, sodium and potassium and some diatomic molecules such as hydroxyl radical, cyano radical, dicarbon, nitrogen monohydride and molecular nitrogen which are mainly dissociated from polyatomic molecules. With the atomic emission line of cadmium at 228.8 nm the treated tissue can be differentiated in tumorous and healthy tissue with correct assignment of 95% for tumour tissue and 92% for normal renal tissue.

  19. High resolution diode laser spectroscopy of H2O spectra broadened by nitrogen and noble gases

    NASA Astrophysics Data System (ADS)

    Kapitanov, Venedikt A.; Osipov, Konstantin Yu.; Protasevich, Alexander E.; Ponurovskiy, Yakov Ya.

    2014-11-01

    The absorption spectra of pure H2O with mixtures of broadening gases N2, Ar, Xe, He, Ar and air have been measured in 1.39 mμ spectral region by high resolution spectrometer based on diode laser (DFB NEL, Japan). For the processing of pure water spectra and it's mixtures with a different broadening gases in a wide pressure range we used a multispectrum fitting procedure developed at IAO. The program is based on a relatively simple Rautian-Sobel'man line profile and linear pressure dependence of the line profile parameters. H2O measured spectra bulk processing results in the retrieving of such line parameters: zero-pressure line center positions, intensities, self-broadening and self-shift coefficients of pure water, broadening and shift coefficients for other gases which are describes the experiment with the minimum residuals in a wide pressure range.

  20. Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry

    SciTech Connect

    Bentley, J.; Horton, L.L.; McHargue, C.J.; McKernan, S.; Carter, C.B.; Revcolevschi, A.; Tanaka, S.; Davis, R.F.

    1993-12-31

    Quantitative electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resolution of <5 nm. Analysis of Fe L{sub 23} white lines indicated a low-spin state with a charge transfer of {approximately}1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2 to 5% in the Co:O stoichiometry were measured across 100-nm-thick Co{sub 3}O{sub 4} layers in an oxidized directionally solidified CoO-ZrO{sub 2} eutectic, with the highest O levels near the ZrO{sub 2}. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for CO{sub 3}O{sub 4} have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid solubility occurred in an AlN-SiC film grown by low-temperature molecular beam epitaxy (MBE) on {alpha}(6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycrystalline AlN on SiC, interfacial 8H sialon (aluminum oxy-nitride) and pockets of Si{sub 3}N{sub 4}-rich {beta}{prime} sialon in the SiC were detected.

  1. Detailed Monte Carlo Simulation of electron transport and electron energy loss spectra.

    PubMed

    Attarian Shandiz, M; Salvat, F; Gauvin, R

    2016-11-01

    A computer program for detailed Monte Carlo simulation of the transport of electrons with kinetic energies in the range between about 0.1 and about 500 keV in bulk materials and in thin solid films is presented. Elastic scattering is described from differential cross sections calculated by the relativistic (Dirac) partial-wave expansion method with different models of the scattering potential. Inelastic interactions are simulated from an optical-data model based on an empirical optical oscillator strength that combines optical functions of the solid with atomic photoelectric data. The generalized oscillator strength is built from the adopted optical oscillator strength by using an extension algorithm derived from Lindhard's dielectric function for a free-electron gas. It is shown that simulated backscattering fractions of electron beams from bulk (semi-infinite) specimens are in good agreement with experimental data for beam energies from 0.1 keV up to about 100 keV. Simulations also yield transmitted and backscattered fractions of electron beams on thin solid films that agree closely with measurements for different film thicknesses and incidence angles. Simulated most probable deflection angles and depth-dose distributions also agree satisfactorily with measurements. Finally, electron energy loss spectra of several elemental solids are simulated and the effects of the beam energy and the foil thickness on the signal to background and signal to noise ratios are investigated. SCANNING 38:475-491, 2016. © 2015 Wiley Periodicals, Inc.

  2. A multichannel electron energy loss spectrometer for low-temperature condensed films

    SciTech Connect

    David, Donald E.; Popovic, Duska B.; Antic, Dean; Michl, Josef

    2004-12-01

    We describe a wide-gap multichannel cylindrical deflection electron energy analyzer suitable for measuring the weak signals characteristic of electronically inelastic electron energy loss spectra. The analyzer has nearly ideal fringing field termination, and its resolution and energy dispersion were characterized as a function of energy by solving numerically the equation of motion of electrons in an ideal cylindrical electric field. The numerical results for the radial location of the electrons at the detector as a function of the entrance location, angle, and energy are closely approximated by a second order polynomial, and match closely with those observed. The detection efficiency of the analyzer is 100-150 times better than that of an equivalent single-channel instrument, but limited energy transmission of the zoom lens system used in our case reduced it by a factor of about 2. The performance of the new instrument was demonstrated by measuring the {sup 3}E{sub 1u} electronic spectrum of benzene in only 2 min and the spectrum of endo-benzotricyclo[4.2.1.0{sup 2.5}]nonane.

  3. High Resolution X-Ray Absorption Spectroscopy: Distribution of Matter in and around Galaxies

    NASA Astrophysics Data System (ADS)

    Schulz, Norbert; MIT/CAT Team

    2015-10-01

    The chemical evolution of the Universe embraces aspects that reachdeep into modern astrophysics and cosmology. We want to know how present and past matter is affected by various levels and types of nucleo-synthesis and stellar evolution. Three major categories were be identified: 1. The study of pre-mordial star formation including periods of super-massive black hole formation, 2. The embedded evolution of the intergalactic medium IGM, 3. The status and evolution of stars and the interstellar medium ISM in galaxies. Today a fourth category relates to our understanding of dark matter in relationwith these three categories. The X-ray band is particularly sensitive to K- and L-shell absorption and scattering from high abundant elements like C, N, O, Ne, Mg, Si, S,Ar, Ca, Fe, and Ni. Like the Lyman alpha forest in the optical band, absorbers in the IGM produce an X-ray line forest along the line of sight in the X-rayspectrum of a background quasar. Similary bright X-ray sources within galaxies and the Milky Way produce a continuum, which is being absorbed by elements invarious phases of the ISM. High resolution X-ray absorption surveys are possible with technologies ready for flight within decade. == high efficiency X-ray optics with optical performance 3== high resolution X-ray gratings with R 3000 for E 1.5 keV== X-ray micro-calorimeters with R 2000 for E 1.5 keV. The vision for the next decade needs to lead to means and strategies which allows us to perform such absorption surveys as effectively as surveys are now or in very near future quite common in astronomy pursued in other wave length bands such as optical, IR, and sub-mm.

  4. KiwiSpec - an advanced spectrograph for high resolution spectroscopy: prototype design and performance

    NASA Astrophysics Data System (ADS)

    Gibson, Steve; Barnes, Stuart I.; Hearnshaw, John; Nield, Kathryn; Cochrane, Dave; Grobler, Deon

    2012-09-01

    A new advanced high resolution spectrograph has been developed by Kiwistar Optics of Industrial Research Ltd., New Zealand. The instrument, KiwiSpec R4-100, is bench-mounted, bre-fed, compact (0.75m by 1.5m footprint), and is well-suited for small to medium-sized telescopes. The instrument makes use of several advanced concepts in high resolution spectrograph design. The basic design follows the classical white pupil concept in an asymmetric implementation and employs an R4 echelle grating illuminated by a 100mm diameter collimated beam for primary dispersion. A volume phase holographic grating (VPH) based grism is used for cross-dispersion. The design also allows for up to four camera and detector channels to allow for extended wavelength coverage at high eciency. A single channel prototype of the instrument has been built and successfully tested with a 1m telescope. Targets included various spectrophotometric standard stars and several radial velocity standard stars to measure the instrument's light throughput and radial velocity capabilities. The prototype uses a 725 lines/mm VPH grism, an off-the-shelf camera objective, and a 2k×2k CCD. As such, it covers the wavelength range from 420nm to 660nm and has a resolving power of R ≍ 40,000. Spectrophotometric and precision radial velocity results from the on-sky testing period will be reported, as well as results of laboratory-based measurements. The optical design of KiwiSpec, and the various multi-channel design options, will be presented elsewhere in these proceedings.

  5. KiwiSpec - an advanced spectrograph for high resolution spectroscopy: optical design and variations

    NASA Astrophysics Data System (ADS)

    Barnes, Stuart I.; Gibson, Steve; Nield, Kathryn; Cochrane, Dave

    2012-09-01

    The KiwiSpec R4-100 is an advanced high resolution spectrograph developed by KiwiStar Optics, Industrial Research Ltd, New Zealand. The instrument is based around an R4 echelle grating and a 100mm collimated beam diameter. The optical design employs a highly asymmetric white pupil design, whereby the transfer collimator has a focal length only 1/3 that of the primary collimator. This allows the cross-dispersers (VPH gratings) and camera optics to be small and low cost while also ensuring a very compact instrument. The KiwiSpec instrument will be bre-fed and is designed to be contained in both thermal and/or vacuum enclosures. The instrument concept is highly exible in order to ensure that the same basic design can be used for a wide variety of science cases. Options include the possibility of splitting the wavelength coverage into 2 to 4 separate channels allowing each channel to be highly optimized for maximum eciency. CCDs ranging from smaller than 2K2K to larger than 4K4K can be accommodated. This allows good (3-4 pixel) sampling of resolving powers ranging from below 50,000 to greater than 100,000. Among the specic design options presented here will be a two-channel concept optimized for precision radial velocities, and a four-channel concept developed for the Gemini High- Resolution Optical Spectrograph (GHOST). The design and performance of a single-channel prototype will be presented elsewhere in these proceedings.

  6. High resolution Raman spectroscopy of complexes and clusters in molecular beams. Performance report

    SciTech Connect

    Felker, P.M.

    1991-12-31

    The DOE-sponsored project in this laboratory has two facets. The first is the development of methods of nonlinear Raman spectroscopy for application in studies of sparse samples. The second is the application of such methods to structural and dynamical studies of species in supersonic molecular beams. The progress we have made in both of these areas is described in this paper. The report is divided into five remaining sections. The first pertains to theoretical and experimental developments in Fourier transform stimulated emission spectroscopy and Fourier transform hole-burning spectroscopy. The second deals with progress in the development of ionization-detected stimulated Raman spectroscopies (IDSRS). The third describes results from the application of IDSRS methods to studies of jet-cooled benzene clusters. The fourth describes IDSRS results from studies of hydrogen-bonded complexes containing phenols. The fifth relates to studies of carbazole-(Ar){sub n} clusters.

  7. High resolution Raman spectroscopy of complexes and clusters in molecular beams

    SciTech Connect

    Felker, P.M.

    1991-01-01

    The DOE-sponsored project in this laboratory has two facets. The first is the development of methods of nonlinear Raman spectroscopy for application in studies of sparse samples. The second is the application of such methods to structural and dynamical studies of species in supersonic molecular beams. The progress we have made in both of these areas is described in this paper. The report is divided into five remaining sections. The first pertains to theoretical and experimental developments in Fourier transform stimulated emission spectroscopy and Fourier transform hole-burning spectroscopy. The second deals with progress in the development of ionization-detected stimulated Raman spectroscopies (IDSRS). The third describes results from the application of IDSRS methods to studies of jet-cooled benzene clusters. The fourth describes IDSRS results from studies of hydrogen-bonded complexes containing phenols. The fifth relates to studies of carbazole-(Ar){sub n} clusters.

  8. A compact, high resolution Michelson interferometer for atmospheric spectroscopy in the near ultraviolet

    NASA Technical Reports Server (NTRS)

    Sander, Stanley P.; Cageao, Richard P.; Friedl, Randall R.

    1993-01-01

    A new, compact Fourier Transform Michelson interferometer (FTUV) with an apodized resolving power greater than 300,000 at 300 nm, high throughput and wide spectral coverage has been developed. The objectives include atmospheric spectroscopy (direct solar absorption and solar scattering) and laboratory spectroscopy of transient species. In this paper, we will briefly describe the prototype FTUV instrument and the results of preliminary laboratory investigations of OH and ClO spectra in emission and absorption.

  9. High-resolution X-ray absorption spectroscopy of iron carbonyl complexes.

    PubMed

    Atkins, Andrew J; Bauer, Matthias; Jacob, Christoph R

    2015-06-07

    We apply high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) to study iron carbonyl complexes. Mono-, bi-, and tri-nuclear carbonyl complexes and pure carbonyl complexes as well as carbonyl complexes containing hydrocarbon ligands are considered. The HERFD-XANES spectra reveal multiple pre-edge peaks with individual signatures for each complex, which could not be detected previously with conventional XANES spectroscopy. These peaks are assigned and analysed with the help of TD-DFT calculations. We demonstrate that the pre-edge peaks can be used to distinguish the different types of iron-iron interactions in carbonyl complexes. This opens up new possibilities for applying HERFD-XANES spectroscopy to probe the electronic structure of iron catalysts.

  10. On-chip near-infrared spectroscopy of CO2 using high resolution plasmonic filter array

    NASA Astrophysics Data System (ADS)

    Chong, Xinyuan; Li, Erwen; Squire, Kenneth; Wang, Alan X.

    2016-05-01

    We report an ultra-compact, cost-effective on-chip near-infrared spectroscopy system for CO2 sensing using narrow-band optical filter array based on plasmonic gratings with a waveguide layer. By varying the periodicity of the gratings, the transmission spectra of the filters can be continuously tuned to cover the 2.0 μm sensing window with high spectral resolution around 10 nm. Our experimental results show that the on-chip spectroscopy system can resolve the two symmetric vibrational bands of CO2 at 2.0 μm wavelength, which proves its potential to replace the expensive commercial IR spectroscopy system for on-site gas sensing.

  11. High-resolution spectroscopy of the zero-phonon line of the deep donor EL2 in GaAs

    SciTech Connect

    Hecht, C.; Kummer, R.; Thoms, M.; Winnacker, A.

    1997-05-01

    We investigated the zero-phonon line (ZPL) of the deep donor EL2 in GaAs by means of high-resolution absorption spectroscopy with a narrow-band laser. Frequency-selective bleaching ({open_quotes}spectral-hole burning{close_quotes}) experiments and the measurement of the temperature broadening of the ZPL prove an essentially homogeneous broadening of the transition. The observed asymmetry of the line shape is interpreted to be caused by a Fano resonance of the {sup 1}T{sub 2} excited state with the conduction band. A splitting of the {sup 1}T{sub 2} state as the reason for the asymmetry seems unrealistic. The homogeneous broadening of the ZPL prevents the use of spectral-hole burning spectroscopy to study the effect of external perturbations on the ZPL of the EL2. {copyright} {ital 1997} {ital The American Physical Society}

  12. HIGH-RESOLUTION INFRARED IMAGING AND SPECTROSCOPY OF THE Z CANIS MAJORIS SYSTEM DURING QUIESCENCE AND OUTBURST

    SciTech Connect

    Hinkley, Sasha; Hillenbrand, Lynne; Crepp, Justin R.; Oppenheimer, Ben R.; Zimmerman, Neil; Brenner, Douglas; Rice, Emily L.; Pueyo, Laurent; Vasisht, Gautam; Roberts, Jennifer E.; Roberts, Lewis C. Jr.; Burruss, Rick; Wallace, J. Kent; Cady, Eric; Zhai, Chengxing; Kraus, Adam L.; Ireland, Michael J.; Beichman, Charles; Dekany, Richard; Parry, Ian R.; and others

    2013-01-20

    We present adaptive optics photometry and spectra in the JHKL bands along with high spectral resolution K-band spectroscopy for each component of the Z Canis Majoris system. Our high angular resolution photometry of this very young ({approx}<1 Myr) binary, comprised of an FU Ori object and a Herbig Ae/Be star, was gathered shortly after the 2008 outburst while our high-resolution spectroscopy was gathered during a quiescent phase. Our photometry conclusively determines that the outburst was due solely to the embedded Herbig Ae/Be member, supporting results from earlier works, and that the optically visible FU Ori component decreased slightly ({approx}30%) in luminosity during the same period, consistent with previous works on the variability of FU Ori type systems. Further, our high-resolution K-band spectra definitively demonstrate that the 2.294 {mu}m CO absorption feature seen in composite spectra of the system is due solely to the FU Ori component, while a prominent CO emission feature at the same wavelength, long suspected to be associated with the innermost regions of a circumstellar accretion disk, can be assigned to the Herbig Ae/Be member. These findings clarify previous analyses of the origin of the CO emission in this complex system.

  13. High-resolution X-ray spectroscopy of late-type stars with CHANDRA

    NASA Astrophysics Data System (ADS)

    Mewe, R.; Raassen, A. J. J.; Kaastra, J. S.; van der Meer, R. L. J.; Brinkman, A. C.

    We have analyzed high-resolution (Δλ ≅ 0.06 Å) X-ray spectra in the region 6-180 Å of the coronae of the cool stars Capella, Procyon, and α Centauri. These stars were observed with the the CHANDRA Low Energy Transmission Grating Spectrometer (LETGS) between Sep. and Dec. 1999. Temperatures are derived from line ratios of helium-like lines and long-wavelength iron lines. Electron densities are obtained for the relatively cooler (few MK) and more tenuous (⪅ 10 11 cm -3) plasma components from the forbidden to intercombination line ratios in the helium-like triplets of O, N, and C and for the hotter (⪆ 5 MK) and denser (⪆ 10 12 cm -3) components (such as occur in Capella) from the helium-like triplets of Mg and Si and the ratios of Fe XIX-Fe XXII 2ℓ-2ℓ' lines above 90 Å. The implications of these results for the coronal structure are discussed.

  14. High-resolution electron momentum spectroscopy of valence satellites of carbon disulfide

    NASA Astrophysics Data System (ADS)

    Huang, Chengwu; Shan, Xu; Zhang, Zhe; Wang, Enliang; Li, Zhongjun; Chen, XiangJun

    2010-09-01

    The binding energy spectrum of carbon disulphide (CS2) in the energy range of 9-23 eV has been measured by a high-resolution (e,2e) spectrometer employing asymmetric noncoplanar kinematics at an impact energy of 2500 eV plus the binding energy. Taking the advantage of the high energy resolution of 0.54 eV, four main peaks and five satellites in the outer-valence region are resolved. The assignments and pole strengths for these satellite states are achieved by comparing the experimental electron momentum profiles with the corresponding theoretical ones calculated using Hartree-Fock and density functional theory methods. The results are also compared in detail with the recent SAC-CI general-R calculations. General agreement is satisfactory, while the present experiment suggests cooperative contributions from Π2u, Σg+2 states to satellite 2 and Σg+2, Π2g states to satellite 3. Besides, relatively low pole strength for X Π2g state is obtained which contradicts all the theoretical calculations [2ph-TDA, ADC(3), SAC-CI general-R, ADC(4)] so far.

  15. High-resolution photoelectron imaging spectroscopy of cryogenically cooled Fe4O- and Fe5O-

    NASA Astrophysics Data System (ADS)

    Weichman, Marissa L.; DeVine, Jessalyn A.; Neumark, Daniel M.

    2016-08-01

    We report high-resolution photodetachment spectra of the cryogenically cooled iron monoxide clusters Fe4O- and Fe5O- obtained with slow photoelectron velocity-map imaging (cryo-SEVI). Well-resolved vibrational progressions are observed in both sets of spectra, and transitions to low-lying excited states of both species are seen. In order to identify the structural isomers, electronic states, and vibrational modes that contribute to the cryo-SEVI spectra of these clusters, experimental results are compared with density functional theory calculations and Franck-Condon simulations. The main bands observed in the SEVI spectra are assigned to the 15A2←16B2 photodetachment transition of Fe4O- and the 17A'←18A″ photodetachment transition of Fe5O-. We report electron affinities of 1.6980(3) eV for Fe4O and 1.8616(3) eV for Fe5O, although there is some uncertainty as to whether the 15A2 state is the true ground state of Fe4O. The iron atoms have a distorted tetrahedral geometry in Fe4O0/- and a distorted trigonal-bipyramidal arrangement in Fe5O0/-. For both neutral and anionic species, the oxygen atom preferably binds in a μ2-oxo configuration along the cluster edge. This finding is in contrast to prior predictions that Fe5O0/- exhibits a μ3 face-bound structure.

  16. Slit-Jet Discharge Studies of Polyacetylenic Molecules: Synthesis and High Resolution Infrared Spectroscopy of Diacetylene

    NASA Astrophysics Data System (ADS)

    Chang, Chih-Hsuan; Roberts, Melanie A.; Nesbitt, David J.

    2013-06-01

    Polyacetylenic molecules play an important role in both combustion chemistry as well as chemistry of the interstellar medium. This talk presents first high resolution infrared spectroscopic efforts on the simplest jet-cooled polyacetylene, namely diacetylene (C_4H_2). Specifically, the fundamental anti-symmetric C-H stretching mode (near 3333 cm^{-1}) and several hot combination bands of diacetylene have been investigated under sub-Doppler, jet cooled conditions in a pulsed supersonic slit discharge. Local Coriolis perturbations in the fundamental anti-symmetric C-H stretch manifold are observed and analyzed. Six hot bands are observed, including the H-C-C bending mode (v_8) not observed in previous room temperature studies. The observation of these hot bands under rotationally jet cooled conditions (T_{rot}=15.7(4) K) indicate the presence of highly non-equilibrium relaxation processes between vibration and rotation. G. Guelachvili, A. M. Craig, and D. A. Ramsay, J. Mol. Spectrosc. 105, 156 (1984)

  17. HIGH-RESOLUTION FOURIER-TRANSFORM MICROWAVE SPECTROSCOPY OF METHYL- AND DIMETHYLNAPTHALENES

    SciTech Connect

    Schnitzler, Elijah G.; Zenchyzen, Brandi L. M.; Jäger, Wolfgang

    2015-06-01

    High-resolution pure rotational spectra of four alkylnaphthalenes were measured in the range of 6–15 GHz using a molecular-beam Fourier-transform microwave spectrometer. Both a- and b-type transitions were observed for 1-methylnaphthalene (1-MN), 1,2-dimethylnaphthalene (1,2-DMN), and 1,3-dimethylnaphthalene (1,3-DMN); only a-type transitions were observed for 2-methylnaphthalene (2-MN). Geometry optimization and vibrational analysis calculations at the B3LYP/6-311++G(d,p) level of theory aided in the assignments of the spectra and the characterization of the structures. Differences between the experimental and predicted rotational constants are small, and they can be attributed in part to low-lying out-of-plane vibrations, which distort the alkylnaphthalenes out of their equilibrium geometries. Splittings of rotational lines due to methyl internal rotation were observed in the spectra of 2-MN, 1,2-DMN, and 1,3-DMN, and allowed for the determination of the barriers to methyl internal rotation, which are compared to values from density functional theory calculations. All four species are moderately polar, so they are candidate species for detection by radio astronomy, by targeting the transition frequencies reported here.

  18. ISIS: An Interactive Spectral Interpretation System for High Resolution X-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Houck, J. C.; Denicola, L. A.

    The Interactive Spectral Interpretation System (ISIS) is designed to facilitate the interpretation and analysis of high resolution X-ray spectra like those obtained using the grating spectrographs on Chandra and XMM and the microcalorimeter on Astro-E. It is being developed as an interactive tool for studying the physics of X-ray spectrum formation, supporting measurement and identification of spectral features, and interaction with a database of atomic structure parameters and plasma emission models. The current version uses the atomic data and collisional ionization equilibrium models in the Astrophysical Plasma Emission Database (APED) of Brickhouse et.al., and also provides access to earlier plasma emission models including Raymond-Smith and MEKAL. Although the current version focuses on collisional ionization equilibrium plasmas, the system is designed to allow use of other databases to provide better support for studies of non-equilibrium and photoionized plasmas. To maximize portability between Unix operating systems, ISIS is being written entirely in ANSI C using free-software components (CFITSIO, PGPLOT and S-Lang).

  19. High-resolution UV-visible spectroscopy of lunar red spots

    NASA Technical Reports Server (NTRS)

    Bruno, B. C.; Lucey, P. G.; Hawke, B. R.

    1991-01-01

    A spectral reflectance study of selected lunar 'red spots', highland areas characterized by an absorption in the ultraviolet relative to the visible was conducted. Some red spots were suggested to be the sites of ancient highland volcanism. High-resolution spectral data of eight red spots on the western portion of the moon over the wavelength region 0.39-0.82 micron were obtained. Much spectral variation among these red spots in the magnitude as well as the wavelength position of the ultraviolet absorption were found. Spectral structure at visible and near-infrared wavelength were also identified. These spectral differences indicate that red spots do not have a single mineralogical composition, which in turn suggests that red spots may have multiple origins. Additional imaging spectroscopic observations were taken of the Herigonius red spot, a morphologically complex region northeast of Mare Humorum. These data reveal significant spectral differences among the various morphological units within the Herigonius red spot. Although some of these are likely due to the effects of the maturation process, others appear to reflect differences in mineral abundances and composition.

  20. Applications of High Resolution Laser: Induced Breakdown Spectroscopy for Environmental and Biological Samples

    NASA Astrophysics Data System (ADS)

    Martin, Madhavi Z.; Labbe, Nicole; Wagner, Rebekah J.

    This chapter details the application of LIBS in a number of environmental areas of research such as carbon sequestration and climate change. LIBS has also been shown to be useful in other high resolution environmental applications for example, elemental mapping and detection of metals in plant materials. LIBS has also been used in phytoremediation applications. Other biological research involves a detailed understanding of wood chemistry response to precipitation variations and also to forest fires. A cross-section of Mountain pine (pinceae Pinus pungen Lamb.) was scanned using a translational stage to determine the differences in the chemical features both before and after a fire event. Consequently, by monitoring the elemental composition pattern of a tree and by looking for abrupt changes, one can reconstruct the disturbance history of a tree and a forest. Lastly we have shown that multivariate analysis of the LIBS data is necessary to standardize the analysis and correlate to other standard laboratory techniques. LIBS along with multivariate statistical analysis makes it a very powerful technology that can be transferred from laboratory to field applications with ease.

  1. HIGH-RESOLUTION IR ABSORPTION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS: THE REALM OF ANHARMONICITY

    SciTech Connect

    Maltseva, Elena; Buma, Wybren Jan; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Tielens, Alexander G. G. M.; Huang, Xinchuan; Lee, Timothy J.; Oomens, Jos E-mail: petrignani@strw.leidenuniv.nl

    2015-11-20

    We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3-μm CH stretching region of polycyclic aromatic hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold (∼4 K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main bands that fall within 0.5% of the experimental frequencies. The implications for the aromatic infrared bands, specifically the 3-μm band, are discussed.

  2. High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons: The Realm of Anharmonicity

    NASA Technical Reports Server (NTRS)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2016-01-01

    We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3 micrometers CH stretching region of Polycyclic Aromatic Hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold ((is) approximately 4K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions enhanced with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main modes that fall within 0.5% of the experimental frequencies. The implications for the Aromatic Infrared Bands, specifically the 3-m band are discussed.

  3. Applications of High Resolution Laser Induced Breakdown Spectroscopy for Environmental and Biological Samples

    SciTech Connect

    Martin, Madhavi Z; Labbe, Nicole; Wagner, Rebekah J.

    2013-01-01

    This chapter details the application of LIBS in a number of environmental areas of research such as carbon sequestration and climate change. LIBS has also been shown to be useful in other high resolution environmental applications for example, elemental mapping and detection of metals in plant materials. LIBS has also been used in phytoremediation applications. Other biological research involves a detailed understanding of wood chemistry response to precipitation variations and also to forest fires. A cross-section of Mountain pine (pinceae Pinus pungen Lamb.) was scanned using a translational stage to determine the differences in the chemical features both before and after a fire event. Consequently, by monitoring the elemental composition pattern of a tree and by looking for abrupt changes, one can reconstruct the disturbance history of a tree and a forest. Lastly we have shown that multivariate analysis of the LIBS data is necessary to standardize the analysis and correlate to other standard laboratory techniques. LIBS along with multivariate statistical analysis makes it a very powerful technology that can be transferred from laboratory to field applications with ease.

  4. High-resolution VUV spectroscopy: New results from the Advanced Light Source

    SciTech Connect

    Schlachter, F.; Bozek, J.

    1996-06-01

    Third-generation synchrotron light sources are providing photon beams of unprecedented brightness for researchers in atomic and molecular physics. Beamline 9.0.1, an undulator beamline at the Advanced Light Source (ALS), produces a beam in the vacuum-ultraviolet (VUV) region of the spectrum with exceptional flux and spectral resolution. Exciting new results from experiments in atomic and molecular VUV spectroscopy of doubly excited autoionizing states of helium, hollow lithium, and photoelectron spectroscopy of small molecules using Beamline 9.0.1 at the ALS are reported.

  5. USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY TO INVESTIGATE PMDI REACTIONS WITH WOOD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solution-state NMR spectroscopy provides a powerful tool for understanding the formation of chemical bonds between wood components and adhesives. Finely ground cell wall (CW) material fully dissolves in a solvent system containing dimethylsulfoxide (DMSO-d6) and N-methyl¬imidazole (NMI-d6), keeping ...

  6. A high-resolution large-acceptance analyzer for X-ray fluorescence and Raman spectroscopy

    SciTech Connect

    Bergmann, Uwe; Cramer, Stephen P.

    2001-08-02

    A newly designed multi-crystal X-ray spectrometer and its applications in the fields of X-ray fluorescence and X-ray Raman spectroscopy are described. The instrument is based on 8 spherically curved Si crystals, each with a 3.5 inch diameter form bent to a radius of 86 cm. The crystals are individually aligned in the Rowland geometry capturing a total solid angle of 0.07 sr. The array is arranged in a way that energy scans can be performed by moving the whole instrument, rather than scanning each crystal by itself. At angles close to back scattering the energy resolution is between 0.3 and 1 eV depending on the beam dimensions at the sample. The instrument is mainly designed for X-ray absorption and fluorescence spectroscopy of transition metals in dilute systems such as metalloproteins. First results of the Mn K{beta} (3p -> 1s) emission in photosystem II are shown. An independent application of the instrument is the technique of X-ray Raman spectroscopy which can address problems similar to those in traditional soft X-ray absorption spectroscopies, and initial results are presented.

  7. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

    SciTech Connect

    Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.

    2015-09-14

    Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.

  8. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

    NASA Astrophysics Data System (ADS)

    Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.

    2015-09-01

    Reflection electron energy loss spectra from some insulating materials (CaCO3, Li2CO3, and SiO2) taken at relatively high incoming electron energies (5-40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO2, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E - Egap)1.5. For CaCO3, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li2CO3 (7.5 eV) is the first experimental estimate.

  9. Diagnosing the Stagnation Conditions of MagLIF Implosions Using High-Resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Harding, Eric

    2016-10-01

    An inertial fusion concept known as Magnetized Liner Inertial Fusion (MagLIF) is currently being pursued on the Z-machine at Sandia National Laboratory. Electrical current from the Z-machine is directly coupled onto the outside surface of a beryllium tube known as a ``liner'' causing it to implode. The liner contains gaseous deuterium (D2) fuel, which is pre-magnetized, pre-heated, and then compressed by the imploding walls of the liner. Target implosions of this type have produced thermonuclear plasmas that generated 2e12 DD neutrons [M.R. Gomez et al., PRL 113, 155003 (2014)]. For the first time we have accurately measured the space-dependent, fuel conditions at the time of stagnation. In addition, the state of the compressed Be liner was determined. This was accomplished by the simultaneous use of high-resolution, x-ray spectroscopic and imaging diagnostics. These new measurements relied on the observation of K-shell spectra emitted by microscopic iron and nickel impurities that naturally occur in the Be. The measurements currently indicate that the non-uniformity of the x-ray emission from the fuel is due to variations in the fuel conditions. Ultimately, the data provides critical insight into the performance of the MagLIF target and will further enable us to enhance the target design. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract No. DE-AC04-94AL85000.

  10. Detection and characterization of Io's atmosphere from high-resolution 4-μm spectroscopy

    NASA Astrophysics Data System (ADS)

    Lellouch, E.; Ali-Dib, M.; Jessup, K.-L.; Smette, A.; Käufl, H.-U.; Marchis, F.

    2015-06-01

    We report on high-resolution and spatially-resolved spectra of Io in the 4.0 μm region, recorded with the VLT/CRIRES instrument in 2008 and 2010, which provide the first detection of the ν1 + ν3 band of SO2 in Io's atmosphere. Data are analyzed to constrain the latitudinal, longitudinal, and diurnal distribution of Io's SO2 atmosphere as well as its characteristic temperature. Equatorial SO2 column densities clearly show longitudinal asymmetry, but with a maximum of ∼1.5 × 1017 cm-2 at central meridian longitude L = 200-220 and a minimum of ∼3 × 1016 cm-2 at L = 285-300, the longitudinal pattern somewhat differs from earlier inferences from Ly α and thermal IR measurements. Within the accuracy of the measurements, no evolution of the atmospheric density from mid-2008 to mid-2010 can be distinguished. The decrease of the SO2 column density towards high latitudes is apparent, and the typical latitudinal extent of the atmosphere found to be ±40° at half-maximum. The data show moderate diurnal variations of the equatorial atmosphere, which is evidence for a partially sublimation-supported atmospheric component. Compared to local noon, factor of 2 lower densities are observed ∼40° before and ∼80° after noon. Best-fit gas temperatures range from 150 to 220 K, with a weighted mean value of 170 ± 20 K, which should represent the column-weighted mean kinetic temperature of Io's atmosphere. Finally, although the data include clear thermal emission due to Pillan (in outburst in July 2008) and Loki, no detectable enhancements in the SO2 atmosphere above these volcanic regions are found, with an upper limit of 4 × 1016 cm-2 at Pillan and 1 × 1017 cm-2 at Loki.

  11. High Resolution Spectroscopy and Global Analysis of the Tetradecad Region of Methane 12CH_4

    NASA Astrophysics Data System (ADS)

    Nikitin, A.; Boudon, V.; Wenger, C.; Brown, L. R.; Bauerecker, S.; Albert, S.; Quack, M.

    2011-06-01

    We present the first detailed analysis of the Tetradecad region of methane 12CH_4 from 2.1 to 1.6 μm (4800 to 6250 Cm-1). New high resolution FTIR spectra measured in a collisional cooling cell at 80 K and at room temperature have allowed us to perform many new assignments. All assigned lines of 12CH_4 in the 0-6200 Cm-1 region have been included in a global fit, extending our previous analysis covering all levels up to and including the Octad (i.e. up to 4800 Cm-1 In the end, 3012 line positions and 1387 intensities of 45 individual subbands were modeled up to J = 14. The root mean square deviations were 0.023 Cm-1 for line positions and 13.86 % for line intensities in the Tetradecad region itself. Although this study is still preliminary, it is already sufficient to characterize the stronger bands throughout the whole of the Tetradecad polyad. The analysis and present success substantially improves our understanding of the methane spectra needed to interpret planetary atmospheres. This work is part of the ANR contract ``CH_4@Titan'' (ref: BLAN08-2_321467). Part of the research described here was also carried out at the Jet Propulsion Laboratory, under a contract with the National Aeronautics and Space Administration. Our work is also supported by the Swiss National Science Foundation. S. Albert, S. Bauerecker, V. Boudon, L. R. Brown, J.-P. Champion, M. Loëte, A. Nikitin, M. Quack, Chem. Phys., 356, 131--146 (2009).

  12. CALCIUM AND LIGHT-ELEMENTS ABUNDANCE VARIATIONS FROM HIGH-RESOLUTION SPECTROSCOPY IN GLOBULAR CLUSTERS

    SciTech Connect

    Carretta, Eugenio; Bragaglia, Angela; Bellazzini, Michele; Gratton, Raffaele; Lucatello, Sara; D'Orazi, Valentina E-mail: angela.bragaglia@oabo.inaf.it E-mail: raffaele.gratton@oapd.inaf.it E-mail: valentina.dorazi@oapd.inaf.it

    2010-03-20

    We use abundances of Ca, O, Na, and Al from high-resolution UVES spectra of 200 red giants in 17 globular clusters (GCs) to investigate the correlation found by Lee et al. between chemical enrichment from SN II and star-to-star variations in light elements in GC stars. We find that (1) the [Ca/H] variations between first and second generation stars are tiny in most GCs ({approx}0.02-0.03 dex, comparable with typical observational errors). In addition, (2) using a large sample of red giants in M 4 with abundances from UVES spectra from Marino et al., we find that Ca and Fe abundances in the two populations of Na-poor and Na-rich stars are identical. These facts suggest that the separation seen in color-magnitude diagrams using the U band or hk index (as observed in NGC 1851 by Han et al.) are not due to Ca variations. Small differences in [Ca/H] as associated with hk variations might be due to a small systematic effect in abundance analysis, because most O-poor/Na-rich (He-rich) stars have slightly larger [Fe/H] (by 0.027 dex on average, due to decreased H in the ratio) than first generation stars and are then located at redder positions in the V, hk plane. While a few GCs (M 54, {omega} Cen, M 22, maybe even NGC 1851) do actually show various degree of metallicity spread, our findings eliminate the need of a close link between the enrichment by core-collapse supernovae with the mechanism responsible for the Na-O anticorrelation.

  13. HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b

    SciTech Connect

    Crossfield, I. J. M.; Hansen, Brad M. S.; Barman, Travis

    2011-08-01

    The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to characterize the planet's atmosphere. By cross-correlating the spectral changes through transit with a suite of theoretical atmosphere models, we search for variations associated with absorption in the planet atmosphere. Our observations are sufficient to rule out tested model atmospheres with wavelength-dependent transit depth variations {approx}> 5 x 10{sup -4} over the wavelength range 2.1-2.4 {mu}m. Our sensitivity is limited by variable slit loss and telluric transmission effects. We find no positive signatures but successfully rule out a number of plausible atmospheric models, including the default assumption of a gaseous, H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made consistent if the absorption due to methane is reduced. Clouds can also render such an atmosphere consistent with our observations, but only if they lie higher in the atmosphere than indicated by recent optical and infrared measurements. When taken in concert with other observational constraints, our results support a model in which the atmosphere of GJ 1214b contains significant H and He, but where CH{sub 4} is depleted. If this depletion is the result of photochemical processes, it may also produce a haze that suppresses spectral features in the optical.

  14. SUBARU HIGH-RESOLUTION SPECTROSCOPY OF STAR G IN THE TYCHO SUPERNOVA REMNANT

    SciTech Connect

    Kerzendorf, Wolfgang E.; Schmidt, Brian P.; Yong, David; Asplund, M.; Nomoto, Ken'ichi; Podsiadlowski, Ph.; Frebel, Anna; Fesen, Robert A. E-mail: brian@mso.anu.edu.au E-mail: nomoto@astron.s.u-tokyo.ac.jp E-mail: anna@astro.as.utexas.edu

    2009-08-20

    It is widely believed that Type Ia supernovae (SNe Ia) originate in binary systems where a white dwarf accretes material from a companion star until its mass approaches the Chandrasekhar mass and carbon is ignited in the white dwarf's core. This scenario predicts that the donor star should survive the supernova (SNe) explosion, providing an opportunity to understand the progenitors of SNe Ia. In this paper, we argue that rotation is a generic signature expected of most nongiant donor stars that is easily measurable. Ruiz-Lapuente et al. examined stars in the center of the remnant of SN 1572 (Tycho SN) and showed evidence that a subgiant star (Star G by their naming convention) near the remnant's center was the system's donor star. We present high-resolution (R {approx_equal} 40, 000) spectra taken with the High Dispersion Spectrograph on Subaru of this candidate donor star and measure the star's radial velocity as 79 {+-} 2 km s{sup -1} with respect to the local standard of rest and put an upper limit on the star's rotation of 7.5 km s{sup -1}. In addition, by comparing images that were taken in 1970 and 2004, we measure the proper motion of Star G to be {mu} {sub l} = -1.6 {+-} 2.1 mas yr{sup -1} and {mu} {sub b} = -2.7 {+-} 1.6 mas yr{sup -1}. We demonstrate that all of the measured properties of Star G presented in this paper are consistent with those of a star in the direction of Tycho SN that is not associated with the SN event. However, we discuss an unlikely, but still viable scenario for Star G to be the donor star, and suggest further observations that might be able to confirm or refute it.

  15. Calcium and Light-elements Abundance Variations from High-resolution Spectroscopy in Globular Clusters

    NASA Astrophysics Data System (ADS)

    Carretta, Eugenio; Bragaglia, Angela; Gratton, Raffaele; Lucatello, Sara; Bellazzini, Michele; D'Orazi, Valentina

    2010-03-01

    We use abundances of Ca, O, Na, and Al from high-resolution UVES spectra of 200 red giants in 17 globular clusters (GCs) to investigate the correlation found by Lee et al. between chemical enrichment from SN II and star-to-star variations in light elements in GC stars. We find that (1) the [Ca/H] variations between first and second generation stars are tiny in most GCs (~0.02-0.03 dex, comparable with typical observational errors). In addition, (2) using a large sample of red giants in M 4 with abundances from UVES spectra from Marino et al., we find that Ca and Fe abundances in the two populations of Na-poor and Na-rich stars are identical. These facts suggest that the separation seen in color-magnitude diagrams using the U band or hk index (as observed in NGC 1851 by Han et al.) are not due to Ca variations. Small differences in [Ca/H] as associated with hk variations might be due to a small systematic effect in abundance analysis, because most O-poor/Na-rich (He-rich) stars have slightly larger [Fe/H] (by 0.027 dex on average, due to decreased H in the ratio) than first generation stars and are then located at redder positions in the V, hk plane. While a few GCs (M 54, ω Cen, M 22, maybe even NGC 1851) do actually show various degree of metallicity spread, our findings eliminate the need of a close link between the enrichment by core-collapse supernovae with the mechanism responsible for the Na-O anticorrelation. Based on data collected at the European Southern Observatory, Chile, programmes 072.D-507, 073.D-0211, 072.D-0742, and 077.D-0182.

  16. Understanding AGB evolution in Galactic bulge stars from high-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Uttenthaler, S.; Blommaert, J. A. D. L.; Wood, P. R.; Lebzelter, T.; Aringer, B.; Schultheis, M.; Ryde, N.

    2015-08-01

    An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and a smaller one in the outer bulge. The data are analysed with the help of hydrostatic model atmospheres and spectral synthesis. We derive the radial velocity of all stars, and the atmospheric chemical mix ([Fe/H], C/O, 12C/13C, Al, Si, Ti, and Y) where possible. Our ability to model the spectra is mainly limited by the (in)completeness of atomic and molecular line lists, at least for temperatures down to Teff ≈ 3100 K. We find that the subsample in the inner and intermediate bulge is quite homogeneous, with a slightly subsolar mean metallicity and only few stars with supersolar metallicity, in agreement with previous studies of non-variable M-type giants in the bulge. All sample stars are oxygen-rich, C/O < 1.0. The C/O and carbon isotopic ratios suggest that third dredge-up (3DUP) is absent among the sample stars, except for two stars in the outer bulge that are known to contain technetium. These stars are also more metal-poor than the stars in the intermediate or inner bulge. Current stellar masses are determined from linear pulsation models. The masses, metallicities and 3DUP behaviour are compared to AGB evolutionary models. We conclude that these models are partly in conflict with our observations. Furthermore, we conclude that the stars in the inner and intermediate bulge belong to a more metal-rich population that follows bar-like kinematics, whereas the stars in the outer bulge belong to the metal-poor, spheroidal bulge population.

  17. High-Resolution Near-Infrared Spectroscopy of Fuors and Fuor-Like Stars

    NASA Astrophysics Data System (ADS)

    Greene, Thomas P.; Aspin, Colin; Reipurth, Bo

    2008-04-01

    We present new high-resolution (R sime 18, 000) near-infrared spectroscopic observations of a sample of classical FU Orionis stars (FUors) and other young stars with FUor characteristics that are sources of Herbig-Haro (HH) flows. Spectra are presented for the region λ = 2.203-2.236 μm which is rich in absorption lines sensitive to both effective temperatures and surface gravities of stars. Both FUors and FUor-like stars show numerous broad and weak-unidentified spectral features in this region. Spectra of the 2.280-2.300 μm region are also presented, with the 2.2935 μm v = 2-0 CO absorption bandhead being clearly the strongest feature seen in the spectra of all FUors and FUor-like stars. A cross-correlation analysis shows that FUor and FUor-like spectra in the 2.203-2.236 μm region are not consistent with late-type dwarfs, giants, nor embedded protostars. The cross-correlations also show that the observed FUor-like HH energy sources have spectra that are substantively similar to those of FUors. Both object groups also have similar near-infrared colors. The large line widths and double-peaked nature of the spectra of the FUor-like stars are consistent with the established accretion disk model for FUors, also consistent with their near-infrared colors. It appears that young stars with FUor-like characteristics may be more common than projected from the relatively few known classical FUors. Much of the data presented herein were obtained at the W.M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  18. High-resolution ultraviolet spectroscopy of gas in galaxy halos and large-scale structures

    NASA Astrophysics Data System (ADS)

    Song, Limin

    This dissertation presents spectroscopic studies of gas in galaxy halos and large-scale structures through high-resolution quasar absorption lines. The broad goal of this effort is to learn how galaxies acquire their gas and how they return it to the intergalactic medium, or more generally, how galaxies interact with their environment. The study of the absorption lines due to the extraplanar 21cm "Outer Arm" (OA) of the Milky Way toward two quasars, H1821+643 and HS0624+6907, provides valuable insight into the gas accretion processes. It yields the following results. (1) The OA is a multiphase cloud and high ions show small but significant offsets in velocity and are unlikely to be cospatial with the low ions. (2) The overall metallicity of the OA is Z=0.3-0.5 Z⊙, but nitrogen is underabundant. (3) The abundance of N, O, and S derived are roughly consistent with outer-galaxy emission-line abundances and the metallicity gradient derived from H II regions. The similarity of the OA kinematics to several nearby high velocity clouds (HVCs, e.g. Complexes C, G, and H) suggests that these clouds could be detritus from a merging satellite galaxy. To test this hypothesis, we build up a simple model including tidal tripping, ram-pressure stripping, and dynamical friction to consider whether the OA could be debris affiliated with the Monoceros Ring. Our model can roughly reproduce the spatial and velocity characteristics of the OA. Moreover, the metallicity of the OA is similar to the higher metallicities measured in the younger stellar components of the Monoceros Ring and the progenitor candidate, the CMa overdensity. However, both our model and the Galactic warp scenario can not explain other HVCs that are likely to be related to the OA. Instead of acquiring gas, some galaxies have their gas removed through various physical processes. Ram-pressure stripping and tidal interaction are important mechanisms for galaxies to loose their gas. The high-resolution spectrum of Mrk

  19. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

    PubMed Central

    Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

    2017-01-01

    Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

  20. High-resolution optical spectroscopy using multimode interference in a compact tapered fibre.

    PubMed

    Wan, Noel H; Meng, Fan; Schröder, Tim; Shiue, Ren-Jye; Chen, Edward H; Englund, Dirk

    2015-07-23

    Optical spectroscopy is a fundamental tool in numerous areas of science and technology. Much effort has focused on miniaturizing spectrometers, but thus far at the cost of spectral resolution and broad operating range. Here we describe a compact spectrometer that achieves both high spectral resolution and broad bandwidth. The device relies on imaging multimode interference from leaky modes along a multimode tapered optical fibre, resulting in spectrally distinguishable spatial patterns over a wide range of wavelengths from 500 to 1,600 nm. This tapered fibre multimode interference spectrometer achieves a spectral resolution down to 40 pm in the visible spectrum and 10 pm in the near-infrared spectrum (corresponding to resolving powers of 10(4)-10(5)). Multimode interference spectroscopy is suitable in a variety of device geometries, including planar waveguides in a broad range of transparent materials.

  1. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

    NASA Astrophysics Data System (ADS)

    Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J.-C.; Traykov, E.; van Beveren, C.; van den Bergh, P.; van Duppen, P.; Wendt, K.; Zadvornaya, A.

    2017-02-01

    Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency.

  2. High-resolution proton nuclear magnetic resonance spectroscopy of ovarian cyst fluid.

    PubMed

    Boss, E A; Moolenaar, S H; Massuger, L F; Boonstra, H; Engelke, U F; de Jong, J G; Wevers, R A

    2000-08-01

    Most ovarian tumors are cystic structures containing variable amounts of fluid. Several studies of ovarian cyst fluid focus on one specific metabolite using conventional assay systems. We examined the potential of (1)H-nuclear magnetic resonance spectroscopy in evaluation of the overall metabolic composition of cyst fluid from different ovarian tumors. Ovarian cyst fluid samples obtained from 40 patients with a primary ovarian tumor (12 malignant and 28 benign) were examined. After deproteinization and pD standardization, we performed (1)H-NMR spectroscopy on a 600 MHz instrument. With (1)H-NMR spectroscopy we found detectable concentrations of 36 metabolites with high intersample variation. A number of unassigned resonances as well as unexpected metabolites were found. We introduce an overall inventory of the low-molecular-weight metabolites in ovarian cyst fluid with corresponding resonances. Significant differences in concentration (p < 0.01) were found for several metabolites (including an unknown metabolite) between malignant and benign ovarian cysts. Furthermore, higher concentrations in malignant- and lower in benign fluids were found compared to normal serum values, indicating local cyst wall metabolic processes in case of malignant transformation. We conclude that (1)H-nuclear magnetic resonance spectroscopy can give an overview of low-molecular-weight proton-containing metabolities present in ovarian cyst fluid samples. The metabolic composition of cyst fluid differs significantly between benign and malignant ovarian tumors. Furthermore, differences between benign subgroups possibly related to histopathological behaviour can be detected. The presence of N-acetyl aspartic acid and 5-oxoproline exclusively in serous cystadenoma samples is remarkable. Future studies will concentrate on these findings and explore the possibilities of extrapolating information from the in vitro studies to in vivo practice, in which metabolic differences between malignant and

  3. Triple Fabry-Pérot Imaging Interferometer for High Resolution Solar Spectroscopy using the ATST

    NASA Astrophysics Data System (ADS)

    Robinson, B. M.; Gary, G. A.; Balasubramaniam, K. S.

    2005-05-01

    We present a telecenrically mounted triple Fabry-Pérot imaging interferometer for the NSOs Advanced Technology Solar Telescope (ATST). It consists of three Fabry-Pérot etalons and the feed and imaging optics. This system provides high throughput, flexibility and breadth of operation when compared to other spectroscopic imaging systems. It can operate in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, an intermediate-band imager, and broadband high-resolution imager. In the proposed telecentric mount configuration, the transmittance of the etalon system is not a function of position in the field, so that instantaneous spectroscopic measurements can be performed across the entire field of view; however, the transmission peak of the interferometer is broadened. Mitigation of this broadening requires a low F# image at the etalons. Together with the requirement that the field of view be large enough to observe large-scale processes in the solar atmosphere, this limitation dictates that the diameter of the etalons have a large aperture. Specifically, for a spectrographic passband full-width at half-maximum (FWHM) of around 2 pm, and entrance pupil diameter of 4 m, and a field of view of 35", the required etalon diameter is around 200 mm. This is beyond the size of current Fabry-Pérot etalons and near the current projected limit of manufacturability. The development of this instrument will bring these large etalons to realization and take Fabry-Pérot imaging interferometry to the next level of operational capability within telescopes of large aperture. This instrument will provide spectral, spatial, and temporal resolution which is not currently available to large aperture solar astronomy, but which is necessary, in conjunction with the new class telescopes, to the continuing discovery of laws that govern the dynamics of the sun and the earth-sun connection. The resolution afforded by higher aperture telescopes and instrumentation will

  4. Estimating photosynthesis with high resolution field spectroscopy in a Mediterranean grassland under different nutrient availability

    NASA Astrophysics Data System (ADS)

    Perez-Priego, O.; Guan, J.; Fava, F.; Rossini, M.; Wutzler, T.; Moreno, G.; Carrara, A.; Kolle, O.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2014-12-01

    Recent studies have shown how human induced N:P imbalances are affecting essential processes (e.g. photosynthesis, plant growth rate) that lead to important changes in ecosystem structure and function. In this regard, the accuracy of the approaches based on remotely-sensed data for monitoring and modeling gross primary production (GPP) relies on the ability of vegetation indices (VIs) to track the dynamics of vegetation physiological and biophysical properties/variables. Promising results have been recently obtained when Chlorophyll-sensitive VIs and Chlorophyll fluorescence are combined with structural indices in the framework of the Monteith's light use efficiency (LUE) model. However, further ground-based experiments are required to validate LUE model performances, and their capability to be generalized under different nutrient availability conditions. In this study, the overall objective was to investigate the sensitivity of VIs to track short- and long-term GPP variations in a Mediterranean grassland under different N and P fertilization treatments. Spectral VIs were acquired manually using high resolution spectrometers (HR4000, OceanOptics, USA) along a phenological cycle. The VIs examined included photochemical reflectance index (PRI), MERIS terrestrial-chlorophyll index (MTCI) and normalized difference vegetation index (NDVI). Solar-induced chlorophyll fluorescence calculated at the oxygen absorption band O2-A (F760) using spectral fitting methods was also used. Simultaneously, measurements of GPP and environmental variables were conducted using a transient-state canopy chamber. Overall, GPP, F760 and VIs showed a clear seasonal time-trend in all treatments, which was driven by the phenological development of the grassland. Results showed significant differences (p<0.05) in midday GPP values between N and without N addition plots, in particular at the peak of the growing season during the flowering stage and at the end of the season during senescence. While

  5. High Resolution Microwave Spectroscopy of CH as a Search for Variation of Fundamental Constants

    NASA Astrophysics Data System (ADS)

    Truppe, S.; Hendricks, R. J.; Tokunaga, S. K.; Hinds, E. A.; Tarbutt, M. R.

    2013-06-01

    The Standard Model of particle physics assumes that fundamental, dimensionless constants like the fine-structure constant, α, or the ratio of the proton to electron mass, μ, remain constant through time and space. Laboratory experiments have set tight bounds on variations of such constants on a short time scale. Astronomical observations, however, provide vital information about possible changes on long time scales. Recent measurements using quasar absorption spectra provide some evidence for a space-time variation of the fine-structure constant α. It is thus important to verify this discovery by using an entirely different method. Recently the prospect of using rotational microwave spectra of molecules as a probe of fundamental constants variation has attracted much attention. Generally these spectra depend on μ, but if fine and hyperfine structure is involved they also become sensitive to variations of α and the nuclear g-factor. Recent calculations show that the Λ-doublet and rotational spectra of CH are particularly sensitive to possible variations of μ and α. We present recent laboratory based high-resolution spectra of the Λ-doublet transition frequencies of the {F}_2, J=1/2 and {F}_1, J=3/2 states of CH, X^{2}{Π} (v=0) at 3.3GHz and 0.7GHz respectively, with {F} labelling the different spin-orbit manifolds of CH. We also present a measurement of the transition frequency between the two spin-orbit manifolds {F}_2, J=1/2 and {F}_1, J=3/2 at 530GHz. By using a molecular beam of CH in combination with a laser-microwave double-resonance technique and Ramsey's method of separated oscillatory fields, we have measured these transition frequencies to unprecedented accuracy. Hence CH can now be used as a sensitive probe to detect changes in fundamental constants by comparing lab based frequencies to radio-astronomical observations from distant gas clouds. T. Rosenband et al., Science {319}(5871), 1808, 2008 J. K. Webb et al., Physical Review Letters {107

  6. High Resolution Spectroscopy Using a Tunable Thz Synthesizer Based on Photomixing

    NASA Astrophysics Data System (ADS)

    Cuisset, Arnaud; Hindle, Francis; Mouret, Gael; Eliet, Sophie; Guinet, Mickael; Bocquet, Robin

    2011-06-01

    Optical heterodyning, also know as photomixing is an attractive solution as a single device able to cover the entire frequency range from 300 GHz to 3 THz. As the THz frequency is extracted from the difference frequency of two lasers, the accuracy with which the generated frequency is known is directly determined by the frequency accuracy of the lasers. In order to fully characterize the spectral fingerprint of a given molecule an accuracy approximately one order of magnitude finer than the Doppler linewidth is required, around 100 kHz for smaller polar compounds. To generate accurate cw-THz the frequency spacing of the modes of a Frequency Comb (FC) has been employed to constrain the emission frequency of a photomixing source.footnote{G. Mouret, F. Hindle, A. Cuisset, C. Yang, R. Bocquet, M. Lours, D. Rovera, Opt. Express, 2009, 17: 22031.} Two phase locked loops are implemented coherently locking the two cw-lasers (CW1 and CW2) to different modes of the FC. Although this solution allows accurate generation of narrowband THz the continuous tuning of the frequency presents some obstacles. To overcome these difficulties a system architecture with a third cw-laser (CW3) phase locked to CW2 has been implemented. The beatnote between CW2 and CW3 is free from the FC modes therefore the PLL frequency can be freely scanned over its entire operating range, in our case around 200 MHz. The most of polar compounds may be studied at high resolution in the THz domain with this synthesizer. Three different examples of THz analysis with atmospherical and astrophysical interests will be presented: The ground and vibrationnally excited states of H_2CO revisited in the 0.5-2 THz frequency region The rotational dependences of the broadening coefficients of CH_3Cl studied at high J and K values The molecular discrimination of a complex mixture containing methanol and ethanol. F. Hindle, A. Cuisset, G. Mouret, R. Bocquet Comptes Rendus Physique, 2008, 9: 262-275.

  7. Activators of photoluminescence in calcite: evidence from high-resolution, laser-excited luminescence spectroscopy

    USGS Publications Warehouse

    Pedone, V.A.; Cercone, K.R.; Burruss, R.C.

    1990-01-01

    Laser-excited luminescence spectroscopy of a red-algal, biogenic calcite and a synthetic Mn-calcite can make the distinction between organic and trace-element activators of photoluminescence. Organic-activated photoluminescence in biogenic calcite is characterized by significant peak shifts and increasing intensity with shorter-wavelength excitation and by significant decreases in intensity after heating to ??? 400??C. In contrast, Mn-activated photoluminescence shows no peak shift, greatest intensity under green excitation and limited changes after heating. Examination of samples with a high-sensitivity spectrometer using several wavelengths of exciting light is necessary for identification of photoluminescence activators. ?? 1990.

  8. Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

    PubMed Central

    Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

    2009-01-01

    A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements. PMID:22291552

  9. An ultrastable Michelson interferometer for high-resolution spectroscopy in the XUV.

    PubMed

    Corsi, C; Liontos, I; Cavalieri, S; Bellini, M; Venturi, G; Eramo, R

    2015-02-23

    We developed an ultra-stable and accurately-controllable Michelson interferometer to be used in a deeply unbalanced arm configuration for split-pulse XUV Ramsey-type spectroscopy with high-order laser harmonics. The implemented active and passive stabilization systems allow one to reach instabilities in the nanometer range over meters of relative optical path differences. Producing precisely delayed pairs of pump pulses will generate XUV harmonic pulses that may significantly improve the achievable spectral resolution and the precision of absolute frequency measurements in the XUV.

  10. High-resolution photodetachment spectroscopy from the lowest threshold of O{sup -}

    SciTech Connect

    Joiner, Anne; Mohr, Robert H.; Yukich, J. N.

    2011-03-15

    We conducted photodetachment spectroscopy near the lowest detachment threshold from O{sup -} in a 1-T field with sufficient resolution to observe a magnetic field structure similar to that observed in experiments conducted at the threshold of the electron affinity. These observations included not only cyclotron structure but also, to a smaller degree, individual Zeeman thresholds. The experiment was conducted in a Penning ion trap and with a single-mode, tunable, amplified diode laser. Finally, analysis of our results yielded a measurement of the lowest threshold energy.

  11. Oxygen-induced changes in electron-energy-loss spectra for Al, Be and Ni. [Al; Be; Ni

    SciTech Connect

    Madden, H.H.; Landers, R.; Kleiman, G.G. , 13081-970 Campinas, Sao Paulo, Brasil); Zehner, D.M. )

    1999-09-01

    Electron-energy-loss spectroscopy (EELS) data are presented to illustrate line shape changes that occur as a result of oxygen interaction with metal surfaces. The metals were aluminum, beryllium and nickel. Core-level EELS data were taken for excitations from Al(2p), Be(1s), Ni(3p/3s) and O(1s) levels to the conduction band (CB) density of states (DOS) of the materials. The primary beam energies for the spectra were 300, 450, 300, and 1135 eV, respectively. The data are presented in both the (as measured) first-derivative and the integral forms. The integral spectra were corrected for coherent background losses and analyzed for CB DOS information. These spectra were found to be in qualitative agreement with published experimental and theoretical studies of these materials. One peak in the spectra for Al oxide is analyzed for its correlation with excitonic screening of the Al(2p) core hole. Similar evidence for exciton formation is found in the Ni(3p) spectra for Ni oxide. Data are also presented showing oxygen-induced changes in the lower-loss-energy EELS curves that, in the pure metal, are dominated by plasmon-loss and interband-transition signals. Single-scattering loss profiles in the integral form of the data were calculated using a procedure of Tougaard and Chorkendorff [S. Tougaard and I. Chorkendorff, Phys. Rev. B. [bold 35], 6570 (1987)]. For all three oxides these profiles are dominated by a feature with a loss energy of around 20[endash]25 eV. Although this feature has been ascribed by other researchers as due to bulk plasmon losses in the oxide, an alternative explanation is that the feature is simply due to O(2s)-to-CB-level excitations. An even stronger feature is found at 7 eV loss energy for Ni oxide. Speculation is given as to its source. The line shapes in both the core-level and noncore-level spectra can also be used simply as [open quotes]fingerprints[close quotes] of the surface chemistry of the materials. Our data were taken using commercially

  12. Development of micro-optics for high-resolution IL spectroscopy with a proton microbeam probe

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

    2014-01-01

    Confocal optics for ion luminescence (IL) was developed for the precise analysis of the chemical composition of microscopic targets with an external proton microbeam probe. Anti-reflection-coated confocal micro-lens optics with an effective focus area of approximately 800 × 800 μm was installed on the microbeam line of a single-ended accelerator. Chromatic aberrations of the confocal optics were examined at wavelengths of 300-900 nm. An electrically-cooled back-thinned charge coupled device spectrometer with a wavelength resolution of 0.5 nm was used for the microscopic spectroscopy and IL imaging of microscopic mineral targets. Simultaneous microscopic IL and micro-PIXE analysis were performed using an external 3 MeV H+ microbeam with a current of less than 100 pA. A spectral resolution of 3 nm was achieved for a single IL peak which corresponded to Cr3+ impurities in a single-crystal of aluminum oxide. The use of IL spectroscopy and imaging for aerosol targets revealed microscopic distributions of the chemical and elemental composition in the atmosphere.

  13. Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire. II. Electron energy loss spectroscopic study

    SciTech Connect

    Lee, Sung Bo Han, Heung Nam; Kim, Young-Min

    2015-07-15

    In Part I, we have shown that the addition of Si into sapphire by ion implantationmakes the sapphire substrate elastically softer than for the undoped sapphire. The more compliant layer of the Si-implanted sapphire substrate can absorb the misfit stress at the GaN/sapphire interface, which produces a lower threading-dislocation density in the GaN overlayer. Here in Part II, based on experimental results by electron energy loss spectroscopy and a first-principle molecular orbital calculation in the literature, we suggest that the softening effect of Si results from a reduction of ionic bonding strength in sapphire (α-Al{sub 2}O{sub 3}) with the substitution of Si for Al.

  14. Titan's 3-micron spectral region from ISO high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena; Negrão, Alberto; Salama, Alberto; Schulz, Bernhard; Lellouch, Emmanuel; Rannou, Pascal; Drossart, Pierre; Encrenaz, Thérèse; Schmitt, Bernard; Boudon, Vincent; Nikitin, Andrei

    2006-01-01

    The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH 4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9-3.1 μm) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625-631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575-578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628-630; Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39-L42]. We report here on the first spectroscopic observations of Titan covering the whole 2.4-4.9 μm region by two instruments on board the Infrared Space Observatory (ISO) in 1997. These observations show the 2.75-μm window in its complete extent for the first time. In this study we have also used a high-resolution Titan spectrum in the 2.9-3.6 μm region taken with the Keck [Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39-L42; Kim, S.J., Geballe, T.R., Noll, K.S., Courtin, R., 2005. Icarus 173, 522-532] to infer information on the atmospheric parameters (haze extinction, single scattering albedo, methane abundance, etc.) by fitting the methane bands with a detailed microphysical model of Titan's atmosphere (updated from Rannou, P., McKay, C.P., Lorenz, R.D., 2003. Planet. Space Sci. 51, 963-976). We have included in this study an updated version of a database for the CH 4 absorption coefficients [STDS, Wenger, Ch., Champion, J.-P., 1998. J. Quant. Spectrosc. Radiat. Transfer 59, 471-480. See also http://www.u-bourgogne.fr/LPUB/TSM/sTDS.html for latest updates; Boudon, V., Champion, J.-P., Gabard, T., Loëte, M., Michelot, F., Pierre, G., Rotger, M., Wenger, Ch., Rey, M., 2004. J. Mol

  15. Structural shimming for high-resolution nuclear magnetic resonance spectroscopy in lab-on-a-chip devices.

    PubMed

    Ryan, Herbert; Smith, Alison; Utz, Marcel

    2014-05-21

    High-resolution proton NMR spectroscopy is well-established as a tool for metabolomic analysis of biological fluids at the macro scale. Its full potential has, however, not been realised yet in the context of microfluidic devices. While microfabricated NMR detectors offer substantial gains in sensitivity, limited spectral resolution resulting from mismatches in the magnetic susceptibility of the sample fluid and the chip material remains a major hurdle. In this contribution, we show that susceptibility broadening can be avoided even in the presence of substantial mismatch by including suitably shaped compensation structures into the chip design. An efficient algorithm for the calculation of field maps from arbitrary chip layouts based on Gaussian quadrature is used to optimise the shape of the compensation structure to ensure a flat field distribution inside the sample area. Previously, the complexity of microfluidic NMR systems has been restricted to simple capillaries to avoid susceptibility broadening. The structural shimming approach introduced here can be adapted to virtually any shape of sample chamber and surrounding fluidic network, thereby greatly expanding the design space and enabling true lab-on-a-chip systems suitable for high-resolution NMR detection.

  16. Structural analysis of IPC zeolites and related materials using positron annihilation spectroscopy and high-resolution argon adsorption.

    PubMed

    Jagiello, J; Sterling, M; Eliášová, P; Opanasenko, M; Zukal, A; Morris, R E; Navaro, M; Mayoral, A; Crivelli, P; Warringham, R; Mitchell, S; Pérez-Ramírez, J; Čejka, J

    2016-06-01

    The advanced investigation of pore networks in isoreticular zeolites and mesoporous materials related to the IPC family was performed using high-resolution argon adsorption experiments coupled with the development of a state-of-the-art non-local density functional theory approach. The optimization of a kernel for model sorption isotherms for materials possessing the same layer structure, differing only in the interlayer connectivity (e.g. oxygen bridges, single- or double-four-ring building units, mesoscale pillars etc.) revealed remarkable differences in their porous systems. Using high-resolution adsorption data, the bimodal pore size distribution consistent with crystallographic data for IPC-6, IPC-7 and UTL samples is shown for the first time. A dynamic assessment by positron annihilation lifetime spectroscopy (PALS) provided complementary insights, simply distinguishing the enhanced accessibility of the pore network in samples incorporating mesoscale pillars and revealing the presence of a certain fraction of micropores undetected by gas sorption. Nonetheless, subtle differences in the pore size could not be discriminated based on the widely-applied Tao-Eldrup model. The combination of both methods can be useful for the advanced characterization of microporous, mesoporous and hierarchical materials.

  17. High Resolution Infrared Spectroscopy of Propargyl Alcohol-Water Complex Embedded in Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Pal, Nitish; Kaufmann, Matin; Schwaab, Gerhard; Havenith, Martina

    2016-06-01

    Propargyl alcohol (hereafter abbreviated as PA) is a molecule of astrophysical interest and has been probed extensively using microwave spectroscopy.1,2 It is a multifunctional molecule and offers multiple sites for hydrogen bonding interactions. Therefore, it has also attracted the attention of groups interested in weak intermolecular interactions. Recently, the Ar…PA complex3 and PA-dimer4 have been studied using microwave spectroscopy. More recently, there have been matrix-isolation infrared spectroscopic studies on PA-water5 and PA-acetylene6 complexes. In the present work, clusters of PA and water were formed in the helium nanodroplets and probed using a combination of infrared spectroscopy and mass spectrometry. Using ab-initio quantum mechanical calculations, PA-water clusters were optimised and five minimum structures were found on the potential energy hypersurface, which were used as a guidance to the experiments. We used D2O for the experiments since our laser sources at Bochum do not cover the IR spectral region of H2O. IR spectra of PA-D2O complex were recorded in the region of symmetric and antisymmetric stretches of the bound D2O. Multiple signals were found in these regions which were dependent on the concentration of PA as well as D2O. Using pickup curves most of these signals could be assigned to 1:1 PA:D2O clusters. The ab-initio calculations helped in a definitive assignment of the spectra to the different conformers of PA-D2O complex. The details will be presented in the talk. References: 1. E. Hirota, J. Mol. Spec. 26, 335 (1968). 2. J.C. Pearson and B.J. Drouin, J. Mol. Spectrosc. 234, 149 (2005). 3. D. Mani and E. Arunan, ChemPhysChem 14, 754 (2013). 4. D. Mani and E. Arunan, J. Chem. Phys. 141, 164311 (2014). 5. J. Saini, K.S. Vishwanathan, J. Mol. Struct. 1118, 147 (2016). 6. K. Sundararajan et al., J. Mol. Struct. 1121, 26 (2016).

  18. Application of the low-finesse γ -ray frequency comb for high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Shakhmuratov, R. N.; Vagizov, F. G.; Scully, Marlan O.; Kocharovskaya, Olga

    2016-10-01

    High-finesse frequency combs (HFC) with large ratio of the frequency spacing to the width of the spectral components have demonstrated remarkable results in many applications such as precision spectroscopy and metrology. We found that low-finesse frequency combs having very small ratio of the frequency spacing to the width of the spectral components are more sensitive to the exact resonance with absorber than HFC. Our method is based on time domain measurements reviling oscillations of the radiation intensity after passing through an optically thick absorber. Fourier analysis of the oscillations allows to reconstruct the spectral content of the comb. If the central component of the incident comb is in exact resonance with the single line absorber, the contribution of the first sideband frequency to oscillations is exactly zero. We demonstrated this technique with γ -photon absorption by Mössbauer nuclei providing the spectral resolution beyond the natural broadening.

  19. Method And Apparatus For High Resolution Ex-Situ Nmr Spectroscopy

    DOEpatents

    Pines, Alexander; Meriles, Carlos A.; Heise, Henrike; Sakellariou, Dimitrios; Moule, Adam

    2004-01-06

    A method and apparatus for ex-situ nuclear magnetic resonance spectroscopy for use on samples outside the physical limits of the magnets in inhomogeneous static and radio-frequency fields. Chemical shift spectra can be resolved with the method using sequences of correlated, composite z-rotation pulses in the presence of spatially matched static and radio frequency field gradients producing nutation echoes. The amplitude of the echoes is modulated by the chemical shift interaction and an inhomogeneity free FID may be recovered by stroboscopically sampling the maxima of the echoes. In an alternative embodiment, full-passage adiabatic pulses are consecutively applied. One embodiment of the apparatus generates a static magnetic field that has a variable saddle point.

  20. Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals

    SciTech Connect

    Edward R. Grant

    2005-09-07

    This report describes the results of a program of research on the thermochemistry, spectroscopy and intramolecular relaxation dynamics of the combustion intermediate, HCO. We prepare this radical from acetaldehyde as a photo-precursor in a differentially pumped laser-ionization source quadrupole mass spectrometer. Using a multiresonant spectroscopic technique established in our laboratory, we select individual rotational states and overcome Franck-Condon barriers associated with neutral-to-cation geometry changes to promote transitions to individual autoionizing series and state-resolved ionization thresholds. Systematic analysis of rotational structure and associated lineshapes provide experimental insight on autoionization dynamics as input for theoretical modeling. Extrapolation of series, combined with direct threshold-photoelectron detection, yield precise ionization potentials that constitute an important contribution to the thermochemical base of information on HCO.

  1. a Study of Vibrational Mode Coupling in 2-FLUOROETHANOL and 1,2-DIFLUOROETHANE Using High-Resolution Infrared Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Mork, Steven Wayne

    High resolution infrared spectroscopy was used to examine intramolecular vibrational interactions in 2 -fluoroethanol (2FE) and 1,2-difluoroethane (DFE). A high resolution infrared spectrophotometer capable of better than 10 MHz spectral resolution was designed and constructed. The excitation source consists of three lasers: an argon-ion pumped dye laser which pumps a color -center laser. The infrared beam from the color-center laser is used to excite sample molecules which are rotationally and vibrationally cooled in a supersonic molecular beam. Rovibrational excitation of the sample molecules is detected by monitoring the kinetic energy of the molecular beam with a bolometer. The high resolution infrared spectrum of 2FE was collected and analyzed over the 2977-2990 cm^ {-1}^ectral region. This region contains the asymmetric CH stretch on the fluorinated carbon. The spectrum revealed extensive perturbations in the rotational fine structure. Analysis of these perturbations has provided a quantitative measure of selective vibrational mode coupling between the C-H stretch and its many neighboring dark vibrational modes. Interestingly, excitation of the C-H stretch is known to induce a photoisomerization reaction between 2FE's Gg^' and Tt conformers. Implications of the role of mode coupling in the reaction mechanism are also addressed. Similarly, the high resolution infrared spectrum of DFE was collected and analyzed over the 2978-2996 cm ^{-1}^ectral region. This region contains the symmetric combination of asymmetric C-H stretches in DFE. Perturbations in the rotational fine structure indicate vibrational mode coupling to a single dark vibrational state. The dark state is split by approximately 19 cm^{-1} due to tunneling between two identical gauche conformers. The coupling mechanism is largely anharmonic with a minor component of B/C-plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. The coupled vibrational

  2. High-resolution synchrotron far infrared spectroscopy of thionyl chloride: Analysis of the ν3 and ν6 fundamental bands

    NASA Astrophysics Data System (ADS)

    Martin-Drumel, Marie-Aline; Mouret, Gaël; Pirali, Olivier; Cuisset, Arnaud

    2015-09-01

    Thionyl chloride (SOCl2) is a volatile inorganic compounds used extensively in industry. Its monitoring in gas phase is critical both for environmental and defense concerns. Previous high-resolution gas phase spectroscopic studies were focused on the microwave region (below 40 GHz) and no rotationally-resolved study of the IR spectrum has been reported to date. We present in this article a rovibrational analysis of the two lowest frequency infrared active bending modes ν3 and ν6 of SOCl2. By means of synchrotron based Fourier-Transform far-infrared spectroscopy on the AILES beamline of the SOLEIL facility, the spectra of the symmetric ν3 (346 cm-1) and asymmetric ν6 (283 cm-1) fundamental bands have been rotationally resolved and analyzed.

  3. Experimentally characterizing the electronic structures of f-electron systems using advanced high resolution Fourier transform microwave spectroscopies

    SciTech Connect

    Cooke, Stephen, A

    2013-02-03

    We aim to (i) provide data that directly addresses the fundamental roles of actinide valence electrons in chemical bonding, and (ii) serve to provide prototypical data for the heavy element computational chemistry community. These goals will be achieved through the first pure rotational spectroscopic measurements on prototypical systems at ultra-high resolution. These systems encompass low oxidation state uranium and thorium compounds including, but not limited to, UX and ThX, X = F, Cl, Br, I, and UY and ThY, Y = O, S, and other simple U and Th-containing compounds. Our primary experimental tools involve time-domain rotational spectroscopy achieving line widths and resolutions of a few kHz.

  4. High-resolution three-dimensional compositional imaging by double-pulse laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Schiavo, C.; Menichetti, L.; Grifoni, E.; Legnaioli, S.; Lorenzetti, G.; Poggialini, F.; Pagnotta, S.; Palleschi, V.

    2016-08-01

    In this paper we present a new instrument specifically realized for high-resolution three-dimensional compositional analysis and mapping of materials. The instrument is based on the coupling of a Double-Pulse Laser-Induced Breakdown Spectroscopy (LIBS) instrument with an optical microscope. The compositional mapping of the samples is obtained by scanning the laser beam across the surface of the sample, while the in depth analysis is performed by sending multiple laser pulses on the same point. Depths of analysis of several tens of microns can be obtained. The instrument presented has definite advantages with respect to Laser Ablation-ICP Mass Spectrometry in many applications related to material analysis, biomedicine and environmental diagnostics. An application to the diagnostics of industrial ceramics is presented, demonstrating the feasibility of Double-Pulse LIBS Imaging and its advantages with respect to conventional single-pulse LIBS imaging.

  5. Analysis of the phase diagram and microstructural transitions in phospholipid microemulsion systems using high-resolution ultrasonic spectroscopy.

    PubMed

    Hickey, Sinead; Lawrence, M Jayne; Hagan, Sue A; Buckin, Vitaly

    2006-06-20

    In the present work, high-resolution ultrasonic spectroscopy was applied to analyze a pseudoternary phase diagram for mixtures consisting of water/isopropyl myristate/Epikuron 200 and a cosurfactant (n-propanol). Changes in the ultrasonic velocity and attenuation in the megahertz frequency range were measured in the course of titration of the oil/surfactant/cosurfactant mixture with water at 25 degrees C. The ultrasonic titration profiles showed several phase transitions in the samples, which allowed the construction of an "ultrasonic" phase diagram. Quantitative analysis of the ultrasonic parameters enabled the characterization of various phases (swollen micelles, microemulsion, coarse emulsion, and pseudo-bicontinuous) as well as the evaluation of the state of the water and the particle size. The particle size obtained for the microemulsion region ranged from 5 to 14 nm over the measured concentrations of water/isopropyl myristate/Epikuron 200 and n-propanol, which agreed well with the previous literature data.

  6. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    PubMed Central

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-01-01

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. PMID:26901199

  7. High-resolution infrared spectroscopy of HCN-Znn (n = 1-4) clusters: structure determination and comparisons with theory.

    PubMed

    Stiles, Paul L; Miller, Roger E

    2006-05-04

    High-resolution infrared laser spectroscopy has been used to obtain rotationally resolved spectra of HCN-Zn(n) (n = 1-4) complexes formed in helium nanodroplets. In the present study the droplets passed through a metal oven, where the zinc vapor pressure was adjusted until one or more atoms were captured by the droplets. A second pickup cell was then used to dope the droplets with a single HCN molecule. Rotationally resolved infrared spectra are obtained for all of these complexes, providing valuable information concerning their structures. Stark spectra are reported and used to determine the corresponding permanent electric dipole moments. Ab initio calculations are also reported for these complexes for comparison with the experimental results.

  8. Design and performance of a soft-x-ray interferometer for ultra-high-resolution fourier transform spectroscopy

    SciTech Connect

    Moler, E.J.; Hussain, Z.; Duarte, R.M.; Howells, M.R.

    1997-04-01

    A Fourier Transform Soft X-ray spectrometer (FT-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory as a branch of beamline 9.3.2. The spectrometer is a novel soft x-ray interferometer designed for ultra-high resolution (theoretical resolving power E/{delta}E{approximately}10{sup 6}) spectroscopy in the photon energy region of 60-120 eV. This instrument is expected to provide experimental results which sensitively test models of correlated electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavelengths of x-rays and desired resolving power are discussed. The fundamental and practical aspects of soft x-ray interferometry are also explored.

  9. High-resolution gamma-ray spectroscopy with a microwave-multiplexed transition-edge sensor array

    SciTech Connect

    Noroozian, Omid; Mates, John A. B.; Bennett, Douglas A.; Brevik, Justus A.; Fowler, Joseph W.; Gao, Jiansong; Hilton, Gene C.; Horansky, Robert D.; Irwin, Kent D.; Schmidt, Daniel R.; Vale, Leila R.; Ullom, Joel N.; Kang, Zhao

    2013-11-11

    We demonstrate very high resolution photon spectroscopy with a microwave-multiplexed two-pixel transition-edge sensor (TES) array. We measured a {sup 153}Gd photon source and achieved an energy resolution of 63 eV full-width-at-half-maximum at 97 keV and an equivalent readout system noise of 86 pA/√(Hz) at the TES. The readout circuit consists of superconducting microwave resonators coupled to radio-frequency superconducting-quantum-interference-devices and transduces changes in input current to changes in phase of a microwave signal. We use flux-ramp modulation to linearize the response and evade low-frequency noise. This demonstration establishes one path for the readout of cryogenic X-ray and gamma-ray sensor arrays with more than 10{sup 3} elements and spectral resolving powers R=λ/Δλ>10{sup 3}.

  10. Beyond the Born-Oppenheimer approximation: High-resolution overtone spectroscopy of H2D+ and D2H+

    NASA Astrophysics Data System (ADS)

    Fárník, Michal; Davis, Scott; Kostin, Maxim A.; Polyansky, Oleg L.; Tennyson, Jonathan; Nesbitt, David J.

    2002-04-01

    Transitions to overtone 2ν2 and 2ν3, and combination ν2+ν3 vibrations in jet-cooled H2D+ and D2H+ molecular ions have been measured for the first time by high-resolution IR spectroscopy. The source of these ions is a pulsed slit jet supersonic discharge, which allows for efficient generation, rotational cooling, and high frequency (100 KHz) concentration modulation for detection via sensitive lock-in detection methods. Isotopic substitution and high-resolution overtone spectroscopy in this fundamental molecular ion permit a systematic, first principles investigation of Born-Oppenheimer "breakdown" effects due to large amplitude vibrational motion as well as provide rigorous tests of approximate theoretical methods beyond the Born-Oppenheimer level. The observed overtone transitions are in remarkably good agreement (<0.1 cm-1) with non-Born-Oppenheimer ab initio theoretical predictions, with small but systematic deviations for 2ν2, ν2+ν3, and 2ν3 excited states indicating directions for further improvement in such treatments. Spectroscopic assignment and analysis of the isotopomeric transitions reveals strong Coriolis mixing between near resonant 2ν3 and ν2+ν3 vibrations in D2H+. Population-independent line intensity ratios for transitions from common lower states indicate excellent overall agreement with theoretical predictions for D2H+, but with statistically significant discrepancies noted for H2D+. Finally, H2D+ versus D2H+ isotopomer populations are analyzed as a function of D2/H2 mixing ratio and can be well described by steady state kinetics in the slit discharge expansion.

  11. Determination of divertor stray light in high-resolution main chamber H α spectroscopy in JET-ILW

    NASA Astrophysics Data System (ADS)

    Neverov, V. S.; Kukushkin, A. B.; Stamp, M. F.; Alekseev, A. G.; Brezinsek, S.; von Hellermann, M.; Contributors, JET

    2017-01-01

    The theoretical model suggested for ITER main chamber H α spectroscopy is applied to the high-resolution spectroscopy (HRS) data of recent JET ITER-like wall (ILW) experiments. The model is aimed at reconstructing the neutral hydrogen isotope density in the SOL, as well as the isotope ratio, by solving a multi-parametric inverse problem with allowance for (i) the strong divertor stray light (DSL) on the main-chamber lines of sight (LoS), (ii) substantial deviation of the neutral atom velocity distribution function (VDF) from a Maxwellian in the SOL, and (iii) data for the direct observation of the divertor. The JET-ILW HRS data on resolving the power at the deuterium and hydrogen spectral lines of the Balmer-alpha series is analysed, with direct observation of the divertor from the top and with observation of the inner wall along the tangential and radial LoS from the equatorial ports. This data allows the spectrum of the DSL and the signal-to-background ratio for the Balmer-alpha light emitted from the far SOL and divertor in the JET-ILW to be evaluated. The results support the expectation of the strong impact of the DSL upon the ITER main chamber H α (and visible light) spectroscopy diagnostics.

  12. High-resolution X-ray emission spectroscopy with transition-edge sensors: present performance and future potential.

    PubMed

    Uhlig, J; Doriese, W B; Fowler, J W; Swetz, D S; Jaye, C; Fischer, D A; Reintsema, C D; Bennett, D A; Vale, L R; Mandal, U; O'Neil, G C; Miaja-Avila, L; Joe, Y I; El Nahhas, A; Fullagar, W; Gustafsson, F Parnefjord; Sundström, V; Kurunthu, D; Hilton, G C; Schmidt, D R; Ullom, J N

    2015-05-01

    X-ray emission spectroscopy (XES) is a powerful element-selective tool to analyze the oxidation states of atoms in complex compounds, determine their electronic configuration, and identify unknown compounds in challenging environments. Until now the low efficiency of wavelength-dispersive X-ray spectrometer technology has limited the use of XES, especially in combination with weaker laboratory X-ray sources. More efficient energy-dispersive detectors have either insufficient energy resolution because of the statistical limits described by Fano or too low counting rates to be of practical use. This paper updates an approach to high-resolution X-ray emission spectroscopy that uses a microcalorimeter detector array of superconducting transition-edge sensors (TESs). TES arrays are discussed and compared with conventional methods, and shown under which circumstances they are superior. It is also shown that a TES array can be integrated into a table-top time-resolved X-ray source and a soft X-ray synchrotron beamline to perform emission spectroscopy with good chemical sensitivity over a very wide range of energies.

  13. High Resolution Optical Spectroscopy of Rosetta Target 67P/Churyumov-Gerasimenko Using Keck HIRES

    NASA Astrophysics Data System (ADS)

    McKay, Adam; Cochran, Anita L.; Bodewits, Dennis; A'Hearn, Michael F.; Altwegg, Kathrin; Gulkis, Samuel; Snodgrass, Colin; de Val-Borro, Miguel; Kelley, Michael S.; Feaga, Lori M.; Wooden, Diane H.; Bauer, James M.; Kramer, Emily A.

    2016-10-01

    We present high spectral resolution optical spectroscopy of Rosetta target 67P/Churyumov-Gerasimenko obtained on UT Dec 26 and 27, 2015 using the HIRES instrument on Keck I when the comet was at a heliocentric distance of approximately 2 AU post-perihelion. The spectra cover a spectral range of 3500-10000 Angstroms at a spectral resolution of 67,000. These observations aim to provide high spectral resolution, large projected field of view context for the high spatial resolution and small projected field of view observations obtained from the Rosetta instrument suite. We report detections of CN, NH2, and [OI] emission. From the [OI]6300 emission we derive a water production rate of approximately 2 x 1027 mol/s. Production rates (or upper limits) for other species will be presented and placed in context with recent results from Rosetta. We will also present results pertaining to the [OI]5577 line, which combined with the [OI]6300 emission can be used as a proxy for CO2. We will compare our results to observations obtained by Rosetta as well as NEOWISE and Spitzer.

  14. High Resolution Photoacoustic Spectroscopy of the Oxygen A-Band to Support the OCO Missions

    NASA Astrophysics Data System (ADS)

    Cich, M. J.; Lunny, E. M.; Bui, T. Q.; Drouin, B. J.; Okumura, M.; Stroscio, G. D.

    2015-12-01

    NASA's Orbiting Carbon Observatory missions require spectroscopic parameterization of the Oxygen A-Band absorption (757-775 nm) with unprecedented detail to meet the objective of delivering space-based column CO2 measurements with an accuracy of better than 1 ppm. This requires spectroscopic parameters with accuracies at the 0.1% level. To achieve this it is necessary for line shape models to include deviations from the Voigt line shape, including the collisional effects of Dicke narrowing, speed-dependence, line mixing (LM), and collision-induced absorption (CIA). To measure these effects to high accuracy, new innovative lab measurements are required. LM and CIA in particular are difficult to measure using standard spectroscopic techniques because, while present at atmospheric temperatures, these effects are difficult to quantify. At pressures of several atmospheres these effects contribute several percent to the A-Band absorption. While the O2 A-band is too weak for direct absorption measurements via a diode laser, a very sensitive photoacoustic spectroscopy technique is being used to study the pressure- dependence of the spectral line shape up to pressures of 5 atm. This spectrometer has a high S/N of about 10,000 and an advantageous zero baseline. In addition, temperature effects on the line shape are studied using a newly developed temperature control scheme. The latest results are reported.

  15. High Resolution Applications of Laser-Induced Breakdown Spectroscopy for Environmental and Forensic Applications

    SciTech Connect

    Martin, Madhavi Z; Labbe, Nicole; Andre, Nicolas O; Harris, Ronny D; Ebinger, Michael H; Wullschleger, Stan D; Vass, Arpad Alexander

    2007-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been used in the elemental analysis for a variety of environmental samples and as a proof of concept for a host of forensic applications. In the first application, LIBS was used for the rapid detection of carbon from a number of different soil types. In this application, a major breakthrough was achieved by using a multivariate analytical approach that has brought us closer towards a "universal calibration curve". In a second application, it has been demonstrated that LIBS in combination with multivariate analysis can be employed to analyze the chemical composition of annual tree growth rings and correlate them to external parameters such as changes in climate, forest fires, and disturbances involving human activity. The objectives of using this technology in fire scar determinations are: 1) To determine the characteristic spectra of wood exposed to forest fires and 2) To examine the viability of this technique for detecting fire occurrences in stems that did not develop fire scars. These examples demonstrate that LIBS-based techniques are inherently well suited for diverse environmental applications. LIBS was also applied to a variety of proof of concept forensic applications such as the analysis of cremains (human cremation remains) and elemental composition analysis of prosthetic implants.

  16. High resolution applications of laser-induced breakdown spectroscopy for environmental and forensic applications

    NASA Astrophysics Data System (ADS)

    Martin, Madhavi Z.; Labbé, Nicole; André, Nicolas; Harris, Ronny; Ebinger, Michael; Wullschleger, Stan D.; Vass, Arpad A.

    2007-12-01

    Laser-induced breakdown spectroscopy (LIBS) has been used in the elemental analysis for a variety of environmental samples and as a proof of concept for a host of forensic applications. In the first application, LIBS was used for the rapid detection of carbon from a number of different soil types. In this application, a major breakthrough was achieved by using a multivariate analytical approach that has brought us closer towards a "universal calibration curve". In a second application, it has been demonstrated that LIBS in combination with multivariate analysis can be employed to analyze the chemical composition of annual tree growth rings and correlate them to external parameters such as changes in climate, forest fires, and disturbances involving human activity. The objectives of using this technology in fire scar determinations are: 1) To determine the characteristic spectra of wood exposed to forest fires and 2) To examine the viability of this technique for detecting fire occurrences in stems that did not develop fire scars. These examples demonstrate that LIBS-based techniques are inherently well suited for diverse environmental applications. LIBS was also applied to a variety of proof of concept forensic applications such as the analysis of cremains (human cremation remains) and elemental composition analysis of prosthetic implants.

  17. New Atomic Data for Doubly Ionized Iron Group Atoms by High Resolution UV Fourier Transform Spectroscopy

    NASA Technical Reports Server (NTRS)

    Smith, Peter L.; Pickering, Juliet C.; Thorne, A. P.

    2002-01-01

    Currently available laboratory spectroscopic data of doubly ionized iron-group element were obtained about 50 years ago using spectrographs of modest dispersion, photographic plates, and eye estimates of intensities. The accuracy of the older wavelength data is about 10 mAngstroms at best, whereas wavelengths are now needed to an accuracy of 1 part in 10(exp 6) to 10(exp 7) (0.2 to 2 mAngstroms at 2000 Angstroms). The Fourier transform (FT) spectroscopy group at Imperial College, London, and collaborators at the Harvard College Observatory have used a unique VUV FT spectrometer in a program focussed on improving knowledge of spectra of many neutral and singly and doubly ionized, astrophysically important, iron group elements. Spectra of Fe II and Fe III have been recorded at UV and VUV wavelengths with signal-to-noise ratios of several hundred for the stronger lines. Wavelengths and energy levels for Fe III are an order of magnitude more accurate than previous work; analysis is close to completion. f-values for Fe II have been published.

  18. High-Resolution Laser-Induced Breakdown Spectroscopy used in Homeland Security and Forensic Applications

    SciTech Connect

    Martin, Madhavi Z; Wullschleger, Stan D; Vass, Arpad Alexander; Martin, Rodger Carl; Grissino-Mayer, Henri

    2006-01-01

    The technique of laser-induced breakdown spectroscopy (LIBS) to detect elements for a variety of homeland security applications such as nuclear materials identification and inventory,and forensic applications has been demonstrated. For nuclear materials applications, we detected and profiled metals in coatings that were used to encapsulate nuclear fuel. Multivariate analysis has been successfully employed in the quantification of elements present in treated wood and engineered wood composites. These examples demonstrate that LIBS-based techniques are inherently well suited for diverse environmental applications related to homeland security. Three key advantages are evident: (1) small samples (mg) are sufficient; (2) samples can be analyzed by LIBS very rapidly, and (3) biological materials such as human and animal bones and wood can be analyzed with minimal sample preparation. For forensic applications they have used LIBS to determine differences in animal and human bones. They have also applied this technique in the determination of counterfeit and non-counterfeit currency. They recently applied LIBS in helping to solve a murder case.

  19. Synchrotron Based High Resolution Far-Ir Spectroscopy of 1,1-DICHLOROETHYLENE

    NASA Astrophysics Data System (ADS)

    Peebles, Rebecca A.; Elmuti, Lena F.; Peebles, Sean A.; Obenchain, Daniel A.

    2013-06-01

    Six vibrational bands of the ^{35}Cl_2C=CH_2 isotopologue of 1,1-dichloroethylene have been recorded in the 350 - 1150 cm^{-1} range using the 0.00096 cm^{-1} resolution far-infrared beamline of the Canadian Light Source synchrotron facility. Results from the analysis of one a-type (ν_9 = 796.01904(8) cm^{-1}, CCl asymmetric stretch) and one c-type (ν_{11} = 868.488626(26) cm^{-1}, CH_2 flap) band will be presented. Over 6000 transitions have now been fitted for these two bands, with ground state rotational and centrifugal distortion constants fixed to values determined by rotational spectroscopy, while the upper state constants have been varied. Anharmonic frequency calculations at the MP2/6-311++G(2d,2p) level were instrumental in assigning the dense spectra. Assignment of additional bands around 603 cm^{-1} (b-type, CCl symmetric stretch, ν_4) and 456 cm^{-1} (c-type, CCl_2 flap, ν_{12}), as well as attempts at assigning the mixed ^{35}Cl^{37}Cl isotopologue spectra for ν_9 and ν_{11}, are in progress. Z. Kisiel, L. Pszczółkowski, Z. Naturforsch, {{50a}, (1995), 347-351.

  20. Light transmission spectroscopy in real time: a high-resolution nanoparticle analysis instrument.

    PubMed

    Tanner, Carol E; Sun, Nan; Deatsch, Alison; Li, Frank; Ruggiero, Steven T

    2017-03-01

    This paper describes light transmission spectroscopy (LTS), a technique for eliminating spectral noise and systematic effects in real-time spectroscopic measurements. In our work, we combine LTS with spectral inversion for the purpose of nanoparticle analysis. This work employs a wideband multi-wavelength light source and grating spectrometers coupled to CCD detectors. The light source ranges from 210 to 2000 nm, the wavelength-dependent light detection system ranges from 200 to 1100 nm with ≤1  nm resolution, and the nanoparticle diameters range from 1 to 3000 nm. The nanoparticles are suspended in pure water or water-based buffer solutions. For testing and calibration purposes, results are presented for nanoparticles composed of polystyrene and gold. Mie theory is used to model the total extinction cross section, and spectral inversion is employed to obtain quantitative particle size distributions, from which information on the size, shape, and number of nanoparticles can be derived. Discussed are the precision, accuracy, resolution, and sensitivity of our results. The LTS technique is quite versatile and can be applied to spectroscopic investigations where wideband, accurate, low-noise, real-time spectra are desired.

  1. High Resolution Stark Spectroscopy of Model Donor-Acceptor Aminobenzonitriles in the Gas Phase.

    NASA Astrophysics Data System (ADS)

    Fleisher, Adam J.; Clements, Casey L.; Bird, Ryan G.; Pratt, David W.; Alvarez-Valtierra, Leonardo

    2011-06-01

    Electronic communication between donor-acceptor systems is prevalent in many chemical processes. Unfortunately, an accurate description of the changes in molecular geometry responsible for intramolecular charge transfer (ICT) is difficult to ascertain. Reported here are the S0, LA, and LB electronic state structures and dipole moments of two model ICT systems, 4-(1H-pyrrol-l-yl)benzonitrile (PBN) and 4-(1-pyrrolidinyl)benzonitrile (PDBN), as measured by rotationally resolved electronic spectroscopy. As was observed for phenylpyrrole, the unsaturted rings of PBN become collectively more planar following excitation with UV light, in support of the planar ICT model. However, in PDBN the twist/inversion angle between rings is nearly zero in both the ground and excited electronic states. The unperturbed dipole moments measured here, taken in conjunction with available solvatochromism data, provide an estimate for the polarization, dispersion, and charge transfer contributions to solvent-mediated excited state stabilization. J.A. Thomas, J.W. Young, A.J. Fleisher, L. Álvarez-Valtierra, and D.W. Pratt, J. Phys. Chem. Lett. 1, 2017 (2010).

  2. The high-resolution absorption spectroscopy branch on the VUV beamline DESIRS at SOLEIL.

    PubMed

    de Oliveira, Nelson; Joyeux, Denis; Roudjane, Mourad; Gil, Jean François; Pilette, Bertrand; Archer, Lucy; Ito, Kenji; Nahon, Laurent

    2016-07-01

    A VUV absorption spectroscopy facility designed for ultra-high spectral resolution is in operation as a dedicated branch on the DESIRS beamline at Synchrotron SOLEIL. This branch includes a unique VUV Fourier transform spectrometer (FTS) and a dedicated versatile gas sample chamber. The FTS instrument can cover a large UV-VUV spectral range from 4 to 30 eV, with an ultimate line width of 0.08 cm(-1) on a large spectral window, ΔE/E = 7%, over which all spectral features can be acquired in a multiplex way. The performance can be considered to be a middle ground between broadband moderate-resolution spectrometers based on gratings and ultra-high-spectral-resolution VUV tunable-laser-based techniques over very narrow spectral windows. The various available gaseous-sample-handling setups, which function over a wide range of pressures and temperatures, and the acquisition methodology are described. A selection of experimental results illustrates the performance and limitations of the FTS-based facility.

  3. High-resolution imaging and spectroscopy of interfacial water at single bond limit

    NASA Astrophysics Data System (ADS)

    Jiang, Ying

    Hydrogen bond is one of the most important weak interactions in nature and plays an essential role in a broad spectrum of physics, chemistry, biology, energy and material sciences. The conventional methods for studying hydrogen-bonding interaction are all based on spectroscopic or diffraction techniques. However, those techniques have poor spatial resolution and only measure the average properties of many hydrogen bonds, which are susceptible to the structural inhomogeneity and local environments, especially when interfacial systems are concerned. The spatial variation and inter-bond coupling of the hydrogen bonds leads to significant spectral broadening, which prohibits the accurate understanding of the experimental data. In this talk, I will present our recent progress on the development of new-generation scanning probe microscopy/spectroscopy (SPM/S) with unprecedentedly high sensitivity and resolution, for addressing weak inter- and intra-molecular interactions, such as hydrogen bonds and van der Waals force. Based on a qPlus sensor, we have succeeded to push the real-space study of a prototypical hydrogen-bonded system, i.e. water, down to single bond limit. Combined with state-of-the-arts quantum simulations, we have discovered exotic nuclear quantum effects (NQEs) in interfacial water and revealed the quantum nature of the hydrogen bond from a completely new perspective

  4. High-resolution absorption spectroscopy of the OH 2Π3/2 ground state line

    NASA Astrophysics Data System (ADS)

    Wiesemeyer, H.; Güsten, R.; Heyminck, S.; Jacobs, K.; Menten, K. M.; Neufeld, D. A.; Requena-Torres, M. A.; Stutzki, J.

    2012-06-01

    The chemical composition of the interstellar medium is determined by gas phase chemistry, assisted by grain surface reactions, and by shock chemistry. The aim of this study is to measure the abundance of the hydroxyl radical (OH) in diffuse spiral arm clouds as a contribution to our understanding of the underlying network of chemical reactions. Owing to their high critical density, the ground states of light hydrides provide a tool to directly estimate column densities by means of absorption spectroscopy against bright background sources. We observed onboard the SOFIA observatory the 2Π3/2, J = 5/2 ← 3/2 2.5 THz line of ground-state OH in the diffuse clouds of the Carina-Sagittarius spiral arm. OH column densities in the spiral arm clouds along the sightlines to W49N, W51 and G34.26+0.15 were found to be of the order of 1014 cm-2, which corresponds to a fractional abundance of 10-7 to 10-8, which is comparable to that of H2O. The absorption spectra of both species have similar velocity components, and the ratio of the derived H2O to OH column densities ranges from 0.3 to 1.0. In W49N we also detected the corresponding line of 18OH.

  5. Helium temperature measurements in a hot filament magnetic mirror plasma using high resolution Doppler spectroscopy

    NASA Astrophysics Data System (ADS)

    Knott, S.; McCarthy, P. J.; Ruth, A. A.

    2016-09-01

    Langmuir probe and spectroscopic diagnostics are used to routinely measure electron temperature and density over a wide operating range in a reconfigured Double Plasma device at University College Cork, Ireland. The helium plasma, generated through thermionic emission from a negatively biased tungsten filament, is confined by an axisymmetric magnetic mirror configuration using two stacks of NdFeB permanent magnets, each of length 20 cm and diameter 3 cm placed just outside the 15 mm water cooling jacket enclosing a cylindrical vacuum vessel of internal diameter 25 cm. Plasma light is analysed using a Fourier Transform-type Bruker spectrometer with a highest achievable resolution of 0.08 cm-1 . In the present work, the conventional assumption of room temperature ions in the analysis of Langmuir probe data from low temperature plasmas is examined critically using Doppler spectroscopy of the 468.6 nm He II line. Results for ion temperatures obtained from spectroscopic data for a variety of engineering parameters (discharge voltage, gas pressure and plasma current) will be presented.

  6. Excited electronic states of thiophene: high resolution photoabsorption Fourier transform spectroscopy and ab initio calculations.

    PubMed

    Holland, D M P; Trofimov, A B; Seddon, E A; Gromov, E V; Korona, T; de Oliveira, N; Archer, L E; Joyeux, D; Nahon, L

    2014-10-21

    The recently introduced synchrotron radiation-based Fourier transform spectroscopy has been employed to study the excited electronic states of thiophene. A highly resolved photoabsorption spectrum has been measured between ∼5 and 12.5 eV, providing a wealth of new data. High-level ab initio computations have been performed using the second-order algebraic-diagrammatic construction (ADC(2)) polarization propagator approach, and the equation-of-motion coupled-cluster (EOM-CC) method at the CCSD and CC3 levels, to guide the assignment of the spectrum. The adiabatic energy corrections have been evaluated, thereby extending the theoretical study beyond the vertical excitation picture and leading to a significantly improved understanding of the spectrum. The low-lying π→π* and π→σ* transitions result in prominent broad absorption bands. Two strong Rydberg series converging onto the X(~)(2)A2 state limit have been assigned to the 1a2→npb1(1)B2 and the 1a2→nda2(1)A1 transitions. A second, and much weaker, d-type series has been assigned to the 1a2→ndb1(1)B2 transitions. Excitation into some of the Rydberg states belonging to the two strong series gives rise to vibrational structure, most of which has been interpreted in terms of excitations of the totally symmetric ν4 and ν8 modes. One Rydberg series, assigned to the 3b1→nsa1(1)B1 transitions, has been identified converging onto the Ã(2)B1 state limit, and at higher energies Rydberg states converging onto the B(~)(2)A1 state limit could be identified. The present spectra reveal highly irregular vibrational structure in certain low energy absorption bands, and thus provide a new source of information for the rapidly developing studies of excited state non-adiabatic dynamics and photochemistry.

  7. Spectroscopy and high-resolution imaging of the gravitational lens SDSS J1206+4332

    NASA Astrophysics Data System (ADS)

    Agnello, Adriano; Sonnenfeld, Alessandro; Suyu, Sherry H.; Treu, Tommaso; Fassnacht, Christopher D.; Mason, Charlotte; Bradač, Maruša; Auger, Matthew W.

    2016-06-01

    We present spectroscopy and laser guide star adaptive optics (LGSAO) images of the doubly imaged lensed quasar SDSS J1206+4332. We revise the deflector redshift proposed previously to zd = 0.745, and measure for the first time its velocity dispersion σ = (290 ± 30) km s-1. The LGSAO data show the lensed quasar host galaxy stretching over the astroid caustic thus forming an extra pair of merging images, which was previously thought to be an unrelated galaxy in seeing limited data. Owing to the peculiar geometry, the lens acts as a natural coronagraph on the broad-line region of the quasar so that only narrow C III]emission is found in the fold arc. We use the data to reconstruct the source structure and deflector potential, including nearby perturbers. We reconstruct the point-spread function (PSF) from the quasar images themselves, since no additional point source is present in the field of view. From gravitational lensing and stellar dynamics, we find the slope of the total mass density profile to be γ' = -log ρ/log r = 1.93 ± 0.09. We discuss the potential of SDSS J1206+4332 for measuring a time-delay distance (and thus H0 and other cosmological parameters), or as a standard ruler, in combination with the time-delay published by the COSMOGRAIL collaboration. We conclude that this system is very promising for cosmography. However, in order to achieve competitive precision and accuracy, an independent characterization of the PSF is needed. Spatially resolved kinematics of the deflector would reduce the uncertainties further. Both are within the reach of current observational facilities.

  8. Changes in plant defense chemistry (pyrrolizidine alkaloids) revealed through high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Carvalho, Sabrina; Macel, Mirka; Schlerf, Martin; Moghaddam, Fatemeh Eghbali; Mulder, Patrick P. J.; Skidmore, Andrew K.; van der Putten, Wim H.

    2013-06-01

    Plant toxic biochemicals play an important role in defense against natural enemies and often are toxic to humans and livestock. Hyperspectral reflectance is an established method for primary chemical detection and could be further used to determine plant toxicity in the field. In order to make a first step for pyrrolizidine alkaloids detection (toxic defense compound against mammals and many insects) we studied how such spectral data can estimate plant defense chemistry under controlled conditions. In a greenhouse, we grew three related plant species that defend against generalist herbivores through pyrrolizidine alkaloids: Jacobaea vulgaris, Jacobaea erucifolia and Senecio inaequidens, and analyzed the relation between spectral measurements and chemical concentrations using multivariate statistics. Nutrient addition enhanced tertiary-amine pyrrolizidine alkaloids contents of J. vulgaris and J. erucifolia and decreased N-oxide contents in S. inaequidens and J. vulgaris. Pyrrolizidine alkaloids could be predicted with a moderate accuracy. Pyrrolizidine alkaloid forms tertiary-amines and epoxides were predicted with 63% and 56% of the variation explained, respectively. The most relevant spectral regions selected for prediction were associated with electron transitions and Csbnd H, Osbnd H, and Nsbnd H bonds in the 1530 and 2100 nm regions. Given the relatively low concentration in pyrrolizidine alkaloids concentration (in the order of mg g-1) and resultant predictions, it is promising that pyrrolizidine alkaloids interact with incident light. Further studies should be considered to determine if such a non-destructive method may predict changes in PA concentration in relation to plant natural enemies. Spectroscopy may be used to study plant defenses in intact plant tissues, and may provide managers of toxic plants, food industry and multitrophic-interaction researchers with faster and larger monitoring possibilities.

  9. Extended electron energy loss fine structure simulation of the local boron environment in sodium aluminoborosilicate glasses containing gadolinium

    SciTech Connect

    Qian, Morris; Li, Hong; Li, Liyu ); Strachan, Denis M. )

    2003-10-15

    Gadolinium can be dissolved in sodium-alumino-borosilicate glasses up to 47 wt% in a baseline borosilicate glass (mol%) 20 B2O3, 5 Al2O3, 60 SiO2,and 20 Na2O. Understanding of Gd dissolution in borosilicate melts is important in glass formulation optimization. Electron energy loss fine structure (ELFS) spectroscopy is chosen, which provides well resolved local atomic structure information for both amorphous and crystalline materials with high sensitivity to low Z elements such as Al, B, Na, O, and Si where the x-ray absorption fine structure (XAFS) technique faces experimental difficulty. In this study, we report our results of boron K-edge ELFS study. Two borosilicate glass samples with 30 and 47 mass% Gd2O3, B20Gd30 and B20Gd47were chosen for B K-edge ELFS study. EEL spectra were acquired on a Philips 430 TEM equipped with Gatan PEELS system 666 and EL/P 2.1 software with Custom function AcqLong. The ELFS data analysis was performed using UWELFS, UWXAFS and FEFF software. From our Gd solubility study, the local structure of Gd in the borate environment possibly resembles double chain structure found in crystalline Gd(BO2)3 as proposed by Chakraborty et al. The B/Gd ratio's in both glasses are smaller then 3, which means the excess Gd atoms in the Si-sites would be 17 and 60 mol% of the total Gd atoms, respectively according to the model, yet the local environment of borate sites saturated with Gd should be remained. To verity above hypothesis, the double chain structure model was applied to fit boron K-edge. The model was shown to well fit experimental boron K-edge EELS spectra for both glasses with some degree of distance distortion which is understandable in amorphous structure. Therefore, it is very likely that Gd stabilized in borate sites has a local structure resembling the double chain Gd(BO2)3 structure as proposed by our solubility study and literature.

  10. X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.; Williams, D. B.

    1992-01-01

    This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be

  11. Ultrasensitive high resolution laser spectroscopy and its application to optical frequency standards

    NASA Astrophysics Data System (ADS)

    Ye, Jun

    1997-09-01

    Advanced laser stabilization techniques now enable one to lock laser frequencies onto line centers of natural atomic/molecular resonances with unprecedented precision and accuracy. In this dissertation we discuss our effort in utilizing these techniques to establish visible optical frequency standards. By summarizing our earlier results on frequency measurements of the 87Rb D2 line at 780 nm 127I2 hyperfine transitions at 532 nm, we show the advantage of using a higher quality reference line, usually characterized by its narrower linewidth, higher attainable signal-to-noise ratio and lower sensitivity toward external perturbations. We then present a novel approach of cavity-enhanced frequency modulation spectroscopy for ultra-sensitive detections. The powerful utility of this new technique in the field of frequency standards is demonstrated by probing saturated molecular overtone transitions in the visible and near infrared. Weakly-absorbing gases such as C2H2 and C2HD are placed inside an external high-finesse resonator to enhance their detection sensitivities. A frequency modulation technique is employed to achieve a shot noise limited signal-to- noise ratio. The rf modulation frequency is chosen to match the cavity's free spectral range in order to avoid the cavity-induced conversion of laser frequency noise into amplitude noise. The molecular saturated dispersion signal is directly recovered after demodulation of the cavity transmitted light. A record high integrated absorption sensitivity of 5× 10-13/ (1× 10-14/cm) (at 1 second averaging time) has been obtained. Systematic studies on this new technique are presented on topics of detection sensitivity, signal line shape, signal size and slope, and pressure dependent linewidth broadening and linecenter shift. A Nd:YAG laser is stabilized on the P(5) transition in the (ν2+3/ ν3) overtone band of C2HD at 1.064 μm. Its absolute frequency is established. The excellent signal- to-noise ratio produces a frequency

  12. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoaceticum metabolic profiles

    SciTech Connect

    Xue, Junfeng; Isern, Nancy G.; Ewing, R James; Liyu, Andrey V.; Sears, Jesse A.; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R.; Ahring, Birgitte K.; Majors, Paul D.

    2014-06-20

    An in-situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch-growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution, high sensitivity NMR (HR-NMR) spectroscopy. In-situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at an NMR frequency of 500 MHz, and aliquots of the bioreactor contents were taken for 600 MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in-situ NMR bioreactor facilitated monitoring of the fermentation process in real time, enabling identification of intermediate and end-point metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with the HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.

  13. In vivo high-resolution localized 1H MR spectroscopy in the awake rat brain at 7 Tesla

    PubMed Central

    Xu, Su; Ji, Yadong; Chen, Xi; Yang, Yihong; Gullapalli, Rao; Masri, Radi

    2012-01-01

    In vivo localized high-resolution 1H MR spectroscopy was performed in multiple brain regions without the use of anesthetic or paralytic agents in awake head-restrained rats that were previously trained in a simulated MRI environment using a 7 Tesla MR system. Spectra were obtained using a short echo time single-voxel point-resolved spectroscopy technique with voxel size ranging from 27–32.4 mm3 in the regions of anterior cingulate cortex, somatosensory cortex, hippocampus, and thalamus. Quantifiable spectra, without the need for any additional post-processing to correct for possible motion were reliably detected including the metabolites of interest such as γ-aminobutyric acid, glutamine, glutamate, myo-inositol, N-acetylaspartate, taurine, glycerophosphorylcholine/phosphorylcholine, creatine/phosphocreatine, and N-acetylaspartate/N-acetylaspartylglutamate. The spectral quality was comparable to spectra from anesthetized animals with sufficient spectral dispersion to separate metabolites such as glutamine and glutamate. Results from this study suggest that reliable information on major metabolites can be obtained without the confounding effects of anesthesia or paralytic agents in rodents. PMID:22570299

  14. Characterization of carbonaceous meteoritic fragments found in Antarctica by high-resolution Raman spectroscopy and SEM/EDS

    NASA Astrophysics Data System (ADS)

    Dall Asen, Analia; Baer, Brandon; Mittelstaedt, Jake; Gerton, Jordan; Bromley, Benjamin; Kenyon, Scott

    2016-03-01

    Carbonaceous chondritic meteorites are composed mainly of chondrules (micro/millimeter-sized inclusions) surrounding by a matrix of microparticles, and are considered the most primitive surviving materials from the early Solar System. Understanding their properties and history may provide clues to the formation of planets from micron-size dust grains in the Solar nebula. Our approach is to study the structure and composition of carbonaceous chondrites with high-resolution micro-Raman spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. These techniques enable us to capture details on a wide range of spatial scales, from micrometers to millimeters. Here we provide the first analysis of a set of meteorite fragments from Antarctica (MIL 07002 and ALH 84028), mapping elemental and molecular abundances, as well as large-scale morphological features. We present characterizations of individual chondrules and the surrounding matrix, and we consider on how our findings reflect physical processes believed to be operating during the early stages of planet formation.

  15. The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars

    SciTech Connect

    Allende Prieto, C.; Sivarani, T.; Beers, T.C.; Lee, Y.S.; Koesterke, L.; Shetrone, M.; Sneden, C.; Lambert, D.L.; Wilhelm, R.; Rockosi, C.M.; Lai, D.

    2007-10-01

    The authors report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which they compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R {approx} 2000) spectroscopy. For F- and G-type stars observed with high signal-to-noise ratios (S/N), they empirically determine the typical random uncertainties in the radial velocities, effective temperatures, surface gravities, and metallicities delivered by the SSPP to be 2.4 km s{sup -1}, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic uncertainties of a similar magnitude in the effective temperatures and metallicities. They estimate random errors for lower S/N spectra based on numerical simulations.

  16. Resonant x-ray emission spectroscopy of liquid water: novel instrumentation, high resolution, and the"map" approach

    SciTech Connect

    Weinhardt, L.; Fuchs, O.; Blum, M.; Bär, M.; Weigand, M.; Denlinger, J.D.; Zubavichus, Y.; Zharnikov, M.; Grunze, M.; Heske, C.; Umbach, E.

    2008-06-17

    Techniques to study the electronic structure of liquids are rare. Most recently, resonant x-ray emission spectroscopy (XES) has been shown to be an extremely versatile spectroscopy to study both occupied and unoccupied electronic states for liquids in thermodynamic equilibrium. However, XES requires high-brilliance soft x-ray synchrotron radiation and poses significant technical challenges to maintain a liquid sample in an ultra-high vacuum environment. Our group has therefore developed and constructed a novel experimental setup for the study of liquids, with the long-term goal of investigating the electronic structure of biological systems in aqueous environments. We have developed a flow-through liquid cell in which the liquid is separated from vacuum by a thin Si3N4 or SiC window and which allows a precise control of temperature. This approach has significant advantages compared to static liquids cells used in the past. Furthermore, we have designed a dedicated high-transmission, high-resolution soft x-ray spectrometer. The high transmission makes it possible to measure complete resonant XES"maps" in less than an hour, giving unprecedented detailed insight into the electronic structure of the investigated sample. Using this new equipment we have investigated the electronic structure of liquid water. Furthermore, our XES spectra and maps give information about ultra-fast dissociation on the timescale of the O 1s core hole lifetime, which is strongly affected by the initial state hydrogen bonding configuration.

  17. Experiments with the High Resolution Kaon Spectrometer at Jlab Hall C and the New Spectroscopy of ^12_Lambda B Hypernuclei

    SciTech Connect

    Tang, Liguang; Chen, Chunhua; Gogami, Toshiyuki; Kawama, Daisuke; Han, Yuncheng; Yuan, Lulin; Matsumura, Akihiko; Okayasu, Yuichi; Seva, Tomislav; Rodriguez, Victor; Baturin, Pavlo; Acha Quimper, Armando; Achenbach, Carsten; Ahmidouch, Abdellah; Albayrak, Ibrahim; Androic, Darko; Asaturyan, Arshak; Asaturyan, Razmik; Ates, Ozgur; Badui, Rafael; Baker, Oliver; Benmokhtar, Fatiha; Boeglin, Werner; Bono, Jason; Bosted, Peter; Brash, Edward; Carter, Philip; Carlini, Roger; Chiba, Atsushi; Christy, Michael; Cole, Leon; Dalton, Mark; Danagoulian, Samuel; Daniel, Aji; De Leo, Raffaele; Dharmawardane, Kahanawita; Doi, Daisuke; Egiyan, Kim; Elaasar, Mostafa; Ent, Rolf; Fenker, Howard; Fujii, Yu; Furic, Miroslav; Gabrielyan, Marianna; Gan, Liping; Garibaldi, Franco; Gaskell, David; Gasparian, Ashot; Gibson, Edward; Gueye, Paul; Hashimoto, Osamu; Honda, D; Horn, Tanja; Hu, Bitao; Hungerford, Ed; Jayalath, Chandana; Jones, Mark; Johnston, Kathleen; Kalantarians, Narbe; Kanda, Hiroki; Kaneta, M; Kato, F; Kato, Seigo; Kawai, Masaharu; Keppel, Cynthia; Khanal, Hari; Kohl, M; Kramer, Laird; Lan, Kejian; Li, Ya; Habarakada Liyanage, Anusha; Luo, Wei; Mack, David; Maeda, Kazushige; Malace, Simona; Margaryan, Amur; Marikyan, Gagik; Markowitz, Pete; Maruta, Tomofumi; Maruyama, Nayuta; Maxwell, Victor; Millener, David; Miyoshi, Toshinobu; Mkrtchyan, Arthur; Mkrtchyan, Hamlet; Motoba, Toshio; Nagao, Sho; Nakamura, Satoshi; Narayan, Amrendra; Neville, Casey; Niculescu, Gabriel; Niculescu, Maria; Nunez, Angel; Nuruzzaman, nfn; Nomura, Hiroshi; Nonaka, Kenichi; Ohtani, Atsushi; Oyamada, Masamichi; Perez, Naipy; Petkovic, Tomislav; Pochodzalla, J; Qiu, Xiyu; Randeniya, Kapugodage; Raue, Brian; Reinhold, Joerg; Rivera, R; Roche, Julie; Samanta, Chhanda; Sato, Yoshinori; Sawatzky, Bradley; Segbefia, Edwin; Schott, Diane; Shichijo, Ayako; Simicevic, Neven; Smith, Gregory; Song, Yushou; Sumihama, Mizuki; Tadevosyan, Vardan; Takahashi, Toshiyuki; Taniya, Naotaka; Tsukada, Kyo; Tvaskis, Vladas; Veilleux, Micah; Vulcan, William; Wells, Steven; Wesselmann, Frank; Wood, Stephen; Yamamoto, Taku; Yan, Chen; Ye, Z; Yokota, Kosuke; Zhamkochyan, Simon; Zhu, Lingyan

    2014-09-01

    Since the pioneering experiment, E89-009 studying hypernuclear spectroscopy using the $(e,e^{\\prime}K^+)$ reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "Tilt Method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet were added to produce precision, high-resolution hypernuclear spectroscopy. These two experiments, E01-011 and E05-115, resulted in two new data sets, producing sub-MeV energy resolution in the spectra of ${}^{7}_{\\Lambda}\\text{He}$, ${}^{12}_{\\Lambda}\\text{B}$ and ${}^{28}_{\\Lambda} \\text{Al}$ and ${}^{7}_{\\Lambda}\\text{He}$, ${}^{10}_{\\Lambda}\\text{Be}$, ${}^{12}_{\\Lambda}\\text{B}$ and ${}^{52}_{\\Lambda}\\text{V}$. All three experiments obtained a ${}^{12}_{\\Lambda}\\text{B}$, spectrum, which is the most characteristic $p$-shell hypernucleus and is commonly used for calibration. Independent analyses of these different experiments demonstrate excellent consistency and provide the clearest level structure to date of this hypernucleus as produced by the $(e,e^{\\prime}K^+)$ reaction. This paper presents details of these experiments, and the extraction and analysis of the observed ${}^{12}_{\\Lambda}\\text{B}$ spectrum.

  18. Structural model of homogeneous As–S glasses derived from Raman spectroscopy and high-resolution XPS

    SciTech Connect

    Golovchak, R.; Shpotyuk, O.; Mccloy, J. S.; Riley, B. J.; Windisch, C. F.; Sundaram, S. K.; Kovalskiy, A.; Jain, H.

    2010-11-28

    The structure of homogeneous bulk As x S100- x (25 ≤ x ≤ 42) glasses, prepared by the conventional rocking–melting–quenching method, was investigated using high-resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It is shown that the main building blocks of their glass networks are regular AsS3/2 pyramids and sulfur chains. In the S-rich domain, the existence of quasi-tetrahedral (QT) S = As(S1/2)3 units is deduced from XPS data, but with a concentration not exceeding ~3–5% of total atomic sites. Therefore, QT units do not appear as primary building blocks of the glass backbone in these materials, and an optimally-constrained network may not be an appropriate description for glasses when x < 40. Finally, it is shown that, in contrast to Se-based glasses, the ‘chain-crossing’ model is only partially applicable to sulfide glasses.

  19. 15N/14N Ratio Determination in the ISM with Herschel with High Resolution Spectroscopy of Nitrogen Radicals

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Bailleux, S.; Wlodarczak, G.; Pirali, O.; Martin-Drumel, M.-A.; Roy, P.; Roueff, E.; Gerin, M.

    2011-06-01

    The very high resolution of the HIFI instrument (134 kHz-1MHz) on board of Herschel needs very accurate laboratory measurements to detect unambiguously the signature of stable and unstable molecular species. Concerning the pure rotation spectra of new species, and particularly of open shell molecules, the first prediction could be far away and up to few hundred MHz. The 15N/14N ratio is not well measured in the ISM. However, the 15N/14N in the isotopomers is a potential tracer of the formation processes and the possible link with cometary molecules. Recent measurements include the detection of 15NH_2D N15NH+ and 15NH_3. The NH and NH_2 species are the simplest nitrogen radicals and are intermediate products in the NH_3 synthesis. They have been easily detected by Herschel and it therefore is interesting to now search for 15NH and 15NH_2. No spectrocopic data have been reported for these two radicals up to now. We present here the studies with high resolution spectroscopy in the THz range. The high sensitivity and the wide range of Synchrotron (0.6-6 THz) was essential to improve the prediction of the spectra of these two species in order to measure them in Lille (0.6-1 THz) with both a higher accuracy and resolution. The combined studies now give the most accurate predictions. ISM searches on these radicals are in progress in the HERSCHEL spectra. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) M. Gerin, N. Marcellino, N. Biver, et al., Astron. & Astrophys. 498 (2009) 9. L. Bizzochi, P. Caselli, and L. Dore, Astron. & Astrophys. 510 (2010) L5. D. C. Lis, A. Wooten, M. Gerin and E. Roueff, Astrophys. J. 710 (2010) L49.

  20. New frontiers of high-resolution spectroscopy: Probing the atmospheres of brown dwarfs and reflected light from exoplanets

    NASA Astrophysics Data System (ADS)

    Birkby, Jayne; Alonso, Roi; Brogi, Matteo; Charbonneau, David; Fortney, Jonathan; Hoyer, Sergio; Johnson, John Asher; de Kok, Remco; Lopez-Morales, Mercedes; Montet, Ben; Snellen, Ignas

    2015-12-01

    High-resolution spectroscopy (R>25,000) is a robust and powerful tool in the near-infrared characterization of exoplanet atmospheres. It has unambiguously revealed the presence of carbon monoxide and water in several hot Jupiters, measured the rotation rate of beta Pic b, and suggested the presence of fast day-to-night winds in one atmosphere. The method is applicable to transiting, non-transiting, and directly-imaged planets. It works by resolving broad molecular bands in the planetary spectrum into a dense, unique forest of individual lines and tracing them directly by their Doppler shift, while the star and tellurics remain essentially stationary. I will focus on two ongoing efforts to expand this technique. First, I will present new results on 51 Peg b revealing its infrared atmospheric compositional properties, then I will discuss an ongoing optical HARPS-N/TNG campaign (due mid October 2015) to obtain a detailed albedo spectrum of 51 Peg b at 387-691 nm in bins of 50nm. This spectrum would provide strong constraints on the previously claimed high albedo and potentially cloudy nature of this planet. Second, I will discuss preliminary results from Keck/NIRSPAO observations (due late September 2015) of LHS 6343 C, a 1000 K transiting brown dwarf with an M-dwarf host star. The high-resolution method converts this system into an eclipsing, double-lined spectroscopic binary, thus allowing dynamical mass and radius estimates of the components, free from astrophysical assumptions. Alongside probing the atmospheric composition of the brown dwarf, these data would provide the first model-independent study of the bulk properties of an old brown dwarf, with masses accurate to <5%, placing a crucial constraint on brown dwarf evolution models.

  1. Properties of the Open Cluster Tombaugh 1 from High-resolution Spectroscopy and uvbyCaHβ Photometry

    NASA Astrophysics Data System (ADS)

    Sales Silva, João V.; Carraro, Giovanni; Anthony-Twarog, Barbara J.; Moni Bidin, Christian; Costa, Edgardo; Twarog, Bruce A.

    2016-01-01

    Open clusters can be the key to deepening our knowledge on various issues involving the structure and evolution of the Galactic disk and details of stellar evolution because a cluster’s properties are applicable to all its members. However, the number of open clusters with detailed analysis from high-resolution spectroscopy or precision photometry imposes severe limitations on studies of these objects. To expand the number of open clusters with well-defined chemical abundances and fundamental parameters, we investigate the poorly studied, anticenter open cluster Tombaugh 1. Using precision uvbyCaHβ photometry and high-resolution spectroscopy, we derive the cluster’s reddening, obtain photometric metallicity estimates, and, for the first time, present a detailed abundance analysis of 10 potential cluster stars (nine clump stars and one Cepheid). Using the radial position from the cluster center and multiple color indices, we have isolated a sample of unevolved, probable single-star members of Tombaugh 1. From 51 stars, the cluster reddening is found to be E(b-y) = 0.221 ± 0.006 or E(B-V) = 0.303 ± 0.008, where the errors refer to the internal standard errors of the mean. The weighted photometric metallicity from m1 and hk is [Fe/H] = -0.10 ± 0.02, while a match to the Victoria-Regina Strömgren isochrones leads to an age of 0.95 ± 0.10 Gyr and an apparent modulus of (m-M) = 13.10 ± 0.10. Radial velocities identify six giants as probable cluster members, and the elemental abundances of Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Y, Ba, Ce, and Nd have been derived for both the cluster and the field stars. Tombaugh 1 appears to be a typical inner thin disk, intermediate-age open cluster of slightly subsolar metallicity, located just beyond the solar circle, with solar elemental abundance ratios except for the heavy s-process elements, which are a factor of two above solar. Its metallicity is consistent with a steep metallicity gradient in the galactocentric region

  2. High resolution infrared spectroscopy from space: A preliminary report on the results of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment on Spacelab 3

    NASA Technical Reports Server (NTRS)

    Farmer, Crofton B.; Raper, Odell F.

    1987-01-01

    The ATMOS (Atmospheric Trace Molecule Spectroscopy) experiment has the broad purpose of investigating the physical structure, chemistry, and dynamics of the upper atmosphere through the study of the distributions of the neutral minor and trace constituents and their seasonal and long-term variations. The technique used is high-resolution infrared absorption spectroscopy using the Sun as the radiation source, observing the changes in the transmission of the atmosphere as the line-of-sight from the Sun to the spacecraft penetrates the atmosphere close to the Earth's limb at sunrise and sunset. During these periods, interferograms are generated at the rate of one each second which yield, when transformed, high resolution spectra covering the 2.2 to 16 micron region of the infrared. Twenty such occultations were recorded during the Spacelab 3 flight, which have produced concentration profiles for a large number of minor and trace upper atmospheric species in both the Northern and Southern Hemispheres. Several of these species have not previously been observed in spectroscopic data. The data reduction and analysis procedures used following the flight are discussed; a number of examples of the spectra obtained are shown, and a bar graph of the species detected thus far in the analysis is given which shows the altitude ranges for which concentration profiles were retrieved.

  3. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas

    SciTech Connect

    Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M; Beiersdorfer, P; Purvis, M A

    2008-05-21

    A large radius, R = 44.3 m, High Resolution Grating Spectrometer (HRGS) with 2400 line/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 {angstrom} wavelength range. The instrument can be run with a 10-20 {micro}m wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 {angstrom}, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (FWHM), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

  4. Vibrational spectral signatures of crystalline cellulose using high resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS)

    DOE PAGES

    Zhang, Libing; Lu, Zhou; Velarde, Luis; ...

    2015-03-03

    Both the C–H and O–H region spectra of crystalline cellulose were studied using the sub-wavenumber high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) for the first time. The resolution of HR-BB-SFG-VS is about 10-times better than conventional scanning SFG-VS and has the capability of measuring the intrinsic spectral lineshape and revealing many more spectral details. With HR-BB-SFG-VS, we found that in cellulose samples from different sources, including Avicel and cellulose crystals isolated from algae Valonia (Iα) and tunicates (Iβ), the spectral signatures in the O–H region were unique for the two allomorphs, i.e. Iα and Iβ, while the spectral signaturesmore » in the C–H regions varied in all samples examined. Even though the origin of the different spectral signatures of the crystalline cellulose in the O–H and C–H vibrational frequency regions are yet to be correlated to the structure of cellulose, these results lead to new spectroscopic methods and opportunities to classify and to understand the basic crystalline structures, as well as variations in polymorphism of the crystalline cellulose.« less

  5. Evaluating Human Breast Ductal Carcinomas with High-Resolution Magic-Angle Spinning Proton Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Leo Ling; Chang, I.-Wen; Smith, Barbara L.; Gonzalez, R. Gilberto

    1998-11-01

    We report the results of a study of human breast ductal carcinomas, conducted by using high resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS 1HMRS). This recently developed spectroscopic technique can measure tissue metabolism from intact pathological specimens and identify tissue biochemical changes, which closely correspond to tumorin vivostate. This procedure objectively indicates diagnostic parameters, independent of the skill and experience of the investigator, and has the potential to reduce the sampling errors inherently associated with procedures of conventional histopathology. In this study, we measured 19 cases of female ductal carcinomas. Our results demonstrate that: (1) highly resolved spectra of intact specimens of human breast ductal carcinomas can be obtained; (2) carcinoma-free tissues and carcinomas are distinguishable by alterations in the intensities and the spin-spin relaxation time T2 of cellular metabolites; and (3) tumor metabolic markers, such as phosphocholine, lactate, and lipids, may correlate with the histopathological grade determined from evaluation of the adjacent specimen. Our results suggest that biochemical markers thus measured may function as a valuable adjunct to histopathology to improve the accuracy of and reduce the time frame required for the diagnosis of human breast cancer.

  6. Vibrational Spectral Signatures of Crystalline Cellulose Using High Resolution Broadband Sum Frequency Generation Vibrational Spectroscopy (HR-BB-SFG-VS)

    SciTech Connect

    Zhang, Libing; Lu, Zhou; Velarde Ruiz Esparza, Luis A.; Fu, Li; Pu, Yunqiao; Ding, Shi-You; Ragauskas, Art J.; Wang, Hongfei; Yang, Bin

    2015-03-03

    Here we reported the first sub-wavenumber high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) study on both the C-H and O-H region spectra of crystalline cellulose. HR-BB-SFG-VS has about 10 times better resolution than the conventional scanning SFG-VS and is known to be able to measure the intrinsic spectral lineshape and to resolve much more spectral details. With HR-BB-SFG-VS, we found that in cellulose from different sources, including Avicel and cellulose crystals isolated from algae Valonia (Iα) and tunicates (Iβ), the spectral signatures in the OH regions were unique for different allomorphs, i.e. Iα and Iβ, while the spectral signatures in the C-H regions varied in all samples examined. Even though the origin of the different behaviors of the crystalline cellulose in the O-H and C-H vibrational frequency regions is yet to be correlated to the structure of cellulose, these results provided new spectroscopic methods and opportunities to classify and understand the basic crystalline structure, as well as variations, in polymorphism of the crystalline cellulose structure.

  7. Evaluation of Cancer Metabolomics Using ex vivo High Resolution Magic Angle Spinning (HRMAS) Magnetic Resonance Spectroscopy (MRS)

    PubMed Central

    Fuss, Taylor L.; Cheng, Leo L.

    2016-01-01

    According to World Health Organization (WHO) estimates, cancer is responsible for more deaths than all coronary heart disease or stroke worldwide, serving as a major public health threat around the world. High resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS) has demonstrated its usefulness in the identification of cancer metabolic markers with the potential to improve diagnosis and prognosis for the oncology clinic, due partially to its ability to preserve tissue architecture for subsequent histological and molecular pathology analysis. Capable of the quantification of individual metabolites, ratios of metabolites, and entire metabolomic profiles, HRMAS MRS is one of the major techniques now used in cancer metabolomic research. This article reviews and discusses literature reports of HRMAS MRS studies of cancer metabolomics published between 2010 and 2015 according to anatomical origins, including brain, breast, prostate, lung, gastrointestinal, and neuroendocrine cancers. These studies focused on improving diagnosis and understanding patient prognostication, monitoring treatment effects, as well as correlating with the use of in vivo MRS in cancer clinics. PMID:27011205

  8. High-Resolution Spectroscopy with a Free-Electron Laser: Vibrational Lifetimes of Hydrogen-related Defects in Silicon

    NASA Astrophysics Data System (ADS)

    Luepke, Gunter

    2009-03-01

    Gunter Luepke, Department of Applied Science, The College of William and Mary, Williamsburg, VA 23187 Vibrational lifetimes of hydrogen- and deuterium-related bending and stretching modes in crystalline silicon are measured by high-resolution infrared absorption spectroscopy and pump-probe transient bleaching technique using the Jefferson Lab. Free-Electron Laser. We find that the vibrational lifetimes of the bending modes follow a universal frequency-gap law, i.e., the decay time increases exponentially with increasing decay order, with values ranging from 1 ps for a one-phonon process to 265 ps for a four-phonon process. The temperature dependence of the lifetime shows that the bending mode decays by lowest-order multi-phonon process. In contrast, the lifetimes of the stretching modes are found to be extremely dependent on the defect structure, ranging from 2 to 295 ps. Against conventional wisdom, we find that lifetimes of Si-D stretch modes typically are longer than for the corresponding Si-H modes. Our results provide new insights into vibrational decay and the giant isotope effect of hydrogen in semiconductor systems. The potential implications of the results on the physics of electronic device degradation are discussed.

  9. Evaluation of Cancer Metabolomics Using ex vivo High Resolution Magic Angle Spinning (HRMAS) Magnetic Resonance Spectroscopy (MRS).

    PubMed

    Fuss, Taylor L; Cheng, Leo L

    2016-03-22

    According to World Health Organization (WHO) estimates, cancer is responsible for more deaths than all coronary heart disease or stroke worldwide, serving as a major public health threat around the world. High resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS) has demonstrated its usefulness in the identification of cancer metabolic markers with the potential to improve diagnosis and prognosis for the oncology clinic, due partially to its ability to preserve tissue architecture for subsequent histological and molecular pathology analysis. Capable of the quantification of individual metabolites, ratios of metabolites, and entire metabolomic profiles, HRMAS MRS is one of the major techniques now used in cancer metabolomic research. This article reviews and discusses literature reports of HRMAS MRS studies of cancer metabolomics published between 2010 and 2015 according to anatomical origins, including brain, breast, prostate, lung, gastrointestinal, and neuroendocrine cancers. These studies focused on improving diagnosis and understanding patient prognostication, monitoring treatment effects, as well as correlating with the use of in vivo MRS in cancer clinics.

  10. High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 1, data analysis and results

    SciTech Connect

    Erskine, David J.; Edelstein, Jerry; Wishnow, Edward H.; Sirk, Martin; Muirhead, Philip S.; Muterspaugh, Matthew W.; Lloyd, James P.; Ishikawa, Yuzo; McDonald, Eliza A.; Shourt, William V.; Vanderburg, Andrew M.

    2016-05-27

    High-resolution broadband spectroscopy at near-infrared wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar. Observations of stars were performed with the “TEDI” interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec near-infrared echelle spectrograph. These are the first multidelay EDI demonstrations on starlight, as earlier measurements used a single delay or laboratory sources. We demonstrate very high (10×) resolution boost, from original 2700 to 27,000 with current set of delays (up to 3 cm), well beyond the classical limits enforced by the slit width and detector pixel Nyquist limit. Significantly, the EDI used with multiple delays rather than a single delay as used previously yields an order of magnitude or more improvement in the stability against native spectrograph point spread function (PSF) drifts along the dispersion direction. We observe a dramatic (20×) reduction in sensitivity to PSF shift using our standard processing. A recently realized method of further reducing the PSF shift sensitivity to zero is described theoretically and demonstrated in a simple simulation which produces a 350× times reduction. We demonstrate superb rejection of fixed pattern noise due to bad detector pixels—EDI only responds to changes in pixel intensity synchronous to applied dithering. This part 1 describes data analysis, results, and instrument noise. Lastly, a section on theoretical photon limited sensitivity is in a companion paper, part 2.

  11. Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Ohno, Atsushi; Hashimoto, Hiroki; Suzuki, Motofumi; Kimura, Kenji

    2010-07-01

    The surface structures of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnMIM][TFSI], n=2,4,6) are studied by high-resolution Rutherford backscattering spectroscopy. The average composition of the surface molecular layer is very close to the stoichiometric composition, showing that neither ion is enriched in the surface layer. A detailed analysis indicates that both cations and anions have preferential molecular orientations at the surface. The alkyl chains of the [CnMIM] cations protrude to the vacuum and the CF3 groups of the [TFSI] anions are also pointing toward the vacuum. While the orientation of the [TFSI] anion becomes weaker with increasing alkyl-chain length, the protrusion of the alkyl chain occurs irrespective of the chain length. It was also found that the N(SO2)2 moiety is located nearly at the same depth as the imidazolium ring, suggesting that one of oxygen atoms in [TFSI] is bonded to the hydrogen of the C2 carbon atom of the imidazolium ring.

  12. Surface structures of equimolar mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Oshima, Shinichi; Suzuki, Motofumi; Kimura, Kenji

    2012-11-01

    Surface structures of equimolar mixtures of imidazolium-based ionic liquids (ILs) having a common cation (1-butyl-3-methylimidazolium ([C4MIM]) or 1-hexyl-3-methylimidazolium ([C6MIM])) and different anions (bis(trifluoromethanesulfonyl)imide ([TFSI]), hexafluorophosphate ([PF6]) or chlorine) are studied using high-resolution Rutherford backscattering spectroscopy (HRBS). Both cations and anions have the same preferential orientations at the surface as in the pure ILs. In the mixture, the larger anion is located shallower than the smaller anion. The [TFSI] anion is slightly enriched at the surface relative to [PF6] with coverage of ~ 60% for the equimolar mixtures of [C4(6)MIM] [TFSI] and [C4(6)MIM] [PF6]. No surface segregation is observed for [C6MIM] [TFSI]0.5[Cl]0.5 and [C6MIM] [PF6]0.5[Cl]0.5. These results are different from the recent TOF-SIMS measurement where very strong surface segregation of [TFSI] was concluded for the mixture of [C4MIM] [TFSI] and [C4MIM] [PF6].

  13. Observation of surface structure of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide using high-resolution Rutherford backscattering spectroscopy.

    PubMed

    Nakajima, Kaoru; Ohno, Atsushi; Hashimoto, Hiroki; Suzuki, Motofumi; Kimura, Kenji

    2010-07-28

    The surface structures of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C(n)MIM][TFSI], n=2,4,6) are studied by high-resolution Rutherford backscattering spectroscopy. The average composition of the surface molecular layer is very close to the stoichiometric composition, showing that neither ion is enriched in the surface layer. A detailed analysis indicates that both cations and anions have preferential molecular orientations at the surface. The alkyl chains of the [C(n)MIM] cations protrude to the vacuum and the CF(3) groups of the [TFSI] anions are also pointing toward the vacuum. While the orientation of the [TFSI] anion becomes weaker with increasing alkyl-chain length, the protrusion of the alkyl chain occurs irrespective of the chain length. It was also found that the N(SO(2))(2) moiety is located nearly at the same depth as the imidazolium ring, suggesting that one of oxygen atoms in [TFSI] is bonded to the hydrogen of the C(2) carbon atom of the imidazolium ring.

  14. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas.

    PubMed

    Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M-F; Beiersdorfer, P; Purvis, M A

    2008-10-01

    A large radius, R=44.3 m, high resolution grating spectrometer (HRGS) with 2400 lines/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 A wavelength range. The instrument can be run with a 10-20 microm wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 A, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (full width at half maximum), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

  15. Vibrational spectral signatures of crystalline cellulose using high resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS)

    SciTech Connect

    Zhang, Libing; Lu, Zhou; Velarde, Luis; Fu, Li; Pu, Yunqiao; Ding, Shi-You; Ragauskas, Arthur; Wang, Hong-Fei; Yang, Bin

    2015-03-03

    Both the C–H and O–H region spectra of crystalline cellulose were studied using the sub-wavenumber high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) for the first time. The resolution of HR-BB-SFG-VS is about 10-times better than conventional scanning SFG-VS and has the capability of measuring the intrinsic spectral lineshape and revealing many more spectral details. With HR-BB-SFG-VS, we found that in cellulose samples from different sources, including Avicel and cellulose crystals isolated from algae Valonia (Iα) and tunicates (Iβ), the spectral signatures in the O–H region were unique for the two allomorphs, i.e. Iα and Iβ, while the spectral signatures in the C–H regions varied in all samples examined. Even though the origin of the different spectral signatures of the crystalline cellulose in the O–H and C–H vibrational frequency regions are yet to be correlated to the structure of cellulose, these results lead to new spectroscopic methods and opportunities to classify and to understand the basic crystalline structures, as well as variations in polymorphism of the crystalline cellulose.

  16. High resolution cathodoluminescence spectroscopy of carbonate cementation in Khurmala Formation (Paleocene-L. Eocene) from Iraqi Kurdistan Region, Northern Iraq

    NASA Astrophysics Data System (ADS)

    Omer, Muhamed F.; Omer, Dilshad; Zebari, Bahroz Gh.

    2014-12-01

    A combination of high resolution cathodoluminsecnce-spectroscopy (HRS-CL) with spatial electron microprobe analysis and optical microscopy is used to determine paragenesis and history of cementation in the limestones and dolostones of Khurmala Formation which is exposed in many parts of Northern Iraq. Khurmala Formation was subjected to different diagenetic processes such as micritization, compaction, dissolution, neomorphism, pyritization and cementation that occurred during marine to shallow burial stages and culminated during intermediate to deep burial later stages. Five dolomite textures are recognized and classified according to crystal size distribution and crystal-boundary shape. Dolomitization is closely associated with the development of secondary porosity that pre-and postdates dissolution and corrosion; meanwhile such porosity was not noticed in the associated limestones. Microprobe analysis revealed three types of cement, calcite, dolomite and ankerite which range in their luminescence from dull to bright. Cathodoluminescence study indicated four main texture generations. These are (1) unzoned microdolomite of planar and subhedral shape, with syntaxial rim cement of echinoderm that show dull to red luminescence, (2) equant calcite cements filling interparticle pores which shows dull luminescence and weak zonal growth, (3.1) homogenous intrinsic blue stoichiometric calcite with dull luminescence and without activators, (3.2) coarse blocky calcite cement with strong oscillatory zoning and bright orange luminescence which postdates other calcite cements, (4) ankerite cement with red to orange, non-luminescence growth zonation which is the last formed cement.

  17. High-resolution line-shape spectroscopy during a laser pulse based on Dual-Broad-Band-CARS interferometry

    SciTech Connect

    Vereschagin, Konstantin A; Vereschagin, Alexey K; Smirnov, Valery V; Stelmakh, O M; Fabelinskii, V I; Clauss, W; Klimenko, D N; Oschwald, M E-mail: Al_Vereshchagin@mail.r E-mail: stelmakh@kapella.gpi.r

    2006-07-31

    A high-resolution spectroscopic method is developed for recording Raman spectra of molecular transitions in transient objects during a laser pulse with a resolution of {approx}0.1 cm{sup -1}. The method is based on CARS spectroscopy using a Fabry-Perot interferometer for spectral analysis of the CARS signal and detecting a circular interferometric pattern on a two-dimensional multichannel photodetector. It is shown that the use of the Dual-Broad-Band-CARS configuration to obtain the CARS process provides the efficient averaging of the spectral-amplitude noise of the CARS signal generated by a laser pulse and, in combination with the angular integration of the two-dimensional interference pattern, considerably improves the quality of interferograms. The method was tested upon diagnostics of the transient oxygen-hydrogen flame where information on the shapes of spectral lines of the Q-branch of hydrogen molecules required for measuring temperature was simultaneously obtained and used. (special issue devoted to the 90th anniversary of a.m. prokhorov)

  18. Neutron irradiation damage of nuclear graphite studied by high-resolution transmission electron microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krishna, R.; Jones, A. N.; McDermott, L.; Marsden, B. J.

    2015-12-01

    Nuclear graphite components are produced from polycrystalline artificial graphite manufacture from a binder and filler coke with approximately 20% porosity. During the operational lifetime, nuclear graphite moderator components are subjected to fast neutron irradiation which contributes to the change of material and physical properties such as thermal expansion co-efficient, young's modulus and dimensional change. These changes are directly driven by irradiation-induced changes to the crystal structure as reflected through the bulk microstructure. It is therefore of critical importance that these irradiation changes and there implication on component property changes are fully understood. This work examines a range of irradiated graphite samples removed from the British Experimental Pile Zero (BEPO) reactor; a low temperature, low fluence, air-cooled Materials Test Reactor which operated in the UK. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) have been employed to characterise the effect of increased irradiation fluence on graphite microstructure and understand low temperature irradiation damage processes. HRTEM confirms the structural damage of the crystal lattice caused by irradiation attributed to a high number of defects generation with the accumulation of dislocation interactions at nano-scale range. Irradiation-induced crystal defects, lattice parameters and crystallite size compared to virgin nuclear graphite are characterised using selected area diffraction (SAD) patterns in TEM and Raman Spectroscopy. The consolidated 'D'peak in the Raman spectra confirms the formation of in-plane point defects and reflected as disordered regions in the lattice. The reduced intensity and broadened peaks of 'G' and 'D' in the Raman and HRTEM results confirm the appearance of turbulence and disordering of the basal planes whilst maintaining their coherent layered graphite structure.

  19. Nuclear and electronic energy loss by 1 keV to 60 keV ions in silicon : comparison of measurement to SRIM

    SciTech Connect

    Funsten, H. O.; Harper, R. W.; Ritzau, S. M.; Korde, R.

    2003-01-01

    Comparison of TRIM simulations with measurements of the energy lost to electronic and nuclear stopping processes using 1 00% internal carrier collection efficiency silicon photodiodes shows a large, systematic overestimation by TRIM of electronic energy loss.

  20. High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 1, data analysis and results

    DOE PAGES

    Erskine, David J.; Edelstein, Jerry; Wishnow, Edward H.; ...

    2016-05-27

    High-resolution broadband spectroscopy at near-infrared wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar. Observations of stars were performed with the “TEDI” interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec near-infrared echelle spectrograph. These are the first multidelay EDI demonstrations on starlight, as earlier measurements used a single delay or laboratory sources. We demonstrate very high (10×) resolution boost, from original 2700 to 27,000 with current set of delays (up to 3 cm), well beyond the classical limits enforced bymore » the slit width and detector pixel Nyquist limit. Significantly, the EDI used with multiple delays rather than a single delay as used previously yields an order of magnitude or more improvement in the stability against native spectrograph point spread function (PSF) drifts along the dispersion direction. We observe a dramatic (20×) reduction in sensitivity to PSF shift using our standard processing. A recently realized method of further reducing the PSF shift sensitivity to zero is described theoretically and demonstrated in a simple simulation which produces a 350× times reduction. We demonstrate superb rejection of fixed pattern noise due to bad detector pixels—EDI only responds to changes in pixel intensity synchronous to applied dithering. This part 1 describes data analysis, results, and instrument noise. Lastly, a section on theoretical photon limited sensitivity is in a companion paper, part 2.« less

  1. High Resolution Infrared Spectroscopy of CH_3F-({ortho}-H_2){n} Cluster in Solid {para}-H_2

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2015-06-01

    The absorption spectrum of the ν3 (C-F stretching) mode of CH_3F in solid {para}-H_2 by FTIR showed a series of equal interval peaks. Their interpretation was that the {}-th peak of this series was due to CH_3F-({ortho}-H_2){n} clusters which were formed CH_3F and {n}'s {ortho}-H_2 in first nearest neighbor sites of the {para}-H_2 crystal with {hcp} structure. In order to understand this system in more detail, we have studied these peaks, especially {n} = 0 - 3 corresponding to 1037 - 1041 wn, by using high-resolution and high-sensitive infrared quantum cascade (QC) laser spectroscopy. Before now, we found many peaks around each {n}-th peak of the cluster, which we didn't know their origins. We observed photochromic phenomenon of these peaks by taking an advantage of the high brightness of the laser. In this study, we focus on satellite series consisting of six peaks which locate at the lower energy side of each main peak. All the peaks showed a common red shouldered line profile, which corresponds to partly resolved transitions of {ortho}- and {para}- CH_3F. The spectral pattern and time behavior of the peaks may suggest that these satellite series originate from a family of CH_3F clusters involving {ortho}-H_2 in second nearest neighbor sites. A model function assuming this idea is used to resolve the observed spectrum into each Lorentzian component, and then some common features of the satellite peaks are extracted and the physical meanings of them will be discussed. K. Yoshioka and D. T. Anderson, J. Chem. Phys. 119 (2003) 4731-4742 A. R. W. McKellar, A. Mizoguchi, and H. Kanamori, J. Chem. Phys. 135 (2011) 124511 A. R. W. McKellar, A. Mizoguchi, and H. Kanamori, Phys. Chem. Chem. Phys. 13 (2011) 11587-11589.

  2. High Resolution Echelle Spectroscopy of Low Redshift Intervening O VI Absorbers with the Space Telescope Imaging Spectrograph

    NASA Astrophysics Data System (ADS)

    Tripp, T. M.; Bowen, D. V.; Jenkins, E. B.; Savage, B. D.

    1999-12-01

    We present high resolution FUV echelle spectroscopy of several low z intervening O VI absorbers (z < 0.3) in the spectra of H1821+643 and PG0953+415. The data were obtained with the Space Telescope Imaging Spectrograph at a resolution of 45,000 (7 km/s FWHM). We also present selected new measurements of galaxy redshifts in the 10' field centered on H1821+643. The observations provide several clues about the nature of these absorbers: (1) In the case of the strong O VI system at z = 0.2250 in the spectrum of H1821+643, we detect multicomponent Si II and Si III absorption as well as O VI and several Lyman series lines of H I. Multiple components are evident in the O VI profiles, but the components have different velocities than the Si III and Si II lines. Furthermore, the Si II and Si III lines are quite narrow, and the O VI lines are broader and spread over a larger velocity range. This evidence strongly indicates that this is a multiphase absorber. (2) We also detect `high velocity' O VI in the z = 0.2250 system. High velocity H I is also seen in the Lyα profile, but substantially offset in velocity from the O VI. This high velocity O VI may be analogous to the highly ionized high velocity clouds seen near the Milky Way. (3) We also present systems at other redshifts including very weak O VI absorption lines accompanied by weak and narrow H I absorption. (4) In all cases, several galaxies are close to the sight lines at the redshift of the O VI systems. We examine whether the O VI absorption can be attributed to the ISM of a single galaxy or the intragroup medium.

  3. High Resolution X-Ray Spectroscopy of the Local Hot Gas along the 3C 273 Sightline

    NASA Astrophysics Data System (ADS)

    Fang, Taotao; Jiang, Xiaochuan

    2014-04-01

    X-ray observations of highly ionized metal absorption lines at z = 0 provide critical information on the hot gas distribution in and around the Milky Way. We present a study of more than 10 yr of Chandra and XMM-Newton observations of 3C 273, one of the brightest extragalactic X-ray sources. Compared with previous works, we obtain much tighter constraints on the physical properties of the X-ray absorber. We also find a large, non-thermal velocity at ~100-150 km s-1, the main reason for the higher line equivalent width when compared with other sightlines. Using joint analysis with X-ray emission and ultraviolet observations, we derive a size of 5-15 kpc and a temperature of (1.5-1.8) × 106 K for the X-ray absorber. The 3C 273 sightline passes through a number of Galactic structures, including radio loops I and IV, the North Polar Spur, and the neighborhood of the newly discovered "Fermi bubbles." We argue that the X-ray absorber is unlikely to be associated with the nearby radio loops I and IV; however, the non-thermal velocity can be naturally explained as the result of the expansion of the "Fermi bubbles." Our data imply a shock-expansion velocity of 200-300 km s-1. Our study indicates a likely complex environment for the production of the Galactic X-ray absorbers along different sightlines, and highlights the significance of probing galactic feedback with high resolution X-ray spectroscopy.

  4. HIGH RESOLUTION X-RAY SPECTROSCOPY OF THE LOCAL HOT GAS ALONG THE 3C 273 SIGHTLINE

    SciTech Connect

    Fang, Taotao; Jiang, Xiaochuan

    2014-04-20

    X-ray observations of highly ionized metal absorption lines at z = 0 provide critical information on the hot gas distribution in and around the Milky Way. We present a study of more than 10 yr of Chandra and XMM-Newton observations of 3C 273, one of the brightest extragalactic X-ray sources. Compared with previous works, we obtain much tighter constraints on the physical properties of the X-ray absorber. We also find a large, non-thermal velocity at ∼100-150 km s{sup –1}, the main reason for the higher line equivalent width when compared with other sightlines. Using joint analysis with X-ray emission and ultraviolet observations, we derive a size of 5-15 kpc and a temperature of (1.5-1.8) × 10{sup 6} K for the X-ray absorber. The 3C 273 sightline passes through a number of Galactic structures, including radio loops I and IV, the North Polar Spur, and the neighborhood of the newly discovered ''Fermi bubbles''. We argue that the X-ray absorber is unlikely to be associated with the nearby radio loops I and IV; however, the non-thermal velocity can be naturally explained as the result of the expansion of the ''Fermi bubbles''. Our data imply a shock-expansion velocity of 200-300 km s{sup –1}. Our study indicates a likely complex environment for the production of the Galactic X-ray absorbers along different sightlines, and highlights the significance of probing galactic feedback with high resolution X-ray spectroscopy.

  5. Development of spatially resolved high resolution x-ray spectroscopy for fusion and light-source research

    NASA Astrophysics Data System (ADS)

    Lu, J.; Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Pablant, N. A.; Efthimion, P.; Beiersdorfer, P.; Chen, H.; Widmann, K.; Sanchez del Rio, M.

    2014-09-01

    One dimensional spatially resolved high resolution x-ray spectroscopy with spherically bent crystals and 2D pixelated detectors is an established technique on magnetic confinement fusion (MCF) experiments world wide for Doppler measurements of spatial profiles of plasma ion temperature and flow velocity. This technique is being further developed for diagnosis of High Energy Density Physics (HEDP) plasmas at laser-plasma facilities and synchrotron/x-ray free electron laser (XFEL) facilities. Useful spatial resolution (micron scale) of such small-scale plasma sources requires magnification, because of the finite pixel size of x-ray CCD detectors (13.5 μm). A von-Hamos like spectrometer using spherical crystals is capable of magnification, as well as uniform sagittal focusing across the full x-ray spectrum, and is being tested in laboratory experiments using a tungsten-target microfocus (5-10 μm) x-ray tube and 13-μm pixel x-ray CCD. A spatial resolution better than 10 μm has been demonstrated. Good spectral resolution is indicated by small differences (0.02 - 0.1 eV) of measured line widths with best available published natural line widths. Progress and status of HEDP measurements and the physics basis for these diagnostics are presented. A new type of x-ray crystal spectrometer with a convex spherically bent crystal is also reported. The status of testing of a 2D imaging microscope using matched pairs of spherical crystals with x rays will also be presented. The use of computational x-ray optics codes in development of these instrumental concepts is addressed.

  6. High-resolution (19)F MAS NMR spectroscopy: structural disorder and unusual J couplings in a fluorinated hydroxy-silicate.

    PubMed

    Griffin, John M; Yates, Jonathan R; Berry, Andrew J; Wimperis, Stephen; Ashbrook, Sharon E

    2010-11-10

    High-resolution (19)F magic angle spinning (MAS) NMR spectroscopy is used to study disorder and bonding in a crystalline solid. (19)F MAS NMR reveals four distinct F sites in a 50% fluorine-substituted deuterated hydrous magnesium silicate (clinohumite, 4Mg(2)SiO(4)·Mg(OD(1-x)F(x))(2) with x = 0.5), indicating extensive structural disorder. The four (19)F peaks can be assigned using density functional theory (DFT) calculations of NMR parameters for a number of structural models with a range of possible local F environments generated by F(-)/OH(-) substitution. These assignments are supported by two-dimensional (19)F double-quantum MAS NMR experiments that correlate F sites based on either spatial proximity (via dipolar couplings) or through-bond connectivity (via scalar, or J, couplings). The observation of (19)F-(19)F J couplings is unexpected as the fluorines coordinate Mg atoms and the Mg-F interaction is normally considered to be ionic in character (i.e., there is no formal F-Mg-F covalent bonding arrangement). However, DFT calculations predict significant (19)F-(19)F J couplings, and these are in good agreement with the splittings observed in a (19)F J-resolved MAS NMR experiment. The existence of these J couplings is discussed in relation to both the nature of bonding in the solid state and the occurrence of so-called "through-space" (19)F-(19)F J couplings in solution. Finally, we note that we have found similar structural disorder and spin-spin interactions in both synthetic and naturally occurring clinohumite samples.

  7. Effects of dynamic diffraction conditions on magnetic parameter determination in a double perovskite Sr2FeMoO6 using electron energy-loss magnetic chiral dichroism.

    PubMed

    Wang, Z C; Zhong, X Y; Jin, L; Chen, X F; Moritomo, Y; Mayer, J

    2016-12-30

    Electron energy-loss magnetic chiral dichroism (EMCD) spectroscopy, which is similar to the well-established X-ray magnetic circular dichroism spectroscopy (XMCD), can determine the quantitative magnetic parameters of materials with high spatial resolution. One of the major obstacles in quantitative analysis using the EMCD technique is the relatively poor signal-to-noise ratio (SNR), compared to XMCD. Here, in the example of a double perovskite Sr2FeMoO6, we predicted the optimal dynamical diffraction conditions such as sample thickness, crystallographic orientation and detection aperture position by theoretical simulations. By using the optimized conditions, we showed that the SNR of experimental EMCD spectra can be significantly improved and the error of quantitative magnetic parameter determined by EMCD technique can be remarkably lowered. Our results demonstrate that, with enhanced SNR, the EMCD technique can be a unique tool to understand the structure-property relationship of magnetic materials particularly in the high-density magnetic recording and spintronic devices by quantitatively determining magnetic structure and properties at the nanometer scale.

  8. Investigations into the Structure and Dynamics of Chalcogenide Glasses using High-Resolution Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kaseman, Derrick Charles

    Chalcogenide glasses constitute an important class of materials that are sulfides, selenides or tellurides of group IV and/or V elements, namely Ge, As, P and Si with minor concentrations of other elements such as Ga, Sb, In. Because of their infrared transparency that can be tuned by changing chemistry and can be actively altered by exposure to band gap irradiation, chalcogenide glasses find use in passive and active optical devices for applications in the areas of photonics, remote sensing and memory technology. Therefore, it is important to establish predictive models of structure-property relationships for these materials for optimization of their physical properties for various applications. Structural elucidation of chalcogenide glasses is experimentally challenging and in order to make predictive structural models, structural units at both short and intermediate -range length scales must be identified and quantified. Nuclear Magnetic Resonance (NMR) spectroscopy is an element-specific structural probe that is uniquely suited for this task, but resolution and sensitivity issues have severely limited the applications of such techniques in the past. The recent development of multi-dimensional solid-state NMR techniques, such as Phase Adjusted Spinning Sidebands (PASS) and Magic Angle Turning (MAT) can potentially alleviate such issues. In this study novel two-dimensional, high-resolution 77Se and 125Te MATPASS NMR spectroscopic techniques are utilized to elucidate quantitatively the compositional evolution of the short- and intermediate- range atomic structure in three binary chalcogenide glass-forming systems, namely: GexSe100-x, AsxSe100-x , and AsxTe100-x. The spectroscopic results provide unambiguous site speciation and quantification for short- and intermediate-range structural motifs present in these glasses. In turn, for all systems, robust structural models and the corresponding structure-property relationships are successfully established as a function

  9. Combined use of high-resolution α-glucosidase inhibition profiling and high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy for investigation of antidiabetic principles in crude plant extracts.

    PubMed

    Kongstad, Kenneth T; Özdemir, Ceylan; Barzak, Asmah; Wubshet, Sileshi G; Staerk, Dan

    2015-03-04

    Type 2 diabetes is a metabolic disorder affecting millions of people worldwide, and new drug leads or functional foods containing selective α-glucosidase inhibitors are needed. Crude extract of 24 plants were assessed for α-glucosidase inhibitory activity. Methanol extracts of Cinnamomum zeylanicum bark, Rheum rhabarbarum peel, and Rheum palmatum root and ethyl acetate extracts of C. zeylanicum bark, Allium ascalonicum peel, and R. palmatum root showed IC50 values below 20 μg/mL. Subsequently, high-resolution α-glucosidase profiling was used in combination with high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy for identification of metabolites responsible for the α-glucosidase inhibitory activity. Quercetin (1) and its dimer (2), trimer (3), and tetramer (4) were identified as main α-glucosidase inhibitors in A. ascalonicum peel, whereas (E)-piceatannol 3'-O-β-D-glucopyranoside (5), (E)-rhapontigenin 3'-O-β-D-glucopyranoside (6), (E)-piceatannol (8), and emodin (12) were identified as main α-glucosidase inhibitors in R. palmatum root.

  10. High-resolution infrared spectroscopy: Jet-cooled halogenated methyl radicals and reactive scattering dynamics in an atom + polyatom system

    NASA Astrophysics Data System (ADS)

    Whitney, Erin Sue

    This thesis describes a series of projects whose common theme comprises the structure and internal energy distribution of gas-phase radicals. In the first two projects, shot noise-limited direct absorption spectroscopy is combined with long path-length slit supersonic discharges to obtain first high-resolution infrared spectra for jet-cooled CH2F and CH2Cl in the symmetric and antisymmetric CH2 stretching modes. Drawing motivation from the question of the equilibrium structures of halogen-substituted methyl radicals, spectral assignment yields refined lower and upper state rotational constants, as well as fine-structure parameters from least-square fits to the sub-Doppler lineshapes for individual transitions. High-level CCSD(T) calculations extrapolated to the complete basis set (CBS) limit confirm the existence of a non-planar (theta=29°) CH2F equilibrium structure with a 132 cm-1 barrier to planarity and a vibrational bend frequency of 276 cm-1. Similar calculations for CH 2Cl predict a slightly nonplanar equilibrium structure (theta=11°) with a vibrationally adiabatic one-dimensional treatment of the bend coordinate yielding a fundamental anharmonic frequency (393 cm-1). Both sets of calculations are in excellent agreement with previous studies. More interesting, however, are the unexpected intensity ratios of the symmetric vs. antisymmetric bands for CH2F and the absence of an antisymmetric band for CH2Cl. While a simple bond-dipole picture predicts a ratio of 1:3 for the symmetric vs. antisymmetric intensities, the experimentally observed value for CH2F is ˜2:1. This ratio is confirmed by DFT [B3LYP/aug-cc-pVTZ] calculations in a novel albeit indirect probe of the effective non-planarity for CH2F. For CH2Cl, similar DFT calculations predict a 30-fold decrease between the intensity of the symmetric and antisymmetric CH2 stretches, leading to the postulation of a nearly perfect cancellation of antisymmetric stretch intensity transition moment with

  11. High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 2, photon noise theory

    SciTech Connect

    Erskine, David J.; Edelstein, Jerry; Wishnow, Edward; Sirk, Martin; Muirhead, Philip S.; Muterspaugh, Matthew W.; Lloyd, James P.

    2016-10-01

    High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoretical photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (~1×) EDI has ~1.4× smaller noise than conventional, and at >10× boost, EDI has ~1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. As a result, for three (or four) steps, we calculate a multiplicative

  12. The subgiant branch of ω Centauri seen through high-resolution spectroscopy. I. The first stellar generation in ω Cen?

    NASA Astrophysics Data System (ADS)

    Pancino, E.; Mucciarelli, A.; Sbordone, L.; Bellazzini, M.; Pasquini, L.; Monaco, L.; Ferraro, F. R.

    2011-03-01

    We analysed high-resolution UVES spectra of six stars belonging to the subgiant branch of ω Centauri, and derived abundance ratios of 19 chemical elements (namely Al, Ba, C, Ca, Co, Cr, Cu, Fe, La, Mg, Mn, N, Na, Ni, Sc, Si, Sr, Ti, and Y). A comparison with previous abundance determinations for red giants provided remarkable agreement and allowed us to identify the sub-populations to which our targets belong. We found that three targets belong to a low-metallicity population at [Fe/H] ≃ -2.0 dex, [α/Fe] ≃ +0.4 dex and [s/Fe] ≃ 0 dex. Stars with similar characteristics were found in small amounts by past surveys of red giants. We discuss the possibility that they belong to a separate sub-population that we name VMP (very metal-poor, at most 5% of the total cluster population), which - in the self-enrichment hypothesis - is the best-candidate first stellar generation in ω Cen. Two of the remaining targets belong to the dominant metal-poor population (MP) at [Fe/H] ≃ -1.7 dex, and the last one to the metal-intermediate (MInt) one at [Fe/H] ≃ -1.2 dex. The existence of the newly defined VMP population could help to understand some puzzling results based on low-resolution spectroscopy for age differences determinations, because the metallicity resolution of these studies was probably not enough to detect the VMP population. The VMP could also correspond to some of the additional substructures of the subgiant-branch region found in the latest HST photometry. After trying to correlate chemical abundances with substructures in the subgiant branch of ω Cen, we found that the age difference between the VMP and MP populations should be small (0 ± 2 Gyr), while the difference between the MP and MInt populations could be slightly larger (2 ± 2 Gyr). Based on data collected at the ESO VLT in Chile, with UVES and FLAMES under programs 68.D-0332(A) and 079.D-0021. Also based on literature data from the ESO WFI, under programs 62.L-0354 and 63.L-0439, and on data

  13. High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: part 2, photon noise theory

    NASA Astrophysics Data System (ADS)

    Erskine, David J.; Edelstein, Jerry; Wishnow, Edward; Sirk, Martin; Muirhead, Philip S.; Muterspaugh, Matthew W.; Lloyd, James P.

    2016-10-01

    High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoretical photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (˜1×) EDI has ˜1.4× smaller noise than conventional, and at >10× boost, EDI has ˜1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. For three (or four) steps, we calculate a multiplicative bandwidth

  14. High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 2, photon noise theory

    DOE PAGES

    Erskine, David J.; Edelstein, Jerry; Wishnow, Edward; ...

    2016-10-01

    High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoreticalmore » photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (~1×) EDI has ~1.4× smaller noise than conventional, and at >10× boost, EDI has ~1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. As a result, for three (or four) steps, we calculate a

  15. Multi-epoch high-resolution spectroscopy of SN 2011fe. Linking the progenitor to its environment

    NASA Astrophysics Data System (ADS)

    Patat, F.; Cordiner, M. A.; Cox, N. L. J.; Anderson, R. I.; Harutyunyan, A.; Kotak, R.; Palaversa, L.; Stanishev, V.; Tomasella, L.; Benetti, S.; Goobar, A.; Pastorello, A.; Sollerman, J.

    2013-01-01

    Aims: The nearby Type Ia supernova (SN) 2011fe has provided an unprecedented opportunity for deriving some of the properties of its progenitor. This work provides additional and independent information on the circumstellar environment in which the explosion took place. Methods: We obtained high-resolution spectroscopy of SN 2011fe for 12 epochs, from 8 to 86 days after the estimated date of explosion, testing in particular the time evolution of Ca II and Na I. Results: Three main absorption systems are identified from Ca II and Na I, one associated to the Milky Way, one probably arising within a high-velocity cloud, and one most likely associated to the halo of M101. The total (Galactic and host galaxy) reddening, deduced from the integrated equivalent widths (EW) of the Na i lines, is EB - V ≲ 0.05 mag. The host galaxy absorption is dominated by a component detected at the same velocity measured from the 21-cm H i line at the projected SN position (~180 km s-1). During the ~3 months covered by our observations its EW peak-to-peak variation is 15.6 ± 6.5 mÅ. This small and marginally significant change is shown to be compatible with the geometric effects produced by the rapid SN photosphere expansion coupled to the patchy fractal structure of the interstellar medium (ISM). The observed behavior is fully consistent with ISM properties similar to those derived for our own Galaxy, with evidences for structures on scales ≲ 100 AU. Conclusions: SN 2011fe appears to be surrounded by a "clean" environment. The lack of blueshifted, time-variable absorption features is fully consistent with the progenitor being a binary system with a main-sequence, or even another degenerate star. Based on observations collected at the Mercator telescope, Telescopio Nazionale Galileo, Nordic Optical Telescope at Roque de los Muchachos, La Palma (Spain), and at the 1.82 m Copernico telescope on Mt. Ekar (Asiago, Italy).

  16. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    SciTech Connect

    Thomé, Lionel Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis; Velisa, Gihan; Miro, Sandrine; Trocellier, Patrick; Serruys, Yves

    2015-03-14

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (S{sub n}) and Electronic (S{sub e}) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (S{sub n} and S{sub e}), whereas single low-energy irradiation (S{sub n} alone) or even sequential (S{sub n} + S{sub e}) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between S{sub n} and S{sub e} in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery S{sub n}/S{sub e} effects may preserve the integrity of nuclear devices.

  17. Measurement of optical constants of Si and SiO2 from reflection electron energy loss spectra using factor analysis method

    NASA Astrophysics Data System (ADS)

    Jin, H.; Shinotsuka, H.; Yoshikawa, H.; Iwai, H.; Tanuma, S.; Tougaard, S.

    2010-04-01

    The energy loss functions (ELFs) and optical constants of Si and SiO2 were obtained from quantitative analysis of reflection electron energy loss spectroscopy (REELS) by a new approach. In order to obtain the ELF, which is directly related to the optical constants, we measured series of angular and energy dependent REELS spectra for Si and SiO2. The λ(E )K(ΔE) spectra, which are the product of the inelastic mean free path (IMFP) and the differential inverse IMFP, were obtained from the measured REELS spectra. We used the factor analysis (FA) method to analyze series of λ(E )K(ΔE) spectra for various emission angles at fixed primary beam energy to separate the surface-loss and bulk-loss components. The extracted bulk-loss components enable to obtain the ELFs of Si and SiO2, which are checked by oscillator strength-sum and perfect-screening-sum rules. The real part of the reciprocal of the complex dielectric function was determined by Kramers-Kronig analysis of the ELFs. Subsequently, the optical constants of Si and SiO2 were calculated. The resulting optical constants in terms of the refractive index and the extinction coefficient for Si and SiO2 are in good agreement with Palik's reference data. The results demonstrate the general applicability of FA as an efficient method to obtain the bulk ELF and to determine the optical properties from REELS measurements.

  18. Effect of electronic energy loss and irradiation temperature on color-center creation in LiF and NaCl crystals irradiated with swift heavy ions

    SciTech Connect

    Schwartz, K.; Trautmann, C.; Voss, K.-O.; Neumann, R.; Volkov, A. E.; Sorokin, M. V.; Lang, M.

    2008-07-01

    LiF and NaCl crystals were irradiated at 8 K and 300 K with various light and heavy ions (C, Ti, Ni, Kr, Sm, Au, Pb, and U) of kinetic energy between about 50 and 2600 MeV, providing electronic energy losses from 0.7 to 26.4 keV/nm. A cryostat installed at the beamline allowed in situ absorption spectroscopy and thermostimulated luminescence (TSL) measurements from 8 K upward. Creation of electron and hole color centers is analyzed as a function of irradiation temperature, fluence, and thermal and optical bleaching. Anion interstitials (I and H centers) were only observed in crystals irradiated at 8 K. These defects are unstable and disappear in the temperature range 10-100 K. For heavy ions (Au, U), the F-center accumulation efficiency at low fluences is larger at 8 K than at room temperature. The opposite effect is observed for light ions (C, Ti, Ni). The results are discussed within the frame of transient heating influencing separation or annealing of point defects.

  19. Electronic and Crystal-field Effects in the Fine Structure of Electron Energy-loss Spectra of Manganites

    SciTech Connect

    Luo, W.; Tao, J.; Varela, M.; Pennycook, S.J.; Pantelides, S.T.

    2009-02-23

    The fine structure of oxygen-K electron energy-loss spectra (EELS) of transition-metal oxides is known to correlate with nominal oxidation states (NOSs) that are often interpreted as charge states. Here we report calculations of O-K EELS in La{sub x}Ca{sub 1-x}MnO{sub 3} that agree with measured spectra and show that the variation in the prepeak's intensity with doping is controlled by the orbital occupancy of the majority-spin Mn 3d states, while its width is controlled by crystal-field splitting. The results confirm an earlier conclusion that the NOS extracted from EELS corresponds only to orbital occupancies, while the physical charge renders all atoms electrically neutral, even in so-called ionic crystals.

  20. Very-high-resolution tandem Fabry-Perot etalon cylindrical beam volume hologram spectrometer for diffuse source spectroscopy.

    PubMed

    Badieirostami, Majid; Momtahan, Omid; Hsieh, Chaoray; Adibi, Ali; Brady, David J

    2008-01-01

    We demonstrate a compact and slitless spectrometer with high resolution formed by cascading a Fabry-Perot etalon (FPE) and a cylindrical beam volume hologram (CBVH). The most significant advantage of this combined spectrometer is that we can independently encode spectral information of a diffuse beam in a 2D plane. Also, we show that in this slitless configuration we can simultaneously benefit from the advantages of both elements: the high resolution of the FPE and the large spectral range of the CBVH. Here, we report on the experimental demonstration of a spectrometer with better than 0.2 nm resolution.

  1. Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

    PubMed

    Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

    2010-07-28

    Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

  2. Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Hippler, Michael; Mohr, Christian; Keen, Katherine A.; McNaghten, Edward D.

    2010-07-01

    Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f =1.35 kHz and Q ≈10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as α ≈4.4×10-9 cm-1 s1/2 (1 s integration time) and 2.6×10-11 cm-1 s1/2 W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

  3. Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy.

    PubMed

    Nakajima, Kaoru; Miyashita, Motoki; Suzuki, Motofumi; Kimura, Kenji

    2013-12-14

    Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

  4. Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Miyashita, Motoki; Suzuki, Motofumi; Kimura, Kenji

    2013-12-01

    Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

  5. CHARACTERIZATION OF NON-DERIVATIZED PLANT CELL WALLS USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A recently described plant cell wall dissolution system has been logically modified to utilize perdeuterated solvents to allow direct in-nmr-tube dissolution and high-resolution solution-state NMR of the whole cell wall without derivatization. Finely ground cell wall material dissolves in a solvent ...

  6. Triple aldose reductase/α-glucosidase/radical scavenging high-resolution profiling combined with high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy for identification of antidiabetic constituents in crude extract of Radix Scutellariae.

    PubMed

    Tahtah, Yousof; Kongstad, Kenneth T; Wubshet, Sileshi G; Nyberg, Nils T; Jønsson, Louise H; Jäger, Anna K; Qinglei, Sun; Staerk, Dan

    2015-08-21

    In this work, development of a new microplate-based high-resolution profiling assay using recombinant human aldose reductase is presented. Used together with high-resolution radical scavenging and high-resolution α-glucosidase assays, it provided the first report of a triple aldose reductase/α-glucosidase/radical scavenging high-resolution inhibition profile - allowing proof of concept with Radix Scutellariae crude extract as a polypharmacological herbal drug. The triple bioactivity high-resolution profiles were used to pinpoint bioactive compounds, and subsequent structure elucidation was performed with hyphenated high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy. The only α-glucosidase inhibitor was baicalein, whereas main aldose reductase inhibitors in the crude extract were baicalein and skullcapflavone II, and main radical scavengers were ganhuangemin, viscidulin III, baicalin, oroxylin A 7-O-glucuronide, wogonoside, baicalein, wogonin, and skullcapflavone II.

  7. High-resolution terahertz spectroscopy with a noise radiation source based on high-T c superconductors

    NASA Astrophysics Data System (ADS)

    Sobakinskaya, E.; Vaks, V. L.; Kinev, N.; Ji, M.; Li, M. Y.; Wang, H. B.; Koshelets, V. P.

    2017-01-01

    Stochastic fields can play a ‘constructive’ role in their interaction with quantum systems. In this paper, we demonstrate that the phase-diffusion field (PDF) in the terahertz range (THz) induces macroscopic polarization in molecular gas. We explain the observed effect using a simple model in which the PDF is treated as a series of ultrashort pulses of a regular signal, resulting in transient absorption in molecular gas. The experimental investigation of this effect is carried out using ammonia, and the PDF is generated by an oscillator based on stacks of Bi2Sr2CaCu2O8 intrinsic Josephson junctions. These radiation sources do not require a phase-lock loop system to provide high resolution, which simplifies the spectrometer considerably. The PDF radiation sources open up new horizons for the development of compact high-resolution THz spectrometers and applications thereof.

  8. Probing the complex environments of GRB host galaxies and intervening systems: high resolution spectroscopy of GRB050922C

    NASA Astrophysics Data System (ADS)

    Piranomonte, S.; Vergani, S.; Fiore, F.; D'Elia, V.; Krongold, Y.; Nicastro, F.; Stella, L.

    2009-05-01

    We use high resolution spectroscopic observations of the afterglow of GRB050922C, in order to investigate the environment of gamma ray bursts (GRBs) and the interstellar matter of their host galaxies. We found that, as for most high resolution spectra of GRBs, the spectrum of the afterglow of GRB050922C is complex. The detection of lines of neutral elements like MgI and the detection of fine-structure levels of the ions FeII, SiII and CII allows us to separate components in the GRB ISM along the line of sight. GRB afterglow spectra can be used to disentangle the contribution of the different parts of the GRB host galaxy and to study their properties.

  9. High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3-micrometers Region: Role of Periphery

    NASA Technical Reports Server (NTRS)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2017-01-01

    In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3-micrometers absorption band. To this purpose we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 per cm range. The experimental spectra are compared with standard harmonic calculations, and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3-micrometers region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive dataset of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly-condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3-micrometers band, and on features such as the two-component emission character of this band and the 3-micrometers emission plateau.

  10. High-resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3 μm Region: Role of Periphery

    NASA Astrophysics Data System (ADS)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2016-11-01

    In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μm absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 cm-1 range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μm region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μm band, and on features such as the two-component emission character of this band and the 3 μm emission plateau.

  11. Crystal structure of silica-ZSM-12 by the combined use of high-resolution solid-state MAS NMR spectroscopy and synchrotron x-ray powder diffraction

    SciTech Connect

    Fyfe, C.A.; Kokotailo, G.T. ); Gies, H.; Marler, B. ); Cox, D.E. )

    1990-05-03

    The crystal structure of the synthetic zeolite silica-ZSM-12, 56 SiO{sub 2}, has been solved by the combined use of high-resolution solid-state MAS NMR spectroscopy and high-resolution synchrotron X-ray powder diffraction ZSM-12 crystallizes in the monoclinic space group C2/c with a{sub 0} = 24.863 {angstrom}, b{sub 0} = 5.012 {angstrom}, c{sub 0} = 24.328 {angstrom}, and {beta} = 107.7{degree}. The zeolite host structure is built from corner-linked SiO{sub 4} tetrahedra to give a three-dimensional 4-connected net. The pores of the structure are one-dimensional channels that do not intersect, with 12-membered ring pore openings of approximately 5.6 {times} 7.7 {angstrom}. The structure of ZSM-12 is frequently twinned with (100) as the twin plane, which indicates a new zeolite structure type.

  12. High-resolution synchrotron infrared spectroscopy of acrolein: The vibrational levels between 700 and 820 cm-1

    NASA Astrophysics Data System (ADS)

    McKellar, A. R. W.; Billinghurst, B. E.

    2015-09-01

    The weak combination bands ν12 + ν18 and ν17 + ν18 of trans-acrolein in the 700-760 cm-1 region are observed at high resolution (<0.001 cm-1) using spectra obtained at the Canadian Light Source synchrotron radiation facility. A detailed rotational analysis of the 121181 and 171181 upper states is made which includes the nearby perturbing states 185, 132181, and 131183. Taking the results of this 5-state fit, together with earlier results on lower lying vibrations, we now have experimental characterization for all 15 excited vibrational states of acrolein lying below 820 cm-1.

  13. High-resolution FTIR spectroscopy of the ν8 and Coriolis perturbation allowed ν12 bands of ketenimine.

    PubMed

    Bane, Michael K; Thompson, Christopher D; Robertson, Evan G; Appadoo, Dominique R T; McNaughton, Don

    2011-04-21

    High resolution FTIR spectra have been recorded in the region 250-770 cm(-1) using synchrotron radiation and over 2000 transitions to the ν(8) and ν(12) states of the short lived species ketenimine have been assigned. Ground state combination differences combined with published microwave transitions were used to refine the constants for the ground vibrational state. Rotational and centrifugal distortion parameters for the v(8) = 1 and v(12) = 1 levels were determined by co-fitting transitions, and treating a strong a-axis Coriolis interaction. Selection rules for the observed ν(12) transitions indicate that they arise solely from "perturbation allowed" intensity resulting from this Coriolis interaction.

  14. Ab initio study of electron energy loss spectra of bulk bismuth up to 100 eV

    NASA Astrophysics Data System (ADS)

    Timrov, Iurii; Markov, Maxime; Gorni, Tommaso; Raynaud, Michèle; Motornyi, Oleksandr; Gebauer, Ralph; Baroni, Stefano; Vast, Nathalie

    2017-03-01

    The dynamical charge-density response of bulk bismuth has been studied within time-dependent density functional perturbation theory, explicitly accounting for spin-orbit coupling. The use of the Liouville-Lanczos approach allows us to calculate electron energy loss spectra for excitation energies as large as 100 eV. Effects of 5 d semicore electronic states, spin-orbit coupling, exchange and correlation, local fields, and anisotropy are thoroughly investigated. The account of the 5 d states in the calculation turns out to be crucial to correctly describe the loss spectra above 10 eV and, in particular, the position and shape of the bulk-plasmon peak at 14.0 eV at vanishing transferred momentum. Our calculations reveal the presence of interband transitions at 16.3 eV, which had never been discussed before. The origin of the peak at 5.8 eV is revisited as due to mixed interband and collective excitations. Finally, our study supplements the lack of experiments at finite transferred momenta.

  15. Momentum-Dependent Lifetime Broadening of Electron Energy Loss Spectra: A Self-Consistent Coupled-Plasmon Model.

    PubMed

    Bourke, J D; Chantler, C T

    2015-02-05

    The complex dielectric function and associated energy loss spectrum of a condensed matter system is a fundamental material parameter that determines both the optical and electronic scattering behavior of the medium. The common representation of the electron energy loss function (ELF) is interpreted as the susceptibility of a system to a single- or bulk-electron (plasmon) excitation at a given energy and momentum and is commonly derived as a summation of noninteracting free-electron resonances with forms constrained by adherence to some externally determined optical standard. This work introduces a new causally constrained momentum-dependent broadening theory, permitting a more physical representation of optical and electronic resonances that agrees more closely with both optical attenuation and electron scattering data. We demonstrate how the momentum dependence of excitation resonances may be constrained uniquely by utilizing a coupled-plasmon model, in which high-energy excitations are able to relax into lower-energy excitations within the medium. This enables a robust and fully self-consistent theory with no free or fitted parameters that reveals additional physical insight not present in previous work. The new developments are applied to the scattering behavior of solid molybdenum and aluminum. We find that plasmon and single-electron lifetimes are significantly affected by the presence of alternate excitation channels and show for molybdenum that agreement with high-precision electron inelastic mean free path data is dramatically improved for energies above 20 eV.

  16. Combined effects of nuclear and electronic energy losses in solids irradiated with a dual-ion beam

    SciTech Connect

    Thome, Lionel; Debelle, Aurelien; Garrido, Frederico; Trocellier, Patrick; Serruys, Yves; Miro, Sandrine

    2013-04-08

    Single and dual-beam irradiations of oxide (c-ZrO{sub 2}, MgO, Gd{sub 2}Ti{sub 2}O{sub 7}) and carbide (SiC) single crystals were performed to study combined effects of nuclear (S{sub n}) and electronic (S{sub e}) energy losses. Rutherford backscattering experiments in channeling conditions show that the S{sub n}/S{sub e} cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO{sub 2} and Gd{sub 2}Ti{sub 2}O{sub 7}. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative S{sub n}/S{sub e} effects may lead to the preservation of the integrity of nuclear devices.

  17. Probing the complex environments of GRB host galaxies and intervening systems: high resolution spectroscopy of GRB050922C

    NASA Astrophysics Data System (ADS)

    Piranomonte, S.; Ward, P. A.; Fiore, F.; Vergani, S. D.; D'Elia, V.; Krongold, Y.; Nicastro, F.; Meurs, E. J. A.; Chincarini, G.; Covino, S.; Della Valle, M.; Fugazza, D.; Norci, L.; Sbordone, L.; Stella, L.; Tagliaferri, G.; Burrows, D. N.; Gehrels, N.; Goldoni, P.; Malesani, D.; Mirabel, I. F.; Pellizza, L. J.; Perna, R.

    2008-12-01

    Aims: The aim of this paper is to investigate the environment of gamma ray bursts (GRBs) and the interstellar matter of their host galaxies. Methods: To this purpose we use high resolution spectroscopic observations of the afterglow of GRB050922C, obtained with UVES/VLT ~ 3.5 h after the GRB event. Results: We found that, as for most high resolution spectra of GRBs, the spectrum of the afterglow of GRB050922C is complex. At least seven components contribute to the main absorption system at z=2.1992. The detection of lines of neutral elements like MgI and the detection of fine-structure levels of the ions FeII, SiII and CII allows us to separate components in the GRB ISM along the line of sight. Moreover, in addition to the main system, we analyzed the five intervening systems between z = 2.077 and z = 1.5664 identified along the GRB line of sight. Conclusions: GRB afterglow spectra are very complex, but full of information. This can be used to disentangle the contribution of the different parts of the GRB host galaxy and to study their properties. Our metallicity estimates agree with the scenario of GRBs exploding in low metallicity galaxies Based on observations collected at the European Southern Observatory (ESO) with the VLT/Kueyen telescope, Paranal, Chile, in the framework of program 075.A-0603.

  18. High-resolution X-Ray Spectroscopy Reveals the Special Nature of Wolf-Rayet Star Winds

    NASA Astrophysics Data System (ADS)

    Oskinova, L. M.; Gayley, K. G.; Hamann, W.-R.; Huenemoerder, D. P.; Ignace, R.; Pollock, A. M. T.

    2012-03-01

    We present the first high-resolution X-ray spectrum of a putatively single Wolf-Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and thus outside the wind acceleration zone where the line-driving instability (LDI) could create shocks. The X-ray emitting plasma reaches temperatures up to 50 MK and is embedded within the unshocked, "cool" stellar wind as revealed by characteristic spectral signatures. We detect a fluorescent Fe line at ≈6.4 keV. The presence of fluorescence is consistent with a two-component medium, where the cool wind is permeated with the hot X-ray emitting plasma. The wind must have a very porous structure to allow the observed amount of X-rays to escape. We find that neither the LDI nor any alternative binary scenario can explain the data. We suggest a scenario where X-rays are produced when the fast wind rams into slow "sticky clumps" that resist acceleration. Our new data show that the X-rays in single WR star are generated by some special mechanism different from the one operating in the O-star winds.

  19. High-Resolution Laser Spectroscopy of the S1 ← S0 Transition of Cl-NAPHTHALENES

    NASA Astrophysics Data System (ADS)

    Kasahara, Shunji; Yamamoto, Ryo

    2015-06-01

    High-resolution fluorescence excitation spectra of the S1 ← S0 electronic transition have been observed for 1-Cl naphthalene (1-ClN) and 2-Cl naphthalene (2-ClN). Sub-Doppler excitation spectra were measured by crossing a single-mode UV laser beam perpendicular to a collimated molecular beam. The absolute wavenumber was calibrated with accuracy 0.0002 cm-1 by measurement of the Doppler-free saturation spectrum of iodine molecule and fringe pattern of the stabilized etalon. For 2-ClN, the rotationally resolved high-resolution spectra were obtained for the 0^0_0 and 0^0_0+1042 cm-1 bands, and these molecular constants were determined in high accuracy. The obtained molecular constants of the 0^0_0 band are good agreement with the ones reported by Plusquellic et. al. For the 0^0_0+1042 cm-1 band, the local energy shifts were found. On the other hand, for 1-ClN, the rotational lines were not fully resolved because the fluorescence lifetime is shorter than the one of 2-ClN. Then we determined the molecular constants of 1-ClN from the comparison the observed spectrum with calculated one. D. F. Plusquellic, S. R. Davis, and F. Jahanmir, J. Chem. Phys., 115, 225 (2001).

  20. Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

    SciTech Connect

    Tan, Haiyan; Zhu, Ye; Dwyer, Christian; Xin, Huolin L.

    2014-12-31

    Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). At greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.