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Sample records for picosecond spectroscopic studies

  1. Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1982-01-01

    Spectroscopic and excited state decay kinetics are reported for monomeric and polymeric forms of ultraviolet stabilizers in the 2-(2'-hydroxyphenyl)-benzotriazole and 2-hydroxybenzophenone classes. For some of these molecules in various solvents at room temperature, (1) ground state absorption spectra, (2) emission spectra, (3) picosecond time-resolved transient absorption spectra, (4) ground state absorption recovery kinetics, (5) emission kinetics, and (6) transient absorption kinetics are reported. In the solid state at low temperatures, emission spectra and their temperature dependent kinetics up to approximately 200K as well as, in one case, the 12K excitation spectra of the observed dual emission are also reported.

  2. Picosecond spectroscopic studies of energy transfer in phycobiliproteins and model dye systems

    SciTech Connect

    Switalski, S.C.

    1987-02-01

    Energy transfer was investigated in the ..cap alpha beta.. monomer and separated ..cap alpha.. and ..beta.. subunits of C-phycocyanin from Anabaena variabilis and Anacystis nidulans, using steady-state and picosecond spectroscopy. Fluorescence excitation polarization spectra were consistent with a sensitizing (s) - fluorescing (f) model using a Forster energy transfer mechanism. The rise in polarization across the absorption band towards longer wavelength for the ..beta.. subunit and the ..cap alpha beta.. monomer was attributed to energy transfer among the three chromophores in the ..cap alpha beta.. monomer and between the 2 chromophores in the ..beta.. subunit. The constant polarization of the ..cap alpha.. subunit, with one chromophore, is consistent with a lack of any possibility of energy transfer. Fluorescence emission maxima were at 640 nm for the ..cap alpha beta.. monomer and the separated subunits of Anabaena variabilis, and 645 nm for the ..beta.. subunit, 640 nm for the ..cap alpha.. subunit, and 644 nm for ..cap alpha beta.. monomer of Anacystis nidulans. We have shown that the labels s and f are not consistent with all the steady-state spectroscopic results. 171 refs., 32 figs., 15 tabs.

  3. Picosecond spectroscopic studies of equilibrium structural fluctuations of native and partially unfolded states of Zinc II-substituted and metal-free cytochromes C

    NASA Astrophysics Data System (ADS)

    Tripathy, Jagnyaseni

    Picosecond time-resolved fluorescence spectroscopy was employed to characterize the equilibrium and non-equilibrium protein structural fluctuations in Zn II-substituted (ZnCytc) and metal-free (fbCytc) cytochromes c using dynamic fluorescence Stokes shift (FSS) and fluorescence anisotropy (FA) measurements. The intrinsic porphyrin chromophore is used as the probe for the structural fluctuations of the surrounding protein and solvent. The FSS experiments examine how the time scales detected from the dynamic solvation of a chromoprotein report changes in the character of motion. ZnCytc and fbCytc serve as limited, single-chromophore models for photosynthetic reaction center and light-harvesting proteins. The dynamic solvation of redox and light-harvesting chromophores in photosynthesis plays an important role in the quantum efficiency of electron transfer and energy transfer performed by these systems, respectively. The FSS response function of fbCytc in water is biexponential over the 100-ps--50-ns regime and the two time constants are 1.4 ns and 9.1 ns. ZnCytc under similar solution conditions shows a biexponential FSS response but with time constants of 0.2 ns and 1.5 ns. The two correlation times from the FSS response function correspond to motions of the hydrophobic core and the solvent-contact layer, respectively. Both FSS correlation times were lengthened and the solvation reorganization energy was reduced from 43 cm-1 to 33 cm-1 in the presence of 50% (v/v) glycerol. A Brownian diffusion model with thermally activated barrier crossings on the protein-folding energy landscape is used to interpret these results. The conclusion is that the mean-squared deviations of the fluctuations exhibited by fbCytc are perhaps a factor of ten larger than those in ZnCytc, which is consistent with the suggestion that fbCytc assumes a dynamic, partially unfolded structure with some of the characteristics of a molten globule. The nature of the motion associated with the

  4. Picosecond Optical Studies of Solids.

    NASA Astrophysics Data System (ADS)

    Broomfield, Seth Emlyn

    Available from UMI in association with The British Library. Requires signed TDF. Hot carrier relaxation is studied in the alloy semiconductor Ga_{rm 1-x} Al_{rm x}As by analysis of time-resolved luminescence at 4K. Photoexcited carrier densities in the range 10^{16 } to 10^{18}cm ^{-3} were created by 5ps laser pulses in alloys with x values ranging from 0 to 0.36. Carrier temperature cooling curves are discussed in terms of emission and absorption of non-equilibrium phonons by carriers, intervalley scattering of electrons and alloy disorder effects. Energy relaxation within a band of localised exciton states is studied in Ga_{rm 1 -x}Al_{rm x} As by analysis of time-resolved photoluminescence at 4K with a photoexcited carrier density of 10 ^{14}cm^{-3 }. It is found that the width of the band of localised states increases with the degree of alloy disorder as x ranges from 0 to 0.36. A form for the density of localised states is obtained. The intersite exciton overlap is estimated. Photoluminescence of the semiconductor gallium selenide is measured for carrier densities below 3 times 10^{18}cm ^{-3} at 2K. Biexcitons are identified by analysis of the photoluminescence at high densities. This is confirmed by induced optical absorption experiments. It is shown that biexciton dissociation by interaction with low-energy optical phonons occurs as the lattice temperature is increased. The group velocity of excitonic polaritons is obtained from measurements of the time-of-flight of 5ps optical pulses across a 1mum thick layer of gallium arsenide at 4K. The group velocity has a minimum value of 4 times 10 ^5ms^{-1} at the transverse exciton energy, and has a dependence on photon energy which agrees well with a model describing spatial dispersion of polaritons.

  5. Mitotic spindle studied using picosecond laser scissors

    NASA Astrophysics Data System (ADS)

    Baker, N. M.; Botvinick, E. L.; Shi, Linda; Berns, M. B.; Wu, George

    2006-08-01

    In previous studies we have shown that the second harmonic 532 nm, from a picosecond frequency doubled Nd:YAG laser, can cleanly and selectively disrupt spindle fiber microtubules in live cells (Botvinick et al 2004, Biophys. J. 87:4303-4212). In the present study we have ablated different locations and amounts of the metaphase mitotic spindle, and followed the cells in order to observe the fate of the irradiated spindle and the ability of the cell to continue through mitosis. Cells of the rat kangaroo line (PTK2) were stably transfected by ECFP-tubulin and, using fluorescent microscopy and the automated RoboLase microscope, (Botvinick and Berns, 2005, Micros. Res. Tech. 68:65-74) brightly fluorescent individual cells in metaphase were irradiated with 0.2447 nJ/micropulse corresponding to an irradiance of 1.4496*10^7 J/(ps*cm^2) . Upon irradiation the exposed part of the mitotic spindle immediately lost fluorescence and the following events were observed in the cells over time: (1) immediate contraction of the spindle pole towards the cut, (2) recovery of connection between pole and cut microtubule, (3) completion of mitosis. This system should be very useful in studying internal cellular dynamics of the mitotic spindle.

  6. Surfaces and thin films studied by picosecond ultrasonics

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse ( pump pulse''). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  7. Picosecond transient absorption study of photodissociated carboxy hemoglobin and myoglobin

    SciTech Connect

    Janes, S.M.; Dalickas, G.A.; Eaton, W.A.; Hochstrasser, R.M.

    1988-09-01

    The optical transient absorption spectra at 30 ps and 6.5 ns after photolysis are compared for both carboxy hemoglobin (HbCO) and carboxy myoglobin (MbCO). Both 355- and 532-nm excitation pulses were used. In all cases the shapes of the optical difference spectra thus generated are stationary over the complete time-scale studied. The photolysis spectra for MbCO are not significantly different from the equilibrium difference spectra generated on the same picosecond spectrometer when measured to an accuracy of +/- 0.5 nm. In addition, spectral parameters for delegated HbCO generated on the same spectrometer but detected by two different techniques, either by a Vidicon detector or point by point with photomultiplier tubes, are reported; the results are different from some of the previously reported picosecond experiments.

  8. Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

    2016-03-01

    In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, <=50um with ps laser, and <=20um with sub-ps laser, respectively was observed as a criteria of selecting the laser pulse width. The effects of laser processing parameters on speed and efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

  9. Spectroscopic studies of protein folding: Linear and nonlinear methods

    PubMed Central

    Serrano, Arnaldo L; Waegele, Matthias M; Gai, Feng

    2012-01-01

    Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics. PMID:22109973

  10. Report on picosecond studies of electron transfer in photosynthetic models

    SciTech Connect

    Netzel, T L; Bucks, R R; Boxer, S G; Fujita, I

    1980-01-01

    Considerable spectroscopic work on reaction centers 8RC) from photosynthetic bacteria and on photosystem I (PSI) particles from green plants has established that the initial photochemical step in these systems is the subnanosecond tranfer of an electron resulting in the creation of an oxidized donor and a reduced acceptor. For both of these systems the electron donor is a dimer. The acceptor for bacterial RC's is bacteriopheophytin, a metal-free bacteriochlorophyll. The acceptor for PSI is thought to be chlorophyll/sub a/. Dimeric and trimeric model molecules containing PChl/sub a/ were studied. However, rather than relying on chemical equilibria to join the potential electron donors and acceptors, we covalently attached all of the subunits to form a single large molecule. The distance was altered between the donor and acceptor subunits by using both 10 atom and 5 atom chains. Also, the effects of altering the relative orientation of the donor and acceptor were probed by contrasting the kinetics observed with added pyridine too those observed with added alcohol. The addition of pyridine prevents the dimer and trimer models from aggregating. However, the addition of alcohol causes intramolecular bonding of the model's subunits though R-OH bridges. Because the dielectric constant (epsilon) of the solvent directly affects the kinetics of electron transfer reactions, several solvents were used: toluene, CH/sub 2/Cl/sub 2/, and CH/sub 3/CN. Also, since a goal of this type of research is to correlate electrochemical, spectroscopic and structural information to predict the likelihood of electron transfer reactions, we varied the redox span of the potential photoproducts.

  11. Spectroscopic Studies of Melanin.

    DTIC Science & Technology

    1986-01-01

    il), and leading to the production of oxygen radicals (12). Gallas (13) and Kozikowski et al. (14) have studied melanin fluorescence. As part of a...Raman scattering unobservable in aqueous solution by continuous wave techniques. As was also observed by Kozikowski et al. (14), the intrinsic...168B. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence spectroscopy of eumelanins. IEEE J Quant Electron 1984;OE20:1379-1382. 15. Slawinski J

  12. Nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  13. Picosecond laser photolysis studies of DMA DMPP in solution

    NASA Astrophysics Data System (ADS)

    Miyasaka, Hiroshi; Itaya, Akira; Rotkiewicz, Krystyna; Rechthaler, Karl

    1999-07-01

    Picosecond transient absorption spectra of: 4-(4'- N,N-dimethylaminophenyl)-3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (DMA-DMPP), 3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (BPP) and 3,5-dimethyl-1,4,7-triphenyl-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (H-DMPP) were measured in solvents of different polarity. The results revealed the previously postulated change of the character of the fluorescing state from a primary excited, low polar state in non-polar solvents to a CT state in highly polar ones. Transient absorption spectra in the equilibrium fluorescent state of DMA-DMPP in polar solvents comprised the band ascribable to the cation radical of the DMA moiety. The charge transfer process is fastest in methanol and acetonitrile; in the former it is not controlled by a dynamic Stokes shift.

  14. Surfaces and thin films studied by picosecond ultrasonics. Progress report, December 1, 1989--November 30, 1992

    SciTech Connect

    Maris, J.H.; Tauc, J.

    1992-05-01

    This research is the study of thin films and interfaces via the use of the picosecond ultrasonic technique. In these experiments ultrasonic waves are excited in a structure by means of a picosecond light pulse (``pump pulse``). The propagation of these waves is detected through the use of a probe light pulse that is time-delayed relative to the pump. This probe pulse measures the change {Delta}R(t) in the optical reflectivity of the structure that occurs because the ultrasonic wave changes the optical properties of the structure. This technique make possible the study of the attenuation and velocity of ultrasonic waves up to much higher frequencies than was previously possible (up to least 500 GHz). In addition, the excellent time-resolution of the method makes it possible to study nanostructures of linear dimensions down to 100 {Angstrom} or less by ultrasonic pulse-echo techniques. 25 refs.

  15. Toward picosecond time-resolved X-ray absorption studies of interfacial photochemistry

    NASA Astrophysics Data System (ADS)

    Gessner, Oliver; Mahl, Johannes; Neppl, Stefan

    2016-05-01

    We report on the progress toward developing a novel picosecond time-resolved transient X-ray absorption spectroscopy (TRXAS) capability for time-domain studies of interfacial photochemistry. The technique is based on the combination of a high repetition rate picosecond laser system with a time-resolved X-ray fluorescent yield setup that may be used for the study of radiation sensitive materials and X-ray spectroscopy compatible photoelectrochemical (PEC) cells. The mobile system is currently deployed at the Advanced Light Source (ALS) and may be used in all operating modes (two-bunch and multi-bunch) of the synchrotron. The use of a time-stamping technique enables the simultaneous recording of TRXAS spectra with delays between the exciting laser pulses and the probing X-ray pulses spanning picosecond to nanosecond temporal scales. First results are discussed that demonstrate the viability of the method to study photoinduced dynamics in transition metal-oxide semiconductor (SC) samples under high vacuum conditions and at SC-liquid electrolyte interfaces during photoelectrochemical water splitting. Opportunities and challenges are outlined to capture crucial short-lived intermediates of photochemical processes with the technique. This work was supported by the Department of Energy Office of Science Early Career Research Program.

  16. A study of transient stimulated Raman scattering and self-focusing in the picosecond time regime

    NASA Technical Reports Server (NTRS)

    Reintjes, J. F.

    1971-01-01

    Two third order processes, stimulated Raman scattering and self-focusing, with picosecond pulses are studied. In the case of transient stimulated scattering, the gain is reduced from the steady state value, and qualitatively new features, such as shortening and delay of the Stokes pulse relative to the laser pulse, appear. These predictions are extended to realistic laser pulses, and experiments confirm all of the theoretical predictions. The self-focusing and frequency broadening of picosecond pulses is studied in the absence of stimulated Raman scattering in several materials with large orientational Kerr constants. Measurements of the relaxation time indicate that the orientational Kerr effect is important in the self-focusing of picosecond pulses. Self-focused filaments are observed to propagate with constant diameters over a distance greater than 10 cm, but disappear before the end of a 20 cm cell. The filaments radiate light continuously along their path and the spectrum of the light shows that the frequency content extends symmetrically for several hundred wave numbers on either side of the laser frequency.

  17. Picosecond-time-resolved studies of nonradiative relaxation in ruby and alexandrite

    SciTech Connect

    Gayen, S.K.; Wang, W.B.; Petricevic, V.; Alfano, R.R.

    1985-01-01

    Dynamics of the nonradiative transitions between the /sup 4/T/sub 2/ pump band and the /sup 2/E storage level of the Cr/sup 3 +/ ion in ruby and alexandrite crystals is studied using the picosecond excite-and-probe absorption technique. A 527-nm picosecond pulse excites the /sup 4/T/sub 2/ state of the Cr/sup 3 +/ ion, and an infrared picosecond probe pulse monitors the subsequent growth and decay of population in the excited states as a function of pump-probe delay. An upper limit of 7 ps is determined for the nonradiative lifetime of the /sup 4/T/sub 2/ state in ruby. A vibrational relaxation time of 25 ps for the /sup 4/T/sub 2/ band in alexandrite is estimated. The time to attain thermal equilibrium population between the /sup 2/E and /sup 4/T/sub 2/ levels of alexandrite following excitation of /sup 4/T/sub 2/ band is estimated to be approx. 100 ps.

  18. Development of a broadband picosecond infrared spectrometer and its incorporation into an existing ultrafast time-resolved resonance Raman, UV/visible, and fluorescence spectroscopic apparatus.

    PubMed

    Towrie, Michael; Grills, David C; Dyer, Joanne; Weinstein, Julia A; Matousek, Pavel; Barton, Robin; Bailey, Philip D; Subramaniam, Naresh; Kwok, Wai M; Ma, Chensheng; Phillips, David; Parker, Anthony W; George, Michael W

    2003-04-01

    We have constructed a broadband ultrafast time-resolved infrared (TRIR) spectrometer and incorporated it into our existing time-resolved spectroscopy apparatus, thus creating a single instrument capable of performing the complementary techniques of femto-/picosecond time-resolved resonance Raman (TR3), fluorescence, and UV/visible/infrared transient absorption spectroscopy. The TRIR spectrometer employs broadband (150 fs, approximately 150 cm(-1) FWHM) mid-infrared probe and reference pulses (generated by difference frequency mixing of near-infrared pulses in type I AgGaS2), which are dispersed over two 64-element linear infrared array detectors (HgCdTe). These are coupled via custom-built data acquisition electronics to a personal computer for data processing. This data acquisition system performs signal handling on a shot-by-shot basis at the 1 kHz repetition rate of the pulsed laser system. The combination of real-time signal processing and the ability to normalize each probe and reference pulse has enabled us to achieve a high sensitivity on the order of deltaOD approximately 10(-4) - 10(-5) with 1 min of acquisition time. We present preliminary picosecond TRIR studies using this spectrometer and also demonstrate how a combination of TRIR and TR3 spectroscopy can provide key information for the full elucidation of a photochemical process.

  19. Electrolytes Ageing in Lithium-ion Batteries: A Mechanistic Study from Picosecond to Long Timescales.

    PubMed

    Ortiz, Daniel; Jiménez Gordon, Isabel; Baltaze, Jean-Pierre; Hernandez-Alba, Oscar; Legand, Solène; Dauvois, Vincent; Si Larbi, Gregory; Schmidhammer, Uli; Marignier, Jean-Louis; Martin, Jean-Frédéric; Belloni, Jacqueline; Mostafavi, Mehran; Le Caër, Sophie

    2015-11-01

    The ageing phenomena occurring in various diethyl carbonate/LiPF6 solutions are studied using gamma and pulse radiolysis as a tool to generate similar species as the ones occurring in electrolysis of Li-ion batteries (LIBs). According to picosecond pulse radiolysis experiments, the reaction of the electron with (Li(+), PF6(-)) is ultrafast, leading to the formation of fluoride anions that can then precipitate into LiF(s). Moreover, direct radiation-matter interaction with the salt produces reactive fluorine atoms forming HF(g) and C2H5F(g). The strong Lewis acid PF5 is also formed. This species then forms various R(1)R(2)R(3) P=O molecules, where R is mainly -F, -OH, and -OC2H5. Substitution reactions take place and oligomers are slowly formed. Similar results were obtained in the ageing of an electrochemical cell filled with the same model solution. This study demonstrates that radiolysis enables a description of the reactivity in LIBs from the picosecond timescale until a few days.

  20. Picosecond nonlinear optical studies of gold nanoparticles synthesised using coriander leaves (Coriandrum sativum)

    NASA Astrophysics Data System (ADS)

    Venugopal Rao, S.

    2011-07-01

    The results are presented from the experimental picosecond nonlinear optical (NLO) studies of gold nanoparticles synthesised using coriander leaf (Coriandrum sativum) extract. Nanoparticles with an average size of ∼30 nm (distribution of 5-70 nm) were synthesised according to the procedure reported by Narayanan et al. [Mater. Lett. 2008, 62, 4588-4591]. NLO studies were carried out using the Z-scan technique using 2 ps pulses near 800 nm. Open-aperture data suggested saturation absorption as the nonlinear absorption mechanism, whereas closed-aperture data suggested a positive nonlinearity. The magnitude of third-order nonlinearity was estimated to be (3.3 ± 0.6) × 10-13 esu. A solvent contribution to the nonlinearity was also identified and estimated. A comparison is attempted with some recently reported NLO studies of similar gold nanostructures.

  1. A theoretical study of the stress relaxation in HMX on the picosecond time scale

    NASA Astrophysics Data System (ADS)

    Long, Yao; Chen, Jun

    2015-12-01

    The stress relaxation model of β-HMX on the picosecond time scale is studied by a theoretical approach. The relaxation of normal stress is contributed by lattice vibration, and the relaxation of shear stress is contributed by molecular rotation. Based on this model, the energy dissipation rule of the elastic wave and the profile of the shock wave are investigated. We find at low frequency the dissipation rate of the elastic wave is proportional to the power function of frequency, and under high speed shock loading the width of the stress relaxation zone is less than 0.3 μm there is a pressure peak with a height of 14 GPa near the wave front.

  2. Picosecond charge transport in rutile at high carrier densities studied by transient terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Zajac, V.; Němec, H.; Kužel, P.

    2016-09-01

    We study terahertz photoconductivity of a rutile single crystal between 10 and 300 K under strong photoexcitation by femtosecond pulses at 266 nm. A marked dependence of the carrier mobility on the carrier density is observed leading to highly complex transport phenomena on a picosecond time scale. We develop a general model of carrier photoconductive response in the case of time dependent inhomogeneous distribution of carrier density and mobility. This allows us to assess an important role of both electrons and holes in the response of photoexcited rutile. At low temperatures, the carrier mobility is initially reduced due to the electron-hole scattering and increases by one order of magnitude upon ambipolar diffusion of the carriers into deeper regions of the sample. At room temperature, contributions of transient hot optical phonons and/or of midinfrared polaron excitations with charge-density-dependent dielectric strength emerge in the photoconductivity spectra.

  3. Study of plasma pressure evolution driven by strong picosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Li, M.; Wang, J. X.; Xu, Y. X.; Zhu, W. J.

    2017-01-01

    Through one dimensional relativistic particle-in-cell simulation of strong laser interaction with the solid-density plasma, the evolution of the plasma impact pressure behind a thin foil has been investigated in details. An energy-compression mechanism has been proposed to help optimizing the laser and plasma parameters. It has been found that by using a picosecond laser with intensity 1015 W cm-2, an impact pressure as high as several hundreds of GPa order of magnitude can be obtained. The numerical analysis demonstrates that the peak pressure is mainly resulted from the ion contribution. These results are of potential application to the laser loading upon solids in order to study the material properties under extra-high dynamic pressure.

  4. Study of self-focusing and self-phase-modulation in the picosecond-time regime.

    NASA Technical Reports Server (NTRS)

    Reintjes, J.; Carman, R. L.; Shimizu, F.

    1973-01-01

    Study of the propagation of a single picosecond pulse of a mode-locked Nd-glass laser in CS2 nitrobenzene and toluene by observations of the birefringence and spectral changes in self-focused laser light. Multiple second-harmonic probing beams are used for birefringence measurements in a single IR pulse in various portions of the active cell. The orientational Kerr effect is found to be the prime factor of induced birefringence in nitrobenzene and toluene. The results for CS2 are also consistent with this mechanism and show that the duration of an IR pulse in the focal volume is less than that of the incident pulse. The properties of beams which are focused within the cell by an external lens are also investigated.

  5. Spectroscopic Studies of Abell Clusters

    NASA Astrophysics Data System (ADS)

    Way, Michael Joseph

    The objectives of this work are to use spectroscopic techniques to accurately categorize galaxies as either HII region star forming galaxies or as Active Galactic Nuclei powered via a black hole, and to use radial velocities and projected positions of galaxies in clusters to obtain the total cluster mass and its distribution. The masses and distributions compare well to X-ray mass measurements. The commonly used Dressler, A., Thompson, I. & Shectman, S. 1985, ApJ, 288, 481 technique for discriminating between Active Galactic Nuclei and HII region galaxies uses the measurement of the equivalent width of the emission lines (OII) 3727 A, H/beta, and (OIII) 5007 A. High quality spectra from 42 galaxies were taken and it is shown that their method is not capable of distinguishing between Active Galactic Nuclei and HII region galaxies. The emission line flux from H/beta, (OIII) 5007 A, (OI) 6300 A, Hα, (NII) 6583 A, and (SII) 6716+6731 A in combination with the method of Veilleux, S. & Osterbrock, D. E. 1987, ApJS, 63, 295 must be used to accurately distinguish between Active Galactic Nuclei and HII region galaxies. Galaxy radial velocities from spectroscopic data and their projected 2-D positions in clusters are used to obtain robust estimates of the total mass and mass distribution in two clusters. The total mass is calculated using the Virial theorem after removing substructure. The mass distribution is estimated via several robust statistical tests for 1-D, 2-D and 3-D structure. It is shown that the derived mass estimates agree well with those found independently from hot X-ray gas emission in clusters.

  6. Energy transfer in LHCII monomers at 77K studied by sub-picosecond transient absorption spectroscopy.

    PubMed

    Kleima, F J; Gradinaru, C C; Calkoen, F; van Stokkum, I H; van Grondelle, R; van Amerongen, H

    1997-12-09

    Energy transfer from chlorophyll b (Chl b) to chlorophyll a (Chl a) in monomeric preparations of light-harvesting complex II (LHCII) from spinach was studied at 77 K using pump-probe experiments. Sub-picosecond excitation pulses centered at 650 nm were used to excite preferentially Chl b and difference absorption spectra were detected from 630 to 700 nm. Two distinct Chl b to Chl a transfer times, approximately 200 fs and 3 ps, were found. A clearly distinguishable energy transfer process between Chl a molecules occurred with a time constant of 18 ps. The LHCII monomer data are compared to previously obtained LHCII trimer data, and both data sets are fitted simultaneously using a global analysis fitting routine. Both sets could be described with the following time constants: 140 fs, 600 fs, 8 ps, 20 ps, and 2.9 ns. In both monomers and trimers 50% of the Chl b to Chl a transfer is ultrafast (<200 fs). However, for monomers this transfer occurs to Chl a molecules that absorb significantly more toward shorter wavelengths than for trimers. Part of the transfer from Chl b to Chl a that occurs with a time constant of 600 fs in trimers is slowed down to several picoseconds in monomers. However, it is argued that observed differences between monomers and trimers should be ascribed to the loss of some Chl a upon monomerization or a shift of the absorption maximum of one or several Chl a molecules. It is concluded that Chl b to Chl a transfer occurs only within monomeric subunits of the trimers and not between different subunits.

  7. Picosecond excitation energy transfer of allophycocyanin studied in solution and in crystals.

    PubMed

    Ranjbar Choubeh, Reza; Sonani, Ravi R; Madamwar, Datta; Struik, Paul C; Bader, Arjen N; Robert, Bruno; van Amerongen, Herbert

    2017-07-28

    Cyanobacteria perform photosynthesis with the use of large light-harvesting antennae called phycobilisomes (PBSs). These hemispherical PBSs contain hundreds of open-chain tetrapyrrole chromophores bound to different peptides, providing an arrangement in which excitation energy is funnelled towards the PBS core from where it can be transferred to photosystem I and/or photosystem II. In the PBS core, many allophycocyanin (APC) trimers are present, red-light-absorbing phycobiliproteins that covalently bind phycocyanobilin (PCB) chromophores. APC trimers were amongst the first light-harvesting complexes to be crystallized. APC trimers have two spectrally different PCBs per monomer, a high- and a low-energy pigment. The crystal structure of the APC trimer reveals the close distance (~21 Å) between those two chromophores (the distance within one monomer is ~51 Å) and this explains the ultrafast (~1 ps) excitation energy transfer (EET) between them. Both chromophores adopt a somewhat different structure, which is held responsible for their spectral difference. Here we used spectrally resolved picosecond fluorescence to study EET in these APC trimers both in crystallized and in solubilized form. We found that not all closely spaced pigment couples consist of a low- and a high-energy pigment. In ~10% of the cases, a couple consists of two high-energy pigments. EET to a low-energy pigment, which can spectrally be resolved, occurs on a time scale of tens of picoseconds. This transfer turns out to be three times faster in the crystal than in the solution. The spectral characteristics and the time scale of this transfer component are similar to what have been observed in the whole cells of Synechocystis sp. PCC 6803, for which it was ascribed to EET from C-phycocyanin to APC. The present results thus demonstrate that part of this transfer should probably also be ascribed to EET within APC trimers.

  8. Comparison of two picosecond lasers to a nanosecond laser for treating tattoos: a prospective randomized study on 49 patients.

    PubMed

    Lorgeou, A; Perrillat, Y; Gral, N; Lagrange, S; Lacour, J-P; Passeron, T

    2017-07-31

    Q-switched nanosecond lasers demonstrated their efficacy in treating most types of tattoos, but complete disappearance is not always achieved even after performing numerous laser sessions. Picosecond lasers are supposed to be more efficient in clearing tattoos than nanosecond lasers, but prospective comparative data remain limited. To compare on different types of tattoos the efficacy of a nanosecond laser with two types of picosecond lasers. We conducted a prospective randomized study performed from December 2014 to June 2016 on adult patients with all types of tattoos. The tattoos were divided into two halves of equal size. After randomization, half of the tattoo was treated with a picosecond laser and the other half with a nanosecond laser. The evaluation was performed on standardized pictures performed before treatment and 2 months after the last session, by two physicians, not involved in the treatment, blinded on the type of treatments received. The main end point was a clearance above 75% of the tattoos. A total of 49 patients were included. Professional tattoos represented 85.7%, permanent make-up 8.2% and non-professional tattoo 6.1%. The majority were black or blue and 10.2% were polychromatic. No patient was lost during follow-up. A reduction of 75% or more of the colour intensity was obtained for 33% of the tattoos treated with the picosecond lasers compared to 14% with the nanosecond laser (P = 0.008). An improvement superior to 75% was obtained in 34% monochromic black or blue tattoos with the picosecond lasers compared to 9% for the nanosecond laser. Only one of the five polychromic tattoos achieved more than 75% of improvement with the two types of laser. Our results show a statistically significant superiority of the picosecond lasers compared to the nanosecond laser for tattoo clearance. However, they do not show better efficacy for polychromic tattoos and the difference in terms of side-effects was also minimal with a tendency of picosecond

  9. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  10. Studying Young Stars with Large Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Martell, Sarah L.

    2016-01-01

    Galactic archaeology is the study of the history of star formation and chemical evolution in the Milky Way, based on present-day stellar populations. Studies of young stars are a key anchor point for Galactic archaeology, since quantities like the initial mass function and the star formation rate can be studied directly in young clusters and star forming regions. Conversely, massive spectroscopic Galactic archaeology surveys can be used as a data source for young star studies.

  11. Microviscosity in polyacrylamide gels with pendant triphenyl-methane leuco derivatives: picosecond time-resolved fluorescence study

    NASA Astrophysics Data System (ADS)

    Tamai, Naoto; Ishikawa, Masazumi; Kitamura, Noboru; Masuhara, Hiroshi

    1991-10-01

    Picosecond fluorescence dynamics of triphenylmethane dyes bonded to polyacrylamide gels before and after swelling was studied by a single-photon timing technique. Microviscosity in the gels after swelling was estimated to be 10-11 cP by examining the viscosity dependence of fluorescence dynamics of malachite green in various alcohols. The results were interpreted in terms of structured stiff water in a microcavity of the gels.

  12. Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

    SciTech Connect

    Hamad, Syed; Nageswara Rao, S. V. S.; Pathak, A. P.; Krishna Podagatlapalli, G.; Mounika, R.; Venugopal Rao, S. E-mail: soma-venu@uohyd.ac.in

    2015-12-15

    We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO{sub 2} NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (<1 ps) and non-radiative transitions (>1 ps). Large third order optical nonlinearities (∼10{sup −14} e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm

  13. The Application Of Picosecond-Resolved Fluorescence Spectroscopy In The Study Of Flavins And Flavoproteins

    NASA Astrophysics Data System (ADS)

    Visser, Antonie J.; van Hoek, Arie

    1988-06-01

    Picosecond relaxation processes of flavins and flavoproteins were investigated with mode-locked and synchronously pumped lasers as source of excitation and time-correlated single photon counting in detection. Free flavin rotational correlation times of 80-150 ps (values depending on the flavin derivative used) could be precisely determined. Picosecond-resolved fluorescence of the flavin bound in the electron-carrier protein flavodoxin from Desulfovibrio vulgaris yields a fluorescence lifetime component of 30 ps in the fluorescence decay. Time-resolved tryptophan fluorescence in flavodoxin exhibits a short lifetime component, which is attributed in part to energy transfer from tryptophan to flavin. Three-dimensional fluorescence spectroscopy and fluorescence anisotropy decay analysis of the two tryptophan residues in flavodoxin provide new evidence for specific flavin-tryptophan interaction. Finally, picosecond-resolved spectroscopy enables the direct measurement of energy transfer between two different chromophores in a protein, from which topographical details can be inferred.

  14. Time-resolved study of formate on Ni( 1 1 1 ) by picosecond SFG spectroscopy

    NASA Astrophysics Data System (ADS)

    Kusafuka, K.; Noguchi, H.; Onda, K.; Kubota, J.; Domen, K.; Hirose, C.; Wada, A.

    2002-04-01

    Time-resolved vibrational measurements were carried out on formate (HCOO) adsorbed on Ni(1 1 1) surface by combining the sum-frequency generation method and picosecond laser system (time resolution of 6 ps). Rapid intensity decrease (within the time resolution) followed by intensity recovery (time constant of several tens of ps) of CH stretching signal was observed when picosecond 800 nm pulse was irradiated on the sample surface. From the results of temperature and pump fluence dependences of temporal behaviour of signal intensity, we concluded that the observed intensity change was induced by non-thermal process. Mechanism of the temporal intensity change was discussed.

  15. Picosecond infrared study of carbonmonoxy cytochrome c oxidase: Ligand transfer dynamics and binding orientations

    SciTech Connect

    Peterson, K.A.; Stoutland, P.O.; Dyer, R.B.; Woodruff, W.H.

    1991-01-01

    Cytochrome c oxidase (CcO), an enzyme which catalyzes the reduction of dioxygen to water in the terminal step of the respiratory chain, combines several fundamental chemical processes in performing its function. The coordination chemistry and ligation dynamics of the cytochrome {alpha}{sub 3}-Cu{sub B} site, where O{sub 2} and other small molecules such as CO, NO and isocyanates can bind, are essential to the function of the enzyme. Recent time-resolved infrared (TRIR) and visible absorption measurements have shown that coordination to Cu{sub B}{sup +} is an obligatory mechanistic step for CO entering the cytochrome {alpha}{sub 3} heme site and departing the protein after photodissociation. The timescale (> 10{sup {minus}7} s) of the TRIR measurements precluded observation of the ligation dynamics immediately following photodissociation. Here we report a picosecond timescale TRIR study of these events. The results reveal that the photoinitiated ligand transfer of CO from Fe{sub a3}{sup 2+} to Cu{sub B}{sup +}, which are believed to lie 4--5 {Angstrom} apart, occurs within 1 ps. 9 refs., 2 figs.

  16. Photooxidation and photoaquation of iron hexacyanide in aqueous solution: A picosecond X-ray absorption study

    PubMed Central

    Reinhard, M.; Penfold, T. J.; Lima, F. A.; Rittmann, J.; Rittmann-Frank, M. H.; Abela, R.; Tavernelli, I.; Rothlisberger, U.; Milne, C. J.; Chergui, M.

    2014-01-01

    We present a picosecond Fe K-edge absorption study of photoexcited ferrous and ferric hexacyanide in water under 355 and 266 nm excitation. Following 355 nm excitation, the transient spectra for the ferrous and ferric complexes exhibit a red shift of the edge reflecting an increased electron density at the Fe atom. For the former, an enhanced pre-edge transition is also observed. These observations are attributed to the aquated [Fe(CN)5OH2]3− species, based on quantum chemical calculations which also provide structural parameters. Upon 266 nm excitation of the ferric complex, a transient reminiscent of the aquated species is observed (appearance of a pre-edge feature and red shift of the edge) but it is different from that obtained under 355 nm excitation. This points to a new reaction channel occurring through an intermediate state lying between these two excitation energies. Finally, 266 nm excitation of the ferrous species is dominated by the photooxidation channel with formation of the ferric complex as main photoproduct. However, we observe an additional minor photoproduct, which is identical to the 266 nm generated photoproduct of the ferric species, suggesting that under our experimental conditions, the pump pulse photooxidises the ferrous complex and re-excites the primary ferric photoproduct. PMID:26798775

  17. Photooxidation and photoaquation of iron hexacyanide in aqueous solution: A picosecond X-ray absorption study.

    PubMed

    Reinhard, M; Penfold, T J; Lima, F A; Rittmann, J; Rittmann-Frank, M H; Abela, R; Tavernelli, I; Rothlisberger, U; Milne, C J; Chergui, M

    2014-03-01

    We present a picosecond Fe K-edge absorption study of photoexcited ferrous and ferric hexacyanide in water under 355 and 266 nm excitation. Following 355 nm excitation, the transient spectra for the ferrous and ferric complexes exhibit a red shift of the edge reflecting an increased electron density at the Fe atom. For the former, an enhanced pre-edge transition is also observed. These observations are attributed to the aquated [Fe(CN)5OH2](3-) species, based on quantum chemical calculations which also provide structural parameters. Upon 266 nm excitation of the ferric complex, a transient reminiscent of the aquated species is observed (appearance of a pre-edge feature and red shift of the edge) but it is different from that obtained under 355 nm excitation. This points to a new reaction channel occurring through an intermediate state lying between these two excitation energies. Finally, 266 nm excitation of the ferrous species is dominated by the photooxidation channel with formation of the ferric complex as main photoproduct. However, we observe an additional minor photoproduct, which is identical to the 266 nm generated photoproduct of the ferric species, suggesting that under our experimental conditions, the pump pulse photooxidises the ferrous complex and re-excites the primary ferric photoproduct.

  18. Spectroscopic study of Mentha oils

    NASA Astrophysics Data System (ADS)

    Rai, A. K.; Singh, A. K.

    The visible fluorescence and excitation spectra of Mentha oils (Japanese mint oil, peppermint oil and spearmint oil) have been recorded. Different physical constants which are characteristic of the fluorescent molecules have been calculated for all three oils. Results reveal that the same group of organic compounds dominate in the oils of peppermint and spearmint, whereas some different compound is present in Japanese mint oil. It is also found that the fluorescence intensity of these oils is comparable to that of Rhodamine 6G dye in methanol solution. Our studies suggest that Mentha oils may be a useful lasing material in the 450-600 nm wavelength range.

  19. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at UTK is involved in heavy-ion physics including both nuclear structure and reaction mechanisms. During the last year experimental work has been in 3 broad areas: structure of nuclei at high angular momentum, structure of nuclei far from stability, and ultra-relativistic heavy-ion physics. Results in these areas are described in this document under: properties of high-spin states, study of low-energy levels of nuclei far from stability, and high-energy heavy-ion physics (PHENIX, etc.). Another important component of the work is theoretical interpretation of experimental results (Joint Institute for Heavy Ion Research).

  20. Spectroscopic studies of the transplutonium elements

    SciTech Connect

    Carnall, W.T.; Conway, J.G.

    1983-01-01

    The challenging opportunity to develop insights into both atomic structure and the effects of bonding in compounds makes the study of actinide spectroscopy a particularly fruitful and exciting area of scientific endeavor. It is also the interpretation of f-element spectra that has stimulated the development of the most sophisticated theoretical modeling attempted for any elements in the periodic table. The unique nature of the spectra and the wealth of fine detail revealed make possible sensitive tests of both physical models and the results of Hartree-Fock type ab initio calculations. This paper focuses on the unique character of heavy actinide spectroscopy. It discusses how it differs from that of the lighter member of the series and what are the special properties that are manifested. Following the introduction, the paper covers the following: (1) the role of systematic studies and the relationships of heavy-actinide spectroscopy to ongoing spectroscopic investigations of the lighter members of the series; (2) atomic (free-ion) spectra which covers the present status of spectroscopic studies with transplutonium elements, and future needs and directions in atomic spectroscopy; (3) the spectra of actinide compounds which covers the present status and future directions of spectroscopic studies with compounds of the transplutonium elements; and other spectroscopies. 1 figure, 2 tables.

  1. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R&D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  2. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  3. Spectroscopic studies of individual plasmon resonant nanoparticles

    NASA Astrophysics Data System (ADS)

    Mock, Jack J.; Smith, David R.; Barbic, Mladen; Oldenburg, Steven J.; Schultz, David A.; Schultz, Sheldon

    2003-11-01

    We present a detailed description of the apparatus and techniques that we have utilized in our experimental study of individual plas on resonant nanoparticles,along with a brief description of some major results. The apparatus consists of a spectroscopic system combined with a modified darkfield microscope, which enables the user to sequentially select individual resonant nanostructures in the microscopic field of view for spectroscopic study. Plasmon resonant nanostructures scatter light elastically,and typically have very large scattering cross-sections at their resonant optical wavelengths. In general, spectra can be obtained with acquisition times between .1 to 30 seconds,and color images can be captured using consumer digital color cameras. Spheres,tetrahedrons,and pentagonal platelets were fabricated using colloidal chemistry techniques. To produce highly anisotropic structures such as nanorods and "barbells", templates were used. Many of these nanostructures have been individually spectroscopically characterized,and their spectra correlated with their shape and size as determined by transmission electron icroscope (TEM). The unique shape,size, composition,and dielectric surroundings of the individual plasmon resonant nanostructures determine their plasmon resonant behavior. We will show how the composition of the substrate on which the particles are immobilized and the dielectric of the surrounding medium have a significant effect on the plasmon resonance of the individual particles.

  4. Study on third-order nonlinear optical properties of 4-methylsulfanyl chalcone derivatives using picosecond pulses

    SciTech Connect

    D'silva, E.D.; Podagatlapalli, G. Krishna; Venugopal Rao, S.; Dharmaprakash, S.M.

    2012-11-15

    Graphical abstract: Photograph and schematic representation of Z-scan experimental setup used to investigate third order nonlinear properties of the chalcone materials. Highlights: ► Br and NO{sub 2} substituted chalcone derivatives were exposed to picosecond laser pulses. ► Third-order nonlinear optical (NLO) properties were investigated. ► Compounds show promising third-order and optical limiting properties. ► These materials found suitable for electrical and optical applications. -- Abstract: In this paper we present results from the experimental study of third-order nonlinear optical (NLO) properties of three molecules of Br and NO{sub 2} substituted chalcone derivatives namely (2E)-1-(4-bromophenyl)-3-[4(methylsulfanyl)phenyl]prop-2-en-1-one (4Br4MSP), (2E)-1-(3-bromophenyl)-3-[4-(methylsulfanyl) phenyl]prop-2-en-1-one (3Br4MSP) and (2E)-3[4(methylsulfanyl) phenyl]-1-(4-nitrophenyl)prop-2-en-1-one (4N4MSP). The NLO properties have been investigated by Z-scan technique using 2 ps laser pulses at 800 nm. The nonlinear refractive indices, nonlinear absorption coefficient, and the magnitude of third-order susceptibility have been determined. The values obtained are of the order of 10{sup −7} cm{sup 2}/GW, 10{sup −3} cm/GW and 10{sup −14} esu respectively. The molecular second hyperpolarizability for the chalcone derivatives is of the order of 10{sup −32} esu. The coupling factor, excited state cross section, ground state cross section etc. were determined. The optical limiting (OL) property was studied. The results suggest that the nonlinear properties investigated for present chalcones are comparable with some of the reported chalcone derivatives and can be desirable for NLO applications.

  5. Unfolding of Ubiquitin Studied by Picosecond Time-Resolved Fluorescence of the Tyrosine Residue

    PubMed Central

    Noronha, Melinda; Lima, João C.; Bastos, Margarida; Santos, Helena; Maçanita, António L.

    2004-01-01

    The photophysics of the single tyrosine in bovine ubiquitin (UBQ) was studied by picosecond time-resolved fluorescence spectroscopy, as a function of pH and along thermal and chemical unfolding, with the following results: First, at room temperature (25°C) and below pH 1.5, native UBQ shows single-exponential decays. From pH 2 to 7, triple-exponential decays were observed and the three decay times were attributed to the presence of tyrosine, a tyrosine-carboxylate hydrogen-bonded complex, and excited-state tyrosinate. Second, at pH 1.5, the water-exposed tyrosine of either thermally or chemically unfolded UBQ decays as a sum of two exponentials. The double-exponential decays were interpreted and analyzed in terms of excited-state intramolecular electron transfer from the phenol to the amide moiety, occurring in one of the three rotamers of tyrosine in UBQ. The values of the rate constants indicate the presence of different unfolded states and an increase in the mobility of the tyrosine residue during unfolding. Finally, from the pre-exponential coefficients of the fluorescence decays, the unfolding equilibrium constants (KU) were calculated, as a function of temperature or denaturant concentration. Despite the presence of different unfolded states, both thermal and chemical unfolding data of UBQ could be fitted to a two-state model. The thermodynamic parameters Tm = 54.6°C, ΔHTm = 56.5 kcal/mol, and ΔCp = 890 cal/mol//K, were determined from the unfolding equilibrium constants calculated accordingly, and compared to values obtained by differential scanning calorimetry also under the assumption of a two-state transition, Tm = 57.0°C, ΔHm= 51.4 kcal/mol, and ΔCp = 730 cal/mol//K. PMID:15454455

  6. Vibrational spectroscopic study of fluticasone propionate

    NASA Astrophysics Data System (ADS)

    Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

    2009-03-01

    Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

  7. The Spectroscopic study of 33Ar

    NASA Astrophysics Data System (ADS)

    Adimi, N.; Dominguez-Reyes, R.; Alcorta, M.; Bey, A.; Blank, B.; Borge, M. J. G.; de Oliveira Santos, F.; Dossat, C.; Fynbo, H. O. U.; Giovinazzo, J.; Knudsen, H. H.; Madurga, M.; Matea, I.; Perea, A.; Sümmerer, K.; Tengblad, O.; Thomas, J. C.

    2011-10-01

    The proton-rich nucleus 33Ar has been produced at the low-energy facility SPIRAL at GANIL. Spectroscopic studies of gamma and p emission of this nucleus were performed with the "Silicon Cube" detection system. The analysis of proton and gamma singles and coincidence spectra allowed us to establish a complete decay scheme of this nucleus. The comparison of the Gamow-Teller strength distribution deduced from our experiment and the theoretical one obtained with the Shell Model permitted the determination of a quenching factor for the Gamow-Teller strength.

  8. The Spectroscopic study of {sup 33}Ar

    SciTech Connect

    Adimi, N.; Dominguez-Reyes, R.; Alcorta, M.; Borge, M. J. G.; Perea, A.; Tengblad, O.; Bey, A.; Blank, B.; Dossat, C.; Giovinazzo, J.; Matea, I.; Fynbo, H. O. U.; Knudsen, H. H.; Suemmerer, K.

    2011-10-28

    The proton-rich nucleus {sup 33}Ar has been produced at the low-energy facility SPIRAL at GANIL. Spectroscopic studies of gamma and p emission of this nucleus were performed with the 'Silicon Cube' detection system. The analysis of proton and gamma singles and coincidence spectra allowed us to establish a complete decay scheme of this nucleus. The comparison of the Gamow-Teller strength distribution deduced from our experiment and the theoretical one obtained with the Shell Model permitted the determination of a quenching factor for the Gamow-Teller strength.

  9. Picosecond Raman Study of Vibrational Cooling and Protein Dynamics in the Primary Photochemistry of Rhodopsin

    NASA Astrophysics Data System (ADS)

    Kim, Judy; Mathies, Richard

    2003-03-01

    Picosecond Stokes and anti-Stokes Raman spectra are used to probe the structural dynamics and reactive energy flow of both the chromophore and binding pocket residues in the primary cis-to-trans isomerization reaction of rhodopsin. The appearance of characteristic ethylenic, hydrogen out-of-plane (HOOP) and low-wavenumber photoproduct bands in the Stokes Raman spectra of the chromophore is instrument-response limited, consistent with a sub-picosecond product appearance time (1,2). Intense high and low-frequency anti-Stokes chromophore peaks demonstrate that the all-trans photoproduct, photorhodopsin, is produced vibrationally hot on the ground-state surface (2). Specifically, the low-frequency modes at 282, 350 and 477 cm-1 are highly vibrationally excited (T > 2000 K) immediately following isomerization, revealing that these low-frequency motions directly participate in the reactive curve-crossing process. The anti-Stokes modes are characterized by a ˜2.5 ps temporal decay that coincides with the conversion of photorhodopsin to bathorhodopsin. This correspondence shows that the photo-to-batho transition is a ground-state cooling process, and that energy storage in the primary visual photoproduct is complete on the picosecond time scale. The remarkable similarity between the room-temperature picosecond vibrational structure of photo- and bathorhodopsin and that of the low-temperature trapped primary photoproduct suggests that chromophore isomerization impulsively excites and drives changes in nearby protein residues. These amino acid changes within the binding pocket are probed by picosecond UV Raman spectroscopy of aromatic residues (3). Difference spectra reveal that at least one tryptophan (trp265) and one tyrosine (tyr191, 268 and/or 178) residue undergoes structural changes in < 5 ps, presumably due to steric interaction with the isomerizing chromophore as well as energy flow from chromophore to the binding pocket. This result indicates that the protein

  10. Ablation Study of WC and PCD Composites Using 10 Picosecond and 1 Nanosecond Pulse Durations at Green and Infrared Wavelengths

    NASA Astrophysics Data System (ADS)

    Eberle, Gregory; Wegener, Konrad

    An ablation study is carried out to compare 10 picosecond and 1 nanosecond pulse durations as well as 532 nanometre and 1064 nanometre wavelengths at each corresponding pulse duration. All laser parameters are kept constant in order to understand the influence of pulse duration and wavelength independently. The materials processed according to the electronic band structure are a metal and an insulator/metal composite, i.e. tungsten carbide and polycrystalline diamond composite respectively. After laser processing said materials, the ablation rate and surface roughness are determined. Analysis into the ablation behaviour between the various laser parameters and the materials processed is given, with a particular emphasis on the graphitisation of diamond.

  11. Applications of infrared free electron lasers in picosecond and nonlinear spectroscopy

    NASA Astrophysics Data System (ADS)

    Fann, W. S.; Benson, S. V.; Madey, J. M. J.; Etemad, S.; Baker, G. L.; Rothberg, L.; Roberson, M.; Austin, R. H.

    1990-10-01

    In this paper we describe two different types of spectroscopic experiments that exploit the characteristics of the infrared FEL, Mark III, for studies of condensed matter: - the spectrum of χ(3)(-3ω; ω, ω, ω) in polyacetylene: an application of the free electron laser in nonlinear optical spectroscopy, and - a dynamical test of Davydov-like solitons in acetanilide using a picosecond free electron laser. These two studies highlight the unique contributions FELs can make to condensed-matter spectroscopy.

  12. A Prospective Split-Face Study of the Picosecond Alexandrite Laser With Specialized Lens Array for Facial Photoaging in Chinese.

    PubMed

    Ge, Yiping; Guo, Lifang; Wu, Qiuju; Zhang, Mengli; Zeng, Rong; Lin, Tong

    2016-11-01

    A 755nm picosecond alexandrite laser with a diffractive lens array has been reported for the treatment of acne scar and photoaging with clinical ef cacy. In this study, we evaluated the application of the 755nm picosecond alexandrite laser with a diffractive lens array for facial photoaging in Chinese. Ten subjects with moderate facial photoaging were enrolled in a prospective, evaluator-blinded, open-label, and split-face trial to assess the ef cacy and safety of the 755nm picosecond alexandrite laser with a diffractive lens array for facial photoaging. Each subject received a series of four treatment sessions on the right side of the face at two-week intervals. The left side of the face served as the control side. Blinded evaluation of baseline, pre-treatment, and two-month follow-up visit was performed by two independent dermatologists on a 5-point global photoaging scale (GPS) and a 6/8-point Asian photographic scale (APS). Adverse events and discomfort associated with the treatment were also assessed. Signi cant improvement in photoaged tissue was observed on the treated side of the face, with a mean GPS score decrease from 2.67 to 1.44 at the two-month follow-up visit. A greater improvement in wrinkles was observed (2.78 vs 1.89; P less than 0.05) when com- pared to the improvement in pigmentation (2.67 vs 2.11; P less than 0.05). No changes were observed on the control side. Treatment results improved gradually throughout the treatment program and continued to the two-month follow up. In addition, skin tightening was perceived in all subjects, and shallower nasolabial folds were observed in 60% of the subjects on the treated side of face. Moderate pain and transient erythema were observed as the two main discomforts associated with the treatment. The 755nm picosecond alexandrite laser with a diffractive lens array is efficacious and safe for rejuvenation of photodamaged facial tissue in Chinese. J Drugs Dermatol. 2016;15(11):1390-1396..

  13. Qualitative spectroscopic study of magnetic nozzle flow

    NASA Technical Reports Server (NTRS)

    Umeki, T.; Turchi, P. J.

    1992-01-01

    The physics of the magnetic nozzle flow for a 100-kW-level quasi-steady MPD thruster was studied by photographic spectroscopy focusing on the plasma model in the flow and the acceleration mechanism. Spectroscopic visualization for the flow-species analysis indicates that the plasma-exhaust flow dominated by NII species were confined by the magnetic nozzle effect to collimate the flow for the better thruster performance. Inside the nozzle, the plasma flow was found to be in nonhomogeneous collisional-radiative condition. There appears to be a substantial flow acceleration from the magnetic nozzle inlet to the outlet with slight expansion. This suggests that the flow resembles that of constant area supersonic duct flow with cooling.

  14. Picosecond and nanosecond studies of the photoreduction of benzophenone by N,N-diethylaniline and triethylamine

    SciTech Connect

    Devadoss, C.; Fessenden, R.W. )

    1991-09-19

    The photoreduction of benzophenone by N,N-diethylaniline and triethylamine has been examined in a number of solvents by both nano- and picosecond laser photolysis. With diethylaniline, electron transfer is the primary step and the spectrum of the ion pair has been detected even in nonpolar solvents such as benzene and cyclohexane. Rapid proton transfer then takes place to form a high yield of the ketyl radical. The lifetime of the ion pair in benzene is about 900 ps. In acetonitrile, the ion pair dissociated into individual ions which then decay by back electron transfer and proton transfer. A spectral shift to the red occurs over 100 ps as the contact ion pair dissociated. In acidic alcohols such as methanol and trifluoroethanol, proton transfer from the alcohol occurs to produce the ketyl radical. In the case of triethylamine, no distinct absorption band for benzophenone anion was seen in picosecond experiments but difference spectra, which removed much of the spectrum of benzophenone triplet, clearly showed some contribution from the anion. For this compound, it is likely that electron transfer occurs first followed by very fast proton transfer.

  15. Picosecond Chemical and Biological Events.

    ERIC Educational Resources Information Center

    Rentzepis, P. M.

    1978-01-01

    Describes a currently used picosecond spectroscopy system capable of reliably recording picosecond events. Two areas of picosecond research are discussed: one concerns the interaction of electrons in fluids; the second, the primary events in vision. (Author/HM)

  16. Femtosecond electron diffraction and spectroscopic studies of a solid state organic chemical reaction

    NASA Astrophysics Data System (ADS)

    Jean-Ruel, Hubert

    Photochromic diarylethene molecules are excellent model systems for studying electrocyclic reactions, in addition to having important technological applications in optoelectronics. The photoinduced ring-closing reaction in a crystalline photochromic diarylethene derivative was fully resolved using the complementary techniques of transient absorption spectroscopy and femtosecond electron crystallography. These studies are detailed in this thesis, together with the associated technical developments which enabled them. Importantly, the time-resolved crystallographic investigation reported here represents a highly significant proof-of-principle experiment. It constitutes the first study directly probing the molecular structural changes associated with an organic chemical reaction with sub-picosecond temporal and atomic spatial resolution---to follow the primary motions directing chemistry. In terms of technological development, the most important advance reported is the implementation of a radio frequency rebunching system capable of producing femtosecond electron pulses of exceptional brightness. The temporal resolution of this newly developed electron source was fully characterized using laser ponderomotive scattering, confirming a 435 +/- 75 fs instrument response time with 0.20 pC bunches. The ultrafast spectroscopic and crystallographic measurements were both achieved by exploiting the photoreversibility of diarylethene. The transient absorption study was first performed, after developing a novel robust acquisition scheme for thermally irreversible reactions in the solid state. It revealed the formation of an open-ring excited state intermediate, following photoexcitation of the open-ring isomer with an ultraviolet laser pulse, with a time constant of approximately 200 fs. The actual ring closing was found to occur from this intermediate with a time constant of 5.3 +/- 0.3 ps. The femtosecond diffraction measurements were then performed using multiple crystal

  17. Competition reactions of H2O•+ radical in concentrated Cl- aqueous solutions: picosecond pulse radiolysis study.

    PubMed

    El Omar, Abdel Karim; Schmidhammer, Uli; Rousseau, Bernard; LaVerne, Jay; Mostafavi, Mehran

    2012-11-29

    Picosecond pulse-probe radiolysis measurements of highly concentrated Cl(-) aqueous solutions are used to probe the oxidation mechanism of the Cl(-). The transient absorption spectra are measured from 340 to 710 nm in the picosecond range for the ultrafast electron pulse radiolysis of halide solutions at different concentrations up to 8 M. The amount of Cl(2)(•-) formation within the electron pulse increases notably with increasing Cl(-) concentration. Kinetic measurements reveal that the direct ionization of Cl(-) cannot solely explain the significant amount of fast Cl(2)(•-) formation within the electron pulse. The results suggest that Cl(-) reacts with the precursor of the OH(•) radical, i.e., H(2)O(•+) radical, to form Cl(•) atom within the electron pulse and the Cl(•) atom reacts subsequently with Cl(-) to form Cl(2)(•-) on very short time scales. The proton transfer reaction between H(2)O(•+) and the water molecule competes with the electron transfer reaction between Cl(-) and H(2)O(•+). Molecular dynamics simulations show that number of water molecules in close proximity decreases with increasing concentration of the salt (NaCl), confirming that for highly concentrated solutions the proton transfer reaction between H(2)O(•+) and a water molecule becomes less efficient. Diffusion-kinetic simulations of spur reactions including the direct ionization of Cl(-) and hole scavenging by Cl(-) show that up to 30% of the H(2)O(•+) produced by the irradiation could be scavenged for solutions containing 5.5 M Cl(-). This process decreases the yield of OH(•) radical in solution on the picosecond time scale. The experimental results for the same concentration of Cl(-) at a given absorbed dose show that the radiation energy absorbed by counterions is transferred to Cl(-) or water molecules and the effect of the countercation such as Li(+), K(+), Na(+), and Mg(2+) on the oxidation yield of Cl(-) is negligible.

  18. UV photolysis of nitromethane studied by sub-picosecond time-resolved CARS experiments

    SciTech Connect

    Rajchenbach, C.; Jonusauskas, G.; Rulliere, C.

    1996-04-01

    Using sub-picosecond CARS experiment we observed direct photolysis of liquid nitromethane after pulse excitation at 299 nm. We measured the dynamics behavior under excitation of three main ground state Raman lines: the {nu} (CN) mode at 917 cm{sup -1}, the {nu}s(NO2) and {delta}s(CH3) modes near 1400 cm{sup -1} and the {nu}s(CH3) mode at 2968 cm{sup -1}. From the evolution of these modes we deduced that the excited state disappears with a lifetime of 1.1{+-}0.3 ps and we measured a photolysis quantum yield at 299 nm of 24%{+-}5%. Important and fast non-radiative desexcitation channel from excited to ground states has been observed.

  19. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    SciTech Connect

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-07

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11–54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  20. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    NASA Astrophysics Data System (ADS)

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-01

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11-54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  1. Individual and collective vibrational modes of nanostructures studied by picosecond ultrasonics.

    PubMed

    Bienville, T; Robillard, J F; Belliard, L; Roch-Jeune, I; Devos, A; Perrin, B

    2006-12-22

    We report on picosecond ultrasonic measurements obtained on aluminum and platinum nanostructures with variable dot size and lateral periodicity which realized a 2D phononic crystal. Performing investigations at different resolution scales, we have identified individual modes of vibration depending on the dot size, and mode of vibration strongly correlated with the bi-dimensional organization. The platinum dots sputtered on an aluminum layer have shown a behavior of isolated oscillators without any coupling between neighbor elements in this phononic crystal. The frequency of such normal modes, extracted from time resolved measurements are in good agreement with 3D finite element simulations. In contrast, with aluminum dot systems where the coupling is more efficient we observe a complex spectrum of vibrational modes related to the band structure induced by the bi-dimensional patterning.

  2. Quadrupole resonance spectroscopic study of narcotic materials

    NASA Astrophysics Data System (ADS)

    Rayner, Timothy J.; West, Rebecca; Garroway, Allen N.; Lyndquist, R.; Yesinowski, James P.

    1997-02-01

    Bulk narcotic detection systems based upon Quadrupole Resonance Analysis (QRA) technology have a major advantage over imaging technologies, in that QRA is chemical-specific and consequently has a lower rate of false alarms. QRA is a magnetic resonance technology which occurs as a result of the inherent molecular properties of the atomic nuclei in crystalline and amorphous solids. The QRA response is characterized by 1) the precessional frequency of the nucleus, and 2) the nature of the electric field gradient experienced by the nucleus,due to its molecular environment. Another important detection parameter is linewidth, resonant quality. All of these parameters depend on sample purity and manufacturing process. Quantum Magnetics recently carried out a study on the QRA signatures of various narcotic materials with the support of the US Army, US Customs, and the Office of National Drug Control Policy. The aim of the study was to fully characterize the variation in QRA spectroscopic parameters of different samples of cocaine base and cocaine hydrochloride. The results from this study ar discussed here.

  3. Preparation of cesium targets for gamma-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Basu, S. K.; Chanda, S.; Deb, P.; Eqbal, Md; Kundu, S.; Joseph, D.

    2000-11-01

    A procedure to prepare monoisotopic cesium compound targets for gamma-spectroscopic experiments is described. Using this procedure, uniform targets up to thicknesses of 0.6-1.2 mg/cm 2 were prepared and used for in-beam spectroscopic studies. The purity of the target was tested by energy dispersive X-ray fluorescence (EDXRF) measurements.

  4. Fundamental spectroscopic studies of carbenes and hydrocarbon radicals

    SciTech Connect

    Gottlieb, C.A.; Thaddeus, P.

    1993-12-01

    Highly reactive carbenes and carbon-chain radicals are studied at millimeter wavelengths by observing their rotational spectra. The purpose is to provide definitive spectroscopic identification, accurate spectroscopic constants in the lowest vibrational states, and reliable structures of the key intermediates in reactions leading to aromatic hydrocarbons and soot particles in combustion.

  5. Spectroscopic studies of nanoscale metal clusters

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, P.

    2013-06-01

    The present article is intended to elucidate a range of novel spectroscopic studies of nanoscale metal clusters. Various bottom-up and top-down techniques have been utilized to synthesize the metal nanoclusters. Materials like metal nanoclusters of cobalt, silver or gold in various dielectric matrices facilitate to explore interesting phenomena through optical, photoluminescence and vibrational spectroscopy. Interaction of uv-visible light with free electrons of metal nanoclusters, for example, leads to fascinating colors of dielectric matrices through an optical effect known as surface-plasmon resonance. This effect of quantum-confinement of the electrons leads to large enhancements of local electric field in metal nanoclusters. Enhancements of Raman scattering from metal nanoclusters are attributed to the increase of local fields. Optical absorption and Raman scattering spectroscopy particularly have been highlighted here as powerful non-destructive experimental methods to study evolution of metal nanoclusters in different dielectric matrices. In relatively large metal nanoclusters, besides dipolar, quadrupolar surface-plasmon resonances have been observed.

  6. Picosecond optoelectronic devices

    SciTech Connect

    Lee, C.L.

    1984-01-01

    Ever since the invention of picosecond lasers, scientists and electronic engineers have been dreaming of inventing electronic devices that can record in real time the physical and electronic events that take place on picosecond time scales. With the exception of the expensive streak camera, this dream has been largely unfullfilled. Today, a real-time oscilloscope with picosecond time resolution is still not available. To fill the need for even better time resolution, researchers have turned to optical pulses and thus a hybrid technology has emerged-picosecond optoelectronics. This technology, based on bulk photoconductors, has had a slow start. However, because of the simplicity, scaleability, and jitterfree nature of the devices, the technology has recently experienced a rapid growth. This volume reviews the major developments in the field of picosecond optoelectronics over the past decade.

  7. Spectroscopic studies of detonating heterogeneous explosives. [HNS

    SciTech Connect

    Renlund, A.M.; Trott, W.M.

    1985-01-01

    The experimental objectives of this work are to use real-time spectroscopic techniques, emission spectroscopy and Raman spectra to monitor chemical and physical changes in shock-loaded or detonating high explosive (HE) samples. The investigators hope to identify chemical species including any transient intermediates. Also, they wish to determine the physical state of the material when the reactions are taking place; measure the temperature and the pressure; and study the effect of different initiation parameters and bulk properties of the explosive material. This work is just part of the effort undertaken to gain information on the detailed chemistry involved in initiation and detonation. In summary, the investigators have obtained vibrational temperatures of some small radical products of detonation, which may correlate with the detonation temperature. They have also observed that NO/sub 2/ is an early product from detonating HNS and RDX, and that other electronically excited radical species such as CN(B) are formed in HNS detonations. In the Raman work, the single-pulse spectra could be obtained even in the severe environment of a detonation, and that the rate of removal of the parent molecule could be monitored. 2 refs., 6 figs.

  8. Spectroscopic studies of microwave plasmas containing hexamethyldisiloxane

    NASA Astrophysics Data System (ADS)

    Nave, A. S. C.; Mitschker, F.; Awakowicz, P.; Röpcke, J.

    2016-10-01

    Low-pressure microwave discharges containing hexamethyldisiloxane (HMDSO) with admixtures of oxygen and nitrogen, used for the deposition of silicon containing films, have been studied spectroscopically. Optical emission spectroscopy (OES) in the visible spectral range has been combined with infrared laser absorption spectroscopy (IRLAS). The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and gas mixture at relatively low pressures, up to 50 Pa, and power values, up to 2 kW. The evolution of the concentration of the methyl radical, CH3, and of seven stable molecules, HMDSO, CH4, C2H2, C2H4, C2H6, CO and CO2, was monitored in the plasma processes by in situ IRLAS using tunable lead salt diode lasers (TDL) and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. To achieve reliable values for the gas temperature inside and outside the plasma bulk as well as for the temperature in the plasma hot and colder zones, which are of great importance for calculation of species concentrations, three different methods based on emission and absorption spectroscopy data of N2, CH3 and CO have been used. In this approach line profile analysis has been combined with spectral simulation methods. The concentrations of the various species, which were found to be in the range between 1011 to 1015 cm-3, are in the focus of interest. The influence of the discharge parameters power, pressure and gas mixture on the molecular concentrations has been studied. To achieve further insight into general plasma chemical aspects the dissociation of the HMDSO precursor gas including its fragmentation and conversion to the reaction products was analyzed in detail.

  9. Rapid Flow Analysis Studies with Spectroscopic Detectors.

    NASA Astrophysics Data System (ADS)

    Thalib, Amlius

    A rapid flow analysis study based on segmented flow and flow injection principles is described in this thesis. The main objective of this study was to establish the response characteristics in continuous flow analysis systems in order to improve sampling rates with several types of spectroscopic detectors. It was found from flame photometric studies that non-segmented flowing streams are applicable to rapid flow analysis with automatic sample aspiration. Calcium was used as a typical example and determined at sampling rates up to 360 h('-1) with a detection limit of 0.05 mg L(' -1). A rapid flow system is reported using direct aspiration for AAS analysis with both manual injection and automatic aspiration techniques, and found to give sampling rates of up to 600-720 samples h('-1). Speed of analysis was reduced by about 50% when using an external peristaltic pump in the flow system design, due to increased sample dispersion. A novel aspect of a rapid flow injection approach reported with ICPAES detection includes the method of injecting samples via a peristaltic pump with simultaneous computer data processing. Determination of serum cations (Na, K, Ca, Mg and Fe) was demonstrated as an example of an application of the technique at sampling rates of 240 h('-1). Precision and detection limits for 13 elements in a single standard solution are reported. The use of automated aspiration sampling is also reported in this method for comparison. Further studies on flow characteristics were carried out by a combination of the rapid flow system with very short sampling times as low as 2 seconds using UV-visible spectrophotometric detection. Analysis of human blood serum samples was used as an example where total protein and inorganic phosphate were determined at sampling rates of 240 h('-1) and 360 h('-1) respectively. The novel aspects of the results from these studies include the very rapid sample throughput developed with simple and inexpensive experimental approaches in

  10. Picosecond laser cross, linking histones to DNA in chromatin: implication in studying histone-DNA interactions

    NASA Astrophysics Data System (ADS)

    Angelov, Dimitar A.; Dimitrov, S.; Keskinova, E.; Pashev, I.; Russanova, V.; Stefanovsky, Yu.

    1991-05-01

    A picosecond UV laser radiation was used to cross-link proteins to DNA in nuclei, whole cells and different chromating preparations. All histones as well as high-mobility group 1 proten were identified immunochemically in the covalently linked protein-DNA complexes. Irradiation of the nuclieohistone resulted in cross-linking 20% of bound histones to DNA as a result of two-quantum photoreaction with a maximum quantum yield 3.10 -4 for double stranded DNA. When nuclei, total bromatin Hi-depleted chromatin and core particles were irradiated and then trypsinized or treated with clostripain to cleave respectively the N-, C- and N- terminal histone tails, no histones have been found covalently linked to DNA. However whilst the yield of cross-links was similar in total and H1-depleted chromatin in core particples the efficiencey was 3-4 times lower for H2A, H2B and H4 10-12 times lower for H3. This finding we consider as a direct evidence for interaction of non structured N- tails of core histones with linker DNA. Cross-linking in core particles depends on the ionic strength. All histones were identified in the complex formed up to 0.4 N NaCl, no cross-linking was observed when irradiation was carried out at salt concentration higher than 0.4 M. The cross-linking ability was preserved both upon physiological acetylation of histones knows to be restriced to the N-terminal tails and with chemically acetylated chromatin. This finding is direct evidence that postsynthetic histone acetylation does not release the N-terminal tails from interaction with DNA.

  11. Reduction of earth alkaline metal salts in THF solution studied by picosecond pulse radiolysis.

    PubMed

    Ma, Jun; Archirel, Pierre; Schmidhammer, Uli; Teuler, Jean-Marie; Pernot, Pascal; Mostafavi, Mehran

    2013-12-27

    Picosecond pulse radiolysis of tetrahydrofuran (THF) solutions containing earth alkaline metal salt, M(II)(ClO4)2, at different concentrations are performed using two different supercontinua as probe pulse, one covering the visible and another the near-infrared (NIR) down to the visible. Two types of line scan detectors are used to record the absorption spectra in the range from 400 to 1500 nm. Because of the strong overlap between the spectra of the absorbing species in the present wavelength range, global matrices were built for each M(II) system, by delay-wise binding the matrix for pure THF with the available matrices for this cation. The number of absorbers was assessed by Singular Value Decomposition of the global matrix, and a MCR-ALS analysis with the corresponding number of species was performed. The analysis of the results show clearly that solvated electron reacts with the earth alkaline metal molecule and the product has an optical absorption band very different than that of solvated electron in pure THF. So, contrarily to the case of solution containing free Na(+), in the presence of Mg(II), Ca(II) and Sr(II) the observed absorption band is not only blueshifted, but its shape is also drastically changed. In fact with Na(+) solvated electron forms a tight-contact pair but with earth alkaline metal cation solvated electron is scavenged by the undissociated molecule M(II)(ClO4)2. In order to determine the structure of the absorbing species observed after the electron pulse, Monte Carlo/DFT simulations were performed in the case of Mg(II), based on a classical Monte Carlo code and DFT/PCM calculation of the solute. The UV-visible spectrum of the solute is calculated with the help of the TDDFT method. The calculated spectrum is close to the experimental one. It is due to two species, a contact pair and an anion.

  12. Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Zheng, Xu-Guang; Meng, Dong-Dong; Xu, Xing-Liang; Guo, Qi-Xin

    2013-06-01

    Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at Tc1 = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm-1, we observed probable signatures of successive magnetic transitions near Tc1 = 18 K and Tc2 = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at Tc1 = 18 K although a long-range order is formed.

  13. Picosecond dynamics of reactions in the liquid phase: studies of iodine photodissociation and development of new laser techniques

    SciTech Connect

    Berg, M.A.

    1985-09-01

    Iodine photodissociation and recombination was studied as a model for processes common to chemical reaction in the liquid phase. Picosecond transient absorption measurements from 1000 to 295 nm were used to monitor the dynamics in a variety of solvents. Most of the atoms which undergo geminate recombination were found to do so in less than or equal to 15 ps, in agreement with the results of existing molecular dynamics simulations. Vibrational relaxation times vary from approx.15 ps near the middle of the ground state well to approx.150 ps for complete relaxation to v = 0. The prediction of strong resonant vibrational energy transfer to chlorinated methane solvents was not supported, but some evidence for this mechanism was found for alkane solvents. Current theory is unable to explain the large variation (65 to 2700 ps) of the excited A'-state lifetime in various solvents. The 10-Hz amplified, synchronously-pumped dye laser which was used in these studies is described and characterized. SERS (Stimulated Electronic Raman Scattering) and difference frequency mixing were used in the generation of the infrared and far-infrared, respectively. 54 refs., 38 figs., 3 tabs. (WRF)

  14. Vibrational spectroscopic and DFT study of trimethoprim

    NASA Astrophysics Data System (ADS)

    Ungurean, Alia; Leopold, Nicolae; David, Leontin; Chiş, Vasile

    2013-02-01

    Structural investigations by different vibrational spectroscopic methods: FTIR, FT-Raman and surface-enhanced Raman scattering (SERS) spectroscopy, as well as density functional theory (DFT) calculations were performed on trimethoprim (5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine). A reliable assignment of vibrational IR, Raman and SERS bands was possible by a proper choice of model used in quantum chemical calculations. Based on SERS spectrum analysis it is shown that the molecule is adsorbed on the silver surface through the pyrimidine ring, in a perpendicular orientation. Two theoretical models were used in order to simulate the silver surface and the interaction with trimethoprim molecule, the accuracy of the models being evaluated by comparing the predicted bands position of the two complexes with the SERS result.

  15. Picosecond infared study of ultrafast electron transfer and vibrational energy relaxation in a mixed-valent ruthenium dimer

    SciTech Connect

    Doorn, S.K.; Stoutland, P.O.; Dyer, R.B.; Woodruff, W.H.

    1992-04-08

    Mixed-valent transition-metal dimers have become key systems for understanding many fundamental aspects of electron-transfer dynamics. The mixed-valent dimer [(NC){sub 5}Ru{sup II}CNRu{sup III}-(NH{sub 3}){sub 5}]{sup 1-} is an interesting member of this class. In this complex, the ruthenium centers are strongly coupled through a short cyanide bridge, but because the [(NC){sub 5}Ru{sub III}CNRu{sub II}(NH{sub 3}){sub 5}]{sub -1} state of this systems lies approximately 8000cm{sup -1} higher in energy, the odd electron is localized on the ruthenium cyanide center. Optical excitation onto the metal-metal charge transfer (MMCT) band leads to reduction of the ruthenium ammine site. This state is highly unstable with respect to back electron transfer. The MMCT excitation is followed by back electron transfer, which may occur on very short time scales, allowing one to observe effects due to ultrafast reorganization processes, to discern excited state/ground state coupling phenomena, and to test modern electron-transfer theories. In this communication, the authors report a picosecond infrared study of the dynamics of [(NC){sub 5}Ru{sup II}CNRu{sup III} (NH{sub 3}){sub 5}]{sup 1-} following MMCT optical excitation. 18 refs., 1 fig., 1 tab.

  16. PLEIADES: a picosecond Compton scattering x-ray source for advanced backlighting and time-resolved material studies

    SciTech Connect

    Gibson, D J; Anderson, S G; Barty, C P; Betts, S M; Booth, R; Brown, W J; Crane, J K; Cross, R R; Fittinghoff, D N; Hartemann, F V; Kuba, J; Le Sage, G P; Tremaine, A M; Springer, P T; Rosenzweig, J B

    2003-10-20

    The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 {micro}m rms, at 57 MeV, with 260 C of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820-nm laser pulse had an energy of 180 mJ and a duration of 54 fs. Initial x-rays were captured with a cooled charge-coupled device using a Cesium Iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3 x 10{sup 6} photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-angle dependence of the x-ray energy. Optimization of the x-ray dose is currently underway, with the goal of reaching 10{sup 8} photons per shot and a peak brightness approaching 10{sup 20} photons/mm{sup 2}/mrad{sup 2}/s/0.1%bandwidth.

  17. Temperature behavior of sound velocity of fluorine-doped vitreous silica thin films studied by picosecond ultrasonics

    NASA Astrophysics Data System (ADS)

    Nagakubo, A.; Ogi, H.; Ishida, H.; Hirao, M.; Yokoyama, T.; Nishihara, T.

    2015-07-01

    Vitreous silica (v-SiO2) shows anomalous temperature dependence of velocity, including positive temperature coefficient of velocity (TCV) and velocity minimum around 70 K. The former characteristic allows its application in acoustic-resonator devices as a temperature compensating material. In this paper, we study the temperature dependence of velocity of fluorine-doped v-SiO2 (v-SiO2-xFx) thin films using picosecond ultrasonic spectroscopy. To correct the temperature increase caused by irradiation with light pulses, we calculated the steady temperature increase in the measuring volume with a finite volume method, considering the temperature dependence of thermal conductivity, and find that temperature in the measurement region remains high even when the back surface is cryogenically cooled. Using the corrected temperature, we determine TCV of v-SiO2-xFx thin films for 0 < x < 0.264 , which increases as x increases and is smaller than reported bulk values by a factor of 0.5 - 0.7 . The velocity minimum is absent for the film with x = 0, but it is clearly observed at 70 K for the film with the highest fluorine concentration of x = 0.264. These temperature behaviors are attributed to the change in the Si-O-Si bond angle caused by the fluorine doping.

  18. Electron thermalization and trapping rates in pure and doped alkali and alkaline-earth iodide crystals studied by picosecond optical absorption

    NASA Astrophysics Data System (ADS)

    Ucer, K. B.; Bizarri, G.; Burger, A.; Gektin, A.; Trefilova, L.; Williams, R. T.

    2014-04-01

    Although light continues to be emitted from insulating crystals used as scintillators over a period of nanoseconds to microseconds after stopping of an energetic particle, much of what determines the nonlinearity of response goes on in the first picoseconds. On this time scale, free carriers and excitons are at high density near the track core and thus are subject to nonlinear quenching. The hot (free) electrons eventually cool to low enough energy that trapping on holes, dopants, or defects can commence. In the track environment, spatial distributions of trapped carriers determined on the picosecond time scale can influence the proportionality between light yield and the initial particle energy throughout the whole light pulse. Picosecond spectroscopy of optical absorption induced by a short pulse of above-gap excitation provides a useful window on what occurs during the crucial early evolution of excited populations. The laser excitation can be tuned to excite carriers that are initially very hot (˜3 eV) relative to the band edges, or that are almost thermalized (˜0.1 eV excess energy) at the outset. Undoped and doped samples of NaI:Tl(0%, 0.1%), CsI:Tl(0%, 0.01%, 0.04%, 0.3%), and SrI2:Eu(0%, 0.2%, 0.5%, 3%) are studied in this work.

  19. [Surfaces and thin films studied by picosecond ultrasonics]. Annual progress report, [December 1, 1993--November 30, 1994

    SciTech Connect

    Maris, H.J.

    1994-10-01

    We are using picosecond optics techniques to perform ultrasonic and thermal transport measurements on thin films and nanostructures. We are investigating the basic physics of sound and phonon propagation in solids, and also attempting to develop practical techniques for the ultrasonic evaluation of thin-film nanostructures.

  20. Spectroscopic Studies of Double Beta Decays and MOON

    NASA Astrophysics Data System (ADS)

    Ejiri, H.

    2007-10-01

    This is a brief review of future spectroscopic experiments of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. Spectroscopic 0νββ experiments of MOON, SuperNEMO and DCBA are planned to study Majorana masses in the quasi-degenerate (QD) and inverted mass hierarchy (IH) regions. MOON aims at 0νββ studies with the ν-mass sensitivities of 100-30 meV by means of a super ensemble of multi-layer modules, each being consist of a scintillator plate, two tracking detector planes and a thin ββ source film.

  1. Tunable picosecond spectroscopy for detection of nitric oxide

    NASA Astrophysics Data System (ADS)

    Tanjaroon, Chakree; Lue, Christopher J.; Reeve, Scott W.; Johnson, J. Bruce; Allen, Susan D.

    2013-05-01

    Nitric oxide (NO) is a major chemical byproduct of many photochemically active nitrogen-containing compounds. As a prototypical free radical with a very well characterized high-resolution spectrum, NO provides a standard spectroscopic fingerprint for indirect quantitative analysis and detection of a number of low vapor pressure nitroaromatic compounds in air through either direct photochemical decomposition of a parent molecule or from its relatively high vapor pressure chemical constituents. In this paper, we will discuss applications of picosecond laser spectroscopy for measurements and detection of NO and the nascent NO generated from photolysis of nitrobenzene. We will give a general overview of our tunable picosecond laser and detection system that we routinely use for probing and exciting the NO gamma band. This broad wavelength tuning capability of our laser allows us to set up pump-probe type experiments for detecting blue shifted rovibronic bands and probing the relative population distribution for NO. In all cases, experiments were performed using UV laser pulses of duration less than 20 ps. Also, we studied the effect of N2 collisions on the photoframentation spectrum of nitrobenzene in 1000 mbar of N2 buffer gas.

  2. Picosecond beam monitor

    DOEpatents

    Schutt, D.W.; Beck, G.O.

    1974-01-01

    The current in the beam of a particle accelerator is monitored with picosecond resolution by causing the beam to impinge upon the center conductor of a coaxial line, generating a pulse of electromagnetic energy in response thereto. This pulse is detected by means such as a sampling oscilloscope. (Official Gazette)

  3. A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

    NASA Astrophysics Data System (ADS)

    Mangote, B.; Gallais, L.; Zerrad, M.; Lemarchand, F.; Gao, L. H.; Commandré, M.; Lequime, M.

    2012-01-01

    A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al2O3, Nb2O5, HfO2, SiO2, Ta2O5, and ZrO2. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

  4. High temperature furnace system for vacuum ultraviolet spectroscopic studies.

    PubMed

    Brown, C M; Naber, R H; Tilford, S G; Ginter, M L

    1973-08-01

    An improved furnace system for use in vacuum ultraviolet spectroscopic studies of atomic and molecular species stable at high temperatures (800-2500 degrees C) is described in detail. A new and improved high resolution spectrum of Mg I and several impurity spectra produced in the furnace are presented.

  5. On-line separator for {gamma}-spectroscopic studies

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2008-05-12

    We report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA.

  6. On-line separator for γ-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2008-05-01

    We report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA [1, 2].

  7. The study of 3.2 mJ picosecond regenerative amplifier at 2 kHz

    NASA Astrophysics Data System (ADS)

    Bai, Zhen-ao; Fan, Zhong-wei; Lian, Fu-qiang; Bai, Zhen-xu; Kan, Zhi-jun; Zhang, Jing; Wang, Jia-zan

    2014-12-01

    We report on a high energy laser diode (LD) side-continuous-pumped Nd:YAG (yttrium aluminum garnet) picosecond regenerative amplifier. The mode-locking picosecond oscillator is used as seed source with 31.3 ps pulse width, 150 mW average power and 1064.4 nm center wavelengths at the repetition frequency of 86 MHz. For the amplifier system, average output power of 6.4 W and 10.8 W are achieved at repetition frequency of 2 kHz and 4.5 kHz, which corresponds to output pulse energy of 3.2 mJ and 2.4 mJ respectively. The regenerative amplifier designed has high compact and high stability.

  8. Halo Nucleus 11Be: A Spectroscopic Study via Neutron Transfer

    SciTech Connect

    Schmitt, Kyle; Jones, K. L.; Bey, A.; Ahn, S.H.; Bardayan, Daniel W; Blackmon, Jeffery C; Brown, S.; Chae, Kyung Yuk; Chipps, K.; Cizewski, J. A.; Kozub, R. L.; Liang, J Felix; Matei, Catalin; Matos, M.; Moazen, Brian H; Nesaraja, Caroline D; Nunes, F. M.; O'Malley, Patrick; Pain, Steven D; Peters, W. A.; Pittman, S. T.; Wilson, G.

    2012-01-01

    The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus 11Be, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the 10Be d;p reaction has been used in inverse kinematics at four beam energies to study the structure of 11Be. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an n j 2s1=2 state coupled to the ground state of 10Be is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p1=2 state.

  9. Picosecond studies of temperature and solvent effects on the fluorescence from coumarin 102 and acridine

    SciTech Connect

    Shapiro, S.L.; Winn, K.R.

    1980-01-01

    Hydrogen bonding characteristics of acridine and coumarin 102 are studied in different solutions. Coumarin 102 upon excitation forms a complex in alcoholic solutions, whereas excited acridine relaxes in aprotic and protic solvents by a process involving an activation energy.

  10. Theoretical study of solitonlike propagation of picosecond light pulses interacting with Wannier excitons

    NASA Astrophysics Data System (ADS)

    Talanina, I.; Burak, D.; Binder, R.; Giessen, H.; Peyghambarian, N.

    1998-07-01

    An analytical and numerical study of light pulse propagation in semiconductors, with pulses spectrally centered at the lowest exciton resonance, is presented. It is shown that, in the limit of negligible phase-space blocking effects, the equation for the excitonic polarization is equivalent to a modified version of the nonlinear Schrödinger equation, for which soliton solutions have been derived by Mihalache et al. [D. Mihalache et al., Phys. Rev. A 47, 3190 (1993)]. The numerical study demonstrates the solitonlike propagation of experimentally relevant input pulses in CdSe crystal and assesses the influence of phase-space blocking effects and dephasing processes.

  11. Picosecond absorption studies on the photodissociation of alpha- and beta-nitrosyl hemoglobin monomers

    SciTech Connect

    Guest, C.R.; Noe, L.J.

    1988-10-01

    Transient absorption studies of the pump-probe type were performed on the NO forms of the alpha- and beta-monomers of hemoglobin using a Nd3+ phosphate-glass laser. A second harmonic 531-nm, 8-ps fwhm pulse pumped the Q-band while a delayed continuum generated pulse was used to monitor pi pi* Soret absorption changes in the 410-453-nm region. Photodissociation of nitrosyl alpha- and beta-monomers was found to differ markedly from the tetramer in what we believe to be the formation of a five-coordinate HbNO (with proximal imidazole detached) photoproduct within the first 50 ps after photon absorption.

  12. Inhibition of urinary calculi -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Govani, Jayesh; Durrer, William; Reza, Layra; Pinales, Luis

    2008-10-01

    Although a considerable number of investigations have already been undertaken and many causes such as life habits, metabolic disorders, and genetic factors have been noted as sources that accelerate calculi depositions and aggregations, there are still plenty of unanswered questions regarding efficient inhibition and treatment mechanisms. Thus, in an attempt to acquire more insights, we propose here a detailed scientific study of kidney stone formation and growth inhibition based on a traditional medicine approach with Rotula Aquatica Lour (RAL) herbal extracts. A simplified single diffusion gel growth technique was used for synthesizing the samples for the present study. The unexpected Zn presence in the sample with RAL inhibitor, as revealed by XPS measurements, explains the inhibition process and the dramatic reflectance of the incident light observed in the infrared transmission studies. Raman data demonstrate potential binding of the inhibitor with the oxygen of the kidney stone. Photoluminescence results corroborate to provide additional evidence of Zn-related inhibition.

  13. ab initio study of hot carriers in the first picosecond after sunlight absorption in silicon.

    PubMed

    Bernardi, Marco; Vigil-Fowler, Derek; Lischner, Johannes; Neaton, Jeffrey B; Louie, Steven G

    2014-06-27

    Hot carrier thermalization is a major source of efficiency loss in solar cells. Because of the subpicosecond time scale and complex physics involved, a microscopic characterization of hot carriers is challenging even for the simplest materials. We develop and apply an ab initio approach based on density functional theory and many-body perturbation theory to investigate hot carriers in semiconductors. Our calculations include electron-electron and electron-phonon interactions, and require no experimental input other than the structure of the material. We apply our approach to study the relaxation time and mean free path of hot carriers in Si, and map the band and k dependence of these quantities. We demonstrate that a hot carrier distribution characteristic of Si under solar illumination thermalizes within 350 fs, in excellent agreement with pump-probe experiments. Our work sheds light on the subpicosecond time scale after sunlight absorption in Si, and constitutes a first step towards ab initio quantification of hot carrier dynamics in materials.

  14. Ab Initio Study of Hot Carriers in the First Picosecond after Sunlight Absorption in Silicon

    NASA Astrophysics Data System (ADS)

    Bernardi, Marco; Vigil-Fowler, Derek; Lischner, Johannes; Neaton, Jeffrey B.; Louie, Steven G.

    2014-06-01

    Hot carrier thermalization is a major source of efficiency loss in solar cells. Because of the subpicosecond time scale and complex physics involved, a microscopic characterization of hot carriers is challenging even for the simplest materials. We develop and apply an ab initio approach based on density functional theory and many-body perturbation theory to investigate hot carriers in semiconductors. Our calculations include electron-electron and electron-phonon interactions, and require no experimental input other than the structure of the material. We apply our approach to study the relaxation time and mean free path of hot carriers in Si, and map the band and k dependence of these quantities. We demonstrate that a hot carrier distribution characteristic of Si under solar illumination thermalizes within 350 fs, in excellent agreement with pump-probe experiments. Our work sheds light on the subpicosecond time scale after sunlight absorption in Si, and constitutes a first step towards ab initio quantification of hot carrier dynamics in materials.

  15. Study of surface relief gratings on azo organometallic films in picosecond regime.

    PubMed

    Luc, J; Bouchouit, K; Czaplicki, R; Fillaut, J-L; Sahraoui, B

    2008-09-29

    Materials for optical data storage and optical information processing must exhibit good holographic properties. Many materials for these applications have been already proposed. Here we describe a grating inscription process characterized by short inscription time and long-time stability. A series of ruthenium-acetylide organometallic complexes containing an azobenzene fragment were synthesized. Photo-induced gratings were produced by short pulse (16 ps, 532 nm) laser irradiation. The surface relief gratings formed at the same time were observed by atomic force microscope. In this work, we highlight the short inscription times brought into play as well as the good temporal stability of these gratings stored at room temperature. We study the influence of the polarization states and the light intensity of writing beams on the dynamics of the surface relief gratings formation and we compare these results with those of a known representative of azobenzene derivative (Disperse Red 1). Lastly, we show that it is possible to write two-dimensional surface relief gratings.

  16. Picosecond melting of peptide nanotubes using an infrared laser: a nonequilibrium simulation study.

    PubMed

    Hoang Viet, Man; Truong, Phan Minh; Derreumaux, Philippe; Li, Mai Suan; Roland, Christopher; Sagui, Celeste; Nguyen, Phuong H

    2015-11-07

    Self-assembled functional peptide biomaterials are emerging with a wide range of envisioned applications in the field of nanotechnology. Currently, methods and tools have been developed to control and manipulate as well as to explore new properties of self-assembled structures. However, considerably fewer studies are being devoted to developing efficient methods to degrade or recycle such extremely stable biomaterials. With this in mind, here we suggest a theoretical framework, inspired by the recent developed mid-infrared free-electron laser pulse technology, to dissociate peptide nanotubes. Adopting a diphenylalanine channel as a prototypical example, we find that the primary step in the dissociation process occurs due to the strong resonance between the carboxylate bond vibrations of the diphenylalanine peptides and the tuned laser frequencies. The effects of laser irradiation are determined by a balance between tube formation and dissociation. Our work shows a proof of concept and should provide a motivation for future experimental developments with the final aim to open a new and efficient way to cleave or to recycle bio-inspired materials.

  17. Fundamental spectroscopic studies of some atmospheric pollutants

    SciTech Connect

    Findley, G.L.; McGlynn, S.P.

    1980-01-01

    Molecular electronic transitions that lie in the vuv (vacuum ultraviolet) spectral region initiate many harmful photochemical modifications in the upper atmosphere. Consequently, investigations have focused on molecules that are primary atmospheric pollutants, but which are simple enough structurally to yield detailed photophysical information. Terminal electronic states for vuv transitions can be either valence or Rydberg and, at low enough energies, the distinction between the two becomes fuzzy. A major thrust of this program has been the classification and characterization of Rydberg transitions in an attempt to gain insight into Rydberg/valence state mixing Rydberg studies. It is concluded that in order to understand the nature of photochemical reactions of molecules in the upper atmosphere, it is necessary to understand the structure and function of high-energy molecular electronic states. It is also necessary to understand the ways in which these states interact and, thereby, facilitate energy transfer. The study of molecular Rydberg states provides information crucial to such an understanding.

  18. Spectroscopic analysis of bones for forensic studies

    NASA Astrophysics Data System (ADS)

    Tofanelli, Mirko; Pardini, Lorenzo; Borrini, Matteo; Bartoli, Fulvio; Bacci, Alessandra; D'Ulivo, Alessandro; Pitzalis, Emanuela; Mascherpa, Marco Carlo; Legnaioli, Stefano; Lorenzetti, Giulia; Pagnotta, Stefano; de Holanda Cavalcanti, Gildo; Lezzerini, Marco; Palleschi, Vincenzo

    2014-09-01

    The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), in order to compare those two techniques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied.

  19. Integrated Spectroscopic Studies of Hydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Lane, M. D.; Bishop, J. L.; OConnor, V.; Cloutis, E.; Hiroi, T.

    2005-01-01

    Sulfate minerals have been identified in Martian meteorites and on Mars using a suite of instruments aboard the MER rovers. These results have confirmed previous groundbased observations and orbital measurements that suggested their presence. The orbiting OMEGA instrument on Mars Express is also finding evidence for sulfate. In order to better interpret remote-sensing data, we present here the results of a coordinated visible/near infrared (VNIR) reflectance, Moussbauer (MB), and thermal emittance study of wellcharacterized hydrous sulfate minerals.

  20. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at the University of Tennessee, Knoxville (UTK) is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While the main emphasis is on experimental problems, the authors have maintained a strong collaboration with several theorists in order to best pursue the physics of their measurements. During the last year they have had several experiments at the ATLAS at Argonne National Laboratory, the GAMMASPHERE at the LBL 88 Cyclotron, and with the NORDBALL at the Niels Bohr Institute Tandem. Also, they continue to be very active in the WA93/98 collaboration studying ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in the PHENIX Collaboration at the RHIC accelerator under construction at Brookhaven National Laboratory. During the last year their experimental work has been in three broad areas: (1) the structure of nuclei at high angular momentum, (2) the structure of nuclei far from stability, and (3) ultra-relativistic heavy-ion physics. The results of studies in these particular areas are described in this document. These studies concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Another area of research is heavy-ion-induced transfer reactions, which utilize the transfer of nucleons to states with high angular momentum to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions.

  1. Spectroscopic Study of Microwave Induced Plasma

    SciTech Connect

    Jovicevic, S.

    2004-12-01

    The results of the spatial distribution studies of electron densities, excitation and rotational temperatures and atomic line intensities of various elements in an atmospheric pressure mini-MIP torch with tangential argon flow. The electron number density, ne, is determined from the width of the hydrogen H{beta} 486.13 nm line while excitation temperature, Texc, is evaluated from the Boltzmann plot of relative line intensities either of carrier gas-argon or neutral iron that is introduced in the form of aerosols in MIP, The rotational temperatures, Trot, are determined from the relative intensities of OH (R2 and Q1 branch) electronic band A2{sigma} - X2{pi} (0,0) and to N{sub 2}{sup +} first negative system B{sup 2} {sigma}{sub u}{sup +} - X{sup 2} {sigma}{sub g}{sup +} (P branch). For the selected input power of 100 W, the influence of hydrogen in the wet and desolvated aerosols and support gas and the corresponding changes of the electron density, excitation and rotational temperature distributions are studied. The influence of potassium, low ionization potential element, to the spatial distribution of ne, Texc and Trot is studied also. Spatial intensity distributions and maximum intensities for investigate atomic line are determinate for the same conditions.

  2. Spectroscopic Studies of Atmospheric Aerosol Chemistry

    NASA Astrophysics Data System (ADS)

    Wamsley, R.; Leather, K.; Horn, A. B.; Percival, C.

    2008-12-01

    Particles are ubiquitous in the troposphere and are involved in chemical and physical processes affecting the composition of the atmosphere, climate, cloud albedo and human health (Finlayson-Pitts and Pitts, 2000). Organic species, such as alcohols, carboxylic acids, ketones, aldehydes, aromatics, alkenes and alkanes, originate both from anthropogenic and natural sources and comprise a large component of atmospheric particles. Gas-phase species, such as ozone, can oxidize these organics, changing the particle's oxygen-to carbon ratio and potentially altering its hygroscopicity, viscosity, morphology and reactivity. One reaction in particular, that between ozone and oleic acid, has been the focus of several recent studies and extensively researched by Ziemann (2005). Oleic acid reacts readily with ozone and has a low vapor pressure making this reaction convenient to study in the laboratory and has become the benchmark for studying heterogeneous reactions representing the oxidative processing of atmospheric organic aerosols. A critical source of uncertainty in reactivity estimates is a lack of understanding of the mechanism through which some VOCs are oxidized. This knowledge gap is especially critical for aromatic compounds. Because the intermediate reaction steps and products of aromatics oxidation are unknown, chemical mechanisms incorporate parameters estimated from environmental chamber experiments to represent their overall contribution to ozone formation, e.g. Volkamer et al. ( 2006). Previous studies of uncertainties in incremental reactivity estimates for VOCs found that the representation of aromatics chemistry contributed significantly to the estimated 40 - 50% uncertainties in the incremental reactivities of common aromatic compounds Carter et al. (2002). This study shows development of an effective IR method that can monitor the reaction and hence obtain the kinetics of the ozonolysis of an aromatic compound in the aerosol phase. The development of such

  3. Picosecond pulse radiolysis study of dynamics of solvation of electron and fluorenone anion in primary alcohols.

    PubMed

    Palit, Dipak K; Torche, Fayçal; Marignier, Jean-Louis

    2014-01-09

    We have studied the dynamics of solvation of electron injected directly into primary alcohols as well as that of fluorenone anion using pulse radiolysis technique with the time resolution of about 15 ps. Unlike in the previous reports, we observe nonexponential dynamics of both electron and anion solvation. While the ultrafast component, τ1 (<15 ps) representing the inertial time scale of the dynamics is faster than the time resolution of the spectrometer, the slower component, τ2, has been assigned to the translational motion leading to structural changes of the hydrogen bonding network of the solvent in the inner solvation cell or alcohol cluster. τ2 agrees well with the electron solvation times reported by the earlier authors. τ3 is associated with the restructuring of the hydrogen bond network structure of the solvent in the region outside the solvation cell. Nonexponential solvation dynamics of the fluorenone anion has been described well by a two-component process. The most important observation in this work is that the lifetime of the shorter component, τ1, determined in four alcoholic solvents, is much longer than the electron solvation time in the corresponding solvents determined in this work or anion solvation time reported earlier. The lifetime of this component is nearly comparable with the average dipolar solvation time but shorter than the longitudinal relaxation time of the solvent. In the case of anion, τ1 has been assigned to the restructuring of the first solvation shell by breakage of solvent hydrogen bonds of the fluorenone molecule and formation of hydrogen bonds with the anion. In this case, too, the longer component, τ2, with the lifetime of a few nanoseconds, has been assigned to reorganization of hydrogen bonds in the solvent hydrogen bond network structure.

  4. Study of Gallstones by Spectroscopic Methods

    NASA Astrophysics Data System (ADS)

    Pichugina, A. A.; Tsyro, L. V.; Afanasyev, D. A.; Kiselev, S. A.; Unger, F. G.

    2017-03-01

    We have conducted studies of cholesterol gallstones by electron paramagnetic resonance (EPR), x-ray diffraction (XRD), and nuclear magnetic resonance (1H NMR). The results obtained indicate that the cholesterol gallstone spectra are identical. We have used EPR to establish the presence in the gallstones of species containing open shell spin orbitals, which act as centers for colloidal particles. The 1H NMR spectra and the XRD data indicate the presence in the gallstones of cholesterol and structures representing a desmosterol transition, which form shells around the spin centers.

  5. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Riedinger, L.L.; Sorensen, S.P.

    1996-01-16

    The experimental program in nuclear physics at the University of Tennessee, Knoxville, is led by Professors Carrol Bingham, Lee Riedinger, and Soren Sorenseni who respectively lead the studies of the exotic decay modes of nuclei far from stability, the program of high-spin research, and our effort in relativistic heavy-ion physics. Over the years, this broad program of research has been successful partially because of the shared University resources applied to this group effort. The proximity of the Oak Ridge National Laboratory has allowed us to build extremely strong programs of joint research, and in addition to play an important leadership role in the Joint Institute for Heavy Ion Research (JIHIR). Our experimental program is also very closely linked with those at other national laboratories: Argonne (collaborations involving the Fragment Mass Analyzer (FMA) and {gamma}-ray arrays), Brookhaven (the RHIC and Phenix projects), and Berkeley (GAMMASPHERE). We have worked closely with a variety of university groups in the last three years, especially those in the UNISOR and now UNIRIB collaborations. And, in all aspects of our program, we have maintained close collaborations with theorists, both to inspire the most exciting experiments to perform and to extract the pertinent physics from the results. The specific areas discussed in this report are: properties of high-spin states; study of low-energy levels of nuclei far from stability; and high energy heavy-ion physics.

  6. Nonlinear spectroscopic studies of interfacial molecular ordering

    SciTech Connect

    Superfine, R.

    1991-07-01

    The second order nonlinear optical processes of second harmonic generation and sum frequency generation are powerful new probes of surfaces. They possess unusual surface sensitivity due to the symmetry properties of the nonlinear susceptibility. In particular, infrared-visible sum frequency generation (SFG) can obtain the vibrational spectrum of sub-monolayer coverages of molecules. In this thesis, we explore the unique information that can be obtained from SFG. We take advantage of the sensitivity of SFG to the conformation of alkane chains to study the interaction between adsorbed liquid crystal molecules and surfactant treated surfaces. The sign of the SFG susceptibility depends on the sign of the molecular polarizability and the orientation, up or down, of the molecule. We experimentally determine the sign of the susceptibility and use it to determine the absolute orientation to obtain the sign of the molecular polarizability and show that this quantity contains important information about the dynamics of molecular charge distributions. Finally, we study the vibrational spectra and the molecular orientation at the pure liquid/vapor interface of methanol and water and present the most detailed evidence yet obtained for the structure of the pure water surface. 32 refs., 4 figs., 2 tabs.

  7. Nonlinear spectroscopic studies of interfacial molecular ordering

    NASA Astrophysics Data System (ADS)

    Superfine, R.

    1991-07-01

    The second order nonlinear optical processes of second harmonic generation and sum frequency generation are powerful new probes of surfaces. They possess unusual surface sensitivity due to the symmetry properties of the nonlinear susceptibility. In particular, infrared-visible sum frequency generation (SFG) can obtain the vibrational spectrum of sub-monolayer coverages of molecules. In this thesis, we explore the unique information that can be obtained from SFG. We take advantage of the sensitivity of SFG to the conformation of alkane chains to study the interaction between adsorbed liquid crystal molecules and surfactant treated surfaces. The sign of the SFG susceptibility depends on the sign of the molecular polarizability and the orientation, up or down, of the molecule. We experimentally determine the sign of the susceptibility and use it to determine the absolute orientation to obtain the sign of the molecular polarizability and show that this quantity contains important information about the dynamics of molecular charge distributions. Finally, we study the vibrational spectra and the molecular orientation at the pure liquid/vapor interface of methanol and water and present the most detailed evidence yet obtained for the structure of the pure water surface.

  8. Spectroscopic studies of silver boro tellurite glasses

    NASA Astrophysics Data System (ADS)

    Kumar, E. Ramesh; Kumari, K. Rajani; Rao, B. Appa; Bhikshamaiah, G.

    2014-04-01

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI-Ag2O-[(1-x)B2O3-xTeO2] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO2 on SBT glass system is that as increasing the concentration of TeO2 the band intensity at 707 cm-1 increase.

  9. Terahertz spectroscopic study of benzodiazepine sedative hypnotics

    NASA Astrophysics Data System (ADS)

    Deng, Fusheng; Shen, Jingling; Wang, Xianfeng

    2011-08-01

    Terahertz time domain spectroscopy (THz-TDS) is used to the pure active ingredient of three benzodiazepine sedative hypnotics with similar molecular structure. The absorption spectra of them are studied in the range of 0.2~2.6THz. Based on the experiment, the theoretical simulation results of diazepam, nitrazepam and clonazepam are got by the Gaussian03 package of DFT/B3LYP/6-31G* method in single-molecule models. The experimental results show that even if the molecular structure and medicine property of them are similar, the accurate identification of them can still be done with their characteristic absorption spectra. Theoretical simulation results are well consistent with the experimental results. It demonstrates that absorption peaks of them in THz range mainly come from intra-molecular forces and are less affected by the intermolecular interaction and crystal effects.ô

  10. Spectroscopic studies near the proton drip line

    SciTech Connect

    Toth, K.S. ); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. ); Robertson, J.D. )

    1990-01-01

    We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.

  11. Spectroscopic studies of silver boro tellurite glasses

    SciTech Connect

    Kumar, E. Ramesh Kumari, K. Rajani Rao, B. Appa Bhikshamaiah, G.

    2014-04-24

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO{sub 2} on SBT glass system is that as increasing the concentration of TeO{sub 2} the band intensity at 707 cm{sup −1} increase.

  12. Spectroscopic study of acetylene and hydrogen cyanide

    NASA Astrophysics Data System (ADS)

    Rozario, Hoimonti Immaculata

    High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213-333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole--quadrupole and pairwise atom--atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1vl 20←0v120 band system from the HCN emission spectrum. The infrared emission spectrum of H12C 14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.

  13. Interactions of Isophorone Derivatives with DNA: Spectroscopic Studies

    PubMed Central

    Deiana, Marco; Matczyszyn, Katarzyna; Massin, Julien; Olesiak-Banska, Joanna; Andraud, Chantal; Samoc, Marek

    2015-01-01

    Interactions of three new isophorone derivatives, Isoa Isob and Isoc with salmon testes DNA have been investigated using UV-Vis, fluorescence and circular dichroism spectroscopic methods. All the studied compounds interact with DNA through intercalative binding mode. The stoichiometry of the isophorone/DNA adducts was found to be 1:1. The fluorescence quenching data revealed a binding interaction with the base pairs of DNA. The CD data indicate that all the investigated isophorones induce DNA modifications. PMID:26069963

  14. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martínez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    2009-02-01

    At the Universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25 pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results of the kinematics of the DUNES sample.

  15. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martinez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    At the universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results on the kinematics of the DUNES sample.

  16. Spectroscopic study of biologically active glasses

    NASA Astrophysics Data System (ADS)

    Szumera, M.; Wacławska, I.; Mozgawa, W.; Sitarz, M.

    2005-06-01

    It is known that the chemical activity phenomenon is characteristic for some inorganic glasses and they are able to participate in biological processes of living organisms (plants, animals and human bodies). An example here is the selective removal of silicate-phosphate glass components under the influence of biological solutions, which has been applied in designing glasses acting as ecological fertilizers of controlled release rate of the nutrients for plants. The structure of model silicate-phosphate glasses containing the different amounts of the glass network formers, i.e. Ca 2+ and Mg 2+, as a binding components were studied. These elements besides other are indispensable of the normal growth of plants. In order to establish the function and position occupied by the particular components in the glass structure, the glasses were examined by FTIR spectroscopy (with spectra decomposition) and XRD methods. It has been found that the increasing amount of MgO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes systematically from a structure of the cristobalite type to a structure corresponding to forsterite type. Whilst the increasing content of CaO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes from a structure typical for cristobalite through one similar to the structure of calcium orthophosphate, to a structure corresponding to calcium silicates. The changing character of domains structure is the reason of different chemical activity of glasses.

  17. Fluorescence spectroscopic studies of DNA dynamics

    SciTech Connect

    Scalettar, B.A.

    1987-04-01

    Random solvent induced motions of DNA are manifest as nanosecond torsional oscillations of the helix backbone, nanosecond through millisecond bending deformations and overall rotational and translational diffusion of the polymer. Fluorescence spectroscopy is used to study this spectrum of DNA motions while ethidium monoazide was covalently bounded. The steady state fluorescence depolarization data indicate that the covalent monoazide/DNA complex exhibits internal motions characterized by an average angular amplitude of 26 degrees confirming reports of fast torsional oscillations in noncovalent ethidium bromide/DNA systems. Data obtained by use of a new polarized photobleaching recovery technique (FPR) reflect both the rotational dynamics of the polymer and the reversible photochemistry of the dye. To isolate the reorientational motion of the DNA, the FPR experiments were ran in two modes that differ only in the polarization of the bleaching light. A quotient function constructed from the data obtained in these two modes monitors only the rotational component of the FPR recovery. In specific applications those bending deformations of long DNA molecules that have characteristic relaxation times on the order of 100 microseconds have been resolved. A fluorescence correlation technique that relates fluctuations in particle number to center-of-mass motion was used to measure translational diffusion on coefficients of the plasmid PBR322 and a short oligomeric DNA. A theory that describes angular correlation in systems exhibiting cyclic, biologically directed reorientation and random Brownian rotation is developed.

  18. Photoelectron spectroscopic studies of 5-halouracil anions

    SciTech Connect

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H.; Sevilla, Michael D.; Rak, Janusz

    2011-01-07

    The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  19. Photoelectron spectroscopic studies of 5-halouracil anions

    NASA Astrophysics Data System (ADS)

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Sevilla, Michael D.; Rak, Janusz; Bowen, Kit H.

    2011-01-01

    The parent negative ions of 5-chlorouracil, UCl- and 5-fluorouracil, UF- have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl- and UF- and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr-, we did not observe it, the mass spectrum exhibiting only Br- fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  20. Integrated Spectroscopic Studies of Anhydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Lane, M. D.; Bishop, J. L.; Dyar, M. D.; Cloutis, E.; Forray, F. L.; Hiroi, T.

    2005-01-01

    Sulfates have been identified in Martian soils and bedrock and are emerging as an important indicator for aqueous activity on Mars. Sulfate minerals can form in a variety of low-temperature (evaporitic; chemical-weathering) and high-temperature (volcanic/fumarolic; hydrothermal) environments and their formational environments can range from alkaline to acidic. Although sulfates generally form in the presence of water, not all sulfates are hydrous or contain water in their structures. Many of these anhydrous sulfates (Dana group 28; Strunz class 67A) are minerals that form as accompanying phases to the main minerals in ore deposits or as replacement deposits in sedimentary rocks. However, some form from thermal decomposition of OH or H2O-bearing sulfates, such as from the reaction [1]: jarosite = yavapaiite + Fe2O3 + H2O. Where known, the stability fields of these minerals all suggest that they would be stable under martian surface conditions [2]. Thus, anhydrous sulfate minerals may contribute to martian surface mineralogy, so they must be well-represented in spectral libraries used for interpretation of the Martian surface. We present here the preliminary results of an integrated study of emittance, reflectance, and Mossbauer spectroscopy of a suite of wel-lcharacterized anhydrous sulfates.

  1. Spectroscopic studies of alkaline activated slag geopolymers

    NASA Astrophysics Data System (ADS)

    Mozgawa, W.; Deja, J.

    2009-04-01

    In the work, results of structural studies of different geopolymers, obtained using a granulated blast furnace slag, are presented. The slag was subjected to an alkaline activation process. As activators, NaOH, Na 2CO 3 and liquid glass were applied. IR and NMR spectroscopy were the main experimental methods used, the results obtained were compared with XRD phase analysis and SEM observations. In the IR spectra of raw slag as well as in the spectra of products of paste hydration, the bands due to the characteristic vibrations of bonds observed in both types of oxygen bridges: Si-O-Si and Si-O-Al, were assigned. These bridges constitute basic structural units, forming tetrahedral geopolymer chains. It was found that the slag composition, mainly SiO 2/Al 2O 3 ratio and modification in oxides concentration, influences the presence of the bands connected with the phases (mainly C-S-H) formed during the hydration in the IR spectra. Additionally, significant effect of amorphous phases share on the spectra shape was established. 29Si and 27Al MAS-NMR spectra of initial slag geopolymers and pastes provided information concerning coordination of both atoms in the structures. It was revealed that the kind of slag geopolymers and the conditions of paste hydration influence connectedness of silicooxygen tetrahedra and coordination number of aluminium atoms. Based on IR spectra, it was also possible to determine the influence of the activator type, activation time and hydration conditions on the products formed. Significant changes were observed for the bands assigned to vibrations of carbonate and hydroxide groups. The changes were also noticed in the case of bands due to vibrations of silicate and aluminosilicate bonds.

  2. Metamictization of zircon: Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Zhang, Ming; Salje, Ekhard K. H.; Farnan, Ian; Graeme-Barber, Ann; Daniel, Philippe; Ewing, Rodney C.; Clark, Andrew M.; Leroux, Hugues

    2000-02-01

    Raman spectroscopy of radiation-damaged natural zircon samples shows increased line broadening and shifts of phonon frequencies with increasing radiation dose. Stretching and bending frequencies of SiO4 tetrahedra soften dramatically with increasing radiation damage. The frequency shifts can be used to determine the degree of radiation damage. Broad spectral bands related to Si-O stretching vibrations between 900 and 1000 cm-1 were observed in metamict/amorphous zircon. The radiation-dose-independent spectral profiles and the coexistence of this broad background and relative sharp Raman modes in partially damaged samples indicate that these bands are correlated with amorphous domains in zircon. The spectral profiles of metamict zircon suggest that in comparison with silica, the SiO4 tetrahedra are less polymerized in metamict zircon. This study also shows that ZrO2 and SiO2 are not the principal products of metamictization in zircon. No indication of bulk chemical unmixing of zircon into ZrO2 and SiO2 was found in 26 samples with a large variation of radiation damage (maximum dose: 23.5 × 1018 icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> -events g-1 ). Only one sample showed clearly, in all measured sample areas, extra sharp lines at 146, 260, 312, 460 and 642 cm-1 characteristic of tetragonal ZrO2 . The geological (and possibly artificial heating) history of this sample is not known. It is concluded that radiation damage without subsequent high temperature annealing does not cause unmixing of zircon into constituent oxides.

  3. Spectroscopic studies of cold, gas-phase biomolecular ions

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas R.; Stearns, Jaime A.; Boyarkin, Oleg V.

    While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionisation for producing large biological molecules in the gas phase together with cooled ion traps and multiple-resonance laser schemes are allowing spectroscopic investigation of individual conformations of peptides with more than a dozen amino acids. Highly resolved infrared spectra of single conformations of such species provide important benchmarks for testing the accuracy of theoretical calculations. This review presents a number of techniques employed in our laboratory and in others for measuring the spectroscopy of cold, gas-phase protonated peptides. We show examples that demonstrate the power of these techniques and evaluate their extension to still larger biological molecules.

  4. BRIEF COMMUNICATIONS: Picosecond spectroscopy of pyrrol pigments

    NASA Astrophysics Data System (ADS)

    Lippitsch, M. E.; Leitner, A.; Riegler, M.; Aussenegg, F. R.

    1982-05-01

    Picosecond fluorescence and absorption spectroscopy methods were used to study pyrromethenone, pyrromethene, and biliverdin. These methods made it possible to determine some details of the kinetics of various relaxation mechanisms. The results obtained provided a better understanding of the biological action of pyrrol pigments.

  5. Picosecond Spin Caloritronics

    NASA Astrophysics Data System (ADS)

    Cahill, David G.

    The coupling of spin and heat, i.e., spin caloritronics, gives rise to new physical phenomena in nanoscale spin devices and new ways to manipulate local magnetization. Our work in this field takes advantage of recent advances in the measurement and understanding of heat transport at the nanoscale using ultrafast lasers. We use a picosecond duration pump laser pulses as a source of heat and picosecond duration probe laser pulses to detect changes in temperature, spin accumulation, and spin transfer torque using a combination of time-domain thermoreflectance and time-resolved magneto-optic Kerr effect Our pump-probe optical methods enable us to change the temperature of ferromagnetic layers on a picosecond time-scale and generate enormous heat fluxes on the order of 100 GW m-2 that persist for ~ 30 ps. Thermally-driven ultrafast demagnetization of a perpendicular ferromagnet leads to spin accumulation in a normal metal and spin transfer torque in an in-plane ferromagnet. The data are well described by models of spin generation and transport based on differences and gradients of thermodynamic parameters. The spin-dependent Seebeck effect of a perpendicular ferromagnetic layer converts a heat current into spin current, which in turn can be used to exert a spin transfer torque (STT) on a second ferromagnetic layer with in-plane magnetization. Using a [Co,Ni] multilayer as the source of spin, an energy fluence of ~ 4 J m-2 creates thermal STT sufficient to induce ~ 1 % tilting of the magnetization of a 2 nm-thick CoFeB layer.

  6. Picosecond Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T.; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G.

    2017-02-01

    We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal metal /Y3Fe5 O12 bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal metal /Y3Fe5 O12 interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of 108 A m-2 K-1 .

  7. Laser induced breakdown spectroscopy with picosecond pulse train

    NASA Astrophysics Data System (ADS)

    Lednev, Vasily N.; Pershin, Sergey M.; Sdvizhenskii, Pavel A.; Grishin, Mikhail Ya; Davydov, Mikhail A.; Stavertiy, Anton Ya; Tretyakov, Roman S.

    2017-02-01

    Picosecond pulse train and nanosecond pulse were compared for laser ablation and laser induced breakdown spectroscopy (LIBS) measurements. A detailed study revealed that the picosecond pulse train ablation improved the quality of laser craters (symmetric crater walls and the absence of large redeposited droplets), which was explained by a smaller heat affected zone and suppression of melt splash. Greater plasma dimensions and brighter plasma emission were observed by gated imaging for picosecond pulse train compared to nanosecond pulse ablation. Increased intensity of atomic and ionic lines in gated and time integrated spectra provided better signal-to-noise ratio for picosecond pulse train sampling. Higher temperature and electron density were detected during first microsecond for the plasma induced by the picosecond pulse train. Improved shot-to-shot reproducibility for atomic/ionic line intensity in the case of picosecond pulse train LIBS was explained by more effective atomization of target material in plasma and better quality of laser craters. Improved precision and limits of detections were determined for picosecond pulse train LIBS due to better reproducibility of laser sampling and increased signal-to-noise ratio.

  8. Spectroscopic studies on ligand-enzyme interactions: complexation of alpha-chymotrypsin with 4',6-diamidino-2-phenylindole (DAPI).

    PubMed

    Banerjee, Debapriya; Srivastava, Sachin Kumar; Pal, Samir Kumar

    2008-02-14

    In the present study, the interaction of two structurally related proteolytic enzymes trypsin and alpha-chymotrypsin (CHT) with 4',6-Diamidino-2-phenylindole (DAPI) has been addressed. The binding of DAPI to CHT has been characterized by steady-state and picosecond time-resolved spectroscopic techniques. Enzymatic activity of CHT and simultaneous binding of the well-known inhibitor proflavin (PF) in the presence of DAPI clearly rule out the possibility of DAPI binding at the catalytic site of the enzyme. The spectral overlap between the emission of DAPI and absorption of PF offers the opportunity to explore the binding site of DAPI using Förster resonance energy transfer (FRET). FRET studies between DAPI and PF indicate that DAPI is bound to CHT with its transition dipole nearly perpendicular to that of PF. Competitive binding of DAPI with another fluorescent probe 2,6-p-toluidinonaphthalene sulfonate (TNS), having a well-defined binding site, indicates that DAPI and TNS bind at the same hydrophobic site of the enzyme CHT. The difference in the interactions of two well-studied, structurally similar enzymes with the same molecule may find its application in the design of specific substrate mimics or inhibitors of the enzymes.

  9. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    SciTech Connect

    Field, R.W.; Silbey, R.J.

    1993-12-01

    The authors have initiated a program to perform spectroscopic and dynamic studies of small molecules. Large amplitude motions in excited acetylene were discussed along with plans to record the dispersed fluorescence (DF) and the stimulated emission pumping (SEP) spectra. SEP spectra were reported for the formyl radical. A Fourier transform spectrometer was discussed with respect to its ability to probe the structure of radicals. This instrument is capable of performing studies using various techniques such as magnetic rotation spectroscopy and sub-Doppler sideband-OODR Zeman (SOODRZ) spectroscopy.

  10. Functionalization of manganite nanoparticles and their interaction with biologically relevant small ligands: picosecond time-resolved FRET studies.

    PubMed

    Giri, Anupam; Makhal, Abhinandan; Ghosh, Barnali; Raychaudhuri, A K; Pal, Samir Kumar

    2010-12-01

    We report molecular functionalization of the promising manganite nanoparticles La0.67Sr0.33MnO3 (LSMO) for their solubilization in aqueous environments. The functionalization of individual NPs with the biocompatible citrate ligand, as confirmed by Fourier transform infrared (FTIR) spectroscopy, reveals that citrates are covalently attached to the surface of the NPs. UV-VIS spectroscopic studies on the citrate functionalized NPs reveals an optical band in the visible region. Uniform size selectivity (2.6 nm) of the functionalization process is confirmed from high resolution transmission electron microscope (HRTEM). In the present study we have used the optical band of the functionalized NPs to monitor their interaction with other biologically important ligands. Förster resonance energy transfer (FRET) of a covalently attached probe 4-nitrophenylanthranilate (NPA) with the capped NPs confirm the attachment of the NPA ligands to the surface functional group (-OH) of the citrate ligand. The FRET of a DNA base mimic, 2-aminopurine (2AP), with the NPs confirms the surface adsorption of 2AP. Our study may find relevance in the study of the interaction of individual manganite NPs with drug/ligand molecules.

  11. Study of Ultrafast Internal Conversion in Molecules and Ultrafast Dephasing in Condensed Matter with Picosecond Dye Lasers.

    NASA Astrophysics Data System (ADS)

    Xie, Yongjin

    A picosecond cascaded transient oscillator (CTO) dye laser system was modified to generate continuous tunable, near transform-limited picosecond pulses. To improve the CTO system, the characteristics of a simple N_2 laser side-pumped dye laser (the first stage of CTO system) was thoroughly examined. It was found that both the pulse shape and the duration were affected strongly by the tuned wavelength, cavity length, pumping intensity, and the feedback signal from both the front and the back reflectors. A single output pulse as short as 40 ps could be generated by optimizing the operating parameters. The final output of the CTO system has a pulse duration less than 10 ps and a bandwidth less than 1 A. The technique of infrared multiphoton ionization was used to obtain state specific internal conversion rates in CrO_2Cl_2. Using narrow-band tunable 10 ps dye laser pulses, different vibrational states in the B_1 manifold were excited and the energy relaxation was monitored by an IR ps laser pulse. The relaxation can be characterized by a fast component, which is due to internal conversion to the ^1A_1 state, and a slow component, which is due to cooling of the vibrationally hot ^1A _1 ground state. The nonradiative energy transfer rate changes by almost three orders of magnitude for an excess vibrational energy change of merely 550 cm ^{-1}. With broadband incoherent picosecond dye laser pulse, the measurement of the dephasing time T _2 in dye solutions and semiconductor-doped glasses by the two pulse correlation method was demonstrated, with T_2<=ss than the correlation time of the excitation pulse tau_ {rm c}. It was found the dephasing time T_2 measured depended on the excitation photon energy relative to the band-edge or the energy difference between the ground state and the first excited electronic state. In the case of band-edge excitation, a quantum beat behavior with a beat frequency about 28 tera-hertz was observed in Rh-560 dye solutions.

  12. Time-resolved SFG study of formate on a Ni( 1 1 1 ) surface under irradiation of picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Noguchi, H.; Okada, T.; Onda, K.; Kano, S. S.; Wada, A.; Domen, K.

    2003-03-01

    Time-resolved sum-frequency generation spectroscopy was carried out on a deuterated formate (DCOO) adsorbed on Ni(1 1 1) surface to investigate the surface reaction dynamics under instantaneous surface temperature jump induced by the irradiation by picosecond laser pulses. The irradiation of pump pulse (800 nm) caused the rapid intensity decrease of both CD and OCO stretching modes of bridged formate on Ni(1 1 1). Different temporal behaviors of intensity recovery between these two vibrational modes were observed, i.e., CD stretching mode recovered faster than OCO. This is the first result to show that the dynamics of adsorbates on metals strongly depends on the observed vibrational mode. From the results of temperature and pump fluence dependence, we concluded that the observed intensity change was not due to the decomposition or desorption, but was induced by a non-thermal process.

  13. Method to control depth error when ablating human dentin with numerically controlled picosecond laser: a preliminary study.

    PubMed

    Sun, Yuchun; Yuan, Fusong; Lv, Peijun; Wang, Dangxiao; Wang, Lei; Wang, Yong

    2015-07-01

    A three-axis numerically controlled picosecond laser was used to ablate dentin to investigate the quantitative relationships among the number of additive pulse layers in two-dimensional scans starting from the focal plane, step size along the normal of the focal plane (focal plane normal), and ablation depth error. A method to control the ablation depth error, suitable to control stepping along the focal plane normal, was preliminarily established. Twenty-four freshly removed mandibular first molars were cut transversely along the long axis of the crown and prepared as 48 tooth sample slices with approximately flat surfaces. Forty-two slices were used in the first section. The picosecond laser was 1,064 nm in wavelength, 3 W in power, and 10 kHz in repetition frequency. For a varying number (n = 5-70) of focal plane additive pulse layers (14 groups, three repetitions each), two-dimensional scanning and ablation were performed on the dentin regions of the tooth sample slices, which were fixed on the focal plane. The ablation depth, d, was measured, and the quantitative function between n and d was established. Six slices were used in the second section. The function was used to calculate and set the timing of stepwise increments, and the single-step size along the focal plane normal was d micrometer after ablation of n layers (n = 5-50; 10 groups, six repetitions each). Each sample underwent three-dimensional scanning and ablation to produce 2 × 2-mm square cavities. The difference, e, between the measured cavity depth and theoretical value was calculated, along with the difference, e 1, between the measured average ablation depth of a single-step along the focal plane normal and theoretical value. Values of n and d corresponding to the minimum values of e and e 1, respectively, were obtained. In two-dimensional ablation, d was largest (720.61 μm) when n = 65 and smallest when n = 5 (45.00 μm). Linear regression yielded the quantitative

  14. Picosecond pulse radiolysis study on the distance dependent reaction of the solvated electron with organic molecules in ethylene glycol.

    PubMed

    El Omar, Abdel Karim; Schmidhammer, Uli; Pernot, Pascal; Murata, Shigeo; Mostafavi, Mehran

    2012-12-13

    The decay of solvated electron e(s)(-) is observed by nanosecond and picosecond pulsed radiolysis, in diluted and highly concentrated solutions of dichloromethane, CH(2)Cl(2), trichloromethane, CHCl(3), tribromomethane, CHBr(3), acetone, CH(3)COCH(3), and nitromethane, CH(3)NO(2), prepared in ethylene glycol. First, second-order rate constants for the reactions between e(-)(s) and the organic scavengers have been determined. The ratio between the highest rate constant that was found for CH(3)NO(2) and the lowest one that was found for acetone is 3. This difference in reactivity cannot be explained by the change of viscosity or the size of the molecules. Then, from the analysis of decay kinetics obtained using ultrafast pulse-probe method, the distance dependent first-order rate constant of electron transfer for each scavenger has been determined. The amplitude of the transient effect observed on the picosecond time scale differs strongly between these solvated electron scavengers. For an identical scavenger concentration, the transient effect lasts ≈650 ps for CH(3)NO(2) compared to ~200 ps for acetone. For acetone, the distance dependent first-order rate constant of electron transfer is decreasing very rapidly with increasing distance, whereas for nitromethane and tribromomethane the rate constant is decreasing gradually with the distance and its value remains non-negligible even at ~10 Å. This rate constant is controlled mostly by the free energy of the reaction. For nitromethane and tribromomethane, the driving force is great, and the reaction can occur even at long distance, whereas for acetone the driving force is small and the reaction occurs almost at the contact distance. For nitromethane and acetone, the one-electron reduction reaction needs less internal reorganization energy than for alkyl halide compounds for which the reaction occurs in concert with bond breaking and geometric adjustment.

  15. Vibrational spectroscopic studies of newly developed synthetic biopolymers.

    PubMed

    Bista, Rajan K; Bruch, Reinhard F; Covington, Aaron M

    2010-05-01

    Vibrational spectroscopic techniques such as near-infrared (NIR), Fourier transform infrared (FTIR), and Raman spectroscopy are valuable diagnostic tools that can be used to elucidate comprehensive structural information of numerous biological samples. In this review article, we have highlighted the advantages of nanotechnology and biophotonics in conjunction with vibrational spectroscopic techniques in order to understand the various aspects of new kind of synthetic biopolymers termed as polyethylene glycol (PEG)ylated lipids. In contrast to conventional phospholipids, these novel lipids spontaneously form liposomes or nanovesicles upon hydration, without the supply of external activation energy. The amphiphiles considered in this study differ in their hydrophobic acyl chain length and contain different units of PEG hydrophilic headgroups. We have further explored the thermotropic phase behaviors and associated changes in the conformational order/disorder of such lipids by using variable-temperature FTIR and Raman spectroscopy. Phase transition temperature profiles and correlation between various spectral indicators have been identified by either monitoring the shifts in the vibrational peak positions or plotting vibrational peak intensity ratios in the C--H stretching region as a function of temperature. To supplement our observations of phase transformations, a thermodynamic approach known as differential scanning calorimetry (DSC) has been applied and revealed a good agreement with the infrared and Raman spectroscopic data. Finally, the investigation of thermal properties of lipids is extremely crucial for numerous purposes, thus the results obtained in this work may find application in a wide variety of studies including the development of PEGylated lipid based drug and substances delivery vehicles.

  16. The Origin, Composition and History of Comets from Spectroscopic Studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1997-01-01

    A wealth of information essential to understanding the composition and physical structure of cometary ice and hence gain deep insight into the comet's origin and history, can be gleaned by carrying out a full range of spectroscopic studies on the returned sample. These studies ought to be among the first performed as they are generally non-destructive and will provide a broad data bank which will be crucial in planning subsequent analysis. Examples of the spectroscopic techniques along with relative sensitivities and transitions probed, are discussed. Different kind of "spectroscopy" is summarized, with emphasis placed on the kind of information each provides. Infrared spectroscopy should be the premier method of analysis as the mid-IR absorption spectrum of a substance contains more global information about the identity and structure of that material than any other property. In fact, the greatest strides in our understanding of the composition of interstellar ices (thought by many to be the primordial material from which comets have formed) have been taken during the past ten years or so because this was when high quality infrared spectra of the interstellar medium (ISM) first became available. The interpretation of the infrared spectra of mixtures, such as expected in comets, is often (not always) ambiguous. Consequently, a full range of other non-destructive, complementary spectroscopic measurements are required to fully characterize the material, to probe for substances for which the IR is not well suited and to lay the groundwork for future analysis. Given the likelihood that the icy component (including some of the organic and mineral phases) of the returned sample will be exceedingly complex, these techniques must be intensely developed over the next decade and then made ready to apply flawlessly to what will certainly be one of the most precious, and most challenging, samples ever analyzed.

  17. Picosecond measurements using photoacoustic detection

    NASA Technical Reports Server (NTRS)

    Heritier, J.-M.; Siegman, A. E.

    1983-01-01

    A report is presented of experimental results on picosecond time-resolved photoacoustic measurements of excited-state lifetimes, cross sections, and polarization properties for organic dye molecules in solution, using a new technique in which the total photoacoustic impulse produced by two ultrashort optical pulses with variable time delay between them is detected. The picosecond photoacoustic detection technique reported here appears to be a promising new way to observe weak excited-state cross sections and to perform picosecond lifetime measurements in a large variety of weakly absorbing and/or nonfluorescing atomic and molecular systems.

  18. SPECTROSCOPIC STUDIES OF STRUCTURE, DYNAMICS AND REACTIVITY IN IONIC LIQUIDS.

    SciTech Connect

    WISHART,J.F.

    2007-11-30

    the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) [1] are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. IL solvation and rotational dynamics are measured by TCSPC in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy.

  19. Z-scan study of thermal nonlinearities in silicon naphthalocyanine-toluene solution with the excitations of the picosecond pulse train and nanosecond pulse.

    PubMed

    Yang, Sidney S; Wei, Tai-Huei; Huang, Tzer-Hsiang; Chang, Yun-Ching

    2007-02-19

    Using the Z-scan technique, we studied the nonlinear absorption and refraction behaviors of a dilute toluene solution of a silicon naphthalocyanine (Si(OSi(n-hexyl)(3))(2), SiNc) at 532 nanometer with both a 2.8-nanosecond pulse and a 21-nanosecond (HW1/eM) pulse train containing 11 18-picosecond pulses 7 nanosecond apart. A thermal acoustic model and its steady-state approximation account for the heat generated by the nonradiative relaxations subsequent to the absorption. We found that when the steady-state approximation satisfactorily explained the results obtained with a 21-nanosecond pulse train, only the thermal-acoustic model fit the 2.8-nanosecond experimental results, which supports the approximation criterion established by Kovsh et al.

  20. Picosecond Spin Seebeck Effect.

    PubMed

    Kimling, Johannes; Choi, Gyung-Min; Brangham, Jack T; Matalla-Wagner, Tristan; Huebner, Torsten; Kuschel, Timo; Yang, Fengyuan; Cahill, David G

    2017-02-03

    We report time-resolved magneto-optic Kerr effect measurements of the longitudinal spin Seebeck effect in normal metal/Y_{3}Fe_{5}O_{12} bilayers driven by an interfacial temperature difference between electrons and magnons. The measured time evolution of spin accumulation induced by laser excitation indicates transfer of angular momentum across normal metal/Y_{3}Fe_{5}O_{12} interfaces on a picosecond time scale, too short for contributions from a bulk temperature gradient in an yttrium iron garnet. The product of spin-mixing conductance and the interfacial spin Seebeck coefficient determined is of the order of 10^{8}  A m^{-2} K^{-1}.

  1. Spectroscopic studies of interactions involving horseradish peroxidase and Tb3+.

    PubMed

    Guo, Shaofen; Zhou, Qing; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

    2008-09-01

    The spectroscopic properties of interactions involving horseradish peroxidase (HRP) and Tb3+ in the simulated physiological solution was investigated with some electrochemical and spectroscopic methods, such as cyclic voltammetry (CV), circular dichroism (CD), X-ray photoelectron spectroscopy (XPS) and synchronous fluorescence (SF). It was found that Tb3+ can coordinate with oxygen atoms in carbonyl groups in the peptide chain of HRP, form the complex of Tb3+ and HRP (Tb-HRP), and then lead to the conformation change of HRP. The increase in the random coil content of HRP can disturb the microstructure of the heme active center of HRP, in which the planarity of the porphyrin cycle in the heme group is increased and then the exposure extent of the electrochemical active center is decreased. Thus Tb3+ can inhibit the electrochemical reaction of HRP and its electrocatalytic activity for the reduction of H2O2 at the Au/Cys/GC electrode. The changes in the microstructure of HRP obstructed the electron transfer of Fe(III) in the porphyrin cycle of the heme group, thus HRP catalytic activity is inhibited. The inhibition effect of Tb3+ on HRP catalytic activity is increased with the increasing of Tb3+ concentration. This study would provide some references for better understanding the rare earth elements and heavy metals on peroxidase toxicity in living organisms.

  2. Novel dipodal Schiff base compounds: Synthesis, characterization and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Obali, Aslihan Yilmaz; Ucan, Halil Ismet

    2015-02-01

    Two novel dipodal Schiff base compounds 1,2-benzyloxy-bis-[2-(benzylideneamino)phenol, L1 and 1,2-benzyloxy-bis[3-(benzylideneamino)pyridine], L2 were synthesized. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II) in methanol medium (1 × 10-4 M). It was found that the dipodal compounds can selectively bind to Cu(II) and Pb(II) metal ions with a significant change in its emission and absorption spectra, while the addition of other metal ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II)) produces insignificant or minor changes. The host-guest complexes formed were determined by Job's plot method. As a chemosensor, L1 and L2 dipodal Schiff base compounds shows a specific selectivity towards Cu(II) and Pb(II) ions in according to all spectroscopic data.

  3. Picosecond laser filamentation in air

    NASA Astrophysics Data System (ADS)

    Schmitt-Sody, Andreas; Kurz, Heiko G.; Bergé, Luc; Skupin, Stefan; Polynkin, Pavel

    2016-09-01

    The propagation of intense picosecond laser pulses in air in the presence of strong nonlinear self-action effects and air ionization is investigated experimentally and numerically. The model used for numerical analysis is based on the nonlinear propagator for the optical field coupled to the rate equations for the production of various ionic species and plasma temperature. Our results show that the phenomenon of plasma-driven intensity clamping, which has been paramount in femtosecond laser filamentation, holds for picosecond pulses. Furthermore, the temporal pulse distortions in the picosecond regime are limited and the pulse fluence is also clamped. In focused propagation geometry, a unique feature of picosecond filamentation is the production of a broad, fully ionized air channel, continuous both longitudinally and transversely, which may be instrumental for many applications including laser-guided electrical breakdown of air, channeling microwave beams and air lasing.

  4. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect

    Sawyer, Karma Rae

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  5. Spectroscopic studies of carbon impurities in PISCES-A

    SciTech Connect

    Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W. . Inst. of Plasma and Fusion Research); Pospieszczyk, A. . Inst. fuer Plasmaphysik)

    1989-08-01

    The graphite used for the limiter of the tokamak reactor produces carbon-containing molecular impurities as a result of the interactions with the edge plasma. The behavior of these molecular impurities has been studied using emission spectroscopy. The present study includes: finding molecular bands and atomic lines in the visible spectral range which can be used for the study of the molecular impurities, studying the breakup processes of the molecular impurities on their way from the source into the plasma, developing a spectroscopic diagnostic method for the absolute measurement of the molecular impurity flux resulting from graphite erosion. For these studies, carbon-containing molecules such as CH{sub 4}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and CO{sub 2} were injected into the tokamak-boundary,like plasma generated by PISCES-A. The spectrograms of these gases were taken. Many useful bands and lines were determined from the spectrograms. The breakup processes of these gases were studied by observing the spatial profiles of the emission of the molecules and their radicals for different plasma conditions. For the absolute measurement of the eroded molecular impurity flux, the photon efficiency of the lines and bands were found by measuring the absolute number of the emitted photons and injected gas molecules. The chemical sputtering yield of graphite by hydrogen plasma was spectroscopically measured using the previously obtained photon efficiencies. It showed good agreement with results obtained by weight loss measurements. 16 refs., 7 figs., 1 tab.

  6. Combined spectroscopic and quantum chemical studies of ezetimibe

    NASA Astrophysics Data System (ADS)

    Prajapati, Preeti; Pandey, Jaya; Shimpi, Manishkumar R.; Srivastava, Anubha; Tandon, Poonam; Velaga, Sitaram P.; Sinha, Kirti

    2016-12-01

    Ezetimibe (EZT) is a hypocholesterolemic agent used for the treatment of elevated blood cholesterol levels as it lowers the blood cholesterol by blocking the absorption of cholesterol in intestine. Study aims to combine experimental and computational methods to provide insights into the structural and vibrational spectroscopic properties of EZT which is important for explaining drug substance physical and biological properties. Computational study on molecular properties of ezetimibe is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set. A detailed vibrational assignment has been done for the observed IR and Raman spectra of EZT. In addition to the conformational study, hydrogen bonding and molecular docking studies have been also performed. For conformational studies, the double well potential energy curves have been plotted for the rotation around the six flexible bonds of the molecule. UV absorption spectrum was examined in methanol solvent and compared with calculated one in solvent environment (IEF-PCM) using TD-DFT/6-31G basis set. HOMO-LUMO energy gap of both the conformers have also been calculated in order to predict its chemical reactivity and stability. The stability of the molecule was also examined by means of natural bond analysis (NBO) analysis. To account for the chemical reactivity and site selectivity of the molecules, molecular electrostatic potential (MEPS) map has been plotted. The combination of experimental and calculated results provide an insight into the structural and vibrational spectroscopic properties of EZT. In order to give an insight for the biological activity of EZT, molecular docking of EZT with protein NPC1L1 has been done.

  7. Time Domain Reflectometric and spectroscopic studies on toluene + butyronitrile solution

    NASA Astrophysics Data System (ADS)

    Karthick, N. K.; Arivazhagan, G.; Kumbharkhane, A. C.; Joshi, Y. S.; Kannan, P. P.

    2016-03-01

    The dielectric parameters of toluene + butyronitrile solution have been obtained by time domain reflectometry (TDR) technique in the frequency range from 10 MHz to 30 GHz at 298 K. Spectroscopic (FTIR and 13C NMR) studies have also been carried out on the solution and the results of the studies show that neat butyronitrile is self-associative through C-H⋯N contacts and weak intermolecular forces of C-H⋯N and C-H⋯π type are operative in the solution. The obtained dielectric parameters such as Kirkwood correlation factor g, relaxation time τ etc. have been analyzed in view of these weak intermolecular forces. The weak non-covalent interactions between heteromolecules appear to have no influence on the ideality of ɛm vs X2 curve of the solution. Heteromolecular entities with weak intermolecular forces experience larger hindrance leading to longer relaxation time τ.

  8. Spectroscopic study of demineralization and restoration processes in dental enamel

    NASA Astrophysics Data System (ADS)

    Sokolova, Tatiana N.; Surmenko, Elena L.; Tuchin, Valery V.; Kishen, A.; Chebotarevsky, Yu. V.

    2007-07-01

    The spectroscopic study of dental enamel by LIBS (laser induced breakdown spectroscopy), FTIR (Fourier transform infrared) and XRD (X-ray diffraction) are represented. The changes of enamel structure and composition in process of natural (caries) and artificial demineralization and restoration were studied. In comparison of sound and carious enamel LIBS showed a decrease of the content of Ca, P and change of the content of some other macro-and trace elements (Mn, Na, Fe, Zn etc). The character of the elemental composition variation was stipulated by the concrete disease. Analysis of FTIR and XRD spectra of dental samples, subjected to artificial demineralization and restoration, showed that restoration action reveals slower, than demineralization. And in some cases the damage of crystals after restoration is more significant than after demineralization.

  9. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples.

  10. Crystallographic and spectroscopic study on a known orally active progestin.

    PubMed

    Ferraboschi, Patrizia; Ciuffreda, Pierangela; Ciceri, Samuele; Grisenti, Paride; Castellano, Carlo; Meneghetti, Fiorella

    2015-12-01

    6,17α-Dimethyl-4,6-pregnadiene-3,20-dione (medrogestone, 2) is for a long time known steroid endowed with progestational activity. In order to study its crystallographic and NMR spectroscopic properties with the aim to fill the literature gap, we prepared medrogestone following a traditional procedure. A careful NMR study allowed the complete assignment of the (1)H and (13)C NMR signals not only of medrogestone but also of its synthetic intermediates. The structural and stereochemical characterizations of medrogestone together with its precursor 17α-methyl-3-ethoxy-pregna-3,5-dien-20-one were described by means of X-ray analysis, allowing a deepened conformational investigation.

  11. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  12. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  13. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    DOE PAGES

    Cao, R. X.; Sun, L.; Miao, B. F.; ...

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of themore » corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.« less

  14. Ultrasonic and spectroscopic studies on photoactivation of euglena

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Morita, Shin

    2006-12-01

    We studied the effect of the irradiation wavelength on the activity of photosynthetic euglena. The ultrasonic manipulation technique was used for both the activity evaluation and the movement restriction in the spectral measurements. Euglenas that had been preserved in darkness became inactive, and accordingly most of them were trapped by the ultrasonic standing wave (0.8mW/mm2). However, when they were exposed to light of 500 or 700nm wavelength (0.13W/m2), they became active enough to escape from the trapping. By contrast, irradiation at 550, 600, or 650nm wavelength had no effect on their activity. Spectroscopic measurements, which used to be difficult for locomotive microorganisms, were conducted successfully by trapping euglena at a node of the ultrasonic standing wave. The absorption bands were observed at around 500 or 700nm, which corresponded to the irradiation wavelengths that activated euglena.

  15. Raman spectroscopic study of cyclohexane at pressures below 1000 MPa

    NASA Astrophysics Data System (ADS)

    Qiao, Erwei; Zheng, Haifei

    2017-10-01

    At present, the room temperature freezing pressure of cyclohexane is still uncertain, and the phase transition pressure of solid I - solid III is not reliable at ambient temperature. In this work, we have performed a Raman spectroscopic study of cyclohexane in a Moissanite anvil cell at pressures below 1000 MPa at 25 °C, and analyzed the characteristic of Raman brands νs(CH2), νas(CH2) and νb(Ring). Two phase transition pressures 80 MPa and 550 MPa were determined by a quartz pressure gauge, and they are the room temperature freezing pressure of cyclohexane and the phase transition pressure of solid I to solid III, respectively. Furthermore, from the phase diagram of cyclohexane, it is inferred that pressure plays an important role on the stability of cyclohexane as the main constituent of oil, and it can be beneficial to understanding the formation, migration and preservation of petroleum in subterranean rock strata.

  16. A detailed spectroscopic study of an Italian fresco

    SciTech Connect

    Barilaro, Donatella; Crupi, Vincenza; Majolino, Domenico; Barone, Germana; Ponterio, Rosina

    2005-02-15

    In the present work we characterized samples of plasters and pictorial layers taken from a fresco in the Acireale Cathedral. The fresco represents the Coronation of Saint Venera, patron saint of this Ionian town. By performing a detailed spectroscopic analysis of the plaster preparation layer by Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD), and of the painting layer by FTIR and confocal Raman microspectroscopy, scanning electron microscopy+energy dispersive x-ray spectroscopy, and XRD, we were able to identify the pigments and the binders present. In particular, Raman investigation was crucial to the characterization of the pigments thanks to the high resolution of the confocal apparatus used. It is worth stressing that the simultaneous use of complementary techniques was able to provide more complete information for the conservation of the artifact we studied.

  17. Spectroscopic Capabilities of XMM for Stellar Coronal Studies

    NASA Astrophysics Data System (ADS)

    Pallavicini, R.

    The turn of the millennium will be a marvelous time for X-ray astronomy with the launch of powerful missions such as AXAF, XMM, and ASTRO-E. Stellar coronae, with their spectra rich in emission lines, will be primary targets to exploit the spectroscopic capabilities of these missions. In particular, the CCD cameras and reflection gratings on XMM will allow us to address a number of key questions in stellar coronal physics. The capabilities of XMM for the study of stellar coronae are illustrated by means of simulations of EPIC and RGS spectra for a variety of typical stellar coronal sources. The mission time-line and the policy for accessing the data are also briefly illustrated.

  18. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    SciTech Connect

    Cao, R. X.; Sun, L.; Miao, B. F.; Li, Q. L.; Zheng, C.; Wu, D.; You, B.; Zhang, W.; Han, P.; Bader, S. D.; Zhang, W. Y.; Ding, H. F.

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of the corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.

  19. Molecular spectroscopic study for suggested mechanism of chrome tanned leather

    NASA Astrophysics Data System (ADS)

    Nashy, Elshahat H. A.; Osman, Osama; Mahmoud, Abdel Aziz; Ibrahim, Medhat

    2012-03-01

    Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins.

  20. Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking

    NASA Astrophysics Data System (ADS)

    Szafraniec, Ewelina; Majzner, Katarzyna; Farhane, Zeineb; Byrne, Hugh J.; Lukawska, Malgorzata; Oszczapowicz, Irena; Chlopicki, Stefan; Baranska, Malgorzata

    2016-12-01

    A broad spectroscopic characterization, using ultraviolet-visible (UV-vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV-vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488 nm and 785 nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level.

  1. Spectroscopic study of photo and thermal destruction of riboflavin

    NASA Astrophysics Data System (ADS)

    Astanov, Salikh; Sharipov, Mirzo Z.; Fayzullaev, Askar R.; Kurtaliev, Eldar N.; Nizomov, Negmat

    2014-08-01

    Influence of temperature and light irradiation on the spectroscopic properties of aqueous solutions of riboflavin was studied using linear dichroism method, absorption and fluorescence spectroscopy. It was established that in a wide temperature range 290-423 K there is a decline of absorbance and fluorescence ability, which is explained by thermodestruction of riboflavin. It is shown that the proportion of molecules, which have undergone degradation, are in the range of 4-28%, and depends on the concentration and quantity of temperature effects. Introduction of hydrochloric and sulfuric acids, as well as different metal ions leads to an increase in the photostability of riboflavin solutions by 2-2.5 times. The observed phenomena are explained by the formation protonation form of riboflavin and a complex between the metal ions and oxygen atoms of the carbonyl group of riboflavin, respectively.

  2. Raman spectroscopic study of "The Malatesta": a Renaissance painting?

    PubMed

    Edwards, Howell G M; Vandenabeele, Peter; Benoy, Timothy J

    2015-02-25

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

  3. Spectroscopic Study of Low Mass Members of NGC 2244

    NASA Astrophysics Data System (ADS)

    Alty, Michelle; Ybarra, Jason E.; Román-Zúñiga, Carlos G.; Lada, Elizabeth A.

    2017-01-01

    The results of a near-infrared spectroscopic study of low-mass stars in open cluster NGC 2244 are presented. JH spectra of the stars were obtained using the FLAMINGOS instrument at KPNO. To determine cluster membership, we used Spitzer Space Telescope mid-infrared photometry along with X-ray detections from the Chandra X-ray Observatory. The stars were spectral typed using absorption line ratios and spectral shapes. The stars were then plotted on an H-R diagram along with theoretical isochrones. We discuss these results in context of cluster evolution in the Rosette Molecular Complex. Work supported, in part, by the Dr. John W. Martin Summer Science Research Institute at Bridgewater College.

  4. Spectroscopic Studies of Quantum Well Structures in Pulsed Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Perry, Clive H.

    1998-03-01

    Magneto-photoluminescence spectroscopy (MPS) at low temperatures is a powerful technique for investigating the ground and excited states of high quality quantum well-type semiconductor heterostructures. The spectra are strongly influenced by electron-electron interactions and the method offers a complimentary tool to electrical transport studies. We have established a MPS facility at NHMFL-LANL and have undertaken a comprehensive investigation of magneto-excitonic and Landau transitions in a large variety of undoped and doped (two-dimensional electron gas, 2DEG) GaAs/AlGaAs and InGaAs/GaAs quantum-well structures. Excitation energies are provided by UV, visible, and NIR lasers. Fiber optic probes are used to switch between steady state (to 18 tesla) and short-pulsed (to 65 tesla) magnetic fields applied perpendicular (Faraday geometry) and parallel (Voigt geometry) to the growth axis of the 2D layers. The experimental techniques, optical layout, and data acquisition are reviewed i n some detail. Short-pulse magnets require that the spectroscopic data acquisition to be obtained in a 2 ms time-frame in the 'flat-top' region at the peak of the field. A broad range of samples have been investigated as a function of temperature, sample geometry, and high pressure. Examples of MPL spectra of single and coupled double quantum wells, modulation-doped quantum wells, single interface structures, and other related semiconductor heterojunction structures are given. The recently commissioned long-pulse magnet at NHMFL-LANL offers several new exciting possibilities: (i) The long exponential decay associated with the crow-bar mode has the potential for spectroscopic studies from 60 -10 T in 0.5 T intervals from a single pulse. (ii) Field steps programmed to last from 100-500 ms or longer offer the opportunity for time-resolved MPL spectroscopy in the 60 - 10 T range.

  5. Spectroscopic study of the peculiar galaxy IC 883

    NASA Astrophysics Data System (ADS)

    Yakovleva, V. A.; Merkulova, O. A.; Karataeva, G. M.; Shalyapina, L. V.; Yablokova, N. V.; Burenkov, A. N.

    2016-04-01

    We analyze new optical spectroscopic observations obtained at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the SCORPIO focal reducer (in the modes of a Fabry-Perot interferometer (FPI) and long-slit spectroscopy) and the Multi-Pupil Fiber Spectrograph for the galaxy IC 883. We have confirmed that the main body of the galaxy rotates around its minor axis. The positions of the dynamical axes of the stellar and gaseous components have been found to differ by ~10°. The velocities in the SE tail do not correspond to the circular rotation around the galaxy's minor axis. This structure is probably a fragment of an unwound curved spiral arm. Regions with high velocity dispersions and peculiarities in the velocity fields have been found along the minor axis. Our study of the age and metallicity of the galaxy's stellar population has shown that the mean values of these parameters in the stellar disk, except for the central region ( r ≤ 5"), are ≈1 Gyr and ≈-0.4 dex, respectively. Both young (2-5 × 108 yr) and old (5-10 × 109 yr) stellar populations are present in the circumnuclear region. Our analysis of the spectroscopic data for the bright feature 8" south of the nucleus coincident in position with a compact X-ray source has shown that this is apparently a dwarf galaxy or a remnant of a companion galaxy. Our FPI observations in the Hα emission line and direct images have revealed a region of ionized gas that together with the already known structures along the minor axis forms a clumpy tidal structure of ionized gas pulled from the companion galaxy. The results of our study confirm the previously proposed hypothesis that the observed peculiar structures were formed by the merger of two galaxies. However, it can be said that IC 883 does not belong to the class of polar-ring galaxies.

  6. The picosecond laser for tattoo removal.

    PubMed

    Hsu, Vincent M; Aldahan, Adam S; Mlacker, Stephanie; Shah, Vidhi V; Nouri, Keyvan

    2016-11-01

    The prevalence of tattoos continues to grow as modern society's stigma towards this form of body art shifts towards greater acceptance. Approximately one third of Americans aged 18-25 and 40 % of Americans aged 26-40 are tattooed. As tattoos continue to rise in popularity, so has the demand for an effective method of tattoo removal such as lasers. The various colors of tattoo inks render them ideal targets for specific lasers using the principle of selective photothermolysis. Traditional laser modalities employed for tattoo removal operate on pulse durations in the nanosecond domain. However, this pulse duration range is still too long to effectively break ink into small enough particles. Picosecond (10(-12)) lasers have emerged at the forefront of laser tattoo removal due to their shorter pulse lengths, leading to quicker heating of the target chromophores, and consequently, more effective tattoo clearance. Recent studies have cited more effective treatment outcomes using picosecond lasers. Future comparative studies between picosecond lasers of various settings are necessary to determine optimal laser parameters for tattoo clearance.

  7. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.

    1993-03-01

    The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.

  8. Laser irradiated gas jet: A spectroscopic experimental and theoretical study

    SciTech Connect

    Lee, R.W.; Matthews, D.L.; Koppel, L.; Busch, G.E.; Charatis, G.; Dunning, M.J.; Mayer, F.J.

    1983-09-01

    We present x-ray spectroscopic measurements of the longitudinal electron density profile and the longitudinal and transverse electron temperature profiles for a laser irradiated gas jet. We attempt to verify our spectroscopic method by laser interferometry and by comparison of inferred quantities to those determined from laser plasma interaction simulations. Because temperature profiles were time dependent, we used a theoretical time dependent radiation transport code to analyze the data.

  9. EPR Spectroscopic Studies of [FeFe]-Hydrogenase Maturation.

    PubMed

    Suess, Daniel L M; Britt, R David

    2015-09-01

    Proton reduction and H2 oxidation are key elementary reactions for solar fuel production. Hydrogenases interconvert H(+) and H2 with remarkable efficiency and have therefore received much attention in this context. For [FeFe]-hydrogenases, catalysis occurs at a unique cofactor called the H-cluster. In this article, we discuss ways in which EPR spectroscopy has elucidated aspects of the bioassembly of the H-cluster, with a focus on four case studies: EPR spectroscopic identification of a radical en route to the CO and CN(-) ligands of the H-cluster, tracing (57)Fe from the maturase HydG into the H-cluster, characterization of the auxiliary Fe-S cluster in HydG, and isotopic labeling of the CN(-) ligands of HydA for electronic structure studies of its Hox state. Advances in cell-free maturation protocols have enabled several of these mechanistic studies, and understanding H-cluster maturation may in turn provide insights leading to improvements in hydrogenase production for biotechnological applications.

  10. Particle in a Disk: A Spectroscopic and Computational Laboratory Exercise Studying the Polycyclic Aromatic Hydrocarbon Corannulene

    ERIC Educational Resources Information Center

    Frey, E. Ramsey; Sygula, Andrzej; Hammer, Nathan I.

    2014-01-01

    This laboratory exercise introduces undergraduate chemistry majors to the spectroscopic and theoretical study of the polycyclic aromatic hydrocarbon (PAH), corannulene. Students explore the spectroscopic properties of corannulene using UV-vis and Raman vibrational spectroscopies. They compare their experimental results to simulated vibrational…

  11. Particle in a Disk: A Spectroscopic and Computational Laboratory Exercise Studying the Polycyclic Aromatic Hydrocarbon Corannulene

    ERIC Educational Resources Information Center

    Frey, E. Ramsey; Sygula, Andrzej; Hammer, Nathan I.

    2014-01-01

    This laboratory exercise introduces undergraduate chemistry majors to the spectroscopic and theoretical study of the polycyclic aromatic hydrocarbon (PAH), corannulene. Students explore the spectroscopic properties of corannulene using UV-vis and Raman vibrational spectroscopies. They compare their experimental results to simulated vibrational…

  12. Solvent and rotational relaxation study in ionic liquid containing reverse micellar system: A picosecond fluorescence spectroscopy study

    NASA Astrophysics Data System (ADS)

    Pramanik, Rajib; Sarkar, Souravi; Ghatak, Chiranjib; Rao, Vishal Govind; Sarkar, Nilmoni

    2011-08-01

    Room-temperature ionic liquid (RTIL), N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([P13][Tf2N]) have been used as polar solvent to form nonaqueous reverse micelle (RMs) with benzene by the aid of cationic surfactant BHDC. Dynamic light scattering (DLS) revealed the formation of the RTIL reverse micelle. Pulsed-field gradient spin echo NMR have been studied to measure the diffusion coefficients of neat [P13][Tf2N] and [P13][Tf2N] in reverse micelle which indicate RTIL containing reverse micelle is formed. Moreover, studies on solvent and rotational relaxation have been investigated in [P13][Tf2N]/BHDC/benzene RMs using steady-state and time-resolved fluorescence spectroscopy using coumarin 480 (C-480) fluorescence probe with variation of RTIL contents RMs.

  13. Spectroscopic and DFT study of 3-quinolyl-α-aminophosphonates

    NASA Astrophysics Data System (ADS)

    Juribašić, Marina; Tušek-Božić, Ljerka

    2009-04-01

    Spectroscopic and DFT study of two types of 3-quinolyl-α-aminophosphonate derivatives obtained by one-pot microwave-assisted synthesis of quinoline-3-carboxaldehyde and aniline as well as 3-aminoquinoline and benzaldehyde, respectively, with diethyl phosphite, have been described. Besides the diethyl [α-anilino- N-(3-quinolylmethyl)]phosphonate ( 1) and diethyl [α-(3-quinolylamino)- N-benzyl]phosphonate ( 4) as the main reaction products, in both cases some unexpected monoester phosphonate derivatives were obtained as the by-products. In the first case along with diester 1, its corresponding monoethyl ester ( 2) and one monoethyl dihydrophosphonate-phosphate derivative ( 3) were formed, while in the second case diester 4 and a hydrogen phosphonamidate ( 5) were isolated. All quinoline-based α-aminophosphonates ( 1- 5) have been characterized by IR spectroscopy, and the results obtained are compared and discussed with those obtained by the NMR studies. Combining experimental IR, 1H and 13C NMR spectra with DFT calculations, most intensive IR spectral bands of diesters 1 and 4, along with 1H and 13C NMR resonances of 1, 2 and 4 derivatives, were assigned.

  14. High brightness picosecond electron gun

    SciTech Connect

    Merano, M.; Collin, S.; Renucci, P.; Gatri, M.; Sonderegger, S.; Crottini, A.; Ganiere, J.D.; Deveaud, B.

    2005-08-15

    We have developed a high brightness picosecond electron gun. We have used it to replace the thermionic electron gun of a commercial scanning electron microscope (SEM) in order to perform time-resolved cathodoluminescence experiments. Picosecond electron pulses are produced, at a repetition rate of 80.7 MHz, by femtosecond mode-locked laser pulses focused on a metal photocathode. This system has a normalized axial brightness of 93 A/cm{sup 2} sr kV, allowing for a spatial resolution of 50 nm in the secondary electron imaging mode of the SEM. The temporal width of the electron pulse is 12 ps.

  15. Infrared Imaging, Spectroscopic, and Photometric Studies of Comets

    NASA Technical Reports Server (NTRS)

    Gehrz, Robert D.

    1997-01-01

    We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have

  16. Spectroscopic Studies of Molecular Systems relevant in Astrobiology

    NASA Astrophysics Data System (ADS)

    Fornaro, Teresa

    2016-01-01

    In the Astrobiology context, the study of the physico-chemical interactions involving "building blocks of life" in plausible prebiotic and space-like conditions is fundamental to shed light on the processes that led to emergence of life on Earth as well as to molecular chemical evolution in space. In this PhD Thesis, such issues have been addressed both experimentally and computationally by employing vibrational spectroscopy, which has shown to be an effective tool to investigate the variety of intermolecular interactions that play a key role in self-assembling mechanisms of nucleic acid components and their binding to mineral surfaces. In particular, in order to dissect the contributions of the different interactions to the overall spectroscopic signals and shed light on the intricate experimental data, feasible computational protocols have been developed for the characterization of the spectroscopic properties of such complex systems. This study has been carried out through a multi-step strategy, starting the investigation from the spectroscopic properties of the isolated nucleobases, then studying the perturbation induced by the interaction with another molecule (molecular dimers), towards condensed phases like the molecular solid, up to the case of nucleic acid components adsorbed on minerals. A proper modeling of these weakly bound molecular systems has required, firstly, a validation of dispersion-corrected Density Functional Theory methods for simulating anharmonic vibrational properties. The isolated nucleobases and some of their dimers have been used as benchmark set for identifying a general, reliable and effective computational procedure based on fully anharmonic quantum mechanical computations of the vibrational wavenumbers and infrared intensities within the generalized second order vibrational perturbation theory (GVPT2) approach, combined with the cost-effective dispersion-corrected density functional B3LYP-D3, in conjunction with basis sets of

  17. In vitro spectroscopic study of piperine-encapsulated nanosize liposomes.

    PubMed

    Pentak, Danuta

    2016-03-01

    Black pepper is a source of effective antioxidants. It contains several powerful antioxidants and is thus one of the most important spices for preventing and curtailing oxidative stress. There is considerable interest in the development of a drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic and amphiphilic molecules. This article focuses on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress. Liposome formulations of piperine were analyzed with various spectroscopic methods. The formulation with the highest entrapment efficiency (90.5%) was formulated with an L-α-phosphatidylcholine dipalmitoyl (DPPC):piperine, 30:1 molar ratio, and total lipid count of 19.47 mg/ml in the final liposomal preparation. The liposome formulation was found to be stable after storage at 4 °C, protected from light, for a minimum of 3 weeks. The incremental process of piperine penetration through the phospholipid membrane was analyzed using the FT-IR, UV-Vis and NMR methods. Temperature stability studies carried out at 37 °C showed the highest percentage of piperine release in the first 3 h of incubation.

  18. A spectroscopic study of the globular Cluster NGC 4147

    NASA Astrophysics Data System (ADS)

    Villanova, S.; Monaco, L.; Moni Bidin, C.; Assmann, P.

    2016-08-01

    We present the abundance analysis for a sample of 18 red giant branch stars in the metal-poor globular cluster NGC 4147 based on medium- and high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Y, Ba, and Eu. We find a metallicity of [Fe/H] = -1.84 ± 0.02 and an α-enhancement of +0.38 ± 0.05 (errors on the mean), typical of halo globular clusters in this metallicity regime. A significant spread is observed in the abundances of light elements C, N, O, Na, and Al. In particular, we found an Na-O anticorrelation and Na-Al correlation. The cluster contains only ˜15 per cent of stars that belong to the first generation (Na-poor and O-rich). This implies that it suffered a severe mass-loss during its lifetime. Its [Ca/Fe] and [Ti/Fe] mean values agree better with the Galactic halo trend than with the trend of extragalactic environments at the cluster metallicity. This possibly suggests that NGC 4147 is a genuine Galactic object at odd with what claimed by some author that proposed the cluster to be member of the Sagittarius dwarf galaxy. An antirelation between the light s-process element Y and Na may also be present.

  19. Spectroscopic study of HNO3 dissociation on ice.

    PubMed

    Marchand, Patrick; Marcotte, Guillaume; Ayotte, Patrick

    2012-12-13

    A detailed spectroscopic study of HNO(3):H(2)O binary amorphous mixtures, and of the adsorption of HNO(3) onto ice, is reported. Using a classical optics model, the extent of intermixing and of ionic dissociation of adsorbed HNO(3), which forms a strong acid with liquid water, is determined as a function of HNO(3) coverage and temperature. Even at temperatures as low as 45 K, where intermixing is limited to at most a few molecular layers at the interface, ionic dissociation of adsorbed HNO(3) is observed to be extensive. While some amount of molecularly adsorbed HNO(3) is observed at the surface of ice at 45 K, its ionic dissociation occurs irreversibly upon heating the ice substrate to 120 K. The molecularly adsorbed state of HNO(3) is not restored upon cooling, suggesting HNO(3) is a metastable entity at the surface of ice. Therefore, despite ionic dissociation of HNO(3) being thermodynamically favored, it appears to be kinetically inhibited at the surface of amorphous solid water at temperatures below 120 K.

  20. Spectroscopic and Microscopic Study of Peroxyformic Pulping of Agave Waste.

    PubMed

    Hernández-Hernández, Hilda M; Chanona-Pérez, Jorge J; Vega, Alberto; Ligero, Pablo; Farrera-Rebollo, Reynold R; Mendoza-Pérez, Jorge A; Calderón-Domínguez, Georgina; Vera, Norma Güemes

    2016-10-01

    The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60-180 min), formic acid concentration (80-95%), temperature (60-80°C), and hydrogen peroxide concentration (2-4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

  1. Spectroscopic studies of cryogenic fluids: Benzene in propane

    NASA Astrophysics Data System (ADS)

    Nowak, R.; Bernstein, E. R.

    1987-03-01

    Energy shifts and bandwidths for the 1B2u↔1A1g optical absorption and emission transitions of benzene dissolved in propane are presented as a function of pressure, temperature, and density. Both absorption and emission spectra exhibit shifts to lower energy as a function of density, whereas no shifts are observed if density is kept constant and temperature and pressure are varied simultaneously. Density is thus the fundamental microscopic parameter for energy shifts of optical transitions. The emission half-width is a linear function of both temperature and pressure but the absorption half-width is dependent only upon pressure. These results are interpreted qualitatively in terms of changes occurring in the intermolecular potentials of the ground and excited states. Both changes in shape of and separation between the ground and excited state potentials are considered as a function of density. Classical dielectric (Onsager-Böttcher), microscopic dielectric (Wertheim) and microscopic quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute electronic spectra are compared with the experimental results. Calculations suggest limited applicability of dielectric theories but good agreement between experiment and microscopic theory. The results demonstrate the usefulness of cryogenic solutions for high pressure, low temperature spectroscopic studies of liquids.

  2. Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Arul Dhas, D.; Hubert Joe, I.; Roy, S. D. D.; Balachandran, S.

    2011-09-01

    Vibrational analysis of the thionocarbamate fungicide tolnaftate which is antidermatophytic, antitrichophytic and antimycotic agent, primarily inhibits the ergosterol biosynthesis in the fungus, was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features, harmonic vibrational wavenumbers and torsional potential energy surface (PES) scan studies have been computed using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bonding orbital (NBO) analysis and optimized molecular structure show the clear evidence for electronic interaction of thionocarbamate group with aromatic ring. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the phenyl and naphthalene ring provide evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity as a fungicide.

  3. Spectroscopic Study on the Interaction of 4-dimethylaminochalcones with Phospholipids

    NASA Astrophysics Data System (ADS)

    Tomečková, V.; Revická, M.; Sassen, A.; Veliká, B.; Stupák, M.; Perjési, P.

    2014-11-01

    The ultraviolet-visible and fluorescence spectroscopic properties of 4'-dimethylaminochalcone ( 1a) and its cyclic analogs 2a-4a have been studied in the presence of phospholipid vesicles (i.e., egg yolk lecithin and dipalmitoylpho sphatidylcholine), bovine serum albumin (BSA), and lipoprotein particles (i.e., bovine serum albumin plus egg yolk lecithin). The spectral results showed that compounds 1a-4a formed hydrophobic interactions with the phospholipids, lipoproteins, and BSA at the polar/nonpolar interface. Compounds 3a and 4a exhibited the strongest hydrophobic interactions of all of the compounds tested towards the phospholipids. Compound 2a gave the best fluorescent fluorophore indicating interactions with the lipids, lipoproteins, and proteins. Fluorescent microscopic imaging of breast cancer cells treated with compounds 1a-4a revealed that they could be used to stain all of the cellular components and destroy the nuclear structure. Compounds 1a-4a were found to be concentrated predominantly on the surfaces of the liposomes and lipoproteins.

  4. Spectroscopic and molecular docking studies on chlorambucil interaction with DNA.

    PubMed

    Charak, Sonika; Shandilya, Manish; Tyagi, Gunjan; Mehrotra, Ranjana

    2012-11-01

    Chlorambucil (CMB) is an anticancer drug used for the treatment of variety of cancers. Structural and conformational changes associated with DNA after binding with CMB were explored using spectroscopic techniques to get insight into the mechanism of action of CMB at molecular level. Different molar ratios of CMB-DNA complex were prepared with constant DNA concentration under physiological conditions. FTIR spectroscopy, UV-visible spectroscopy, CD spectroscopy and molecular docking studies were employed to determine the binding site and binding constant of CMB with DNA. The results show CMB binds DNA through nitrogenous bases (thymine, guanine and cytosine). The binding constant was calculated to be 1.3 × 10³ M⁻¹, which suggests weak binding of CMB with DNA double helix. FTIR and CD results show that CMB do not disturb native B-conformation of DNA and it continues to remain in its B conformation even at higher concentrations of CMB. The molecular docking results are in corroboration with our experimental results and provides structural insight into the interaction site. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Spectroscopic Studies of Dehydrogenation of Ammonia Borane in Carbon Cryogel

    SciTech Connect

    Sepehri, Saghar; Feaver, Aaron M.; Shaw, Wendy J.; Howard, Christopher J.; Zhang, Qifeng; Autrey, Thomas; Cao, Guozhong

    2007-12-27

    The reaction pathways leading to the thermal decomposition of solid state ammonia borane (AB) incorporated in carbon cryogels (CC) have been studied by spectroscopic methods. The time dependent thermal decomposition was followed by in situ 11B NMR and showed a significant increase in hydrogen release kinetics. Both 11B NMR and Fourier Transform Infrared Spectroscopy (FTIR) show new reaction products formed in the thermal decomposition of AB-CC that are assigned to reactions with surface oxygen groups. The results indicate that incorporation of AB in CC enhance kinetics due to reactions with residual surface-bound oxygen functional groups. The formation of new products with surface-O-B bonds is consistent with the greater reaction exothermicity observed when hydrogen is released from AB-CC materials. Scanning electron microscopy (SEM) shows different morphology of AB in ammonia borane – carbon cryogel (AB-CC) nanocomposite as compared to neat AB. Support for this work is provided by NSF (DMR-0605159), WTC, and EnerG2 LLC as well as the DoE Center of Excellence in Chemical Hydrogen Storage funded by the DOE H2 Program. FTIR experiments were performed in Professor Zhang’s lab in MSE department at UW. Part of this research was performed in the William R. Wiley Environmental Molecular Sciences Laboratory, located at the Pacific Northwest National Laboratory, which is operated by the Battelle for the U.S. Department of Energy.

  6. Vibrational spectroscopic study of vinyl substituted polycyclic aromatic hydrocarbons.

    PubMed

    Maurya, Anju; Rastogi, Shantanu

    2015-12-05

    The mid infrared emission features observed in various astrophysical sources are attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The models of emission spectra from a collection of PAHs show uncertainty in matching the 6.2 μm feature. This indicates the need to consider a larger variety of PAHs and PAH derivatives. Chemical pathways towards formation of PAHs in the astrophysical environments involve vinyl substituted PAHs as intermediate products. Vibrational spectroscopic study of vinyl-PAHs is reported in the present work. The vinyl group is substituted at similar positions in eight different PAHs. The obtained optimized structures show that vinyl substitution at 2 position in acenes gives planar geometry, while all other vinyl-PAHs are non-planar. Infrared spectra is simulated for neutrals as well as for cations. The results are compared with the spectra of corresponding plain PAHs and analyzed for possible match with astrophysical observations. New features, due to vinyl group in the composite spectra, identified at 6.64, 6.92, 7.27, 8.77 and 10.35 μm fall close to some sub features of the observed emission spectra. The paper provides data that may be used in the emission models particularly along proto planetary nebulae type cool objects. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Molecular docking, spectroscopic studies and quantum calculations on nootropic drug.

    PubMed

    Uma Maheswari, J; Muthu, S; Sundius, Tom

    2014-04-05

    A systematic vibrational spectroscopic assignment and analysis of piracetam [(2-oxo-1-pyrrolidineacetamide)] have been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G++(d,p) basis set. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, and harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption wavelengths λmax were determined by the time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PED) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. Molecular docking studies have been carried out in the active site of piracetam by using Argus Lab. In addition, the potential energy surface, HOMO and LUMO energies, first-order hyperpolarizability and the molecular electrostatic potential have been computed.

  8. NO binding kinetics in myoglobin investigated by picosecond Fe K-edge absorption spectroscopy

    PubMed Central

    Silatani, Mahsa; Lima, Frederico A.; Penfold, Thomas J.; Rittmann, Jochen; Reinhard, Marco E.; Rittmann-Frank, Hannelore M.; Borca, Camelia; Grolimund, Daniel; Milne, Christopher J.; Chergui, Majed

    2015-01-01

    Diatomic ligands in hemoproteins and the way they bind to the active center are central to the protein’s function. Using picosecond Fe K-edge X-ray absorption spectroscopy, we probe the NO-heme recombination kinetics with direct sensitivity to the Fe-NO binding after 532-nm photoexcitation of nitrosylmyoglobin (MbNO) in physiological solutions. The transients at 70 and 300 ps are identical, but they deviate from the difference between the static spectra of deoxymyoglobin and MbNO, showing the formation of an intermediate species. We propose the latter to be a six-coordinated domed species that is populated on a timescale of ∼200 ps by recombination with NO ligands. This work shows the feasibility of ultrafast pump–probe X-ray spectroscopic studies of proteins in physiological media, delivering insight into the electronic and geometric structure of the active center. PMID:26438842

  9. Measurements of Electron Transport in Foils Irradiated with a Picosecond Time Scale Laser Pulse

    SciTech Connect

    Brown, C. R. D.; Hoarty, D. J.; James, S. F.; Swatton, D.; Hughes, S. J.; Morton, J. W.; Guymer, T. M.; Hill, M. P.; Chapman, D. A.; Andrew, J. E.; Comley, A. J.; Shepherd, R.; Dunn, J.; Chen, H.; Schneider, M.; Brown, G.; Beiersdorfer, P.; Emig, J.

    2011-05-06

    The heating of solid foils by a picosecond time scale laser pulse has been studied by using x-ray emission spectroscopy. The target material was plastic foil with a buried layer of a spectroscopic tracer material. The laser pulse length was either 0.5 or 2 ps, which resulted in a laser irradiance that varied over the range 10{sup 16}-10{sup 19} W/cm{sup 2}. Time-resolved measurements of the buried layer emission spectra using an ultrafast x-ray streak camera were used to infer the density and temperature conditions as a function of laser parameters and depth of the buried layer. Comparison of the data to different models of electron transport showed that they are consistent with a model of electron transport that predicts the bulk of the target heating is due to return currents.

  10. Process and parameter optimisation for micro structuring of 3D freeform metallic surfaces: a comparative study of short-pulse (nanosecond) and ultrafast (picosecond, femtosecond) laser ablation

    NASA Astrophysics Data System (ADS)

    Scholz, Steffen G.; Sampaio, Daniel J. B. S.; Mangang, Melanie; Pfleging, Wilhelm

    2017-02-01

    Layer-based laser ablation of three dimensional micro structured freeform surfaces has become of significant importance for technical applications such as biomimetic surfaces in recent years. In order to identify the optimum set of process parameters for a complex laser ablation operation, a design of experiments (DoE) study has been carried out with laser sources covering pulse durations regime of femtosecond (fs), picosecond (ps) and nanosecond (ns). The aim was to identify the optimum parameter set for achieving best surface roughness and, as a second criteria, for machining time to be reduced to a minimum. In a first step, rectangular pockets have been machined and a DoE based parameter variation was performed. In particular, the parameters wavelength (1030 nm, 515 nm, 343 nm), machining speed, laser power, and laser pulse duration (fs, ps, ns) have been modified. Surface roughness and ablated depth were measured and an optimum set of parameters was calculated. The results show that the ultraviolet laser type (343nm) has the best performance to achieve lowest surface roughness and with a laser pulse duration of 3445 fs reaches also the best ablation efficiency in relation to machining time. While machining speed and laser power have an almost linear influence on achievable roughness, laser pulse duration has a quadratic influence in relation to a global minimum on the surface roughness result. For the ablated depth, machining speed and laser power have an almost linear influence while laser pulse duration has a quadratic influence in relation to a global maximum.

  11. A comparative study of emission efficiencies in low-pressure argon plasmas induced by picosecond and nanosecond Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Mangasi Marpaung, Alion; Ramli, Muliadi; Idroes, Rinaldi; Suyanto, Hery; Lahna, Kurnia; Nur Abdulmadjid, Syahrun; Idris, Nasrullah; Pardede, Marincan; Hedwig, Rinda; Sukra Lie, Zener; Putra Kurniawan, Davy; Hendrik Kurniawan, Koo; Jie Lie, Tjung; Tjia, May On; Kagawa, Kiichiro

    2016-11-01

    An experimental study is performed on the comparative advantages of nanosecond (ns) and picosecond (ps) lasers in laser-induced breakdown spectroscopy (LIBS) analysis. The experiment focused on the relative efficiencies of the plasma emission induced by the two lasers in low-pressure Ar ambient gas for samples of various hardnesses. It is shown that the emission intensities are consistenly reduced when the ns laser is replaced by the ps laser. This is explained as the consequence of the increased power density delivered by the ps laser, which results in a time mismatch between the passage of the ablated atoms and the formation of the shock wave. The time mismatch in turn leads to less effective thermal excitation by the shock wave plasma and the hence reduced emission intensity. Furthermore, this adverse effect is found to worsen for softer samples due to the slower formation of the shock wave. These results are obtained with the same volumes of craters produced by the two lasers on the same sample, which implies that ns laser irradiation has higher emission efficiency than ps laser irradiation.

  12. Study on vibrational relaxation dynamics of phenol-water complex by picosecond time-resolved IR-UV pump-probe spectroscopy in a supersonic molecular beam

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yasunori; Inokuchi, Yoshiya; Ebata, Takayuki; Petković, Milena

    2013-06-01

    A comparative study of vibrational energy relaxation (VER) between the monohydrated complexes of phenol-d0 and phenol-d1 is investigated in a supersonic molecular beam. The direct time-resolved measurement of energy redistribution from the phenolic OH/OD stretching mode of the phenol-d0-H2O/phenol-d1-D2O is performed by picosecond IR-UV pump-probe spectroscopy. Two complexes follow the same relaxation process that begins with the intramolecular vibrational energy redistribution (IVR) and the intermolecular vibrational energy redistribution (IVR), which is followed by the vibrational predissociation (VP). The difference in the relaxation lifetimes between them is discussed by anharmonic force field and RRKM calculations. Anharmonic analysis implies that intra- (IVR) and intermolecular (IVR) relaxations occur in parallel in the complexes. The RRKM-predicted dissociation (VP) lifetimes show qualitative agreement with the observed results, suggesting that VP takes place after the statistical energy distribution in the complexes.

  13. Optothermal response of plasmonic nanofocusing lens under picosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Du, Z.; Chen, C.; Traverso, L.; Xu, X.; Pan, L.; Chao, I.-H.; Lavine, A. S.

    2014-03-01

    This work studied the optothermal response of plasmonic nanofocusing structures under picosecond pulsed laser irradiation. The surface plasmon polariton is simulated to calculate the optical energy dissipation as the Joule heating source and the thermal transport process is studied using a two temperature model (TTM). At the picosecond time scale that we are interested in, the Fourier heat equation is used to study the electron thermal transport and the hyperbolic heat equation is used to study the lattice thermal transport. For comparison, the single temperature model (STM) is also studied. The difference between TTM and STM indicates that TTM provides more accurate estimates in the picosecond time scale and the STM results are only reliable when the local electron and lattice temperature difference is negligible.

  14. Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone

    NASA Astrophysics Data System (ADS)

    Gu, Chunju; Katti, Dinesh R.; Katti, Kalpana S.

    2013-02-01

    Chemical pretreatment has been the prevailing sample preparation procedure for infrared (IR) spectroscopic studies on bone. However, experiments have indicated that chemical pretreatment can potentially affect the interactions between the components. Typically the IR techniques have involved transmission experiments. Here we report experimental studies using photoacoustic Fourier transform infrared spectroscopy (PA-FTIR). As a nondestructive technique, PA-FTIR can detect absorbance spectrum from a sample at controllable sampling depth and with little or no sample preparation. Additionally, the coupling inert gas, helium, which is utilized in the PA-FTIR system, can inhibit bacteria growth of bone by displacing oxygen. Therefore, we used this technique to study the undisturbed human cortical bone. It is found that photoacoustic mode (linear-scan, LS-PA-FTIR) can obtain basically similar spectra of bone as compared to the traditional transmission mode, but it seems more sensitive to amide III and ν2 carbonate bands. The ν3 phosphate band is indicative of detailed mineral structure and symmetry of native bone. The PA-FTIR depth profiling experiments on human cortical bone also indicate the influence of water on OH band and the cutting effects on amide I and mineral bands. Our results indicate that phosphate ion geometry appears less symmetric in its undisturbed state as detected by the PA-FTIR as compared to higher symmetry observed using transmission techniques on disturbed samples. Moreover, the PA-FTIR spectra indicate a band at 1747 cm-1 possibly resulting from Cdbnd O stretching of lipids, cholesterol esters, and triglycerides from the arteries. Comparison of the spectra in transverse and longitudinal cross-sections demonstrates that, the surface area of the longitudinal section bone appears to have more organic matrix exposed and with higher mineral stoichiometry.

  15. Picosecond spectroscopy of dihydro biliverdin

    NASA Astrophysics Data System (ADS)

    Ditto, Manfred; Brunner, Harald; Lippitsch, Max E.

    1991-10-01

    Picosecond time-resolved fluorescence and absorption spectroscopy was performed on dihydro biliverdin, a model for the chromophore in the plant pigment phytochrome, a chromoprotein governing plant growth. Close agreement between the model compound and the native chromophore proves the importance of the saturated pyrrol ring for the decay kinetics and renders chromophore protonation in phytochrome unlikely.

  16. Lead sorption on ruthenium oxide: a macroscopic and spectroscopic study.

    PubMed

    Scheckel, Kirk G; Impellitteri, Christopher A; Ryan, James A

    2004-05-15

    The sorption and desorption of Pb on RuO2.xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity and interaction of nearest atomic neighbors, bond distances (R), and coordination numbers (N). The kinetics of the Pb-Ru-oxide sorption reaction are rapid with the equilibrium loading of Pb on the surface achieving approximately 1:1 wt/wt (129 micromol m(-2)). XAS data indicate that Pb adsorbed as bidentate innersphere complexes with first shell Pb-O parameters of RPb-O = 2.27 A and NPb-O = 2.1-2.5. Pb-Ru interatomic associations suggest two distinct bidentate surface coordinations of Pb to edges (RPb-RuI approximately 3.38 A, NPb-RuI approximately 1.0) and shared corners (RPb-RuII approximately 4.19 A, NPb-RuII approximately 0.8) on RuO2 octahedra (cassiterite-like structure), and an additional second neighbor backscattering of Pb indicates the formation of Pb-Pb dimers (RPb-Pb degrees 3.89 A, NPb-Pb approximately 0.9). Desorption studies as a function of aging time (1 h to 1 year) using a continuous stirred-flow reactor with a background electrolyte (0.01 M NaNO3, pH 6) demonstrated that Pb was tightly bound (99.7-99.9% retained). The Pb sorption capacity and retention on RuO2.xH2O is greater than that of other metal oxides examined in the literature. The results of this study imply that RuO2.xH2O may serve as a high capacity remediation treatment media.

  17. Effect of temperature on the methotrexate BSA interaction: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Maciążek, M.; Równicka, J.; Bojko, B.; Pentak, D.; Sułkowski, W. W.

    2007-05-01

    Rheumatoid arthritis (RA) is an autoimmune and chronic inflammatory illness which affects about one percent of the world's population. Methotrexate (4-amino-10-methylfolic acid) (MTX) also known as amethopterin is commonly used to treat rheumatoid arthritis (RA). It is transported in the circulary system as a complex with serum albumin. The aim of this study was to investigate the interactions of MTX with transporting protein with the use of spectroscopic methods. The binding of MTX to bovine serum albumin (BSA) was studied by monitoring the changes in the emission fluorescence spectra of protein in the presence of MTX at excitation wavelength of 280 nm and 295 nm. The quenching of protein fluorescence at temperature range from 298 K to 316 K was observed. Energy transfer between methotrexate and fluorophores contained in the serum albumin structure was found at the molar ratio MTX:BSA 7.5:1. The relative fluorescence intensity of BSA decreases with increase of temperature. Similar results were observed for BSA excited with 280 nm and 295 nm at the same temperature range. The presence of MTX seems to prevent these changes. Temperature dependence of the binding constant has been presented. The binding and quenching constants for equilibrium complex were calculated using Scatchard and Stern-Volmer method, respectively. The results show that MTX forms π-π complex with aromatic amino acid residues of BSA. The binding site for MTX on BSA was found to be situated in the hydrophobic IIA or IB subdomain where the Trps were located. The spontaneity of MTX-BSA complex formation in the temperature range 298-316 K was ascertained.

  18. Spectroscopic study of graphene oxide membranes exposed to ultraviolet light

    SciTech Connect

    Schwenzer, Birgit; Kaspar, Tiffany C.; Shin, Yongsoon; Gotthold, David W.

    2016-05-16

    Research on graphene oxide (GO) as anything but a precursor material for synthesizing graphene started to pick up in 20061,2 and was soon followed by a first report of freestanding GO membranes (also referred to as GO paper) from R. S. Ruoff’s group at Northwestern University.3 The first GO membranes were prepared by vacuum filtration. More recently, larger scale GO membranes have been prepared by tape casting4 and other methods.5 In step with the development of new fabrication techniques, GO membranes are now tested for a wide array of applications6 ranging from energy-related4,7 or biomedical8 applications to more conventional uses for filtration9 and dehumidification.10 For all these proposed and implemented applications it remains to be seen how sensitive each of them is with respect to chemical and physical changes of the GO membranes over time. In this study, we report the effects of UV exposure on 2D-hierarchically stacked (Fig. S1 in ESI†) GO membranes. Macroscopically observable changes, such as darkening and mechanical deformation, have been correlated to chemical changes at the molecular level through spectroscopic measurements. Not only do the results of this work offer insights into the stability of GO membranes under UV light, but the findings will enable researchers, who are studying the use of these materials for different applications, to better understand the shelf life and packaging requirements for GO membranes. Furthermore, our results demonstrate the feasibility of deep ultraviolet (DUV) photolithography for graphene oxide-based devices. This approach is readily scalable as opposed to previous reports on photolithographic patterned reduction of GO to graphene by AFM,11 electron-beam12 or with an extreme ultraviolet (λ = 46.9 nm) laser.13

  19. A spectroscopic study of anomalous stellar populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney Elizabeth

    A population of stars exists in the old, open cluster M67, whose photometry, color magnitude diagram locations and associated evolutionary states cannot be explained by current, standard single star evolution theory. These stars are often referred to as "yellow straggler" stars. Yellow stragglers have been identified in multiple star clusters suggesting that these stars constitute a real population. Additionally, according to independent studies, at least some of the yellow straggler stars in M67 are likely cluster members. Therefore, cluster non-membership is not a sufficient explanation for the observed anomalous photometry of these stars. It is possible that the yellow stragglers occupy their precarious color magnitude diagram positions as a result of the evolution of mass transfer blue straggler stars. These are stars which have been formed by Roche Lobe overflow mass transfer in close binary systems. If this the case for the yellow stragglers, it is hypothesized that they could potentially exhibit two spectroscopic characteristics that can be indicative of this type of mass transfer system. Specifically, variable radial velocities can be used to indicate that the yellow stragglers exist in binary systems and enhancements of s-process elements in yellow stragglers can indicate Roche Lobe overflow mass transfer from a once asymptotic giant branch star which has since evolved into a white dwarf. This dissertation details the radial velocity survey and the chemical abundance analysis that have been conducted to investigate the yellow stragglers with regard to this hypothesis. The radial velocity survey revealed that eight of the ten yellow stragglers studied exhibit variable radial velocities indicating that the yellow straggler population of M67 possess a high binary frequency. However, the chemical abundance analysis revealed that none of the yellow stragglers exhibited enhancements of the s-process elements Y and Ba. Therefore, a history which involves Roche

  20. The spectroscopic study of building composites containing natural sorbents

    NASA Astrophysics Data System (ADS)

    Król, M.; Mozgawa, W.

    2011-08-01

    This work presents the results of FT-IR spectroscopic studies of heavy metal cations (Ag +, Pb 2+, Zn 2+, Cd 2+ and Cr 3+) immobilization from aqueous solutions on natural sorbents. The sorption has been conducted on sodium forms of zeolite (clinoptilolite) and clay minerals (mixtures containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. In the next part of the work both sorbents were used to obtain new building composites. It was proven those heavy metal cations' sorption causes changes in IR spectra of the zeolite and clay minerals. These alterations are dependent on the way the cations were sorbed. In the case of zeolite, variations of the bands corresponding to the characteristic ring vibrations have been observed. These rings occur in pseudomolecular complexes 4-4-1 (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. The most significant changes have been determined in the region of pseudolattice vibrations (650-700 cm -1). In the instance of clay minerals, changes in the spectra occur at two ranges: 1200-800 cm -1 - the range of the bands assigned to asymmetric Si-O(Si,Al) and bending Al-OH vibrations and 3800-3000 cm -1 - the range of the bands originating from OH - groups stretching vibrations. Next results indicate possibilities of applying the used natural sorbents for the obtainment of new building materials having favourable composition and valuable properties. The zeolite was used for obtaining autoclaved materials with an addition of CaO, and the clay minerals for ceramic sintered materials with an addition of quartz and clinoptilolite were produced. FT-IR studies were also conducted on the obtained materials.

  1. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...

  2. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...

  3. Optical and spectroscopic study of erbium doped calcium borotellurite glasses

    NASA Astrophysics Data System (ADS)

    Gomes, J. F.; Lima, A. M. O.; Sandrini, M.; Medina, A. N.; Steimacher, A.; Pedrochi, F.; Barboza, M. J.

    2017-04-01

    In this study, 10CaF2 - (29.9-0.4x)CaO - (60-0.6x)B2O3 - xTeO2 - 0,1Er2O3 (x = 10, 16, 22, 30 and 50 mol %) glasses were synthesized, and their optical and spectroscopic properties were investigated. X-ray diffraction, density, glass transition temperature (Tg), crystallization temperature (Tx), refraction index, luminescence, radiative lifetime and optical absorption measurements were carried out. Molar volume (Vm), thermal stability (Tx-Tg), electronic polarizability (αm), optical bang gap energy (Eg) and Judd-Ofelt (JO) parameters Ωt (2,4,6) were also calculated. The results are discussed in terms of tellurium oxide content. The increase of TeO2 in the glasses composition increases density, refractive index and electronic polarizability. The optical band gap energy decreases varying from 3.37 to 2.71 eV for the glasses with 10 and 50 mol% of TeO2, respectively. The optical absorption coefficient spectra show characteristic bands of Er3+ ions. Furthermore, these spectra in NIR region show a decrease of hydroxyl groups as a function of TeO2 addition. Luminescence intensity and radiative lifetimes at 1530 nm show an increasing with the TeO2 content. The JO parameters of Er:CaBTeX glasses follow the trend Ω2 > Ω4 > Ω6 and the quality factor values (Ω4/Ω6) were between 1.37 and 3.07. By comparing the measured lifetime with the calculated radiative decay time, quantum efficiency was calculated. The luminescence emission intensity at 1530 nm decreases with the increase of temperature. The lifetime values show a slight trend to decrease with the temperature increase, from 300 to 420 K, for all the samples.

  4. Preparation of water soluble L-arginine capped CdSe/ZnS QDs and their interaction with synthetic DNA: Picosecond-resolved FRET study

    SciTech Connect

    Giri, Anupam; Goswami, Nirmal; Lemmens, Peter; Pal, Samir Kumar

    2012-08-15

    Graphical abstract: Förster resonance energy transfer (FRET) studies on the interaction of water soluble arginine-capped CdSe/ZnS QDs with ethidium bromide (EB) labeled synthetic dodecamer DNA. Highlights: ► We have solubilized CdSe/ZnS QD in water replacing their TOPO ligand by L-arginine. ► We have studied arginine@QD–DNA interaction using FRET technique. ► Arginine@QDs act as energy donor and ethidium bromide-DNA acts as energy acceptor. ► We have applied a kinetic model to understand the kinetics of energy transfer. ► Circular dichroism studies revealed negligible perturbation in the DNA B-form in the arg@QD-DNA complex. -- Abstract: We have exchanged TOPO (trioctylphosphine oxide) ligand of CdSe/ZnS core/shell quantum dots (QDs) with an amino acid L-arginine (Arg) at the toluene/water interface and eventually rendered the QDs from toluene to aqueous phase. We have studied the interaction of the water soluble Arg-capped QDs (energy donor) with ethidium (EB) labeled synthetic dodecamer DNA (energy acceptor) using picoseconds resolved Förster resonance energy transfer (FRET) technique. Furthermore, we have applied a model developed by M. Tachiya to understand the kinetics of energy transfer and the distribution of acceptor (EB-DNA) molecules around the donor QDs. Circular dichroism (CD) studies revealed a negligible perturbation in the native B-form structure of the DNA upon interaction with Arg-capped QDs. The melting and the rehybridization pathways of the DNA attached to the QDs have been monitored by the CD which reveals hydrogen bonding is the associative mechanism for interaction between Arg-capped QDs and DNA.

  5. Spectroscopic studies of cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Totir, Dana Alexa

    2000-10-01

    Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ measurements allows direct correlations to be made between the state of charge of the material and its structural and electronic characteristics. LiCoO2, LiMn2O4 and LiCo0.15Ni 0.85O2 electrodes were evaluated using cycling voltammetry and the mean diffusion coefficient for Li-ions in the lattice (DLi) was calculated for LiMn2O4. LiMn2O4 electrodes prepared by this technique have been studied in situ using Mn K-edge XAS. Data analysis for the species formed at different potentials indicated a contraction of the lattice associated with the increase in the oxidation state of manganese. In situ Raman spectra of particles of LiMn2O 4, and LiCoO2 embedded in Au and also of KS-44 graphite and carbon microfibers MCF28 embedded in thermally annealed Ni have been recorded as a function of the applied potential. Fe K-edge XAFS of pyrite electrodes in a Li/PEO(LiClO4)/FeS 2 cell and S K-edge XANES measurements of a FeS2 electrode in a non-aqueous electrolyte have been acquired as a function of the state of charge. The studies have clearly evidenced the formation of metallic Fe and Li2S as intermediates after 4 e- discharge and the formation of Li2FeS2 after 2 e- recharge. While Fe K-edge studies have indicated that there is no change in the Fe environment and oxidation state upon 4 e- recharge, the results obtained from S K-edge studies are inconclusive for this stage. Finally, in situ Co K-edge XAFS data were obtained for the first time during the electrochemical cycling of electrodeposited Co(OH) 2 films in alkaline solutions. The results support

  6. Spectroscopic studies of uranium species for environmental decontamination applications

    NASA Astrophysics Data System (ADS)

    Eng, Charlotte

    After the Cold War, Department of Energy began to concentrate its efforts on cleanup of former nuclear material processing facilities, especially uranium-contaminated groundwater and soil. This research aims to study uranium association to both organic and inorganic compounds found in the contaminated environment in the hopes that the information gathered can be applied to the development and optimization of cost-effective remediation techniques. Spectroscopic and electrochemical methods will be employed to examine the behavior of uranium in given conditions to further our understanding of its impact on the environment. Uranium found in groundwater and soil bind with various ligands, especially organic ligands present in the environment due to natural sources (e.g. metabolic by-products or degradation of plants and animals) or man-made sources (e.g. chelating agents used in operating or cleanup of uranium processing facilities). We selected reasonable analogs of naturally occurring matter and studied their structure, chemical and electrochemical behavior and found that the structure of uranyl complexes depends heavily on the nature of the ligand and environmental factors such as pH. Association of uranium-organic complexes with anaerobic bacteria, Clostridium sp. was studied to establish if the bacteria can effectively bioreduce uranium while going through normal bacterial activity. It was found that the nature of the organic ligand affected the bioavailability and toxicity of the uranium on the bacteria. In addition, we have found that the type of iron corrosion products and uranyl species present on the surface of corroded steel depended on various environmental factors, which subsequently affected the removal rate of uranium by a citric acid/hydrogen peroxide/deionized water cleaning process. The method was found to remove uranium from only the topmost corrosion layers and residual uranium could be found (a) deeper in the corrosion layers where it is occluded by

  7. X-ray spectroscopic studies of secondary battery materials

    NASA Astrophysics Data System (ADS)

    Kostov, Svilen Dimitar

    1998-09-01

    X-ray spectroscopic methods, both NEXAFS and EXAFS were used in the study of the structural and electronic properties of different types of new battery materials. NEXAFS analysis of the spectra of Lisb{1-x}CoO2 secondary battery cathodes revealed that the addition of Li proceeds is strongly correlated to the increase in electronic charge on the Co ion. A structural phase transition is confirmed for x=0.5. The presence of Mnsp{+2} is detected in the conventionally made LiMnOsb2 cathodes but not in ones prepared according to the new ADL process. Lisb{x}Vsb6Osb{13} cathode material, where 0≤ x≤6, was measured using x-ray absorption, EPR and NMR techniques. The intercalation mechanism involves a conversion of Vsp{+5} to Vsp{+4} in Vsb6Osb{13} until the composition Lisb2Vsb6Osb{13} is reached. Further addition of lithium is accompanied by the conversion of Vsp{+4} to Vsp{+3} until Lisb8Vsb6Osb{13} is reached. The process is complicated and involves structural phase changes and increasing structural disorder within the multi-phase system as Li concentration is increased. Studies of LiNi/CoOsb2 intercalation cathodes prepared by a novel sol-gel technique suggests that although the partial substitution of Co for Ni stabilizes the system by removing Nisp{+2}, a Jahn-Teller type structural distortion in the predominantly Nisp{=3} system persists. In-situ EXAFS measurements of the pyrite cathode in a new Li/CPE/FeSsb2 showed two distinct environments of the Fe ion, which were interpreted as those of metallic Fe and residual FeSsb2 at high lithium concentration, and Lisb2FeSsb2 and residual FeSsb2 at low lithium concentration. The formation of FeS was not detected. A new type of hydrogen ion battery incorporating a MnSOsb4sp&*slash;Hsb2O based cathode and polymer electrolyte was also studied. Heavily cycled and discharged cathodes showed an almost identical Mn local structure to that of single cycled ones. The Mn environment becomes very different in the charged cathodes

  8. Spectroscopic Studies of the Several Isomers of UO3

    SciTech Connect

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-09-26

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  9. Structural, spectroscopic and theoretical study of novel ephedrinum salt

    NASA Astrophysics Data System (ADS)

    Ivanova, B.; Kolev, T.; Lamshöft, M.; Mayer-Figge, H.; Seidel, R.; Sheldrick, W. S.; Spiteller, M.

    2010-05-01

    Ephedrinum violurate dihydrate was synthesized, spectroscopically and structural elucidated. The data are compared with those of the free-base ephedrine hemihydrate. Discussion on the stable conformer of the ephedrinum cation is carried out. Quantum chemical calculations were performed for the theoretical elucidation of the conformational preference of the ephedrinum cation and its vibrational properties. The model systems neutral ephedrine hemihydrate ( 1) and violurate salt dihydrate ( 2) are elucidated.

  10. The electronic structure of pyracene: a spectroscopic and computational study.

    PubMed

    Auerswald, Johannes; Engels, Bernd; Fischer, Ingo; Gerbich, Thiemo; Herterich, Jörg; Krueger, Anke; Lang, Melanie; Schmitt, Hans-Christian; Schon, Christof; Walter, Christof

    2013-06-07

    We report a synthetic, spectroscopic and computational study of the polycyclic aromatic molecule pyracene, which contains aliphatic five-membered rings annealed to a naphthalene chromophore. An improved route to synthesize the compound is described. Gas-phase IR and solid-state Raman spectra agree with a ground-state D2h structure. The electronically excited S1 A(1)B3u state has been studied by resonance-enhanced multiphoton ionisation. An adiabatic excitation energy T0 = 30,798 cm(-1) (3.818 eV) was determined. SCS-ADC(2) calculations found a D2h minimum energy structure of the S1 state and yielded an excitation energy of +3.98 eV, including correction for zero point vibrational energy. The spectrum shows a rich low-frequency vibrational structure that can be assigned to the overtones of out-of-plane deformation modes of the five-membered rings by comparison with computations. The appearance of these modes as well as the frequency reduction in the excited state indicate that the potential in the S1 state is very flat. At higher excess energies most bands can be assigned to fundamentals, overtones and combination bands of either totally symmetric ag modes or of b2g modes that appear due to vibronic coupling. Lifetimes between 43 ns and 76 ns were measured for a number of vibronic bands. For the S2 state an equilibrium geometry with a non-planar carbon framework was computed. In addition a signal from the pyracene dimer was present. The spectrum shows several broad and structureless transitions. The origin band has a maximum at around 329 nm (30,400 cm(-1)). Again lifetimes between 60 ns and 70 ns were found. The dimer ion signal rises within less than 10 ps. Computations show that a crossed geometry with the long axis of one unit aligned with the short axis of the second constitutes the most stable structure. The broadening of the bands is most likely caused by excimer formation.

  11. A comparative study of pressure-dependent emission characteristics in different gas plasmas induced by nanosecond and picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers.

    PubMed

    Abdulmadjid, Syahrun Nur; Idris, Nasrullah; Marpaung, Alion Mangasi; Pardede, Marincan; Jobiliong, Eric; Hedwig, Rinda; Suliyanti, Maria Margaretha; Ramli, Muliadi; Suyanto, Heri; Kagawa, Kiichiro; Tjia, May On; Lie, Zener Sukra; Lie, Tjung Jie; Kurniawan, Hendrik Koo

    2013-11-01

    An experimental study has been performed on the pressure-dependent plasma emission intensities in Ar, He, and N2 surrounding gases with the plasma induced by either nanosecond (ns) or picosecond (ps) yttrium aluminum garnet laser. The study focused on emission lines of light elements such as H, C, O, and a moderately heavy element of Ca from an agate target. The result shows widely different pressure effects among the different emission lines, which further vary with the surrounding gases used and also with the different ablation laser employed. It was found that most of the maximum emission intensities can be achieved in Ar gas plasma generated by ps laser at low gas pressure of around 5 Torr. This experimental condition is particularly useful for spectrochemical analysis of light elements such as H, C, and O, which are known to suffer from intensity diminution at higher gas pressures. Further measurements of the spatial distribution and time profiles of the emission intensities of H I 656.2 nm and Ca II 396.8 nm reveal the similar role of shock wave excitation for the emission in both ns and ps laser-induced plasmas, while an additional early spike is observed in the plasma generated by the ps laser. The suggested preference of Ar surrounding gas and ps laser was further demonstrated by outperforming the ns laser in their applications to depth profiling of the H emission intensity and offering the prospect for the development of three-dimensional analysis of a light element such as H and C.

  12. Molecular collision processes in the presence of picosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Lee, H. W.; George, T. F.

    1979-01-01

    Radiative transitions in molecular collision processes taking place in the presence of picosecond pulses are studied within a semiclassical formalism. An expression for adiabatic potential surfaces in the electronic-field representation is obtained, which directly leads to the evaluation of transition probabilities. Calculations with a Landau-Zener-type model indicate that picosecond pulses can be much more effective in inducing transitions than a single long pulse of the same intensity and the same total energy, if the intensity is sufficiently high that the perturbation treatment is not valid.

  13. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    NASA Astrophysics Data System (ADS)

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  14. Spectroscopic and structural studies of environmentally relevant neptunyl carbonate complexes

    SciTech Connect

    Palmer, P.D.; Clark, D.L.; Neu, M.P.

    1995-12-01

    Carbonate and bicarbonate are common anions in many natural waters, consequently carbonate complexes of the actinides may play an important role in actinide migration from a nuclear waste repository. Due to its relatively high solubility, neptunium is the most important actinide for consideration. Carbonate complexation was examined for NpO{sub 2}{sup +} and NpO{sub 2}{sup 2+} ions using a variety of techniques including UV-Vis-NIR and NMR spectroscopics. NpO{sub 2}{sup +} carbonates have been difficult to observe by UV-Vis-NIR spectroscopy due to the formation of insoluble NaNp{sub 2}O{sub 2}(CO{sub 3}) or Na{sub 3}NpO{sub 2}(CO{sub 3}){sub 2} salts. However, by employing tetrabutylammonium as the counter cation, millimolar concentrations have been obtained and utilized for temperature dependent carbonate complexation studies by conventional UV-Vis-NIR methods. The NpO{sub 2}{sup 2+} carbonate complexes were examined as a function of pH using {sup 13}C and {sup 17}O NMR spectroscopy. The NMR data are consistent with the formation of NpO{sub 2}(CO{sub 3}){sub 3}{sup 4-} and (NpO{sub 2}){sub 3}(CO{sub 3}){sub 6}{sup 6-}. The pH dependence of the {sup 13}C NMR spectra was used to determine the equilibrium constant for the reaction: 3NpO{sub 2}CO{sub 3}{sub 3}{sup 4-} +3H{sup +}{r_reversible}(NpO{sub 2}){sub 3}(CO{sub 3}){sub 6}{sup 6-}+3HCO{sub 3}{sup -}, log K=19.7({plus_minus}0.8) (I=2.5m). This work was supported by the Yucca Mountain Site Characterization Project Office as part of the Civilian Radioactive Waste Management Program, managed by the U.S. D.O.E., YMP project office.

  15. A Raman Spectroscopic Study of Kernite to 25 GPa

    NASA Astrophysics Data System (ADS)

    Silva, M. E.; O'Bannon, E. F., III; Williams, Q. C.

    2015-12-01

    A Raman spectroscopic study of kernite to 25 GPaMarcus Silva, Earl O'Bannon III, and Quentin Williams Department of Earth & Planetary Sciences, University of California Santa Cruz The Raman spectrum of kernite (Na2B4O6(OH)2·3(H2O)) has been characterized up to ~25 GPa in order to explore pressure-induced changes in a structurally novel mineral that contains mixed coordination borate groups (three- and four-fold), and both hydroxyl units and water. During compression, all of the ~30 modes monitored shift positively and monotonically until ~2.2 GPa where a few low frequency modes disappear and tetrahedral borate modes merge. The low frequency modes that disappear at ~2.2 GPa are likely associated with Na vibrations, and their disappearance suggests that dramatic changes occur in the Na sites at ~2.2 GPa. The merging of the boron bending and stretching modes at ~2.2 GPa suggests that the local symmetry of the BO4 tetrahedra changes at this pressure, and likely becomes more symmetric. The remaining modes shift positively up to ~7.4 GPa where a second notable change occurs. All but 5 modes (with initial frequencies of 150, 166, 289, 307, and 525 cm-1) disappear at ~7.4 GPa. This indicates that a second phase transition has occurred which affects both the BO3H and BO4­ groups: based on the loss of modes, this transition may be associated with disordering of the crystal. These 5 modes persist and shift monotonically up to ~25 GPa. On decompression, the 5 modes shift smoothly down to ~2.0 GPa where a few new modes appear in the spectrum. When fully decompressed to room pressure, the Raman spectrum of the recovered sample is significantly different from the ambient spectrum of the initial sample. Thus, our results are suggest a phase transition occurring at 2.2 GPa with changes in the Na and tetrahedral boron sites, followed by an additional transition at 7.4 GPa that may involve disordering of the crystal. In the latter transition, at least the BO3H groups appear to be

  16. Transport and spectroscopic studies of liquid and polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Bopege, Dharshani Nimali

    trifluoromethanesulfonate, LiCF3SO3, abbreviated here as lithium triflate(LiTf). The molar absorption coefficients of nus(SO3), deltas(CF3), and deltas(SO3) vibrational modes of triflate anion in the LiTf-2-pentanone system were found to be 6708+/-89, 5182+/-62, and 189+/-2 kg mol-1 cm-1, respectively using Beer-Lambert law. Our results show that there is strong absorption by nu s(SO3) mode and weak absorption by deltas(CF 3) mode. Also, the absorptivity of each mode is independent of the ionic association with Li ions. This work allows for the direct quantitative comparison of calculated concentrations in different samples and different experimental conditions. In addition, this dissertation reports the temperature-dependent vibrational spectroscopic studies of pure poly(ethylene oxide) and LiTf-poly(ethylene oxide) complexes. A significant portion of this dissertation focuses on crystallographic studies of ketone-salt (LiTf:2-pentanone and NaTf:2-hexanone) and amine-acid (diethyleneamine: H3PO4, N,N'-dimethylethylenediamine:H 3PO4, and piperazine:H3PO4) systems. Here, sodium trifluoromethanesulfonate, NaCF3SO3 is abbreviated as NaTf. As model compounds, these systems provide valuable information about ion-ion interactions, which are helpful for understanding complex polymer systems. During this study, five crystal structures were solved using single X-ray diffractometry, and their vibrational modes were studied in the mid-infrared region. In the secondary amine/phosphoric acid systems, the nature of hydrogen-bonding network was examined.

  17. Picosecond Fresnel transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Schliep, Karl B.; Quarterman, P.; Wang, Jian-Ping; Flannigan, David J.

    2017-05-01

    We report the demonstration of picosecond Fresnel imaging with an ultrafast transmission electron microscope (UEM). By operating with a low instrument repetition rate (5 kHz) and without objective-lens excitation, the picosecond demagnetization of an FePt film, via in situ, femtosecond laser excitation, is directly imaged. The dynamics are quantified and monitored as a time-dependent change in the degree of electron coherence within the magnetic domain walls. The relative coherence of conventional (thermionic) Fresnel transmission electron microscopy is also directly compared to that of Fresnel UEM through the domain-wall size. Further, the robustness and reversibility of the domain-wall dynamics are illustrated by repeating the picosecond image scans at defocus values having the same magnitude but different signs (e.g., +25 mm vs. -25 mm). Control experiments and approaches to identifying and isolating systematic errors and sources of artifacts are also described. This work, and continued future developments also described here, opens the way to direct correlation of transient structure, morphology, and magnetic dynamics in magnetic thin films and spintronic devices.

  18. Spectroscopic studies of the cytochrome P450 reaction mechanisms.

    PubMed

    Mak, Piotr J; Denisov, Ilia G

    2017-06-28

    The cytochrome P450 monooxygenases (P450s) are thiolate heme proteins that can, often under physiological conditions, catalyze many distinct oxidative transformations on a wide variety of molecules, including relatively simple alkanes or fatty acids, as well as more complex compounds such as steroids and exogenous pollutants. They perform such impressive chemistry utilizing a sophisticated catalytic cycle that involves a series of consecutive chemical transformations of heme prosthetic group. Each of these steps provides a unique spectral signature that reflects changes in oxidation or spin states, deformation of the porphyrin ring or alteration of dioxygen moieties. For a long time, the focus of cytochrome P450 research was to understand the underlying reaction mechanism of each enzymatic step, with the biggest challenge being identification and characterization of the powerful oxidizing intermediates. Spectroscopic methods, such as electronic absorption (UV-Vis), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), electron nuclear double resonance (ENDOR), Mössbauer, X-ray absorption (XAS), and resonance Raman (rR), have been useful tools in providing multifaceted and detailed mechanistic insights into the biophysics and biochemistry of these fascinating enzymes. The combination of spectroscopic techniques with novel approaches, such as cryoreduction and Nanodisc technology, allowed for generation, trapping and characterizing long sought transient intermediates, a task that has been difficult to achieve using other methods. Results obtained from the UV-Vis, rR and EPR spectroscopies are the main focus of this review, while the remaining spectroscopic techniques are briefly summarized. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Spectroscopic study of the extremely fast rotating star 44 Geminorum

    NASA Astrophysics Data System (ADS)

    Iliev, L.; Vennes, S.; Kawka, A.; Kubat, J.; Nemeth, P.; Borisov, G.; KRaus, M.

    Stars with extremely fast rotation represent interesting challenge to modern understanding of the stellar evolution. The reasons why such a spin-up process should occur during the evolution to otherwise normal star are still not well understood. Already in the beginning of the XX century Otto Struve proposed that fast rotation of the group of stars spectroscopically classified as Be could be the main reason for the formation of observed disks of circumstellar material around them. This circumstellar material is responsible for the emission lines observed in the spectrum of Be-stars as well as for the whole complex of spectral and photometrical patterns called in general Be-phenomenon.

  20. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Stimulated emission pumping (SEP) spectroscopy was used on acetylene and on formyl radical. An attempt was made for pattern recognition based on statistics; a method was invented that combined CNPI (complete nuclear permutation-inversion) group theory and SCC (spectral cross-correlation). But the direction away from statistical pattern recognition back to traditional spectroscopic pattern recognition was taken. Vibrational states and quantum numbers are discussed. For the formyl radical, the fluorescence excitation spectrum was recorded and a rotational analysis of the 0(sup 0)(sub 0) band performed.

  1. The use of picosecond lasers beyond tattoos.

    PubMed

    Forbat, E; Al-Niaimi, F

    2016-10-01

    Picosecond lasers are a novel laser with the ability to create a pulse of less than one nanosecond. They have been available in the clinical context since 2012. Dermatologists are now using picosecond lasers regularly for the treatment of blue and green pigment tattoo removal. This article reviews the use of picosecond lasers beyond tattoo removal. The overall consensus for the use of picosecond lasers beyond tattoo treatment is positive. With examples of this in the treatment of nevus of Ota, minocycline-induced pigmentation, acne scarring, and rhytides.

  2. Comparative study of wound healing in rat skin following incision with a novel picosecond infrared laser (PIRL) and different surgical modalities

    PubMed Central

    Tavakoli, Fatemeh; Kruber, Sebastian; Münscher, Adrian; Gliese, Alexandra; Hansen, Nils‐Owe; Uschold, Stephanie; Eggert, Dennis; Robertson, Wesley D.; Gosau, Tobias; Sehner, Susanne; Kwiatkowski, Marcel; Schlüter, Hartmut; Schumacher, Udo; Knecht, Rainald; Miller, R.J. Dwayne

    2016-01-01

    Background and Objective As a result of wound healing the original tissue is replaced by dysfunctional scar tissue. Reduced tissue damage during surgical procedures beneficially affects the size of the resulting scar and overall healing time. Thus the choice of a particular surgical instrument can have a significant influence on the postoperative wound healing. To overcome these problems of wound healing we applied a novel picosecond infrared laser (PIRL) system to surgical incisions. Previous studies indicated that negligible thermal, acoustic, or ionization stress effects to the surrounding tissue results in a superior wound healing. Study Design/Materials and Methods Using the PIRL system as a surgical scalpel, we performed a prospective wound healing study on rat skin and assessed its final impact on scar formation compared to the electrosurgical device and cold steel. As for the incisions, 6 full‐thickness, 1‐cm long‐linear skin wounds were created on the dorsum of four rats using the PIRL, an electrosurgical device, and a conventional surgical scalpel, respectively. Rats were euthanized after 21 days of wound healing. The thickness of the subepithelial fibrosis, the depth and the transverse section of the total scar area of each wound were analyzed histologically. Results After 21 days of wound healing the incisions made by PIRL showed minor scar tissue formation as compared to the electrosurgical device and the scalpel. Highly significant differences (P < 0.001) were noted by comparing the electrosurgical device with PIRL and scalpel. The transverse section of the scar area also showed significant differences (P = 0.043) when comparing PIRL (mean: 141.46 mm2; 95%CI: 105.8–189.0 mm2) with scalpel incisions (mean: 206.82 mm2; 95%CI: 154.8–276.32 mm2). The subepithelial width of the scars that resulted from using the scalpel were 1.3 times larger than those obtained by using the PIRL (95%CI: 1.0–1.6) though the difference was not

  3. Raman spectroscopic study of a genetically altered kidney cell

    NASA Astrophysics Data System (ADS)

    Joshi, Joel; Garcia, Francisco; Centeno, Silvia P.; Joshi, N. V.

    2008-02-01

    A Raman spectroscopic investigation of a genetically altered Human Embryonic Kidney Cell (HEK293) along with a pathologically normal cell has been carried out by a conventional method. The genetic alteration was carried out with a standard protocol by using a Green Fluorescence Protein (GFP). Raman spectra show that there are dramatic differences between the spectrum obtained from a genetically altered cell and that obtained from a pathologically normal cell. The former shows three broad bands; meanwhile the latter shows several sharp peaks corresponding to the ring vibrational modes of Phen, GFP and DNA. The present analysis provides an indication that the force field near Phen located at 64, 65 and 66 was altered during the genetic transformation. The Raman spectrum could be a direct experimental evidence for substantial modifications triggered due to the expression of specific genes.

  4. Structure and vibrational spectroscopic study of alpha-tocopherol

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Sachdeva, Ritika; Rai, Bimal; Saini, G. S. S.

    2017-09-01

    We report here the vibrational and structural analysis of alpha-tocopherol. The vibrational analysis has been accomplished experimentally by infrared and Raman spectroscopic techniques and theoretically by density functional theory. Two conformers of alpha-tocopherol have been optimized with the help of density functional theory. Energy minimized structures have been further used for vibrational frequencies calculations. Calculated values of molecular parameters of both the conformers have been comparable with the available experimental values in literature. All the observed vibrational bands have been assigned with the help of potential energy distribution calculations and intensity patterns of the simulated spectra. The ultraviolet-visible spectrum has been reported in wavelength range of 200 nm-500 nm. Observed ultraviolet-visible bands have been assigned to various electronic transitions, which have also been calculated using time dependent density functional theory.

  5. Spectroscopic study of Er:Sm doped barium fluorotellurite glass.

    PubMed

    Bahadur, A; Dwivedi, Y; Rai, S B

    2010-09-15

    In this paper, we report the physical and spectroscopic properties of Er(3+), Sm(3+) and Er(3+):Sm(3+) ions codoped barium fluorotellurite (BFT) glasses. Different Stokes and anti-Stokes emissions were observed under 532 nm and 976 nm laser excitations. Energy transfer from Er(3+) ion to Sm(3+) ion was confirmed on the basis of luminescence intensity variation and decay curve analysis in both the cases. Under green (532 nm) excitation emission intensity of Sm(3+) ion bands improves whereas on NIR (976 nm) excitation new emission bands of Sm(3+) ions were observed in Er:Sm codoped samples. Ion interactions and the different energy transfer parameters were also calculated. Copyright 2010 Elsevier B.V. All rights reserved.

  6. A Spectroscopic Study of Anomalous Stellar Populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney; King, Jeremy R.; Deliyannis, Constantine P.

    2015-01-01

    A population of so-called "yellow straggler" stars occupy precarious color magnitude diagram positions in the old open cluster M67 that cannot be explained by standard single star evolution theory. These stars may have been formed by Roche lobe overflow mass transfer in close binary systems. We present new radial velocities and spectroscopic abundances of M67 yellow stragglers to test this hypothesis, and find that these objects possess a high binary frequency, but no enhancements of s-process elements that might be a smoking gun signature of mass transfer. Observations were conducted using the WIYN 3.5 m telescope in conjunction with the HYDRA spectrograph at Kitt Peak National Observatory. Support for this project was provided by NSF grants AST 09-08342, AST 0607567, and AST 1211699.

  7. Using Spectroscopic Profiles to Study the Morphology of Comets

    NASA Astrophysics Data System (ADS)

    Harris, Ien; Pierce, Donna M.; Cochran, Anita L.

    2016-10-01

    We have used the integral-field unit spectrograph (the George and Cynthia Mitchell Spectrograph) on the 2.7m Harlan J. Smith telescope at McDonald Observatory to obtain spectroscopic images of the comae of several comets. The images were obtained for various radical species (C2, C3. CH, CN, NH2). Radial and azimuthal average profiles of the radical species were created to enhance any observed cometary coma morphological features. We compare the observed coma features across the observed species and over the different observation periods in order to constrain possible rotational states of the observed comets. We will present results for several comets, including 2009P1 (Garradd). This work was funded by NASA's Planetary Atmospheres program (Award No. NNX14AH186).

  8. Models of chemical biosignatures - a vibrational spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bödeker, B.; Böttger, U.; Hübers, H.-W.; deVera, J.-P.; Fox, S.; Strasdeit, H.

    2013-09-01

    Investigating possible biosignatures is of central interest in the search for the oldest traces of terrestrial life. Possible biosignatures are: (i) physical structures, such as fossilized single-celled or colonyforming microorganisms; (ii) biomolecules and their altered residues (chemical biosignatures); (iii) altered element, isotope and mineral compositions in former microbial habitats and related effects caused by metabolic activity [1]. New insights in this field of research are also important in the search for life on other planets and moons, especially Mars. However, abiotically formed organic compounds are widely distributed in the universe. Therefore, in future Mars missions, it will be essential to know whether organic molecules are actually of biological origin. Here, we describe the syntheses and spectroscopic (Raman and infrared) properties of artificial chemical biosignatures that might help answering this question.

  9. Spectroscopic and Photometric Study of Open Cluster Trumpler 27

    NASA Astrophysics Data System (ADS)

    Obonyo, W. O.; Baki, P.

    2016-12-01

    Open clusters are essential laboratories for understanding stellar evolution, as they allow constraints to be placed on stellar ages and luminosities. As distance indicators, they are important tracers of star formation in the Milky Way. One such cluster is Trumpler 27. Spectroscopic and photometric data of Trumpler 27 was used to estimate its distance, radial velocity, age, membership and reddening. The Spectroscopic data collected from SAAO's 1.9m telescope and photometric ones from catalogues were used to estimate reddening, identify cluster stars and approximate cluster distance. Classification of spectra was done by comparing them to spectral templates. The result from this work suggests that Trumpler 27 is made up of ∼55 stars which are at different stages of evolution. The stars include main sequence stars, blue supergiants, two cool supergiants and maybe the two WR stars. The cluster's age and distance were found to be 10Myrs old and 2.6 ± 0.2 kpc away from the Sun respectively suggesting that it is located on the outer part of Scutum Centaurus arm of the Galaxy. Its reddening, E(B - V) varies substantially across the field with the average value being 1.3±0.2. It has a radial velocity of -15.3±3km/s, as approximated from some of its cool supergiants. There is a likelihood of a younger population of OB stars located at 3.5 kpc away from the sun, that is right behind Trumpler 27 interpreted as either a cluster or background stars that mimic a cluster.

  10. Comparative study of wound healing in rat skin following incision with a novel picosecond infrared laser (PIRL) and different surgical modalities.

    PubMed

    Petersen, Hannes; Tavakoli, Fatemeh; Kruber, Sebastian; Münscher, Adrian; Gliese, Alexandra; Hansen, Nils-Owe; Uschold, Stephanie; Eggert, Dennis; Robertson, Wesley D; Gosau, Tobias; Sehner, Susanne; Kwiatkowski, Marcel; Schlüter, Hartmut; Schumacher, Udo; Knecht, Rainald; Miller, R J Dwayne

    2016-04-01

    As a result of wound healing the original tissue is replaced by dysfunctional scar tissue. Reduced tissue damage during surgical procedures beneficially affects the size of the resulting scar and overall healing time. Thus the choice of a particular surgical instrument can have a significant influence on the postoperative wound healing. To overcome these problems of wound healing we applied a novel picosecond infrared laser (PIRL) system to surgical incisions. Previous studies indicated that negligible thermal, acoustic, or ionization stress effects to the surrounding tissue results in a superior wound healing. Using the PIRL system as a surgical scalpel, we performed a prospective wound healing study on rat skin and assessed its final impact on scar formation compared to the electrosurgical device and cold steel. As for the incisions, 6 full-thickness, 1-cm long-linear skin wounds were created on the dorsum of four rats using the PIRL, an electrosurgical device, and a conventional surgical scalpel, respectively. Rats were euthanized after 21 days of wound healing. The thickness of the subepithelial fibrosis, the depth and the transverse section of the total scar area of each wound were analyzed histologically. After 21 days of wound healing the incisions made by PIRL showed minor scar tissue formation as compared to the electrosurgical device and the scalpel. Highly significant differences (P < 0.001) were noted by comparing the electrosurgical device with PIRL and scalpel. The transverse section of the scar area also showed significant differences (P = 0.043) when comparing PIRL (mean: 141.46 mm2; 95% CI: 105.8-189.0 mm2) with scalpel incisions (mean: 206.82 mm2; 95% CI: 154.8-276.32 mm2). The subepithelial width of the scars that resulted from using the scalpel were 1.3 times larger than those obtained by using the PIRL (95% CI: 1.0-1.6) though the difference was not significant (P < 0.083). The hypothesis that PIRL results in minimal scar

  11. Dielectric dispersion, relaxation dynamics and thermodynamic studies of Beta-Alanine in aqueous solutions using picoseconds time domain reflectometry

    NASA Astrophysics Data System (ADS)

    Vinoth, K.; Ganesh, T.; Senthilkumar, P.; Sylvester, M. Maria; Karunakaran, D. J. S. Anand; Hudge, Praveen; Kumbharkhane, A. C.

    2017-09-01

    The aqueous solution of beta-alanine characterised and studied by their dispersive dielectric properties and relaxation process in the frequency domain of 10×106 Hz to 30×109 Hz with varying concentration in mole fractions and temperatures. The molecular interaction and dielectric parameters are discussed in terms of counter-ion concentration theory. The static permittivity (ε0), high frequency dielectric permittivity (ε∞) and excess dielectric parameters are accomplished by frequency depended physical properties and relaxation time (τ). Molecular orientation, ordering and correlation factors are reported as confirmation of intermolecular interactions. Ionic conductivity and thermo dynamical properties are concluded with the behaviour of the mixture constituents. Solute-solvent, solute-solute interaction, structure making and breaking abilities of the solute in aqueous medium are interpreted. Fourier Transform Infrared (FTIR) spectra of beta- alanine single crystal and liquid state have been studied. The 13C Nuclear Magnetic Resonance (NMR) spectral studies give the signature for resonating frequencies and chemical shifts of beta-alanine.

  12. Picosecond real time study of the bimolecular reaction O(3P)+C2H4 and the unimolecular photodissociation of CH3CHO and H2CO

    NASA Astrophysics Data System (ADS)

    Abou-Zied, Osama K.; McDonald, J. Douglas

    1998-07-01

    The bimolecular reaction of O(3P) with ethylene and the unimolecular photodissociation of acetaldehyde and formaldehyde have been studied using a picosecond pump/probe technique. The bimolecular reaction was initiated in a van der Waals dimer precursor, C2H4ṡNO2, and the evolution of the vinoxy radical product monitored by laser-induced fluorescence. The NO2 constituent of the complex was photodissociated at 266 nm. The triplet oxygen atom then attacks a carbon atom of C2H4 to form a triplet diradical (CH2CH2O) which subsequently dissociates to vinoxy (CH2CHO) and H. The rise time of vinoxy radical production was measured to be 217 (+75-25) ps. RRKM theory was applied and a late high exit barrier was invoked in order to fit the measured rise time. The structure and binding energy of the van der Waals complex have been modeled using Lennard-Jones type potentials and the results were compared with other systems. The unimolecular side of the potential energy surfaces of this reaction has been investigated by photodissociating acetaldehyde at the same pump energy of 266 nm. The resulting photoproducts, acetyl radical (CH3CO) and formyl radical (HCO), have been monitored by resonance enhanced multiphoton ionization (REMPI) combined with a time-of-flight mass spectrometer. The similarity in the measured evolution times of both radicals indicates the same photodissociation pathway of the parent molecule. The photodissociation rate of acetaldehyde is estimated from RRKM theory to be very fast (3×1012s-1). The T1←S1 intersystem crossing (ISC) rate is found to be the rate determining step to photodissociation and increases with energy. The REMPI mechanism for the production of CH3CO+ is proposed to be the same as that of HCO+(2+1). The HCO product from the photodissociation of formaldehyde at 266 nm reveals a faster T1←S1 ISC rate than in acetaldehyde.

  13. Solvent/solute Interactions Probed by Picosecond Transient Raman Spectroscopy: a Study of S(1) 1,4-DIPHENYL -1,3-BUTADIENE and its Structural Analogues

    NASA Astrophysics Data System (ADS)

    Morris, Daniel Lamon, Jr.

    1995-01-01

    Many important chemical/biochemical reactions involve a short-lived photochemical intermediate. From a practical standpoint, understanding the behavior of such a transient species would allow effective manipulation of many chemical and biochemical processes. In this study, Raman spectroscopy on a picosecond time scale is used to examine the character of the S_1 states of several simple probe molecules and the effect(s) that different solvents have on the behavior of the excited state species in solution. We present the S_1 Raman spectra of 1,4-diphenyl-1,3-butadiene (DPB) in the series of linear alkanes pentane, hexane, heptane, octane, decane, and dodecane. DPB has virtually degenerate electronic states in the vicinity of S_1 (2 ^1A_{rm g} and 1^1B _{rm u}). The electronic state probed by the transient Raman measurements exhibits both 2^1A_{ rm g} and 1^1B _{rm u} character (i.e. a "mixed" state). It appears that a state exhibiting more 2^1A_{ rm g} character is favored by more viscous solvents while a state of significant 1^1 B_{rm u} character is preferred by less viscous solvents. We also observe very broad features (>50 cm ^{-1}) in the S_1 Raman spectra that are associated with motions of the butadiene portion of the molecule. In order to verify that these broad bands arise from a distribution of s-trans conformers in DPB, we have obtained the transient Raman spectra of 1,4-diphenyl-1,3 - cyclopentadiene (DPCP), a "stiff" analogue of DPB. As predicted, the DPCP spectra contain only sharp bands. We also provide evidence for assigning the lowest excited singlet state of DPCP in solution as the 1B state. We evaluate the effect of geometrical constraints on the photophysics of DPCP by obtaining the S _1 Raman spectra of 1,2,3,4-tetraphenyl-1,3 -cyclopentadiene (TPCP) in solution. The addition of the extra phenyl rings to DPCP forces the molecule to take on a non-planar geometry. We confirm that the viscosity -dependent S_1 lifetime of TPCP is due to a

  14. The effect of picosecond laser pulses on redox-dependent processes in mice red blood cells studied in vivo

    NASA Astrophysics Data System (ADS)

    Voronova, Olga; Gening, Tatyana; Abakumova, Tatyana; Sysolyatin, Aleksey; Zolotovskiy, Igor; Antoneeva, Inna; Ostatochnikov, Vladimir; Gening, Snezhanna

    2014-02-01

    The study highlights the effect of different modes of in vivo laser irradiation of mice using a PFL8LA laser with λ = 1560 nm, pulse duration of 1,4•10-12 s, peak power of 3,72•103 W and average output power of 20•10-3 W on the lipid peroxidation parameters: conjugated dienes, ketodienes and conjugated trienes, malondialdehyde, Schiff bases and the activity of antioxidant enzymes - catalase, glutathione -S-transferase and superoxide dismutase in erythrocytes and plasma of mice. Two groups of mice received a total dose of 3.8 J/cm2 per group, but the 1st group was irradiated only once, while the 2nd - four times. Significant differences in the parameters of the 1st and 2nd groups indicate different effects of the irradiation modes on redox-dependent processes in red blood cells of mice.

  15. Picosecond lasers for tattoo removal: a systematic review.

    PubMed

    Reiter, Ofer; Atzmony, Lihi; Akerman, Lehavit; Levi, Assi; Kershenovich, Ruben; Lapidoth, Moshe; Mimouni, Daniel

    2016-09-01

    Given that the pigment particles in tattoos have a relaxation time of <10 ns, picosecond lasers would be expected to be more effective than nanosecond lasers in tattoo removal. To systematically review the evidence regarding the effectiveness and safety of picosecond lasers for tattoo removal, Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and reference lists were searched for relevant trials. The primary outcome was >70 % clearance of tattoo pigment. Secondary outcomes were 90-100 % clearance of tattoo pigment, number of laser sessions required, and adverse effects. Eight trials were included, six with human participants (160 participants) and 2 with animal models. Seven of the eight trials explored the usage of either 755, 758, 795, 1064, or 1064/532-nm picosecond lasers for black and blue ink tattoos. In the human trials, 69-100 % of tattoos showed over 70 % clearance of pigment after 1-10 laser treatments. Reported side effects included pain, hyperpigmentation and hypopigmentation, blister formation and transient erythema, edema, and pinpoint bleeding. Included articles varied in type of laser investigated, mostly non-comparative studies and with a medium to high risk of bias. There is sparse evidence that picosecond lasers are more effective than their nanosecond counterparts for mainly black and blue ink tattoo removal, with minor side effects.

  16. Picosecond lasers: the next generation of short-pulsed lasers.

    PubMed

    Freedman, Joshua R; Kaufman, Joely; Metelitsa, Andrea I; Green, Jeremy B

    2014-12-01

    Selective photothermolysis, first discussed in the context of targeted microsurgery in 1983, proposed that the optimal parameters for specific thermal damage rely critically on the duration over which energy is delivered to the tissue. At that time, nonspecific thermal damage had been an intrinsic limitation of all commercially available lasers, despite efforts to mitigate this by a variety of compensatory cooling mechanisms. Fifteen years later, experimental picosecond lasers were first reported in the dermatological literature to demonstrate greater efficacy over their nanosecond predecessors in the context of targeted destruction of tattoo ink. Within the last 4 years, more than a decade after those experiments, the first commercially available cutaneous picosecond laser unit became available (Cynosure, Westford, Massachusetts), and several pilot studies have demonstrated its utility in tattoo removal. An experimental picosecond infrared laser has also recently demonstrated a nonthermal tissue ablative capability in soft tissue, bone, and dentin. In this article, we review the published data pertaining to dermatology on picosecond lasers from their initial reports to the present as well as discuss forthcoming technology.

  17. Picosecond coherent anti-Stokes Raman scattering (CARS) study of vibrational dephasing of carbon disulfide and benzene in solution

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Woodward, Anne M.; Stephenson, John C.

    1986-01-01

    The vibrational dephasing of the 656/cm mode (nu1, a1g) of CS2 and the 991/cm mode (nu2, a1g) of benzene have been studied as a function of concentration in mixtures with a number of solvents using a ps time-resolved CARS technique. This technique employs two tunable synchronously-pumped mode-locked dye lasers in a stimulated Raman pump, coherent anti-Stokes Raman probe time-resolved experiment. Results are obtained for CS2 in carbon tetrachloride, benzene, nitrobenzene, and ethanol and for benzene nu2 in CS2. The dephasing rates of CS2 nu1 increase on dilution with the polar solvents and decrease or remain constant on dilution with the nonpolar solvents. The CS2/benzene solutions show a contrasting behavior, with the CS2 nu1 dephasing rate being nearly independent of concentration whereas the benzene nu2 dephasing rate decreases on dilution. These results are compared to theoretical models for vibrational dephasing of polyatomic molecules in solution.

  18. Simultaneous picosecond and femtosecond solitons delivered from a nanotube-mode-locked all-fiber laser.

    PubMed

    Han, D D; Liu, X M; Cui, Y D; Wang, G X; Zeng, C; Yun, L

    2014-03-15

    We propose a compact nanotube-mode-locked all-fiber laser that can simultaneously generate picosecond and femtosecond solitons at different wavelengths. The pulse durations of picosecond and femtosecond solitons are measured to be ∼10.6  ps and ∼466  fs, respectively. Numerical results agree well with the experimental observations and clearly reveal that the dynamic evolutions of the picosecond and femtosecond solitons are qualitatively distinct in the intracavity. Our study presents a simple, stable, low-cost, and dual-scale ultrafast-pulsed laser source suitable for practical applications in optical communications.

  19. Picosecond Studies of Chemical Intermediates

    DTIC Science & Technology

    1991-05-01

    encapsulation significantly modify photoisomerization reaction rates. In the case of t-stilbene complexed to various cyclodextrins we directly observed...43 Figure 7.6 Schematic of equilibrium between tight and loose stilbene/ cyclodextrin complexes...how frictional effects due to the local (or "restricted") environment of the inner cyclodextrin cavity modifed the motion necessary for reaction

  20. Optical properties of InN studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  1. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-08-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  2. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-06-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effect of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that, after a 20-sec 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum chamber (UHV), and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface layer, after being heated to about 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  3. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Technical Reports Server (NTRS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-01-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  4. Microcrystalline silicon thin films studied using spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Kang, T. D.; Lee, Hosun; Park, S. J.; Jang, J.; Lee, Soonil

    2002-09-01

    We used spectroscopic ellipsometry to characterize four different microcrystalline silicon (muc-Si) films, which were fabricated by crystallizing a-Si:H films predeposited on glass substrates using solid phase crystallization (SPC), excimer laser annealing (ELA), Ni induced silicide-mediated crystallization (Ni-SMC), and field enhanced silicide-mediated crystallization (FESMC) method, respectively. A linear regression analysis, which took the effective dielectric function of muc-Si layer into account using effective medium approximation, showed that all these films were homogeneous throughout their thickness except the oxide overlayers, and completely crystallized regardless of the crystallization method. In our linear regression analysis, the complex dielectric function of silicon microcrystallites was represented by the Adachi model dielectric function (MDF) [T. Suzuki and S. Adachi, Jpn. J. Appl. Phys., Part1 32, 4900 (1993)], and the broadening parameters of the critical points (CPs) in MDF were allowed to vary. The dielectric function of silicon microcrystallites showed systematic broadening and shrinking of the peak features corresponding to the E1 and E2 CPs, from which we concluded that the average microcrystallite size increased in the order of SPC, ELA, Ni-SMC, and FESMC muc-Si. The Raman spectra and the transmission-electron-microscopy images of these films also supported the idea of systematic variation in the microcrystallite size.

  5. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  6. Acid doping of polyaniline: Spectroscopic and electrochemical studies

    SciTech Connect

    Hatchett, D.W.; Josowicz, M.; Janata, J.

    1999-12-16

    A detailed investigation of the acid doping behavior of polyaniline has led to a robust and reproducible procedure for controlled adjustment of the redox state of dry polyaniline films. The initial step in this procedure is the casting of PANI films from formic acid. The subsequent exchange of the trapped formic acid for other primary dopants obtained from mono- and polyprotic acids (e.g., CH{sub 3}COO{sup {minus}}, BF{sub 4}{sup {minus}}, HSO{sub 4}{sup {minus}}, SO{sub 4}{sup 2{minus}}, H{sub 2}PO{sub 4}{sup {minus}}, and HPO{sub 4}{sup 2{minus}}) is demonstrated. The voltammetric and the spectroscopic behavior of the PANI doped with different anions indicate that both the protons and the anions of dopant acids influence the structure and redox properties of the polymer. The redox state of PANI doped with homologous series of chloroacetic and carboxylic acids correlates with the pK{sub a} of the dopant acid. These results show that it is possible to prepare the polymer with a desired oxidation state according to the pK{sub a} of the dopant acid of a given homologous series. The exchange of the formic acid for both stronger and weaker doping acid can be repeatedly accomplished by electrochemical cycling.

  7. Precise Theoretical Study of Spectroscopic Constants in Diatomics

    NASA Astrophysics Data System (ADS)

    Skripnikov, L. V.; Petrov, A. N.; Titov, A. V.; Mosyagin, N. S.

    2013-06-01

    During the last decade a significant progress in methods of molecular spectroscopy was achieved. One of the most important applications of these methods is a measurement of an electron electric dipole moment in diatomic molecules and cations containing heavy elements. In order to speed up such experiments, which usually prepared for many years, one can apply accurate ab initio quantum-chemical methods to predict different spectroscopic constants of a molecule or cation under consideration: scheme of electronic terms, vibrational and rotation constants, hyperfine structure constants, g-factors, lifetimes etc. In such calculations both correlation and relativistic effects should be taken into account. This is not a trivial problem for systems containing transition elements and especially lanthanides and actinides. %Therefore, ``direct'' 4-component Hamiltonians are not always the best choice and some alternative We report results of our recent investigations of a number of diatomics including theoretical investigation of HfF^{+}. Details of used methods are discussed. K. C. Cossel, D. N. Gresh, L. C. Sinclair, T. Coffey, L. V. Skripnikov, A. N. Petrov, N. S. Mosyagin, A. V. Titov, R. W. Field, E. R. Meyer, E. A. Cornell and J. Ye, Chem. Phys. Lett., 546, 1 (2012).

  8. Broadly tunable picosecond ir source

    DOEpatents

    Campillo, A.J.; Hyer, R.C.; Shapiro, S.L.

    1980-04-23

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 ..mu..m picosecond pulses (1) pass through a 4.5 cm long LiNbO/sub 3/ optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO/sub 3/ optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 ..mu..m along both pump lines are 6 to 8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 ..mu..m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 ..mu..J of tunable radiation over the 14.8 to 18.5 ..mu..m region. The bandwidth and wavelength of both the 2 and 16 ..mu..m radiation output are controlled solely by the diffraction grating.

  9. Broadly tunable picosecond IR source

    DOEpatents

    Campillo, Anthony J.; Hyer, Ronald C.; Shapiro, Stanley J.

    1982-01-01

    A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 .mu.m picosecond pulses (1) pass through a 4.5 cm long LiNbO.sub.3 optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO.sub.3 optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 .mu.m along both pump lines are 6-8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 .mu.m which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 .mu.J of tunable radiation over the 14.8 to 18.5 .mu.m region. The bandwidth and wavelength of both the 2 and 16 .mu.m radiation output are controlled solely by the diffraction grating.

  10. Raman spectroscopic study of the Chromobacterium violaceum pigment violacein using multiwavelength excitation and DFT calculations.

    PubMed

    Jehlička, Jan; Edwards, Howell G M; Němec, Ivan; Oren, Aharon

    2015-01-01

    Violacein is a bisindole pigment occurring as a biosynthetic product of Chromobacterium violaceum and Janthinobacterium lividum. It has some structural similarities to the cyanobacterial UV-protective pigment scytonemin, which has been the subject of comprehensive spectroscopic and structural studies. A detailed experimental Raman spectroscopic study with visible and near-infrared excitation of violacein produced by C. violaceum has been undertaken and supported using theoretical DFT calculations. Raman spectra with 514 and 785 nm excitation of cultivated cells as well as extracts and Gaussian (B3LYP/6-311++G(d,p)) calculations with proposed molecular vibrational assignments are reported here.

  11. Spectroscopic studies of yellow supergiants in the Cepheid instability strip

    NASA Astrophysics Data System (ADS)

    Usenko, I. A.

    2017-04-01

    High-resolution spectra of nine yellow nonvariable supergiants (NVSs) located within the canonical Cepheid instability strip from Sandage and Tammann (1969) ( α Aqr, ɛ Leo, μ Per, ω Gem, BD+60 2532, HD 172365, HD 187299, HD 190113, and HD 200102) were taken with the 1-m Zeiss and 6-m BTA telescopes at the Special Astrophysical Observatory of the Russian Academy of Sciences in the 1990s. These have been used to determine the atmospheric parameters, chemical composition, radial velocities, reddenings, luminosities, distances, and radii. The spectroscopic estimates of T eff and the luminosities determined from the Hipparcos parallaxes have shown eight of the nine program NVSs on the T eff-log( L/ L ⊙) diagram to be outside the canonical Cepheid instability strip. When the edges of the Cepheid instability strip from Bono et al. (2000) are used, out of the NVSs from the list on the diagram one is within the Cepheid instability strip but closer to the red edge, two are at the red edge, three are beyond the red edge, two are at the blue edge, and one is beyond the blue edge. The evolutionary masses of the objects have been estimated. The abundances of α-elements, r- and s-process elements for all program objects have turned out to be nearly solar. The CNO, Na, Mg, and Al abundance estimates have shown that eight of the nine NVSs from the list have already passed the first dredge-up. Judging by the abundances of the key elements and its position on the T eff-log( L/ L ⊙) diagram, the lithium-rich supergiant HD 172365 is at the post-main-sequence evolutionary stage of gravitational helium core contraction and moves toward the first crossing of the Cepheid instability strip. The star ɛ Leo should be assigned to bright supergiants, while HD 187299 and HD 190113 may have already passed the second dredge-up and move to the asymptotic branch.

  12. Electrochemical and spectroscopic study of octadecyltrimethylammonium bromide/DNA surfoplexes.

    PubMed

    Rodríguez-Pulido, Alberto; Aicart, Emilio; Junquera, Elena

    2009-04-21

    The use of cationic micelles consisting of octadecyltrimethylammonium bromide (C18TAB) to compact calf thymus DNA has been investigated in aqueous buffered solution at 310.15 K by means of conductometry, electrophoretic mobility, and several fluorescence spectroscopy methods. The results indicate that C18TAB micelles, consisting of 44 monomers on average, may compact DNA molecule by an electrostatic interaction that takes place at the cationic spherical micelle surface. The surfoplexes thus formed show a surface density charge that goes from negative to positive values at a Lmic/D mass ratio of around 1.0 (where Lmic and D are the masses of micellized cationic surfactant and DNA), called the isoneutrality ratio (Lmic/D)phi. Values of this characteristic parameter, determined in this work not only from the electrochemical experimental data but also from spectroscopic measurements, are in very good agreement with those ones calculated from molecular parameters and some other properties also obtained in this work. The electrostatic character of the DNA-micelle interaction has been confirmed by analyzing the decrease in fluorescence emission of the fluorophore ethidium bromide, EtBr, initially intercalated between DNA base pairs, as long as the surfoplexes are formed. Fluorescence anisotropy experiments have revealed that micelle packing becomes more rigid in the presence of DNA, but once the surfoplex is formed, the fluidity increases with the Lmic/D mass ratio, attaining its maximum when the isoneutrality ratio is exceeded. This fact, together with the net positive charge of the surfoplexes with the Lmic/D mass ratio over the isoneutrality ratio, makes this regimen of lipid and DNA content the optimum for efficiency in the transfection process.

  13. Picosecond adsorbate dynamics at condensed phase interfaces

    SciTech Connect

    Scott, T.W.; Chang, Y.J.; Martorell, J.

    1993-12-31

    Picosecond surface second harmonic generation has been used to probe a variety of elementary adsorbate reactions at liquid-solid interfaces. Electron transfer reactions at semiconductor-liquid junctions, geminate recombination of photogenerated free radical pairs and the orientational dynamics of dipolar adsorbates have all been explored in varying degrees of detail. These kinetic studies have led to a detailed analysis of adsorbate detection on the surface of non-centrosymmetric substrates as well as the use of total internal reflection geometries for signal enhancement from optically absorbing liquids. Particular emphasis has been placed on the static and dynamic characterization of adsorbate orientational distribution functions and how these are determined from the torque exerted on adsorbates by the angular part of the molecule-surface interaction potential.

  14. Spectroscopic study of molecular structure, antioxidant activity and biological effects of metal hydroxyflavonol complexes

    NASA Astrophysics Data System (ADS)

    Samsonowicz, Mariola; Regulska, Ewa

    2017-02-01

    Flavonols with varied hydroxyl substitution can act as strong antioxidants. Thanks to their ability to chelate metals as well as to donate hydrogen atoms they have capacity to scavenge free radicals. Their metal complexes are often more active in comparison with free ligands. They exhibit interesting biological properties, e.g. anticancer, antiphlogistic and antibacterial. The relationship between molecular structure and their biological properties was intensively studied using spectroscopic methods (UV-Vis, IR, Raman, NMR, ESI-MS). The aim of this paper is review on spectroscopic analyses of molecular structure and biological activity of hydroxyflavonol metal complexes.

  15. Spectroscopic Signatures and Structural Motifs of Dopamine: a Computational Study

    NASA Astrophysics Data System (ADS)

    Srivastava, Santosh Kumar; Singh, Vipin Bahadur

    2016-06-01

    Dopamine (DA) is an essential neurotransmitter in the central nervous system and it plays integral role in numerous brain functions including behaviour, cognition, emotion, working memory and associated learning. In the present work the conformational landscapes of neutral and protonated dopamine have been investigated in the gas phase and in aqueous solution by MP2 and DFT (M06-2X, ωB97X-D, B3LYP and B3LYP-D3) methods. Twenty lowest energy structures of neutral DA were subjected to geometry optimization and the gauche conformer, GIa, was found to be the lowest gas phase structure at the each level of theory in agreement with the experimental rotational spectroscopy. All folded gauche conformers (GI) where lone electron pair of the NH2 group is directed towards the π system of the aromatic ring ( 'non up' ) are found more stable in the gas phase. While in aqueous solution, all those gauche conformers (GII) where lone electron pair of the NH2 group is directed opposite from the π system of the aromatic ring ('up' structures) are stabilized significantly.Nine lowest energy structures, protonated at the amino group, are optimized at the same MP2/aug-cc-pVDZ level of theory. In the most stable gauche structures, g-1 and g+1, mainly electrostatic cation - π interaction is further stabilized by significant dispersion forces as predicted by the substantial differences between the DFT and dispersion corrected DFT-D3 calculations. In aqueous environment the intra-molecular cation- π distance in g-1 and g+1 isomers, slightly increases compared to the gas phase and the magnitude of the cation- π interaction is reduced relative to the gas phase, because solvation of the cation decreases its interaction energy with the π face of aromatic system. The IR intensity of the bound N-H+ stretching mode provides characteristic 'IR spectroscopic signatures' which can reflect the strength of cation- π interaction energy. The CC2 lowest lying S1 ( 1ππ* ) excited state of neutral

  16. Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector

    SciTech Connect

    Smith, Richard J.; Light, Roger A.; Johnston, Nicholas S.; Pitter, Mark C.; Somekh, Mike G.; Sharples, Steve D.

    2010-02-15

    This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

  17. Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector.

    PubMed

    Smith, Richard J; Light, Roger A; Sharples, Steve D; Johnston, Nicholas S; Pitter, Mark C; Somekh, Mike G

    2010-02-01

    This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

  18. Laser Raman and infrared spectroscopic studies of molecular systems: Structural analysis of some clathrate compounds

    NASA Astrophysics Data System (ADS)

    Akyuz, S.

    1990-09-01

    The structural analyses of some molecular systems, namely clathrates, depending on the laser Raman and infrared spectroscopic studies are reported. The following subject areas are covered: Raman effect; Raman spectroscopy; IR spectroscopy; mutual exclusion principle; vibrational spectra of the polymeric layers; and fundamental vibrations of pyrazine molecules.

  19. A Spectroscopic study on the fuel value of softwoods in relation to chemical composition

    Treesearch

    Chi-Leung So; Thomas L. Eberhardt; Les Groom; Todd F. Shupe

    2012-01-01

    The recent focus on bioenergy has led to interest in developing alternative technologies for assessing the fuel value of available biomass resources. In this study, both near- and mid-infrared spectroscopic datawere used to predict fuel value in relation to extractives and lignin contents for longleaf pine wood. Samples were analyzed both before and after extraction....

  20. Fundamentals of picosecond laser ultrasonics.

    PubMed

    Matsuda, Osamu; Larciprete, Maria Cristina; Li Voti, Roberto; Wright, Oliver B

    2015-02-01

    The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned.

  1. Spectroscopic properties of alexandrite crystals

    NASA Astrophysics Data System (ADS)

    Powell, Richard C.; Xi, Lin; Gang, Xu; Quarles, Gregory J.; Walling, John C.

    1985-09-01

    Details of the optical-spectroscopic properties of alexandrite (BeAl2O4:Cr3+) crystals were studied by different laser-spectroscopy techniques. The temperature dependences of the fluorescence lifetimes and widths of the zero-phonon lines were found to be quite different for Cr3+ ions in the mirror and inversion crystal-field sites. The results indicate that direct phonon-absorption processes dominate both thermal line broadening and lifetime quenching for ions in the mirror sites while phonon-scattering processes dominate the line broadening of inversion-site ions and leave their lifetime independent of temperature. Tunable-dye-laser site-selection methods were used to obtain the excitation spectra of the Cr3+ ions in inversion sites at low temperature and to identify six types of exchange-coupled pairs of Cr3+ ions in the lattice. Time-resolved site-selection spectroscopy was used to monitor the energy transfer between Cr3+ ions in mirror and inversion sites at both low and high temperature. Finally, high-power, picosecond pulse excitation was used to produce two-photon absorption, and the resulting emission spectrum was found to exhibit a new fluorescence band in the 400-nm spectral region.

  2. Comparative shock wave analysis during corneal ablation with an excimer laser, picosecond laser, and femtosecond laser

    NASA Astrophysics Data System (ADS)

    Krueger, Ronald R.; Juhasz, Tibor

    1995-05-01

    With the event of topographic steep central islands following excimer laser surgery and the potential damage to the corneal endothelium, shock waves are playing an increasingly important role in laser refractive surgery. With this in mind, we performed a comparative shock wave analysis in corneal tissue using an excimer laser, picosecond laser, and femtosecond laser. We used a Lambda Physik excimer laser at 308 nm wavelength, a Nd:YLF picosecond laser at 1053 nm wavelength and a synchronously pumped linear cavity femtosecond laser at 630 nm wavelength. The pulse widths of the corresponding lasers were 8 ns, 18 ps, 150 fs, respectively. The energy density of irradiation was 2.5 to 8 times the threshold level being 2 J/cm2 (excimer laser), 86 J/cm2 (picosecond laser) and 10.3 J/cm2 (femtosecond laser). Shock wave dynamics were analyzed using time-resolved photography on a nanosecond time scale using the picosecond laser in corneal tissue, water and air. Shock wave dynamics using the femtosecond laser were studied in water only while the excimer laser induced shock wave during corneal ablation was studied in air only. We found the dynamics of shock waves to be similar in water and corneal tissue indicating that water is a good model to investigate shock wave effects in the cornea. The magnitude of the shock wave velocity and pressure decays over time to that of a sound wave. The distance over which it decays is 3 mm in air with the excimer laser and 600 - 700 micrometers in air with the picosecond laser. In water, the picosecond laser shock wave decays over a distance of 150 micrometers compared to the femtosecond laser shock wave which decays over a distance of 30 micrometers . Overall the excimer laser shock wave propagates 5 times further than that of the picosecond laser and the picosecond laser shock wave propagates 5 times further than that of the femtosecond laser. In this preliminary comparison, the time and distance for shock wave decay appears to be directly

  3. Study of Characterization of Pure and Malachite Green Doped Samples Using Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Mishra, Jyoti; Mishra, Pankaj K.; Khare, P. K.

    2011-07-01

    This paper describes the results of SEM, EDX, UV-vis and TSDC study of malachite green doped PVK thermelectrets. TSDC study has been carried out in the temperature range 300 °C to 1500 °C with four different polarizing fields. One peak was observed at 110±10 °C which shifts toward high temperature with the increase in polarizing field. The activation energy found by initial rise method are 0.27±0.02 eV for pure and 0.40±0.03 eV for malachite green doped PVK thermoelectrets. Spectroscopic study concluded that impregnation of malachite green in polymer matrix forms charge transfer complexes.

  4. Vibrational spectroscopic studies to acquire a quality control method of Eucalyptus essential oils.

    PubMed

    Baranska, M; Schulz, H; Reitzenstein, S; Uhlemann, U; Strehle, M A; Krüger, H; Quilitzsch, R; Foley, W; Popp, J

    2005-08-05

    This article presents a novel and original approach to analyze in situ the main components of Eucalyptus oil by means of Raman spectroscopy. The obtained two-dimensional Raman maps demonstrate a unique possibility to study the essential oil distribution in the intact plant tissue. Additionally, Fourier Transform (FT)-Raman and attenuated total reflection (ATR)-IR spectra of essential oils isolated from several Eucalyptus species by hydrodistillation are presented. Density Functional Theory (DFT) calculations were performed in order to interpret the spectra of the essential oils of the Eucalyptus species. It is shown that the main components of the essential oils can be recognized by both vibrational spectroscopic techniques using the spectral information of the pure terpenoids. Spectroscopic analysis is based on the key bands of the individual volatile substances and therefore allows one to discriminate different essential oil profiles of several Eucalyptus species. It has been found that the presented spectroscopic data correlate very well with those obtained by gas chromatography (GC) analysis. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with vibrational spectroscopic techniques in combination with DFT calculations.

  5. How specific Raman spectroscopic models are: a comparative study between different cancers

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Kumar, K. Kalyan; Chowdary, M. V. P.; Maheedhar, K.; Krishna, C. Murali

    2010-02-01

    Optical spectroscopic methods are being contemplated as adjunct/ alternative to existing 'Gold standard' of cancer diagnosis, histopathological examination. Several groups are actively pursuing diagnostic applications of Ramanspectroscopy in cancers. We have developed Raman spectroscopic models for diagnosis of breast, oral, stomach, colon and larynx cancers. So far, specificity and applicability of spectral- models has been limited to particular tissue origin. In this study we have evaluated explicitly of spectroscopic-models by analyzing spectra from already developed spectralmodels representing normal and malignant tissues of breast (46), cervix (52), colon (25), larynx (53), and oral (47). Spectral data was analyzed by Principal Component Analysis (PCA) using scores of factor, Mahalanobis distance and Spectral residuals as discriminating parameters. Multiparametric limit test approach was also explored. The preliminary unsupervised PCA of pooled data indicates that normal tissue types were always exclusive from their malignant counterparts. But when we consider tissue of different origin, large overlap among clusters was found. Supervised analysis by Mahalanobis distance and spectral residuals gave similar results. The 'limit test' approach where classification is based on match / mis-match of the given spectrum against all the available spectra has revealed that spectral models are very exclusive and specific. For example breast normal spectral model show matches only with breast normal spectra and mismatch to rest of the spectra. Same pattern was seen for most of spectral models. Therefore, results of the study indicate the exclusiveness and efficacy of Raman spectroscopic-models. Prospectively, these findings might open new application of Raman spectroscopic models in identifying a tumor as primary or metastatic.

  6. Structural, functional and spectroscopic MRI studies of methamphetamine addiction.

    PubMed

    Salo, Ruth; Fassbender, Catherine

    2012-01-01

    This chapter reviews selected neuroimaging findings related to long-term amphetamine and methamphetamine (MA) use. An overview of structural and functional (fMRI) MR studies, Diffusion Tensor Imaging (DTI), Magnetic Resonance Spectroscopy (MRS) and Positron Emission Tomography (PET) studies conducted in long-term MA abusers is presented. The focus of this chapter is to present the relevant studies as tools to understand brain changes following drug abstinence and recovery from addiction. The behavioral relevance of these neuroimaging studies is discussed as they relate to clinical symptoms and treatment. Within each imaging section this chapter includes a discussion of the relevant imaging studies as they relate to patterns of drug use (i.e., duration of MA use, cumulative lifetime dose and time MA abstinent) as well as an overview of studies that link the imaging findings to cognitive measures. In our conclusion we discuss some of the future directions of neuroimaging as it relates to the pathophysiology of addiction.

  7. In vivo localized proton spectroscopic studies of human gastrocnemius muscle

    SciTech Connect

    Narayana, P.A.; Jackson, E.F.; Hazle, J.D.; Fotedar, L.K.; Kulkarni, M.V.; Flamig, D.P.

    1988-10-01

    In vivo proton magnetic resonance spectroscopy studies of gastrocnemius muscle were performed in six normal volunteers. Both spatially resolved spectroscopy (SPARS) and stimulated echo acquisition mode (STEAM) sequences were used for volume localization. A number of water suppression sequences have been combined with these localization schemes. Among the various techniques investigated in these studies, STEAM with an inversion pulse (T1-discriminated spectrum) seems to have the best potential for in vivo localized high-resolution proton spectroscopy studies of human muscle.

  8. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle.

    PubMed

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-02-24

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

  9. New and Advanced Picosecond Lasers for Tattoo Removal.

    PubMed

    Adatto, Maurice A; Amir, Ruthie; Bhawalkar, Jayant; Sierra, Rafael; Bankowski, Richard; Rozen, Doran; Dierickx, Christine; Lapidoth, Moshe

    2017-01-01

    Early methods of tattoo removal ultimately resulted in unacceptable cosmetic outcomes. While the introduction of laser technology was an improvement over the existing chemical, mechanical, and surgical procedures, the use of nonselective tattoo removal with carbon dioxide and argon lasers led to scarring. Q-switched lasers with nanosecond (10-9) pulse domains were considered to have revolutionized tattoo treatment, by selectively heating the tattoo particles, while reducing the adverse sequelae to adjacent normal skin. Theoretical considerations of restricting pulse duration, to heat tattoo particles to higher temperatures, proposed the use of sub-nanosecond pulses to target particles with thermal relaxation times lower than the nanosecond pulses in Q-switched lasers. Initial studies demonstrated that picosecond (10-12) pulses were more effective than nanosecond pulses in clearing black tattoos. Advances in picosecond technology led to the development of commercially available lasers, incorporating several different wavelengths, to further refine pigment targeting.

  10. Polydiacetylene as an all-optical picosecond Switch

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A.; Frazier, D. O.; Paley, M. S.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Polydiacetylene derivative of 2-methyl-4-nitroaniline (PDAMNA) shows a picosecond switching property, which illustrated a partial all-optical picosecond NAND logic gate. The switching phenomenon was demonstrated by waveguiding two collinear beams at 633 nm and 532 nm through a hollow fiber of 50 micrometers diameter, coated from inside with a thin film of PDAMNA. A Z-scan investigations of a PDAMNA thin film on quartz substrate revealed that the switching effect was attributed to an excited state absorption in the systems. The studies also showed that the polymer suffers a photo-oxidation beyond an intensity level of 2.9 x 10(exp 6) w/square cm. The photo-oxidized film has different physical properties that are different from the original film before oxidation. The life time of both excited states before and after oxidation as well as their absorption coefficients were estimated by fitting a three level system model to the experimental results.

  11. Picosecond resolution soft x-ray laser plasma interferometry

    SciTech Connect

    Moon, S; Nilsen, J; Ng, A; Shlyaptsev, V; Dunn, J; Hunter, J; Keenan, R; Marconi, M; Filevich, J; Rocca, J; Smith, R

    2003-12-01

    We describe a soft x-ray laser interferometry technique that allows two-dimensional diagnosis of plasma electron density with picosecond time resolution. It consists of the combination of a robust high throughput amplitude division interferometer and a 14.7 nm transient inversion soft x-ray laser that produces {approx} 5 ps pulses. Due to its picosecond resolution and short wavelength scalability, this technique has potential for extending the high inherent precision of soft x-ray laser interferometry to the study of very dense plasmas of significant fundamental and practical interest, such as those investigated for inertial confined fusion. Results of its use in the diagnostics of dense large scale laser-created plasmas are presented.

  12. SPECTROSCOPIC STUDIES OF MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE

    SciTech Connect

    Greenbaum, Steven G.

    2014-03-01

    Several battery materials research projects were undertaken, suing NMR spectroscopy as a primary analytical tool. These include transport proerties of liquid and solid electrolytes and structural studies of Li ion electrodes.

  13. SPECTROSCOPIC STUDY OF SORPTION OF NITROGEN HETEROCYCLIC COMPOUNDS ON PHYLLOSILICATES

    EPA Science Inventory

    The present study focused on understanding the sorption characteristics of acridine (AcN)and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in...

  14. Conceptual design study to determine optimal enclosure vent configuration for the Maunakea Spectroscopic Explorer (MSE)

    NASA Astrophysics Data System (ADS)

    Szeto, Kei; Vogiatzis, Konstantinos; Hangan, Horia; Jubayer, Chowdhury M.; Breckenridge, Craig; Loewen, Nathan; Bauman, Steven; Salmon, Derrick

    2014-07-01

    The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed.

  15. Spectroscopic and time domain reflectometry studies on acetonitrile - Ethylene glycol binary solutions

    NASA Astrophysics Data System (ADS)

    Mahendraprabu, A.; Kumbharkhane, A. C.; Joshi, Y. S.; Shaikh, S. S.; Kannan, P. P.; Karthick, N. K.; Arivazhagan, G.

    2017-05-01

    Spectroscopic (FTIR and 13C NMR) and time domain reflectometry (in the frequency range from 10 MHz to 25 GHz) studies have been carried out on the binary solutions of acetonitrile (AN) with ethylene glycol (EG). The presence of EG-EG multimers of various orders in neat EG has been confirmed by spectroscopic studies. AN-EG association through the formation of ∁ ≡ N ⋯ H - O , ∁ ≡ N ⋯ H - C(EG) and (EG) C - O ⋯ H - C(AN) hydrogen bonds have been identified using spectral studies. The principal relaxation process of the heteromolecular entities that involve higher order alcohol association in ethylene glycol rich solutions is found to be relatively slower than that in acetonitrile rich solutions in which lower order alcohol association involves in heterointeraction. The angular correlation among the dipoles appears to be described more precisely when the experimental ε∞ values rather than ε∞ =n2 are used for the calculation of geff .

  16. Spectroscopic and theoretical study on alkali metal phenylacetates

    NASA Astrophysics Data System (ADS)

    Regulska, E.; Świsłocka, R.; Samsonowicz, M.; Lewandowski, W.

    2013-07-01

    The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of phenylacetic acid was studied. The FT-IR, FT-Raman and 1H and 13C NMR spectra were recorded for studied compounds. Characteristic shifts in IR and NMR spectra along alkali metal phenylacetates were observed. Good correlations between the wavenumbers of the vibrational bands in the IR spectra of phenylacetates and some alkali metal parameters such as ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy were found. The density functional hybrid method B3LYP with 6-311++G** basis set was used to calculate optimized geometrical structures of studied compounds. Aromaticity indices, atomic charges, dipole moments and energies were calculated as well as the wavenumbers and intensities of IR spectra and chemical shifts in NMR spectra. The theoretical parameters were compared to experimental characteristic of alkali metal phenylacetates.

  17. Spectroscopic and Raman excitation profile studies of 3-benzoylpyridine

    NASA Astrophysics Data System (ADS)

    Sett, Pinaky; Datta, Shirsendu; Chowdhury, Joydeep; Ghosh, Manash; Mallick, Prabal Kumar

    2017-03-01

    In the present work IR, UV absorption and Raman spectra including Raman excitation profiles and structure of 3-benzoyl pyridine have been investigated. Detailed studies on the vibrational and electronic properties of the molecule have been carried out. All these studies are aided with valuable quantum chemical calculations. The structural changes encountered on excitation to the low lying excited states have been investigated. Theoretical profiles determined by the sum-over-states method based on pertinent Franck-Condon and Herzberg-Teller terms have satisfactorily simulated the experimentally measured relative Raman intensities and these are also in compliance with the structural changes and potential energy distributions.

  18. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    Metal oxide phases play an important role in governing the sorption and desorption mechanisms of metals in water, soils, and sediments. Many researchers have examined the efficiency of Pb sorption on Mn, Fe, Al, Ti, and Si oxide surfaces. Most studies concluded that adsorption ...

  19. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    Metal oxide phases play an important role in governing the sorption and desorption mechanisms of metals in water, soils, and sediments. Many researchers have examined the efficiency of Pb sorption on Mn, Fe, Al, Ti, and Si oxide surfaces. Most studies concluded that adsorption ...

  20. Optical spectroscopic studies of heme proteins at high pressure

    SciTech Connect

    Swanson, B.I.; Agnew, S.F.; Ondrias, M.R.; Alden, R.G.

    1986-01-22

    There has been considerable interest in studying the physical and chemical behavior of small molecules at high static pressure by using diamond-anvil cells. In contrast to the relatively rich chemistry now developing on small molecules at high densities, studies of metalloproteins have largely been limited to relatively low pressures (<7 kbar) using UV-vis absorption, magnetic susceptibility, or NMR spectroscopy. Low-pressure studies of a variety of oxidized heme proteins have conclusively shown evidence for spin-state changes for the iron site at pressures above 1 kbar. Optical absorption studies of reduced heme proteins, while not conclusive, have also been interpreted in terms of spin-state changes. Other changes within the heme pocket most notably in the proximal histidine in the ..beta..-chain of Hb via proton NMR, have also been detected. The molecular bases for these changes and the behavior of the heme electronic states at higher pressures, however, remain open questions. In this paper both resonance Raman and absorption spectroscopy are used to address these problems in reduced heme proteins. Resonance Raman scattering is well suited for this application as it provides a structurally specific probe of the heme active site. 11 references, 2 figures.

  1. Spectroscopic studies of the interfacial interactions between polymers and nanostructures

    NASA Astrophysics Data System (ADS)

    Sampson, William M.

    Optical and vibrational spectroscopies are used to study the interactions of various polymers with several nanoscopic materials. First, two new conjugated polymers manufactured by the Ferraris Group in the Department of Chemistry at The University of Texas at Dallas, poly [1,4-bis-2-ethylhexylmercapto]- p-phenylenevinylene (BEHM-PPV)and poly [1,4-bis-(2-ethylhexyl-sulfinyl)]- p-phenylenevinylene (BEHSO-PPV) are studied along with poly (2,5-bis (2'-ethylhexyloxy)-1,4-p-phenylenevinylene) (BEH-PPV). It is found that the two sulphur containing polymers BEHM-PPV and BEHSO-PPV have a greater tendency to aggregate than does BEH-PPV, and also have bluer photoluminescence. These three polymers are then studied in composite with single walled carbon nanotubes where charge transfer occurs across the interface from the polymer to the nanotubes. These three polymers are studied in mixture with aggregated quantum dots, where it is seen that the quantum dot aggregation prevents significant interactions to occur. The energy transfer interaction between conjugated polymers and transparent, conducting multiwalled carbon nanotubes films is investigated. It is found that a coating of PEDOT-PSS between the nanotubes and conjugated polymer suppresses the quenching of photoluminescence. This effect is important for enhancement of electroluminescence of organic LED devices, in which MWCNT hole injectors are used instead of the usual ITO. The University of Texas developed peptide nano-1 has been shown to engage in charge transfer interactions with SWNTs and, perhaps more importantly, can enable self assembly of complex nanotube structures. Finally, poly [2-methoxy-5-(2'-ethylhexyloxy)- p-phenylenevinylene] (MEH-PPV) and poly[3-hexyl thiophene] (P3HT) are studied in composite with titanium dioxide and an increase in the photoluminescence is seen, induced by interfacial interactions between the polymer and TiO 2. An explanation based on polaron mediated triplet to singlet exciton conversion

  2. Green-synthesis, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods.

    PubMed

    Marwani, Hadi M; Asiri, Abdullah M; Khan, Salman A

    2012-01-01

    Preparation, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods were achieved. The Schiff base dyes were prepared by the reaction of salicylaldehyde/2-Hydroxy-1-naphthaldehyde with aminophenazone under microwave irradiation. The spectroscopic (FT-IR, 1H NMR, 13C-NMR, Mass) studies and elemental analyses were in good agreement with chemical structure of synthesized compounds. In addition, UV-Vis and fluorescence spectroscopic experiments showed that these dyes are good absorbent and fluorescent. Based on the photostability study of these dyes, minimal to no loss in fluorescence intensities of 4-[(2-Hydroxy-benzylidene)-amino] 1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D1) (6.14%) and 4-[(2-Hydroxy-naphthalen-1-ylmethylene)-amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D2) (2.95%) was observed with an increase in the exposure time using time-based fluorescence steady-state experiments. These studies also inferred that these Schiffbase dyes have a high photostability against photobleaching. In addition, Dye 2 is found to be more sensitive than Dye 1 to the polarity of the microenvironment provided by different solvents based on the results of fluorescence polarity studies.

  3. Magnetic resonance and optical spectroscopic studies of carotenoids

    SciTech Connect

    Kispert, L.D.

    1991-05-01

    It is our goal to study the role of a host lattice in the formation of radicals and excited singlet and triplet states that are relevant to photosynthesis. Particular emphasis is being placed on determining what is special about carotenoids that natural photosynthetic systems require them as antennae as well as for protection. We are thus manipulating the host matrix so as to understand the carotenoid function (protection, quenching, energy transfer and antenna) and the structure of carotenoid cations. To characterize their properties, we have carried out EPR, ENDOR, optical, molecular orbital and electrochemical studies of carotenoids and carotenoid cations produced chemically, electrochemically, radiolytically (x-ray irradiated freon matrices) and photolytically (solution photolysis by excimer radiation) as a function of the host matrix. 36 refs.

  4. Studies of tropical fruit ripening using three different spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Huang, Jing; Li, Tianqi; Wu, Xiuxiang; Svanberg, Sune; Svanberg, Katarina

    2014-06-01

    We present a noninvasive method to study fruit ripening. The method is based on the combination of reflectance and fluorescence spectroscopies, as well as gas in scattering media absorption spectroscopy (GASMAS). Chlorophyll and oxygen are two of the most important constituents in the fruit ripening process. Reflectance and fluorescence spectroscopies were used to quantify the changes of chlorophyll and other chromophores. GASMAS, based on tunable diode laser absorption spectroscopy, was used to measure free molecular oxygen in the fruit tissue at 760 nm, based on the fact that the free gases have much narrower spectral imprints than those of solid materials. The fruit maturation and ripening processes can be followed by studying the changes of chlorophyll and oxygen contents with these three techniques.

  5. Chemical and spectroscopic studies of metal oxide surfaces

    SciTech Connect

    Goodman, D.W.

    1996-05-01

    Thin oxide films (e.g., 5{endash}10 nm of SiO{sub 2}, Al{sub 2}O{sub 3}, NiO, MgO) supported on a refractory metal substrate (e.g., Mo, W, Ta, Re) have been prepared by deposition of the oxide metal precursor in a background of oxygen. The thin-film nature of these samples facilitates investigation by an array of surface techniques, many of which cannot be effectively utilized on the corresponding bulk oxide. The structural, electronic, and chemical properties of these films have been studied with temperature programmed desorption, Auger electron spectroscopy, X-ray photoelectron spectroscopy, ion scattering spectroscopy, high resolution electron energy loss spectroscopy, and infrared reflection absorption spectroscopy. The results of these studies demonstrate the viability of using thin oxide films as models for the corresponding bulk oxide. {copyright} {ital 1996 American Vacuum Society}

  6. Photoelectron spectroscopic and computational study of hydrated pyrimidine anions.

    PubMed

    Kelly, John T; Xu, Shoujun; Graham, Jacob; Nilles, J Michael; Radisic, Dunja; Buonaugurio, Angela M; Bowen, Kit H; Hammer, Nathan I; Tschumper, Gregory S

    2014-12-26

    The stabilization of the pyrimidine anion by the addition of water molecules is studied experimentally using photoelectron spectroscopy of mass-selected hydrated pyrimidine clusters and computationally using quantum-mechanical electronic structure theory. Although the pyrimidine molecular anion is not observed experimentally, the addition of a single water molecule is sufficient to impart a positive electron affinity. The sequential hydration data have been used to extrapolate to -0.22 eV for the electron affinity of neutral pyrimidine, which agrees very well with previous observations. These results for pyrimidine are consistent with previous studies of the hydrated cluster anions of uridine, cytidine, thymine, adenine, uracil, and naphthalene. This commonality suggests a universal effect of sequential hydration on the electron affinity of similar molecules.

  7. Spectroscopic Studies of Metal-Ligand-Surface Interactions

    DTIC Science & Technology

    1988-10-01

    consistent with the deduced relative bonding strength in the different complexes. In the second study of the complexation of hydrazine, the Raman spectra of...hydrazine dimer. The assignments of the monomer bands in Figure 4 were deduced primarily by comparison of matrix wavenumbers with predicted wavenumbers...be deduced by referring to Figure 12. Hydrazine has a pair of inner and a pair of outer hydrogen-atom sites. Normally, substitution by another

  8. Spectroscopic and computational study of a new isomer of salinomycin

    NASA Astrophysics Data System (ADS)

    Pankiewicz, Radosław

    2013-09-01

    A new derivative of polyether ionophore salinomycin was obtained as a result of a rearrangement catalysed by sulphuric acid in two-phase medium of water/methylene chloride solution. The new isomer was fully characterized by multinuclear 2D NMR, NOESY and MALDI-TOF. The properties of the new compound were additionally study by semiempirical (PM5) and DFT (B3LYP) methods. A potential mechanism of the rearrangement was also proposed.

  9. Spectroscopic studies of model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Koehler, Birgit G.; Middlebrook, Ann M.

    1993-01-01

    Fourier transform infrared (FTIR) spectroscopy has been used to study nitric-acid/ice films representative of type I polar stratospheric clouds (PSCs). These studies reveal that in addition to amorphous nitric acid/ice mixtures, there are three stable stoichiometric hydrates of nitric acid: nitric-acid monohydrate (NAM), dihydrate (NAD), and trihydrate (NAT). We also observe two distinct crystalline forms of the trihydrate, which we denote alpha- and beta-NAT. These two forms appear to differ in their concentration of crystalline defects, but not in their chemical composition. In addition to probing the composition of type I PSCs, we have also used FTIR spectroscopy to study the interaction of HCl with model PSC films. In this work we find that for HCl pressures in the range 10 exp -5 to 10 exp -7 Torr, HCl is taken up by ice at 155 K to form a thin layer of HCl.6H2O. At 193 K, the uptake of HCl by ice was consistent with less than or equal to monolayer coverage. Uptake of HCl by alpha and beta-NAT at 175 K was also consistent with less than or equal to monolayer coverage.

  10. Excited-state characters and dynamics of [W(CO)(5)(4-cyanopyridine)] and [W(CO)(5)(piperidine)] studied by picosecond time-resolved IR and resonance Raman spectroscopy and DFT calculations: roles of W --> L and W --> CO MLCT and LF excited states revised.

    PubMed

    Zális, Stanislav; Busby, Michael; Kotrba, Tomás; Matousek, Pavel; Towrie, Mike; Vlcek, Antonín

    2004-03-08

    The characters, dynamics, and relaxation pathways of low-lying excited states of the complexes [W(CO)(5)L] [L = 4-cyanopyridine (pyCN) and piperidine (pip)] were investigated using theoretical and spectroscopic methods. DFT calculations revealed the delocalized character of chemically and spectroscopicaly relevant molecular orbitals and the presence of a low-lying manifold of CO pi-based unoccupied molecular orbitals. Traditional ligand-field arguments are not applicable. The lowest excited states of [W(CO)(5)(pyCN)] are W --> pyCN MLCT in character. They are closely followed in energy by W --> CO MLCT states. Excitation at 400 or 500 nm populates the (3)MLCT(pyCN) excited state, which was characterized by picosecond time-resolved IR and resonance Raman spectroscopy. Excited-state vibrations were assigned using DFT calculations. The (3)MLCT(pyCN) excited state is initially formed highly excited in low-frequency vibrations which cool with time constants between 1 and 20 ps, depending on the excitation wavelength, solvent, and particular high-frequency nu(CO) or nu(CN) mode. The lowest excited states of [W(CO)(5)(pip)] are W --> CO MLCT, as revealed by TD-DFT interpretation of a nanosecond time-resolved IR spectrum that was measured earlier in a low-temperature glass (Johnson, F. P. A.; George, M. W.; Morrison, S. L.; Turner, J. J. J. Chem. Soc., Chem. Commun. 1995, 391-393). MLCT(CO) excitation involves transfer of electron density from the W atom and, to a lesser extent, the trans CO to the pi orbitals of the four cis CO ligands. Optical excitation into MLCT(CO) transition of either complex in fluid solution triggers femtosecond dissociation of a W-N bond, producing [W(CO)(5)(solvent)]. It is initially vibrationally excited both in nu(CO) and anharmonicaly coupled low-frequency modes. Vibrational cooling occurs with time constants of 16-22 ps while the intramolecular vibrational energy redistribution from the v = 1 nu(CO) modes is much slower, 160-220 ps. No LF

  11. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  12. Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karthick, N. K.; Kumbharkhane, A. C.; Joshi, Y. S.; Mahendraprabu, A.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

    2017-05-01

    Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) Csbnd H ⋯ Odbnd C (EA), (EA) methylene Csbnd H ⋯ π electrons (CBZ) and (EA) methyl Csbnd H ⋯ Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (εE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

  13. Fourier Transform Infrared Spectroscopic Studies of Small Pure Carbon Clusters

    NASA Astrophysics Data System (ADS)

    Kranze, Richard Harlow

    1996-01-01

    Fourier transform infrared studies of small pure carbon linear chains have been carried out by trapping the products of the vacuum ultraviolet photolysis of 2 -methyl-1,3,-butadiene and by the high temperature evaporation of graphite, in solid Ar at 10 K. Isotopic data obtained for each of the species studied enabled the unambiguous assignments. Comparison of these assignments with theoretical calculations yielded very good agreement. The results of the presented research have resulted in new information on two pure carbon linear chains, C _5 and C_9, and have cleared up considerable confusion surrounding previous assignments to the linear C_6 carbon cluster. In the course of the C_9 study, however, it was also determined that in certain circumstances extreme care must be taken when making assignments based on isotopic substitutions. The v_4(sigma_{u }) antisymmetric stretch at 1446.6 cm ^{-1} of the linear C_5 carbon cluster has been identified for the first time by the analysis of isotopic data. This assignment agrees well with the predicted frequencies of both Botschwina and Sebald (1989) and Ewing and Shavitt (1992). Several isotopic bands belonging to the v_3(sigma u) antisymmetric stretch were also reassigned as a result of the better resolution available in the present study. Both the v_4(sigma_ {u}) and v_5(sigma u) assignments for the linear C_6 carbon cluster were confirmed through the analysis of isotopic data. Prior to publication of this work, it had been suggested by Neumark et al. (1993) that the assignments particularly for v_5( sigmau) were incorrect on the basis of force constant adjustment calculations. However, publication of the present work with the isotopic evidence, which definitively proved that the proposed assignments were correct, Neumark et al. agreed and concluded their difficulty resulted from the large anharmonicity involved with the v_5(sigma_{u }) mode. A second antisymmetric stretch, v_7( sigmau), for the linear C_9 cluster has

  14. Spectroscopic studies of the molecular imprinting self-assembly process.

    PubMed

    Svenson, J; Andersson, H S; Piletsky, S A; Nicholls, I A

    1998-01-01

    A method for the rapid estimation of the extent of complex formation in molecular imprinting prepolymerization mixtures is described. By the use of a UV spectroscopy titration procedure, apparent binding constants for such self-assembly processes have been obtained. This method was used for comparison of the interactions between a dipeptide template (N-acetyl-L-phenylalaninyl-L-tryptophanyl methyl ester) and the functional monomer methacrylic acid, and the monomer analogues acetic acid and trifluoroacetic acid. The importance of template-monomer association during the molecular imprinting prepolymerization phase is discussed with respect to the systems studied.

  15. Fourier transform Raman spectroscopic studies of human and animal skins

    NASA Astrophysics Data System (ADS)

    Barry, Brian W.; Edwards, Howell G.; Williams, Adrian C.

    1994-01-01

    The stratum corneum is the outermost layer of the skin and provides the principal barrier for the ingress of chemicals and environmental toxins into human and animal tissues. However, human skin has several advantages for the administration of therapeutic agents (transdermal drug delivery), but problems occur with the supply, storage, and biohazardous nature of human tissue. Hence, alternative animal tissues have been prepared to model drug diffusion across human skin but the molecular basis for comparison is lacking. Here, FT-Raman spectra of mammalian (human and pig) and reptilian (snake) skins have been obtained and the structural dissimilarities are correlated with drug diffusion studies across the tissues.

  16. Electrochemical and spectroscopic studies of fuel cell reactions

    NASA Astrophysics Data System (ADS)

    Shao, Minhua

    Fuel cells, especially proton exchange membrane fuel cells (PEMFCs) are expected soon to become a major source of clean energy. However, the sluggish kinetics of the fuel cell reactions, i.e., the fuel oxidation and oxygen reduction, hinders the wide-spread application of PEMFCs. These problems prompted our studies to focus on elucidating the nature of the reaction intermediates during the oxidation of fuels and the reduction of oxygen on electrocatalysts, and understanding the mechanisms of these reactions. The results from these studies will provide basic information for designing new electrocatalysts. In this dissertation, the oxidation reactions of ethanol and dimethyl ether (DME) on Pt were investigated by the surface enhanced infrared absorption spectroscopy with an attenuated total reflection configuration (ATR-SEIRAS). Various reaction intermediates were detected and their electrochemical behaviors were studied. We also benefited from advantages of the ATR-SEIRAS technique and observed superoxide anion (O2-) and hydrogen peroxide anion (H2-) as the intermediates in the oxygen reduction reaction (ORR) on Pt and Au electrodes for the first time. The other main goal of this study is design of new electrocatalysts for ORR with low cost and high activity. Two novel electrocatalysts were developed. One is Pt monolayer electrocatalysts consisting of a Pt monolayer formed by a red-ox replacement of the Cu monolayer by Pt atoms on non-noble metal-noble metal core-shell nanoparticles. In such catalyst, the total noble mass activity of the catalyst was 2--6 times larger that of commercial Pt catalyst. Another way of lowering the cost of catalysts and enhancing the ORR activity involves alloying less expensive noble metals with other non-noble elements. In this dissertation, the nano-structured Pd based alloy electrocatalysts have been explored. The results showed that their ORR activities surpass that of commercial Pt. The density functional theory (DFT) calculations

  17. Mössbauer spectroscopic study of iron-chelate trammels

    NASA Astrophysics Data System (ADS)

    Pal, Sangita; Meena, S. S.; Ningthoujam, R. S.; Goswami, D.

    2014-04-01

    Any kind of waste effluent in the Indian context and other countries contains a lot of iron in any ore. During mining, milling, extraction and purification process iron acts as contaminant towards other metal's purity. It is essential to remove iron to the maximum extent. In this case, an "IN-HOUSE" resin polyacrylamidehydroxamic acid (PHOA) has been designed and developed which is highly hydrophilic three dimensionally cross-linked. It has an excellent iron binding capacity with almost no leaching. Interaction of resin with ammonium ferrous sulphate and red-mod (Fe2O3) is studied using Mössbauer spectroscopy.

  18. Raman and infrared spectroscopic study of turquoise minerals.

    PubMed

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L

    2015-10-05

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed.

  19. Raman and infrared spectroscopic study of turquoise minerals

    NASA Astrophysics Data System (ADS)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  20. Vibrational spectroscopic studies of adsorbates on bimetallic surfaces. Doctoral thesis

    SciTech Connect

    Kuhn, W.K.

    1992-12-01

    In this work, well-defined bimetallic surfaces have been studied using carbon monoxide adsorption in conjunction with infrared reflection absorption spectroscopy (IRAS). These studies have indicated that for CO adsorbed on Cu overlayers, the bond between the CO and the Cu adatoms is comprised of both pi-back-donation and polarization interaction components. The sum of the contributions from these effects determines the observed bond strength with the observed CO stretching frequency being determined by the relative contributions of the components. In addition, it was determined that IR spectra of adsorbed CO show a remarkable sensitivity to surface structure. Three-dimensional Cu clusters, well-ordered two dimensional Cu islands and isolated Cu atoms are distinctively characterized by their CO IR peaks. In addition, both disorder-order and order-order transitions are observed for the metal overlayers on the single crystal metal substrates. It was also observed that localized segregation and ordering of mixed Co and S overlayers on a Mo(110) substrate occurs upon annealing.

  1. Ligand exchange in quaternary alloyed nanocrystals--a spectroscopic study.

    PubMed

    Gabka, Grzegorz; Bujak, Piotr; Giedyk, Kamila; Kotwica, Kamil; Ostrowski, Andrzej; Malinowska, Karolina; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

    2014-11-14

    Exchange of initial, predominantly stearate ligands for pyridine in the first step and butylamine (BA) or 11-mercaptoundecanoic acid (MUA) in the second one was studied for alloyed quaternary Cu-In-Zn-S nanocrystals. The NMR results enabled us to demonstrate, for the first time, direct binding of the pyridine labile ligand to the nanocrystal surface as evidenced by paramagnetic shifts of the three signals attributed to its protons to 7.58, 7.95 and 8.75 ppm. XPS investigations indicated, in turn, a significant change in the composition of the nanocrystal surface upon the exchange of initial ligands for pyridine, which being enriched in indium in the 'as prepared' form became enriched in zinc after pyridine binding. This finding indicated that the first step of ligand exchange had to involve the removal of the surface layer enriched in indium with simultaneous exposure of a new, zinc-enriched layer. In the second ligand exchange step (replacement of pyridine with BA or MUA) the changes in the nanocrystal surface compositions were much less significant. The presence of zinc in the nanocrystal surface layer turned out necessary for effective binding of pyridine as shown by a comparative study of ligand exchange in Cu-In-Zn-S, Ag-In-Zn-S and CuInS2, carried out by complementary XPS and NMR investigations.

  2. Vibrational spectroscopic studies of Isoleucine by quantum chemical calculations.

    PubMed

    Moorthi, P P; Gunasekaran, S; Ramkumaar, G R

    2014-04-24

    In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of Isoleucine (2-Amino-3-methylpentanoic acid). The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments, thermodynamics properties, NBO analyses, NMR chemical shifts and ultraviolet-visible spectral interpretation of Isoleucine have been studied by performing MP2 and DFT/cc-pVDZ level of theory. The FTIR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The UV-visible absorption spectra of the compound were recorded in the range of 200-800 nm. Computational calculations at MP2 and B3LYP level with basis set of cc-pVDZ is employed in complete assignments of Isoleucine molecule on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA-4 program. The calculated wavenumbers are compared with the experimental values. The difference between the observed and calculated wavenumber values of most of the fundamentals is very small. (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method and compared with experimental results. The formation of hydrogen bond was investigated in terms of the charge density by the NBO calculations. Based on the UV spectra and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. Besides, molecular electrostatic potential (MEP) were investigated using theoretical calculations.

  3. Raman spectroscopic study of Lactarius spores (Russulales, Fungi)

    NASA Astrophysics Data System (ADS)

    De Gussem, Kris; Vandenabeele, Peter; Verbeken, Annemieke; Moens, Luc

    2005-10-01

    Fungi are important organisms in ecosystems, in industrial and pharmaceutical production and are valuable food sources as well. Classical identification is often time-consuming and specialistic. In this study, Raman spectroscopy is applied to the analysis of fungal spores of Lactarius, an economically and ecologically important genus of Basidiomycota. Raman spectra of spores of Lactarius controversus Pers.: Fr., Lactarius lacunarum (Romagn.) ex Hora, Lactarius quieticolor Romagn. and Lactarius quietus (Fr.: Fr.) Fr. are reported for the first time. The spectra of these species show large similarity. These spectra are studied and compared with the Raman spectra of reference substances known to occur in macrofungi, including saccharides, lipids and some minor compounds that may serve as specific biomarkers (adenine, ergosterol and glycine). Most Raman bands could be attributed to specific components. In agreement with the biological role of fungal spores, high amounts of lipids were observed, the main fatty acid being oleate. In addition to different types of lipids and phospholipids, the polysaccharides chitin and amylopectin could be detected as well. The presence of trehalose is not equivocally shown, due to overlapping bands. Raman band positions are reported for the observed bands of the different species and reference products.

  4. Spectroscopic Studies on the Molecular Ageing of Serum Albumin.

    PubMed

    Chudzik, Mariola; Maciążek-Jurczyk, Małgorzata; Pawełczak, Bartosz; Sułkowska, Anna

    2016-12-27

    Pathological states in the organism, e.g., renal or hepatic diseases, cataract, dysfunction of coronary artery, diabetes mellitus, and also intensive workout, induce the structural modification of proteins called molecular ageing or N-A isomerization. The aim of this study was to analyze the structural changes of serum albumin caused by alkaline ageing using absorption, spectrofluorescence, and circular dichroism spectroscopy. The N-A isomerization generates significant changes in bovine (BSA) and human (HSA) serum albumin subdomains-the greatest changes were observed close to the tryptophanyl (Trp) and tyrosyl (Tyr) residue regions while a smaller change was observed in phenyloalanine (Phe) environment. Moreover, the changes in the polarity of the Trp neighborhood as well as the impact of the ageing process on α-helix, β-sheet content, and albumin molecule rotation degree have been analyzed. Based on the spectrofluorescence study, the alterations in metoprolol binding affinity to the specific sites that increase the toxicity of the drug were investigated.

  5. Photoacoustic FTIR spectroscopic study of undisturbed nacre from red abalone

    NASA Astrophysics Data System (ADS)

    Verma, Devendra; Katti, Kalpana; Katti, Dinesh

    2006-07-01

    In this work, photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy has been utilized to study interfacial interactions of undisturbed nacre and nacre powder from red abalone shell. The spectra of both undisturbed nacre and nacre powder showed characteristic bands of aragonite and proteins. Although nacre powder and undisturbed nacre are chemically identical, PA-FTIR spectrum of undisturbed nacre is found to be significantly different from that of nacre powder. A broad and strong band is observed at around 1485 cm -1 in nacre powder. The intensity of this band is notably reduced in undisturbed nacre. This result is explained on the basis of interfacial interactions between aragonite platelets and acidic proteins. It is also observed that band at around 1788 cm -1 originates from three overlapping bands 1797, 1787 and 1778 cm -1. The band at around 1787 cm -1 is assigned to C dbnd O stretching of carboxylate groups of acidic proteins. The other two bands at 1797 and 1778 cm -1, originate from aragonite and have been assigned to combination bands, ν 3 + ν 4a and ν 3 + ν 4b, respectively. For the study of stratification in undisturbed nacre, PA-FTIR spectra have been collected in step scan mode. The variation in spectra with depth can be attributed to changes in conformation of proteins as well as interfacial interactions.

  6. [Infrared spectroscopic study on leaf senescence of evergreen tree].

    PubMed

    Li, Lun; Zhou, Xiang-Ping; Liu, Gang; Zhang, Li; Ou, Quan-Hong; Hao, Jian-Ming

    2013-02-01

    In order to investigate plant physiological process of leaf senescence and aging, Fourier transform infrared (FTIR) spectroscopy was used to study the young, mature, and old yellow leaves from seven species of evergreen trees. The spectra of the leaves from different growing period are different in the region of 1 800-700 cm(-1). The absorption ratios A1 070/A2 927, A1 070/A1 160 were used to evaluate the relative changes of polysaccharides, and A1 318/A2 922 was used to estimate the change of calcium oxalate during leaf senescence. Decomposition and curve-fitting analysis was performed in the region of 1 800 -1 500 cm(-1). The sub-band absorption ratio H1 650/H1 740 was used to evaluate the relative changes of protein in the leaves. The results show that the accumulation and mobilization of polysaccharides, protein, and calcium oxalate during leaf growing period were different in different plant species. This study demonstrates the potential of mid-infrared spectroscopy for investigation of plants senescence, as well as physiological and biochemical changes of plants.

  7. Multinuclear nuclear magnetic resonance spectroscopic study of cartilage proteoglycans

    SciTech Connect

    Lerner, L.

    1985-01-01

    Hyaline cartilage is a composite material whose major function is to withstand compression while retaining flexibility. Its mechanical properties are affected by tissue hydration and ionic composition. Models of the mechanical behavior of cartilage have incorporated certain assumptions about the interactions of the major components of cartilage: collagen, proteoglycans, water, and cations. To determine the validity of these assumption, the authors have used nuclear magnetic resonance spectroscopy (NMR). Two approaches have been used: (a) natural abundance carbon-13 NMR; and (b) NMR of sodium-23, potassium-39, magnesium-25, and calcium-43. Evidence from studies in intact tissues are reinforced by extensive measurements on solutions of proteoglycans and other relevant macromolecules. Based on the measurements of NMR relaxation rates and lineshapes reported here, it is concluded that neither sodium nor potassium interact strongly with bovine nasal proteoglycan aggregates or their substituent glycosaminoglycan chains in solution. Proteoglycans do bind magnesium and calcium. Therefore there is a qualitative difference between monovalent and divalent cations, which is not taken into account by polyelectrolyte models or models for the ionic dependence of mechanical properties. Cation binding to heparin, which has a higher charge density than cartilage proteoglycans, was also studied. The results presented here establish that heparin binds sodium, magnesium, and calcium.

  8. Spectroscopic, structural and drug docking studies of carbocysteine

    NASA Astrophysics Data System (ADS)

    Manivannan, M.; Rajeshwaran, K.; Govindhan, R.; Karthikeyan, B.

    2017-09-01

    Carbocysteine or carbocisteine having the empirical formula C5H9NO4S,is one of the most therapeutically prescribed expectorant, sold under the brand name viz., Mucodyne (UK and India), Rhinathiol and Mucolite. In pediatric respiratory pathology, it can relieve the symptoms of obstructive pulmonary disease (COPD) and bronchiectasis. On the consideration of its extensive pharmaceutical usage and medicinal value, we have investigated its chemical structure and composition by employing various spectral techniques like 1H, 13C NMR, FT-IR,Raman, UV-Visible spectroscopy and powder X-ray diffraction method. Density Functional Theoretical (DFT) studies on its electronic structure is also carried out. Drug docking studies were carried out to ascertain the nature of molecular interaction with the biological protein system. Furthermore theoretical Raman spectrum of this molecule has been computed and compared with the experimental Raman spectrum. The forbidden energy gap between its frontier molecular orbitals, viz., HOMO-LUMO is calculated and correlated with its observed λmax value. Atomic orbitals which are mainly contributes to the frontier molecular orbitals were identified. Molecular electrostatic potential diagram has been mapped to explain its chemical activity. Based on the results, a suitable mechanism of its protein binding mode and drug action has been discussed.

  9. Theoretical spectroscopic study of protonated and deuteronated PAHs

    NASA Astrophysics Data System (ADS)

    Buragohain, Mridusmita; Pathak, Amit

    The study of Polycyclic Aromatic Hydrocarbon (PAH) plays a key role to understand astrophysical environments as they are ubiquitous in the Interstellar Medium (ISM). They account for about 5-10% of carbon budget in the universe and are responsible for the strong IR emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7mum seen towards most of the interstellar objects including HII regions, reflection nebulae, planetary nebulae, late-type stars, as well as active star-forming regions. These IR features result from the relaxation of vibrationally excited PAHs. As PAHs are stable enough to survive the interstellar conditions, they could possibly be responsible for the enigmatic Diffuse Interstellar Bands (DIBs) which are optical absorption features on the interstellar extinction curve. The fact that interstellar PAHs are more likely to be ions has motivated the study of radical PAHs. Protonated PAHs formed by H(+) addition to neutral parent molecules, denoted as HPAH(+) , are an important form of closed shell PAH cation. Protonated forms show electronic transitions in the visible part of the spectrum where most DIBs are present, whereas neutral forms generally show their strongest electronic transitions in the UV region. We also report quantum chemical calculations on HPAH(+) and DPAH(+) (D(+) attached to PAH) to get the electronic and IR spectra to understand the IR emission and DIB features. A comparison of theoretical spectra with the available experimental spectra has also been carried out.

  10. Impedance and modulus spectroscopic study of nano hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.

    2016-05-01

    Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.

  11. Kinetic and Spectroscopic Studies of Heterogeneous Catalytic Reactions

    NASA Astrophysics Data System (ADS)

    Wilke, Todd E.

    1990-01-01

    The selective oxidation of ethylene was studied on a high surface area colloidal silver catalyst. In 0.1 to 1 torr of 20% ethylene in oxygen, the catalyst produced ethylene oxide with a selectivity of 20 to 30% at temperatures between 473 and 573 K. Surface-enhanced Raman (SER) spectra exhibited a distinct feature at 995 cm^ {-1}. This band was also observed for catalysts exposed to just oxygen, and it shifted to 980 cm^{-1} after heating the catalyst to 873 K in ^{18} O_2. No isotopic shift was observed with ^{18}O _2 at temperatures below 573 K. Similar spectral results were obtained at atmospheric pressure. For silver catalysts that contain adsorbed chlorine, SER bands were observed at 240, 1015, and 1045 cm^ {-1} in oxygen-containing atmospheres; the 995 cm^{-1} band was not evident. The extension of SERS to other metals that do not exhibit the surface-enhanced effect was examined by electrodepositing thin layers (2 to 3 monolayers) of platinum, rhodium, and ruthenium on a roughened gold substrate. At atmospheric pressure and temperatures between 298 and 473 K, metal-oxygen features were observed at 500 cm ^{-1}, and 490 and 600 cm ^{-1} in SER spectra of rhodium and ruthenium surfaces exposed to oxygen, respectively. Bands attributed to adsorbed carbon monoxide were observed in SER spectra of platinum (470, 2060, 390, and 1890 cm ^{-1}) and rhodium (465 and 2040 cm^{-1}) surfaces exposed to carbon monoxide and oxygen mixtures. The temporal replacement of adsorbed carbon monoxide by nitric oxide as well as temperature-induced changes in the surface composition were studied on a seconds timescale with a spectrograph -charge coupled device detector arrangement. The adsorption and oxidation of sulfur dioxide was also studied. A band assigned to the S-O stretch of molecularly adsorbed sulfur dioxide was observed at 1130 cm^{-1} on unmodified gold and platinum-coated gold surfaces exposed to sulfur dioxide at 298 K. Dissociative chemisorption of sulfur dioxide on

  12. Negative ion photoelectron spectroscopic studies of transition metal cluster

    NASA Astrophysics Data System (ADS)

    Marcy, Timothy Paul

    The studies reported in this thesis were performed using a negative ion photoelectron spectrometer consisting of a cold cathode DC discharge ion source, a flowing afterglow ion-molecule reactor, a magnetic sector mass analyzer, an argon ion laser for photodetachment and a hemispherical electron kinetic energy analyzer and microchannel plate detector for photoelectron spectrum generation. The 476.5 nm (2.601 eV), 488.0 nm (2.540 eV) and 514.5 nm (2.410 eV) negative ion photoelectron spectra of VMn are reported and compared to the previously studied spectra of isoelectronic Cr2.1 The photoelectron spectra are remarkably similar to those of Cr2 in electron affinity and vibrational frequencies. The 488.0 nm photoelectron spectra and electron affinities of Nb n- (n = 1 - 9) are reported with discussion of observed vibrational structure. There are transitions to several electronic states of Nb2 in the reported spectra with overlapping vibrational progressions. The spectra of Nb3, Nb4 and Nb6 show partially resolved vibrational structure in the transitions to the lowest observed electronic state of each cluster. There is a single distinct active vibrational mode in the transition to the ground state of Nb8. Spin-orbit energies of Nb- are also reported. The 488.0 nm negative ion photoelectron spectra of Nb3H(D) are reported and compared to those of Nb3. There is a single vibrational mode active in the spectra of Nb3H(D) which is very similar to the most distinct mode active in the spectrum of Nb3. The 488.0 nm photoelectron spectra of the NbxCyH(D) y- (x = 1, 2, 3, y = 2, 4, 6) dehydrogenated products of the reactions of ethylene with niobium cluster anions are reported. Temperature studies of some of these species give evidence for the presence of multiple isomers of each molecule in the ion beam. The spectra of NbC6H(D) 6 are identical to those obtained from the reactions of benzene with niobium clusters and indicate that benzene is being formed from ethylene in the flow

  13. Spectroscopic STM studies of single gold(III) porphyrin molecules.

    PubMed

    Müllegger, Stefan; Schöfberger, Wolfgang; Rashidi, Mohammad; Reith, Lorenz M; Koch, Reinhold

    2009-12-16

    Low-temperature scanning tunneling microscopy, a well-established technique for single-molecule investigations in an ultrahigh vacuum environment, has been used to study the electronic properties of Au(III) 5,10,15,20-tetraphenylporphyrin (AuTPP) molecules on Au(111) at the submolecular scale. AuTPP serves as a model system for chemotherapeutically relevant Au(III) porphyrins. For the first time, real-space images and local scanning tunneling spectroscopy data of the frontier molecular orbitals of AuTPP are presented. A comparison with results from density functional theory reveals significant deviations from gas-phase behavior due to a non-negligible molecule/substrate interaction. We identify the oxidation state of the central metal ion in the adsorbed AuTPP as Au(3+).

  14. Raman spectroscopic study of plasma-treated salmon DNA

    SciTech Connect

    Lee, Geon Joon; Kim, Yong Hee; Choi, Eun Ha; Kwon, Young-Wan

    2013-01-14

    In this research, we studied the effect of plasma treatment on the optical/structural properties of the deoxyribonucleic acid (DNA) extracted from salmon sperm. DNA-cetyltrimethylammonium (CTMA) films were obtained by complexation of DNA with CTMA. Circular dichroism (CD) and Raman spectra indicated that DNA retained its double helical structure in the solid film. The Raman spectra exhibited several vibration modes corresponding to the nuclear bases and the deoxyribose-phosphate backbones of the DNA, as well as the alkylchains of CTMA. Dielectric-barrier-discharge (DBD) plasma treatment induced structural modification and damage to the DNA, as observed by changes in the ultraviolet-visible absorption, CD, and Raman spectra. The optical emission spectra of the DBD plasma confirmed that DNA modification was induced by plasma ions such as reactive oxygen species and reactive nitrogen species.

  15. Spectroscopic structural studies of salicylic acid, salicylamide and aspirin

    NASA Astrophysics Data System (ADS)

    El-Shahawy, Anwar S.

    The electronic absorption spectra of the salicylic acid and the salicylamide molecules have been studied using SCF—CL calculations. The singlet and the triplet electronic transition energies have been calculated. The state functions of eight excited states for these molecules have been calculated in addition to the oscillator strengths, charge densities, ionization potentials and electron affinities. Our calculations lead to the presence of salicylic acid and salicylamide in the β-forms in which the carboxylic hydroxyl group or the amino group is directed toward the enolic hydroxyl group. The salicylic acid and the salicylamide molecules have the Cs point group symmetry, but the aspirin molecule has the C1 point group symmetry, in which the acetyl group does not lie in the plane of the salicylic acid molecule.

  16. Raman and infrared spectroscopic study of kamphaugite-(Y)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo

    2015-05-01

    We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH)·H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm-1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed.

  17. Mechanism of Arsenic Adsorption Using Wheat Biomass -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Calvo, Oscar; Manciu, Felicia; Maldonado, Josefina; Gardea-Torresdey, Jorge

    2006-10-01

    Arsenic is a trace element that is toxic to animals, humans included. Since the current Environmental Protection Agency guidelines regarding water quality standards indicate that arsenic concentrations in excess of 50 ppb are hazardous to welfare of humans, the search for new water remediation methods or improvements of previous methods have been a focus in environmental technology. Investigations of arsenic uptake have used wide range of sorbents including iron oxides and oxyhydroxides, for which it have been proved that arsenic shows high affinity. In this study, we used far-infrared spectroscopy to examine the arsenic reduction using biomaterials. pH dependence analysis by FTIR demonstrates the sorption of iron oxides and oxyhydroxides by the wheat biomass. The splitting of 350 cm-1 amorphous iron oxide vibrations is a direct proof of the arsenic uptake. In addition, there is evidence of sorption of arsenic at sulfhydryl group of cysteine existent in wheat.

  18. Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1986-01-01

    Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

  19. Spectroscopic Study of Sediments from Chapala Lake in Western Mexico

    NASA Astrophysics Data System (ADS)

    Arízaga, G. G. Carbajal; Doumer, M. E.; Lucio, G. Álvarez; Salazar, S. Gómez; Mangrich, A. S.; Huerta, A. García

    2016-11-01

    The first 10 cm of sediment from Lake Chapala, Western Mexico are in constant activity related to the exchange and speciation of metal cations. Samples of this sediment were analyzed in electron paramagnetic resonance (EPR) equipment to study the paramagnetic metals. Assays indicated that only Fe3+ was present in a detectable amount. This cation, along with chemical fractions of sediment obtained by sequential extraction, was analyzed by EPR. The analysis supported by infrared data revealed that Fe3+ was present in diluted and concentrated domains. Easily exchangeable iron was retained by carbonyl groups in organic matter. The carbonate fraction and oxides contained iron in concentrated domains. The alumina-silicate fraction (that resisted the sequential extraction digestions) presented diluted domains of iron in the octahedral alumina sheet along with occlusions of concentrated domains. This last inference was obtained by comparing EPR results against the spectrum of iron in synthetic model clay.

  20. Computational and vibrational spectroscopic studies of ipratropium bromide.

    PubMed

    Ali, H R H; Edwards, H G M; Kendrick, J; Scowen, I J

    2009-02-01

    In this study, ipratropium bromide is investigated using vibrational spectroscopy and quantum chemical calculations. The structure of ipratropium bromide was optimised using density functional theory calculations and the geometry optimisation has been carried out on two conformations with and without intramolecular hydrogen bonding. Infrared and Raman spectra were calculated from the optimised structures. Many modes in the calculated spectra could be matched with the experimental spectra and a description of the modes is given. By analysis of the theoretical vibrational modes, it is shown that ipratropium bromide specimens are likely to be a mixture of the two conformations with and without intramolecular hydrogen bonding. In addition, several spectral features and band intensities in the CH and OH stretching regions are explained. Quantum mechanical calculations allowed improved understanding of ipratropium bromide and its vibrational spectra.

  1. Spectroscopic study of low-temperature hydrogen absorption in palladium

    SciTech Connect

    Ienaga, K. Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T.; Tsujii, H.; Kimura, T.

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  2. A spectroscopic study of the blue stragglers in M67

    NASA Astrophysics Data System (ADS)

    Liu, G. Q.; Deng, L.; Chávez, M.; Bertone, E.; Davo, A. Herrero; Mata-Chávez, M. D.

    2008-10-01

    Based on spectrophotometric observations from the Guillermo Haro Observatory (Cananea, Mexico), a study of the spectral properties of the complete sample of 24 blue straggler stars (BSs) in the old Galactic open cluster M67 (NGC 2682) is presented. All spectra, calibrated using spectral standards, were recalibrated by means of photometric magnitudes in the Beijing-Arizona-Taipei-Connecticut system, which includes fluxes in 11 bands covering ~3500-10000 Å. The set of parameters was obtained using two complementary approaches that rely on a comparison of the spectra with (i) an empirical sample of stars with well-established spectral types and (ii) a theoretical grid of optical spectra computed at both low and high resolution. The overall results indicate that the BSs in M67 span a wide range in Teff(~ 5600 -12600 K) and surface gravities that are fully compatible with those expected for main-sequence objects (log g = 3.5 -5.0 dex).

  3. Identification and derivatization of selected cathinones by spectroscopic studies.

    PubMed

    Nycz, Jacek E; Pazdziorek, Tadeusz; Malecki, Grzegorz; Szala, Marcin

    2016-09-01

    In this study we identified three novel hydrochloride salts of cathinones 2-(pyrrolidin-1-yl)-1-(5,6,7,8-tetrahydronaphthalen-2-yl)pentan-1-one (1a) (TH-PVP), 2-(methylamino)-1-(2-methylphenyl)-1-propanone (1b) (2-MMC) and 1-(4-chlorophenyl)-2-(methylamino)propan-1-one (1c) (4-CMC). Their properties have been examined through combinations of GC-MS, IR, NMR, electronic absorption spectroscopy and single crystal X-ray diffraction method. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, N-methyl and carbonyl groups. Additionally the use of thionation and amination reactions for identification of selected cathinones was presented.

  4. Micro-Ft Spectroscopic Studies of Breast Tissues

    NASA Astrophysics Data System (ADS)

    Anastassopoulou, J.; Arapantoni, P.; Boukaki, E.; Konstadoudakis, S.; Theophanides, T.; Valavanis, C.; Conti, C.; Ferraris, P.; Giorgini, G.; Sabbatini, S.; Tosi, G.

    Micro-FT-IR spectroscopy was used to study breast cancer tissues and, in particular osteosarcoma tissue. By analysing the spectra, we have found characteristic bands in the infrared regions, where the main components of these signature bands are located. In the region between 1680-1660 cm-1 are found the characteristic bands of Amide I and II of proteins. The bands, which correspond to the vibrations of the phosphate groups, are found in the region near 1140-900 cm-1. These characteristic bands have been monitored as a function of the degree of cancer progression. The results have been obtained with chemometric methods, such as cluster analysis, principal component analysis and custom analysis in order to distinguish the neoplastic zones from the normal zones.

  5. Spectroscopic and quantum chemical calculation study on 2-ethoxythiazole molecule

    NASA Astrophysics Data System (ADS)

    Avcı, Davut; Dede, Bülent; Bahçeli, Semiha; Varkal, Döndü

    2017-06-01

    In this study, the 2-ethoxythiazole molecule (C5H7NSO) which is a member of the five-membered heterocyles with one nitrogen atom group has been investigated by using the experimental UV-vis (in three different solvents) and FT-IR spectral results as well as some magnetic properties. Furthermore, the calculated molecular geometric parameters, vibrational wavenumbers, HOMO-LUMO energies, 1H and 13C NMR chemical shift values and natural bond orbitals (NBO) of the title molecule have been calculated at the B3LYP and HSEH1PBE levels of theory with the 6-311++G(d,p) basis set. The spectral results obtained from the quantum chemical calculations are in good agreement with the experimental results.

  6. Preparations and spectroscopic studies of organotin complexes of diclofenac*1

    NASA Astrophysics Data System (ADS)

    Kourkoumelis, Nikolaos; Demertzis, Mavroudis A.; Kovala-Demertzi, Dimitra; Koutsodimou, Aglaia; Moukarika, Alice

    2004-08-01

    The reactions of the potent and widely used anti-inflammatory drug diclofenac, HL, with diorganotin(IV) oxides were studied. The dimeric tetraorganodistannoxane complexes [Me 2LSnOSnLMe 2] 2, [Bu 2LSnOSnLBu 2] 2, [Ph 2LSnOSnLPh 2] 2 and the dibutyltin complex [Bu 2SnL 2], have been prepared and structurally characterized in the solid state by means of vibrational and 119Sn Mössbauer spectroscopy. Determination of lattice dynamics by temperature-dependent 119Sn Mössbauer spectroscopy. From the variable-temperature Mössbauer effect, the Debye temperature was determined. The complexes have been characterized in solution by NMR ( 1H and 13C) spectroscopy. Vibrational, Mössbauer, and NMR data are discussed in terms of the proposed structures.

  7. [Spectroscopic studies of guanidine hydrochloride-induced unfolding of hemoglobin].

    PubMed

    Li, Jin-Jing; Tang, Qian; Cao, Hong-Yu; Zhang, Yu-Jiao; Zhang, Tao; Zheng, Xue-Fang

    2012-09-01

    In the present paper, based on the ultraviolet-visible (UV-Vis) absorption spectroscopy, fluorescence spectroscopy, and stopped flow-fluorescence spectroscopy, the authors studied the protein unfolding process of hemoglobin induced by GdmHcl. The experiments result shows that there were two different procedures about GdmHcl inducing hemoglobin unfolding from the evidences of UV-Vis absorption spectrum and fluorescence phase diagrams. Namely, the hemoglobin subunit exhibits depolymerization, forming the intermediates when incubated with GdmHcl at the concentration of 1. 0 mol x L(-1). With the increase in the concentration, various subunit structure became loose gradually, and the protoheme collapsed eventually. UV-Vis absorption spectroscopy indicates that the addition of reductant can cooperate with the depolymerization of hemoglobin subunit and the disaggregation of protoheme. The reductant results in the unfolding procedure that hemoglobin from "three-state model" turns into "two-state model".

  8. Conformational analysis and vibrational spectroscopic studies on dapsone

    NASA Astrophysics Data System (ADS)

    Ildiz, Gulce Ogruc; Akyuz, Sevim

    2012-11-01

    In this study, the theoretical conformation analysis of free dapsone has been performed by single point energy calculations at both semi-empirical PM3 and DFT/B3LYP-3-21G theory levels and three stable conformers were determined. Both the IR and Raman spectra of the molecule in solid phase have been recorded. The IR intensities and harmonic vibrational wavenumbers of each conformer were calculated by DFT method at B3LYP/6-31++G(d,p) theory level. For the fundamental characterization, the total energy distribution (TED) calculations of the vibrational modes were done using parallel quantum mechanic solution program (SQM) and the fundamental modes were assigned. The theoretical results are in agreement with the experimental ones.

  9. Raman spectroscopic study of ancient South African domestic clay pottery.

    PubMed

    Legodi, M A; de Waal, D

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.

  10. Raman spectroscopic study of ancient South African domestic clay pottery

    NASA Astrophysics Data System (ADS)

    Legodi, M. A.; de Waal, D.

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al 2Si 2O 5(OH) 5), illite (KAl 4(Si 7AlO 20)(OH) 4), feldspar (K- and NaAlSi 3O 8), quartz (α-SiO 2), hematite (α-Fe 2O 3), montmorillonite (Mg 3(Si,Al) 4(OH) 2·4.5H 2O[Mg] 0.35), and calcium silicate (CaSiO 3). Gypsum (CaSO 4·2H 2O) and calcium carbonates (most likely calcite, CaCO 3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO 2) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO 4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 °C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.

  11. FTIR Spectroscopic Studies on Cross Linking of SU-8 Photoresist

    NASA Astrophysics Data System (ADS)

    Kalaiselvi, S. M. P.; Tan, T. L.; Rawat, R. S.; Lee, P.; Heussler, S. P.; Breese, M. B. H.

    2013-11-01

    The usage of chemically-amplified, negative tone SU-8 photoresist is numerous, spanning industrial, scientific and medical fields. Hence, in this study, some preliminary studies were conducted to understand the dosage and heat treatment requirements of the SU-8 photoresist essential for pattern generation using X-ray lithography. In this work, using Synchrotron as the X-ray source, SU-8 photoresist was characterized for X-ray lithography in terms of its process parameters such as X-ray exposure dose, post exposure bake (PEB) time and temperature for various photoresist thicknesses which is considered worthwhile in view of applications of SU-8 for the fabrication of very high aspect ratio micro structures. The process parameters were varied and the resultant cross linking of the molecular chains of the photoresist was accurately monitored using a Fourier Transform Infra-Red (FTIR) spectrometer and the results are discussed. The infrared absorption peak at 914 cm-1 in the spectrum of the SU-8 photoresist was found to be a useful indicator for the completion of cross linking in the SU-8 photoresist. Results show that the cross linking of the SU-8 photoresist is at a higher rate from 0 J/cm3 to 30 J/cm3 after which the peak almost saturates regardless of the PEB time. It is a good evidence for the validation of dosage requirement of SU-8 photoresist for effective completion of cross linking, which in turn is a requirement for efficient fabrication of micro and nano structures. An analogous behavior was also observed between the extent of cross linking and the PEB time and temperature. The rate of cross linking declines after a certain period of PEB time regardless of PEB temperature. The obtained results also show a definite relation between variation of the absorbance area of the peak at 914 cm-1 and the X-ray exposure dose.

  12. Raman spectroscopic studies of carbon in extra-terrestrial materials

    NASA Technical Reports Server (NTRS)

    Macklin, John; Brownlee, Donald; Chang, Sherwood; Bunch, Ted

    1990-01-01

    The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at various temperatures and natural material, as well as several acid residues from the Allende and Murchison meteorites in order to establish new spectra-structure relationships. Structural features of many of the materials in this study have been measured by x ray analysis and electron microscopy: thus, their structural differences can be directly correlated with differences in the Raman spectra. The spectral parameters consequently affirmed as indicators of structure are used as a measure of structure in materials that have unknown carbon structure, especially IDPs. The unique applicability of micro-Raman spectroscopy is realized not only in the ability to conveniently measure spectra of micron-size IDPs, but also micro-sized parts of an inhomogeneous material. Microcrystalline graphite is known to give Raman spectra that differ dependent on crystallite size (see e.g., Lespade, et. al., 1984, or Nemanich and Solin, 1979). The spectral changes that accompany decreasing particle size include increase in the ratio (R) of the intensity of the band near 1350 cm(-1) (D band) to that of the band near 1600 cm(-1) (G band) increase in the half width of the D band (wD) increase in the frequency maximum of the G band and increase in the half-width (wG) of the 2nd order band near 2700 cm(-1) (G) band.

  13. Raman spectroscopic studies of carbon in extra-terrestrial materials

    NASA Technical Reports Server (NTRS)

    Macklin, John; Brownlee, Donald; Chang, Sherwood; Bunch, Ted

    1990-01-01

    The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at various temperatures and natural material, as well as several acid residues from the Allende and Murchison meteorites in order to establish new spectra-structure relationships. Structural features of many of the materials in this study have been measured by x ray analysis and electron microscopy: thus, their structural differences can be directly correlated with differences in the Raman spectra. The spectral parameters consequently affirmed as indicators of structure are used as a measure of structure in materials that have unknown carbon structure, especially IDPs. The unique applicability of micro-Raman spectroscopy is realized not only in the ability to conveniently measure spectra of micron-size IDPs, but also micro-sized parts of an inhomogeneous material. Microcrystalline graphite is known to give Raman spectra that differ dependent on crystallite size (see e.g., Lespade, et. al., 1984, or Nemanich and Solin, 1979). The spectral changes that accompany decreasing particle size include increase in the ratio (R) of the intensity of the band near 1350 cm(-1) (D band) to that of the band near 1600 cm(-1) (G band) increase in the half width of the D band (wD) increase in the frequency maximum of the G band and increase in the half-width (wG) of the 2nd order band near 2700 cm(-1) (G) band.

  14. Spectroscopic study of intermolecular complexes between FAD and some β-carboline derivatives

    NASA Astrophysics Data System (ADS)

    Codoñer, Armando; Monzó, Isidro S.; Tomás, Francisco; Valero, Rosa

    The formation of molecular complexes between flavine adenine dinucleotide (FAD) and some β-carboline derivatives [antidepressant drugs that have a pronounced inhibition of monoamine oxidase (MAO)] has been studied by using electronic absorption and fluorescence spectroscopic methods. Thermodynamic parameters have been determined from the values of association constants for the molecular complexes at various temperatures. The influence of substituents in the β-carboline molecule on the stability of the complexes formed was also investigated.

  15. Ir Spectroscopic Studies on Microsolvation of HCl by Water

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Schwan, Raffael; Fischer, Theo; Dey, Arghya; Kaufmann, Matin; Redlich, Britta; van der Meer, Lex; Schwaab, Gerhard; Havenith, Martina

    2016-06-01

    Acid dissociation reactions are at the heart of chemistry. These reactions are well understood at the macroscopic level. However, a microscopic level understanding is still in the early stages of development. Questions such as 'how many H_2O molecules are needed to dissociate one HCl molecule?' have been posed and explored both theoretically and experimentally.1-5 Most of the theoretical calculations predict that four H_2O molecules are sufficient to dissociate one HCl molecule, resulting in the formation of a solvent separated H_3O+(H_2O)3Cl- cluster.1-3 IR spectroscopy in helium nanodroplets has earlier been used to study this dissociation process.3-5 However, these studies were carried out in the region of O-H and H-Cl stretch, which is dominated by the spectral features of undissociated (HCl)m-(H_2O)n clusters. This contributed to the ambiguity in assigning the spectral features arising from the dissociated cluster.4,5 Recent predictions from Bowman's group, suggest the presence of a broad spectral feature (1300-1360 wn) for the H_3O+(H_2O)3Cl- cluster, corresponding to the umbrella motion of H_3O+ moiety.6 This region is expected to be free from the spectral features due to the undissociated clusters. In conjunction with the FELIX laboratory, we have performed experiments on the (HCl)m(H_2O)n (m=1-2, n≥4) clusters, aggregated in helium nanodroplets, in the 900-1700 wn region. Mass selective measurements on these clusters revealed the presence of a weak-broad feature which spans between 1000-1450 wn and depends on both HCl as well as H_2O concentration. Measurements are in progress for the different deuterated species. The details will be presented in the talk. References: 1) C.T. Lee et al., J. Chem. Phys., 104, 7081 (1996). 2) H. Forbert et al., J. Am. Chem. Soc., 133, 4062 (2011). 3) A. Gutberlet et al., Science, 324, 1545 (2009). 4) S. D. Flynn et al., J. Phys. Chem. Lett., 1, 2233 (2010). 5) M. Letzner et al., J. Chem. Phys., 139, 154304 (2013). 6) J. M

  16. Fourier Transform Infrared and Resonance Raman Spectroscopic Studies of Bacteriorhodopsin.

    NASA Astrophysics Data System (ADS)

    Earnest, Thomas Nixon

    Fourier transform infrared and resonance Raman spectroscopy were used to investigate the structure and function of the light-activated, transmembrane proton pump, bacteriorhodopsin, from the purple membrane of Halobacterium halobium. Bacteriorhodopsin (bR) is a 27,000 dalton integral membrane protein consisting of 248 amino acids with a retinylidene chromophore. Absorption of a photon leads to the translocation of one or two protons from the inside of the cell to the outside. Resonance Raman spectroscopy allows for the study of the configuration of retinal in bR and its photointermediates by the selective enhancement of vibrational modes of the chromophore. This technique was used to determine that the chromophore is attached to lysine-216 in both the bR _{570} and the M _{412} intermediates. In bR with tyrosine-64 selectively nitrated or aminated, the chromophore appears to have the same configuration in that bR _{570} (all- trans) and M _{412} (13- cis) states as it does in unmodified bR. Polarized Fourier transform infrared spectroscopy (FTIR) permits the study of the direction of transition dipole moments arising from molecular vibrations of the protein and the retinal chromophore. The orientation of alpha helical and beta sheet components was determined for bR with the average helical tilt found to lie mostly parallel to the membrane normal. The beta sheet structures also exhibit an IR linear dichroism for the amide I and amide II bands which suggest that the peptide backbone is mostly perpendicular to the membrane plane although it is difficult to determine whether the bands originate from sheet or turn components. The orientation of secondary structure components of the C-1 (residues 72-248) and C-2 (residues 1-71) fragments were also investigated to determine the structure of these putative membrane protein folding intermediates. Polarized, low temperature FTIR -difference spectroscopy was then used to investigate the structure of bR as it undergoes

  17. Raman spectroscopic study of chemically-doped few layer graphenes

    NASA Astrophysics Data System (ADS)

    Tan, Pingheng; Zhao, Weijie; Zhang, Jun; Liu, Jian

    2011-03-01

    Graphene, the latest carbon allotrope discovered at 2004, has attracted intensively scientific interest owing to its distinctive properties. Chemical doping is expected to substantially increase the density of free charge carriers by charge transfer and to modify the Fermi level of doped materials. Here, we investigated charge transfer and optical phonon mixing in few layer graphenes in detail by utilizing sulfuric acid as an electron-acceptor dopant. Sulfuric acid molecules are found to be only physically adsorbed on the surface layers of graphenes and no intercalation happens. The top and bottom layers of bilayer graphenes can be intentionally doped differently by concentrated sulfuric acid. The difference of hole doping between the top and bottom layers results in phonon mixing of symmetric and antisymmetric modes in bilayer graphenes. The Raman frequency evolution with the doping level qualitatively agrees with recent ab initio theoretical calculations. Sulfuric acid molecules can be expected as a stable electron-acceptor dopant for graphenes to study the physical properties of few layer graphenes at different doping levels.

  18. Spectroscopic study of neodymium doped lead-bismuth-borate glasses

    NASA Astrophysics Data System (ADS)

    Pasha, Altaf; Dayani, P.; Negalur, Mahesh; Swamy, Manjunatha; Abhiram, J.; Rajaramakrishna, R.

    2016-05-01

    This paper reports on different physical and optical properties of rare earth doped heavy metal oxide glasses. The glass composition of 10Bi2O3-30PbO-60B2O3-xNd2O3 where x = 0, 0.1, 0.2, 0.5 and 1 (in mol %) has been synthesized using melt-quenching technique. Refractive index measurements for these glasses were done and physical parameters were studied. Structural properties of these glasses were analysed through infrared spectra that was recorded between 1600cm-1 and 300cm-1 in transmission mode. The optical absorption spectra were recorded in the wavelength range from 300 to 700 nm. The transitions originated from ground state energy 4I9/2. The energy level analysis has been carried out by considering absorption spectral bands. The results thus obtained are comparable with reports on similar glasses, indicating that the prepared glasses may have potential laser applications.

  19. Spectroscopic study on binding of rutin to human serum albumin

    NASA Astrophysics Data System (ADS)

    Pastukhov, Alexander V.; Levchenko, Lidiya A.; Sadkov, Anatoli P.

    2007-10-01

    Steady-state and time-resolved fluorescence spectroscopy techniques were used to study the interaction of the flavonoid rutin with human serum albumin (HSA) as well as spectral properties of the protein-bound flavonoid. Both quenching of the intrinsic fluorescence of the protein (Trp214) and the ligand fluorescence, appearing upon complexation with HSA, were used to determine binding parameters. The binding constant determined from the quenching of the Trp214 fluorescence by rutin is equal to 6.87 ± 0.22 × 10 4 M -1 and that obtained from the fluorescence of HSA-bound rutin is 3.8 ± 0.4 × 10 4 M -1. Based on the Job plot analysis, the 1:1 binding stoichiometry for the HSA-rutin complex was determined. The efficient quenching of the Trp214 fluorescence by rutin, fluorescence resonance energy transfer from excited Trp214 to rutin, and competitive binding of warfarin indicate that the binding site for the flavonoid is situated within subdomain IIA of HSA. The presence of the sugar moiety in the flavonoid molecule reduces affinity of rutin for binding to HSA but does not affect the binding stoichiometry and location of the binding site compared with aglycone analogues.

  20. Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes

    NASA Astrophysics Data System (ADS)

    Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.

    2015-09-01

    An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

  1. A spectroscopic study of the open cluster NGC 6250

    NASA Astrophysics Data System (ADS)

    Martin, A. J.; Stift, M. J.; Fossati, L.; Bagnulo, S.; Scalia, C.; Leone, F.; Smalley, B.

    2017-04-01

    We present the chemical abundance analysis of 19 upper main-sequence stars of the young open cluster NGC 6250 (log t ∼ 7.42 yr). This work is part of a project aimed at setting observational constraints on the theory of atomic diffusion in stellar photospheres, by means of a systematic study of the abundances of the chemical elements of early F-, A- and late B-type stars of well-determined age. Our data set consists of low-, medium- and high-resolution spectra obtained with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument of the ESO Very Large Telescope (VLT). To perform our analysis, we have developed a new suite of software tools for the chemical abundance analysis of stellar photospheres in local thermodynamical equilibrium. Together with the chemical composition of the stellar photospheres, we have provided new estimates of the cluster mean radial velocity, proper motion, refined the cluster membership, and we have given the stellar parameters including masses and fractional age. We find no evidence of statistically significant correlation between any of the parameters, including abundance and cluster age, except perhaps for an increase in Ba abundance with cluster age. We have proven that our new software tool may be successfully used for the chemical abundance analysis of large data sets of stellar spectra.

  2. Vibrational spectroscopic and computational studies on diisopropylammonium bromide

    NASA Astrophysics Data System (ADS)

    Sahoo, Shradhanjali; Ravindran, T. R.; Chandra, Sharat; Sarguna, R. M.; Das, B. K.; Sairam, T. N.; Sivasubramanian, V.; Thirmal, C.; Murugavel, P.

    2017-09-01

    Diisopropylammonium bromide (DIPAB) can be crystallized either in an orthorhombic (P212121) or in a monoclinic (P21) structure at room temperature depending on synthesis conditions. The non-polar orthorhombic structure exhibits a subtle, irreversible transformation into the ferroelectric monoclinic-II (m-II) phase above 421 K. At a slightly higher temperature of 426 K this m-II (P21) phase reversibly transforms into a disordered, paraelectric monoclinic-I (P21/m) structure. We synthesized DIPAB in the orthorhombic structure, heated it to obtain the m-II phase and carried out a systematic study of their Raman and IR spectra. We obtained the phonon irreducible representations from factor group analysis of the orthorhombic and m-II structures based on the reported structural information. DIPAB is an organic molecular crystal, and the vibrational spectra in the intramolecular region (200-3500 cm- 1) of the two different phases are identical to each other, indicating weak inter-molecular interactions in both crystalline structures. In the low wavenumber region (10-150 cm- 1) the Raman spectra of the two phases are different due to their sensitivity to molecular environment. We also carried out first principles calculations using Gaussian 09 and CASTEP codes to analyze the vibrational frequencies. Mode assignments were facilitated by isolated molecule calculations that are also in good agreement with intramolecular vibrations, whereas CASTEP (solid state) results could explain the external modes.

  3. HPLC assisted Raman spectroscopic studies on bladder cancer

    NASA Astrophysics Data System (ADS)

    Zha, W. L.; Cheng, Y.; Yu, W.; Zhang, X. B.; Shen, A. G.; Hu, J. M.

    2015-04-01

    We applied confocal Raman spectroscopy to investigate 12 normal bladder tissues and 30 tumor tissues, and then depicted the spectral differences between the normal and the tumor tissues and the potential canceration mechanism with the aid of the high-performance liquid chromatographic (HPLC) technique. Normal tissues were demonstrated to contain higher tryptophan, cholesterol and lipid content, while bladder tumor tissues were rich in nucleic acids, collagen and carotenoids. In particular, β-carotene, one of the major types of carotenoids, was found through HPLC analysis of the extract of bladder tissues. The statistical software SPSS was applied to classify the spectra of the two types of tissues according to their differences. The sensitivity and specificity of 96.7 and 66.7% were obtained, respectively. In addition, different layers of the bladder wall including mucosa (lumps), muscle and adipose bladder tissue were analyzed by Raman mapping technique in response to previous Raman studies of bladder tissues. All of these will play an important role as a directive tool for the future diagnosis of bladder cancer in vivo.

  4. Borax methylene blue: a spectroscopic and staining study.

    PubMed

    Donaldson, P T; Russo, A; Reynolds, C; Lillie, R D

    1978-07-01

    Borax methylene blue is quite stable at room temperatures of 22-25 C. At 30 C polychroming is slow; during 50 days in a water bath at this temperature the absorption peak moves from 665 to 656 nm. At 35 C, the absorption peak reaches 660 nm in 7 days, 654 nm in 14. At 60 C polychroming is rapid, the absorption peak reaching 640-620 nm in 3 days. When the pH of the borax methylene blue solutions, normally about 9.0, is adjusted to pH 6.5, the absorption peak remains at 665 nm even when incubated at 60 C for extended periods. When used as a blood stain 0.4 ml borax methylene blue (1% methylene blue in 1% borax), 4 ml acetone, 2 ml borax-acid phosphate buffer to bring the solution to pH 6.5, and distilled water to make 40 ml, with 0.2 ml 1% eosin added just before using, an excellent Nocht-Giemsa type stain is achieved after 30 minutes staining. The material plasmodia P. falciparum, P. vivax, and P. berghei stain moderate blue with dark red chromatin and green to black pigment granules. The study confirms Malachowski's 1891 results and explains Gautier's 1896-98 failure to duplicate it.

  5. Raman spectroscopic studies of gas/aerosol chemical reactions

    SciTech Connect

    Aardahl, C.L.; Davis, E.J.

    1995-12-31

    Reactions between sorbent particles and SO{sub 2} can be used to reduce atmospheric pollution either by {open_quotes}dry scrubbing{close_quotes} or {open_quotes}wet scrubbing{close_quotes} processes. This paper reports Raman spectroscopy results for single electrodynamically levitated droplets of NaOH reacting with SO{sub 2} and studies of the dehydration reactions of some hygroscopic salt species. The NaOH/SO{sub 2} reaction products and the liquid or solid state of the products are shown to depend on the gas phase SO{sub 2} concentration. Deliquesced particles of NaOH exhibit enhanced light scattering intensities associated with morphological resonances of the incident laser light, but crystalline materials show no such resonances. Raman-active hygroscopic salts exhibit bond frequencies characteristic of the stretching vibrations of the anionic group, but these frequencies are different in the presence of water because hydrogen bonding changes the bond force. This allows efficient tracking of the dehydration reactions in hygroscopic aerosols by Raman spectroscopy as the intensities of the two different modes are related to the degree of dehydration in the particle.

  6. Effects of dust absorption on spectroscopic studies of turbulence

    NASA Astrophysics Data System (ADS)

    Kandel, D.; Lazarian, A.; Pogosyan, D.

    2017-09-01

    We study the effect of dust absorption on the recovery velocity and density spectra as well as on the anisotropies of magnetohydrodynamic turbulence using the velocity channel analysis (VCA), velocity coordinate spectrum (VCS) and velocity centroids. The dust limits volume up to an optical depth of unity. We show that in the case of the emissivity proportional to the density of emitters, the effects of random density get suppressed for strong dust absorption intensity variations arise from the velocity fluctuations only. However, for the emissivity proportional to squared density, both density and velocity fluctuations affect the observed intensities. We predict a new asymptotic regime for the spectrum of fluctuations for large scales exceeding the physical depths to unit optical depth. The spectrum gets shallower by unity in this regime. In addition, the dust absorption removes the degeneracy resulted in the universal K-3 spectrum of intensity fluctuations of self-absorbing medium reported by Lazarian & Pogosyan. We show that the predicted result is consistent with the available H ii region emission data. We find that for sub-Alfvénic and trans-Alfvénic turbulence one can get the information about both the magnetic field direction and the fundamental Alfvén, fast and slow modes that constitute MHD turbulence.

  7. Spectroscopic and kinetic studies of lipases solubilized in reverse micelles.

    PubMed

    Walde, P; Han, D; Luisi, P L

    1993-04-20

    The conformation and activity of three different lipases have been studied in reverse micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in isooctane. In the case of human pancreatic lipase, the conformation of the polypeptide chain--as judged from far-UV circular dichroism measurements--is only slightly altered after the enzyme is transferred from a bulk aqueous solution into the microenvironment of reverse micelles. Significant spectral changes in the near-UV circular dichroism and fluorescence spectrum indicate, however, that the solvation of aromatic amino acid side chains is considerably different in reverse micelles. Conversely, the circular dichroism spectra of the lipases from Candida rugosa and Pseudomonas sp. are considerably different in reverse micelles, compared with the spectra in aqueous solution, indicating that both enzymes loose the native structure at the water/AOT/oil interface. Bound substrate and/or product can prevent this denaturation. While Pseudomonas sp. and human pancreatic lipase are inhibited by tetrahydrolipstatin (THL), the lipase from Candida rugosa is not. These data, together with additional activity and inhibition data, indicate that the micellar microenvironment accentuates the difference between the different enzymes in terms of the relation structure/activity.

  8. Micro-Raman spectroscopic study of thyroid tissues.

    PubMed

    Medeiros Neto, Lázaro Pinto; das Chagas E Silva de Carvalho, Luis Felipe; Santos, Laurita Dos; Tellez Soto, Cláudio Alberto; de Azevedo Canevari, Renata; de Oliveira Santos, André Bandiera; Mello, Evandro Sobroza; Pereira, Marina Aparecida; Cernea, Cláudio Roberto; Brandão, Lenine Garcia; Martin, Aírton Abrahão

    2017-03-01

    Thyroid carcinomas are the most common endocrine malignancy. Inconclusive results for the analysis of malignancies are an issue in the diagnosis of thyroid carcinomas; 20% of thyroid cancer diagnoses are indeterminate or suspicious, resulting in a surgical procedure without immediate need. The use of Raman spectroscopy may help improve the diagnosis of thyroid carcinoma. In this study, 30 thyroid samples, including normal thyroid, goiter and thyroid cancer, were analyzed by confocal Raman spectroscopy. Principal component analysis (PCA), linear discriminant analysis (LDA) with cross validation and binary logistic regression (BLR) analysis were applied to discriminate among tissues. Significant discrimination was observed, with a consistent rate of concordant pairs of 89.2% for normal thyroid versus cancer, 85.7% for goiter versus cancer and 80.6% for normal thyroid versus goiter using just the amide III region. Raman spectroscopy was thus proven to be an important and fast tool for the diagnosis of thyroid tissues. The spectral region of 1200-1400cm(-1) discriminated normal versus goiter tissues despite the great similarity of these tissues.

  9. A spectroscopic study of laser ablation plasma from Mo target

    NASA Astrophysics Data System (ADS)

    Jakubowska, Katarzyna; Kubkowska, Monika; Blagoev, Alexander; Rosiński, Marcin; Parys, Piotr; Gąsior, Paweł

    2014-05-01

    The goal of this contribution is to present time-resolved optical spectroscopy studies of laser ablation of the Mo target with ˜ 3.5 ns, 0.4 J pulses delivered by the Nd-YAG laser system at 1.06 μm. The sample was placed in a vacuum chamber under 5 × 10-5 mbar pressure and irradiated, with power densities varied up to 22.7 GW cm-2. The ion emission from the plasma plume was measured using an electrostatic ion energy analyzer (IEA) and ion collector, which allowed us to estimate the ion kinetic energy and charge independent of the applied power densities. The signal collected by the IEA indicated the presence of molybdenum ions up to eight-ion charge. Simultaneously after the ion emission, the optical spectra acquired within 2 μs of exposure time were observed in the wavelength range from 200 to 1000 nm with a Mechelle 5000 spectrometer equipped with an iCCD (iStar) detector. The plasma electron temperature was estimated from a Boltzmann plot based on the registered spectra as well as from the ion measurements.

  10. High resolution spectroscopic study of BeΛ10

    DOE PAGES

    Gogami, T.; Chen, C.; Kawama, D.; ...

    2016-03-10

    Spectroscopy of amore » $$^{10}_{\\Lambda}$$Be hypernucleus was carried out at JLab Hall C using the $$(e,e^{\\prime}K^{+})$$ reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using the $$p(e,e^{\\prime}K^{+})\\Lambda,\\Sigma^{0}$$ reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1$$^{-}$$ and 2$$^{-}$$ states) was obtained to be B$$_{\\Lambda}$$=8.55$$\\pm$$0.07(stat.)$$\\pm$$0.11(sys.) MeV. Furthermore, the result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on charge symmetry breaking effect in the $$\\Lambda N$$ interaction.« less

  11. Luminescence and spectroscopic studies of halosulfate phosphors: a review.

    PubMed

    Gedam, S C; Thakre, P S; Dhoble, S J

    2015-03-01

    This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4 Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na6 (SO4 )2 FCl (doped with Dy, Ce or Eu) were prepared using a solid-state diffusion method. The mechanism of energy transfer from Eu(2+) →Dy(3+) , Ce(3+) →Dy(3+) and Ce(3+) →Mn(2+) has also been studied. Dy(3+) emission in the host at 475 and 570 nm is observed due to (4) F9/2 →(6) H15/2 and (4) F9/2 →(6) H13/2 transition, whereas the PL emission spectra of Na6 (SO4 )2 FCl:Ce phosphor shows Ce(3+) emission at 322 nm due to 5d→4f transition of the Ce(3+) ion. The main property of KCaSO4 Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4 F, Na6 Pb4 (SO4 )6 Cl2 , Na21 Mg(SO4 )10 Cl3 and Na15 (SO4 )5 F4 Cl. Copyright © 2014 John Wiley & Sons, Ltd.

  12. Spectroscopic studies on the antioxidant activity of ellagic acid

    NASA Astrophysics Data System (ADS)

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-01

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2‧-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  13. [The IR spectroscopic study of hydrothermal synthetic KTP].

    PubMed

    Xie, Hao; Pei, Jing-Cheng; Qi, Li-Jian; Zhong, Zeng-Qiu

    2010-05-01

    In the present paper, different-generation hydrothermally grown KTP crystals were tested by the Nicolet 550 type FIR spectrometer with the reflective technique. They were studied on different crystal faces. Since the hydrothermally grown KTP crystal usually grows (100), (011) and (201) crystal faces, these faces were tested in different-generation products, and they were tested by two spectral wave bands, 2 000-4 000 and 400-2 000 cm(-1). The figures were compared with the flux-melt grown KTP crystal. In addition, making reference to the method of calculation about the consistence of OH- in quartz, the consistence of OH- in different -generation hydrothermally grown KTP crystals was estimated. In the hydrothermal grown KTP crystals, the stretching vibration of OH- shows distinct directivity characteristic. The absorption at [100] direction is obvious and the frequency is about 30 cm(-1) higher than the flux-melt grown KTP. Each new generation weakened the consistency of OH-, which restrained the growth of the KTP crystal. Accordingly, increasing the purity of rough materials plays a very important role in improving the quality of the crystals.

  14. Spectroscopic studies on the antioxidant activity of ellagic acid.

    PubMed

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-15

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  15. Spectroscopic studies of aluminosilicate formation in tank waste simulants

    SciTech Connect

    Su, Y.; Wang, L.; Bunker, B.C.; Windisch, C.F.

    1997-12-31

    Aluminosilicates are one of the major class of species controlling the volume of radioactive high-level waste that will be produced from future remediation at Hanford site. Here the authors present studies of the phases and structures of aluminosilicates as a function of sludge composition using X-ray powder diffraction, solid state {sup 27}Al and {sup 29}Si NMR, and Raman spectroscopy. The results show that the content of NaNO{sub 3} in solution has significant effects on the nature of the insoluble aluminosilicate phases produced. It was found that regardless of the initial Si:Al ratio, nitrate cancrinite was the main phase formed in the solution with pH of 13.5 and 5 M NaNO{sub 3}. However, at lower NaNO{sub 3} concentration with initial Si:Al ratios of 1.1, 2.2, and 11.0 in the solutions, a range of aluminosilicate zeolites was produced with Si:Al ratios of 1.1, 1.3, and 1.5, respectively. Lowering the solution pH appears to promote the formation of amorphous aluminosilicates. The results presented here are important for the prediction of the solubility and dissolution rate of Al in tank wastes.

  16. A Spectroscopic Study of the Blue Component of Albireo

    NASA Astrophysics Data System (ADS)

    Whight, Kenneth R.

    2013-05-01

    This paper describes an investigation into what can be learned about the physical properties of the blue component of the Albireo double star system from both low (150 lines/mm) and high (2400 lines/mm) resolution spectra, based on the simple model that the star is a rotating uniformly emitting oblate spheroid with a photosphere that is a single layer in thermal equilibrium. The blue component of Albireo is an interesting target in that it exhibits emission at both Halpha and Hbeta wavelengths; this emission is believed to originate from an equatorial decretion disk spun off from the star. The aim of this work was to split the observed high resolution spectra into an absorption component, from the star, and an emission component, from the disk. To achieve this aim the continuum spectrum was modeled as a "black body" to obtain an effective temperature and the Hgamma absorption line was studied to obtain values for the star's model parameters. These results were then used to predict the expected absorption at Halpha and Hbeta wavelengths. Measured Halpha and Hbeta lines were then divided by their expected absorption lines to reveal the pure disk emission for further analysis.

  17. A theoretical and spectroscopic study of conformational structures of piroxicam

    NASA Astrophysics Data System (ADS)

    Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

    2010-02-01

    Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

  18. Spectroscopic study of neodymium doped lead-bismuth-borate glasses

    SciTech Connect

    Pasha, Altaf; Dayani, P.; Negalur, Mahesh; Swamy, Manjunatha; Abhiram, J.; Rajaramakrishna, R.

    2016-05-06

    This paper reports on different physical and optical properties of rare earth doped heavy metal oxide glasses. The glass composition of 10Bi{sub 2}O{sub 3}-30PbO-60B{sub 2}O{sub 3}-xNd{sub 2}O{sub 3} where x = 0, 0.1, 0.2, 0.5 and 1 (in mol %) has been synthesized using melt-quenching technique. Refractive index measurements for these glasses were done and physical parameters were studied. Structural properties of these glasses were analysed through infrared spectra that was recorded between 1600cm{sup −1} and 300cm{sup −1} in transmission mode. The optical absorption spectra were recorded in the wavelength range from 300 to 700 nm. The transitions originated from ground state energy {sup 4}I{sub 9/2}. The energy level analysis has been carried out by considering absorption spectral bands. The results thus obtained are comparable with reports on similar glasses, indicating that the prepared glasses may have potential laser applications.

  19. Spectroscopic studies of particulate formation in fuel blends

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Subramanya, Mahesh; Govani, Jayesh; Choudhuri, Ahsan

    2007-10-01

    The Raman and infrared absorption spectroscopy were used to investigate the properties of carbon nanotubes (CNTs) flame-synthesized using CH4-H2 low calorific value gases. The development of large amounts of CNTs benefits from flame synthesis processes, where the fuel serves as both the heating and the reactant source. As a result of flame condition studies it was determined that the CNT growth region is at 20-30% of the visible flame height and at a flow rate between 7.18E-07 m^3/s and 9.57E-07 m^3/s. Preliminary characterizations of the samples by Scanning Electron Microscopy demonstrate that the formation of nanostructure occurs only for <10% H2 concentration. The Raman analysis of the pristine samples shows the existence of distinctive multi-walled carbon nanotube (MWNT) D and G bands at 1321 cm-1 and 1595 cm-1, respectively. Besides the vibrational lines characteristic to MWNTs, infrared absorption measurements also reveal the presence of C-H bonds.

  20. Speciation of Rhenium in Chloride Melts: Spectroscopic and Electrochemical Study

    NASA Astrophysics Data System (ADS)

    Danilov, Danil A.; Volkovich, Vladimir A.; Vasin, Boris D.; Aleksandrov, Denis E.; Polovov, Ilya B.; Griffiths, Trevor R.

    2008-06-01

    Speciation of rhenium in high-temperature alkali chloride-based melts was studied using electronic absorption and IR spectroscopy of molten salts and diffuse reflectance spectroscopy of quenched melts. Rhenium was added to the melts by anodic dissolution of the metal (at anodic current densities of 0.005 - 0.05 A/cm2), by reacting Re and ReO2 with Cl2 and HCl, and by dissolving K2[ReCl6]. The melts included 3LiCl-2KCl and NaCl-2CsCl eutectics, an NaCl-KCl equimolar mixture, and pure NaCl, KCl and CsCl between 450 and 850 ◦C. Rhenium was present in the melts as Re(IV) hexachloro-ions, [ReCl6]2-; no evidence of species containing rhenium in oxidation states below four was obtained. The kinetics of [ReCl6]2- disproportionation in molten alkali chlorides were investigated, and the IR spectra of [ReO4]- ions in molten CsCl-CsI and CsI were measured for the first time.

  1. Chemical and spectroscopic study of ferredoxin l from Azotobacter vinellandii

    SciTech Connect

    Malikayil, J.A.

    1987-01-01

    Ferredoxin l of Azotobacter vinelandii is an iron sulfur protein containing one (4Fe-S) cluster and one (3Fe-3S) cluster. The structure and geometry of the 3Fe cluster is under dispute. The X-ray crystal structure of the protein describes the 3Fe cluster as a planar (3Fe-3S) cluster in which one of the iron atoms is ligated to a solvent accessible oxoligand, presumably from water or hydroxide. Efforts to displace the oxoligand were unsuccessful even when the protein was demonstrably denatured in 80% (V/V) dimethyl sulfoxide. In addition, comparison of the electron spin echo envelopes for H/sub 2/O and D/sub 2/O-equilibrated samples of ferredoxin l showed only a slight deuterium modulation, far less than would be expected were water to be bound as an iron ligand. Studies were also conducted in an effort to characterize the hyperfine-shifted resonances in the proton magnetic resonance spectrum of ferredoxin l. A. vinelandii was grown on synthetic media that contained isotopically labelled cystine as the only sulfur source. In independent experiments ferredoxin l was isolated from organism that was shown on such medium that contained alpha-/sup 2/H-dl-cystine, beta=/sup 2/H-dl-cystine, or betal-/sup 13/C-dl-cystine. However, ferredoxins isolated from these media were devoid of the corresponding isotopic labels. Thus, the experiments designed to characterize the hyperfine-shifted resonances of ferredoxin l were unsuccessful.

  2. Spectroscopic Studies on the Characterization of a Persian Playing Card.

    PubMed

    Holakooei, Parviz; Niknejad, Maryam; Vaccaro, Carmela

    2016-01-01

    This paper presents the results of our investigations on a playing card preserved at The Mūzih-i Āynih va Rushanāī in Yazd, Iran. Conducting micro X-ray fluorescence spectrometry (μ-XRF), micro-Raman spectroscopy (μ-Raman), infrared reflectography (IRR), ultraviolet fluorescence photography, radiography, and optical microscopy, various paints applied on the playing card were identified. According to our analytical studies, red, green, blue, black, and gold-like metallic paints were identified to be a red monoazo pigment (β-naphthol PR 53:1), chrome green, artificial ultramarine blue, carbon black, and brass powder (Dutch metal powder), respectively, dating the playing card to 1895 onward based on the manufacturing date of the red monoazo pigment. Barite was also shown to be mixed with the pigments as an extender. On the other hand, the portrait's face of the playing card was peculiarly blackened. Our analytical approach toward characterizing the blackened face showed that the black paint was achieved by carbon black and, in other words, the face was not blackened due to the darkening of Pb-bearing pigments. Moreover, it was shown that there was no underdrawing under the black face and the black paint was most probably executed in the same time with the other paints. Considering the possible use of the playing card, it was suggested not to remove the blackened face in the cleaning process since the black paint was a part of the integrity of the playing card. © The Author(s) 2015.

  3. Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye

    NASA Astrophysics Data System (ADS)

    Patra, Digambara; Barakat, Christelle

    2011-09-01

    Curcumin, the main yellow bioactive component of turmeric, has recently acquired attention by chemists due its wide range of potential biological applications as an antioxidant, an anti-inflammatory, and an anti-carcinogenic agent. This molecule fluoresces weakly and poorly soluble in water. In this detailed study of curcumin in thirteen different solvents, both the absorption and fluorescence spectra of curcumin was found to be broad, however, a narrower and simple synchronous fluorescence spectrum of curcumin was obtained at Δ λ = 10-20 nm. Lippert-Mataga plot of curcumin in different solvents illustrated two sets of linearity which is consistent with the plot of Stokes' shift vs. the ET30. When Stokes's shift in wavenumber scale was replaced by synchronous fluorescence maximum in nanometer scale, the solvent polarity dependency measured by λSFSmax vs. Lippert-Mataga plot or ET30 values offered similar trends as measured via Stokes' shift for protic and aprotic solvents for curcumin. Better linear correlation of λSFSmax vs. π* scale of solvent polarity was found compared to λabsmax or λemmax or Stokes' shift measurements. In Stokes' shift measurement both absorption/excitation as well as emission (fluorescence) spectra are required to compute the Stokes' shift in wavenumber scale, but measurement could be done in a very fast and simple way by taking a single scan of SFS avoiding calculation and obtain information about polarity of the solvent. Curcumin decay properties in all the solvents could be fitted well to a double-exponential decay function.

  4. Synthesis, structural, spectroscopic and biological studies of Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Diab, M. A.; El-Sonbati, A. Z.; Shoair, A. F.; Eldesoky, A. M.; El-Far, N. M.

    2017-08-01

    Schiff base ligand 4-((pyridin-2- yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (PDMP) and its complexes were prepared and characterized on the basis of elemental analysis, IR, mass spectra and thermogravimetric analysis. All results confirm that the complexes have 1:1 (M: PMDP) stoichiometric formula [M(PMDP)Cl2H2O ] (M = Cu(II), Co(II), Ni(II) and Mn(II)), [Cd(PMDP)Cl2] and the ligand behaves as a bi/tridentate forming five-membered chelating ring towards the metal ions, bonding through azomethine nitrogen/exocyclic carbonyl oxygen, azomethine pyridine nitrogen and exocyclic carbonyl oxygen. The shift in the band positions of the groups involved in coordination has been utilized to estimate the metal-nitrogen and/or oxygen bond lengths. The complexes of Co(II), Ni(II) and Cu(II) are paramagnetic and the magnetic as well as spectral data suggest octahedral geometry, whereas the Cd(II) complex is tetrahedral. The XRD studies show that both the ligand and its metal complexes (1 and 3) show polycrystalline with crystal structure. Molecular docking was used to predict the binding between PMDP ligand and the receptors. The corrosion inhibition of mild steel in 2 M HCl solution by PDMP was explored utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and (EFM) electrochemical frequency modulation method. Potentiodynamic polarization demonstrated that PDMP compound is mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the protective ability. The percentage of inhibition efficiency was found to increase with increasing the inhibitor concentration.

  5. Influence of environment on piroxicam polymorphism: vibrational spectroscopic study.

    PubMed

    Taddei, P; Torreggiani, A; Simoni, R

    2001-01-01

    FTIR and FT-Raman spectroscopies were used to evaluate the mechanism of transformation of piroxicam into its different forms (alpha, beta, and monohydrate), depending on the environment. These vibrational techniques allowed us to identify the forms of piroxicam that crystallize from different solvents at different cooling rates and the conformation of the drug in some of its derivatives: piroxicam hydrochloride, piroxicam thallium and sodium salt hemihydrates, and piroxicam sodium salt. The usefulness of Raman spectroscopy in characterizing piroxicam:beta-cyclodextrin (PbetaCD) inclusion compounds was described. The Raman spectrum of 1:2 PbetaCD was discussed in comparison with that of the corresponding piroxicam sodium salt containing inclusion compound (1:2 PNabetaCD) in order to study the influence of the piroxicam derivative used on the structure of the inclusion compound. The Raman results showed that in both of the inclusion compounds the piroxicam mainly assumes the zwitterionic structure typical of a monohydrate; therefore, the kind of derivative used does not affect the conformation of the drug in its inclusion compound. The effect of the method of synthesis utilized (freeze-drying or freeze-thaw cycling) to obtain 1:2.5 PbetaCD was investigated. The inclusion compound obtained by freeze-thaw cycling proved to be more crystalline and to contain a higher amount of the beta form than the freeze-dried inclusion compound. Raman spectroscopy proved to be a useful technique for evaluating the effectiveness of the manufacturing process in relation to the pharmaceutical properties of the drug and to the nondestructive and noninvasive on-line quality control of the industrial products.

  6. Electron spin resonance spectroscopic studies of radical cation reactions

    SciTech Connect

    Dai, S.

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra is derived using the general effective Hamiltonian theory in the usual Schroedinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between [beta]-hydrogen coupling constants and their geometric orientations are derived using a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and synsesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl[sub 3] matrix at low temperature. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is the 3-iminiopropyl distonic species(3-iminium-1-propyl radical). The nucleophilic endocylization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran-3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexdiyne have resulted in characterization the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5-hexatetraene radical cation. The symmetric (C[sub 2v]) bicyclo[3.3.0]-octa-2,6-diene-4,8-diyl(a bridged 1,4-bishomobenzene species) radical cation is produced by the radiolytic oxidation of semibullvalene in Freon matrices. The ring-opening 3,4-dimethylenecyclobutene radical cation to 1,2,4,5-hexatetraene radical cation was observed in the photolysis of 3,4-dimethylenecyclobutene radical cation. The cyclooctatetraene radical cation generated by radiolytic oxidation photoisomerizes to bicyclo[3.3.0]octa-2,6-diene-4,8-diyl radical cation.

  7. Raman spectroscopic study of the tellurite minerals: rajite and denningite.

    PubMed

    Frost, Ray L; Dickfos, Marilla J; Keeffe, Eloise C

    2008-12-15

    Tellurites may be subdivided according to formula and structure. There are five groups based upon the formulae (a) A(XO3), (b) A(XO3).xH2O, (c) A2(XO3)3.xH2O, (d) A2(X2O5) and (e) A(X3O8). Raman spectroscopy has been used to study rajite and denningite, examples of group (d). Minerals of the tellurite group are porous zeolite-like materials. Raman bands for rajite observed at 740, and 676 and 667 cm(-1) are attributed to the nu1 (Te2O5)(2-) symmetric stretching mode and the nu3 (TeO3)(2-) antisymmetric stretching modes, respectively. A second rajite mineral sample provided a more complex Raman spectrum with Raman bands at 754 and 731 cm(-1) assigned to the nu1 (Te2O5)(2-) symmetric stretching modes and two bands at 652 and 603 cm(-1) are accounted for by the nu3 (Te2O5)(2-) antisymmetric stretching mode. The Raman spectrum of dennigite displays an intense band at 734 cm(-1) attributed to the nu1 (Te2O5)(2-) symmetric stretching mode with a second Raman band at 674 cm(-1) assigned to the nu3 (Te2O5)(2-) antisymmetric stretching mode. Raman bands for rajite, observed at (346, 370) and 438 cm(-1) are assigned to the (Te2O5)(2-)nu2 (A1) bending mode and nu4 (E) bending modes.

  8. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L{sub cm} (I), {beta}{sup 18} (II), and {alpha}{sup AP-B} (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A{sub max} = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  9. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L[sub cm] (I), [beta][sup 18] (II), and [alpha][sup AP-B] (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A[sub max] = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  10. Reaction and spectroscopic study of supported metal oxide catalysts

    NASA Astrophysics Data System (ADS)

    Ramani, Narayanan C.

    The role of surface structure, cation reducibility, surface acidity and the effect of the support was examined in the reaction of 1-butene over well characterized, supported metal oxide catalysts. Cr, Mo and W oxides supported on SiOsb2 were used to study the effect of structure, surface acidity and cation reducibility in the isomerization and selective oxidation of 1-butene. Supported oxides of Mo on TiOsb2,\\ Alsb2Osb3 and SiOsb2 were used to understand the role of the support in the selective oxidation of 1-butene. The surface acidity of SiOsb2 supported Cr, Mo, W and V oxide catalysts was examined by pyridine adsorption. Existing theoretical models of acidity were compared against experimental data. Over Mo(VI)/SiOsb2 and W(VI)/SiOsb2, isomerization through both a Bronsted catalyzed pathway and an allylic pathway were observed, while only the allylic pathway was observed over Cr(VI)/SiOsb2. The greater reducibility of the Cr cation compared to Mo and W cations was identified as the reason for the allylic pathway being dominant over Cr(VI)/SiOsb2. Cation reducibility was again seen to play an important role in the selective oxidation of 1-butene over SiOsb2 supported metal oxides. The turn over frequencies for 1,3-butadiene formation followed the trend in red-ox ability, with Cr > Mo > W. The activity to 1,3-butadiene formation did not change with increasing weight loading of Mo over TiOsb2 and Alsb2Osb3 supports. An analysis of the turn over frequencies of the supports and the supported cations revealed that a support effect, through the bridging oxygen ligand, dominated the intrinsic cation reducibility of Mo for these catalysts. The existence of Bronsted acidity over SiOsb2 supported Cr, Mo and V oxides was shown by an analysis of the OH region of the infrared spectrum, and by the adsorption of 1-butene and pyridine. Existing theoretical models for Bronsted acidity over supported metal oxides were shown to be inadequate to describe the observed results over

  11. Spectroscopic studies of molybdenum complexes as models for nitrogenase

    SciTech Connect

    Walker, T.P.

    1981-05-01

    Because biological nitrogen fixation requires Mo, there is an interest in inorganic Mo complexes which mimic the reactions of nitrogen-fixing enzymes. Two such complexes are the dimer Mo/sub 2/O/sub 4/ (cysteine)/sub 2//sup 2 -/ and trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ (dppe = 1,2-bis(diphenylphosphino)ethane). The H/sup 1/ and C/sup 13/ NMR of solutions of Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ are described. It is shown that in aqueous solution the cysteine ligands assume at least three distinct configurations. A step-wise dissociation of the cysteine ligand is proposed to explain the data. The Extended X-ray Absorption Fine Structure (EXAFS) of trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ is described and compared to the EXAFS of MoH/sub 4/(dppe)/sub 2/. The spectra are fitted to amplitude and phase parameters developed at Bell Laboratories. On the basis of this analysis, one can determine (1) that the dinitrogen complex contains nitrogen and the hydride complex does not and (2) the correct Mo-N distance. This is significant because the Mo inn both complexes is coordinated by four P atoms which dominate the EXAFS. A similar sort of interference is present in nitrogenase due to S coordination of the Mo in the enzyme. This model experiment indicates that, given adequate signal to noise ratios, the presence or absence of dinitrogen coordination to Mo in the enzyme may be determined by EXAFS using existing data analysis techniques. A new reaction between Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ and acetylene is described to the extent it is presently understood. A strong EPR signal is observed, suggesting the production of stable Mo(V) monomers. EXAFS studies support this suggestion. The Mo K-edge is described. The edge data suggests Mo(VI) is also produced in the reaction. Ultraviolet spectra suggest that cysteine is released in the course of the reaction.

  12. A spectroscopic and dynamical study of binary and other Cepheids

    NASA Astrophysics Data System (ADS)

    Petterson, Orlon King Lee

    High resolution observations have been made of a number of southern Cepheids to make an observational and theoretical study of Cepheid variables using radial velocities. The stars studied were part of a long term programme to observe southern variable stars, from which a valuable database of radial velocities gathered over a long period were available. Sixteen échelle spectrograph orders in the wavelength region 5400 - 8600Å were used, which included a number of absorption lines covering a range of species and excitation potentials. The line bisector technique was used to measure stellar and telluric lines and to obtain radial velocities. To improve the precision of the radial velocities we used telluric lines to calibrate the observations to a common reference frame. The radial velocities have a precision of ~300ms-1 allowing the detection of velocity differences of ~1 kms-1 with confidence. The radial velocity data obtained at Mount John University Observatory (MJUO) was combined with data from various sources to determine the orbits of any Cepheids exhibiting orbital motion. The various orbital parameters were determined for a number of systems and where radial velocities for the companions exist, some estimate of the mass was made. The precision of the radial velocities obtained from MJUO also allowed us to search for line level effects for a number of species among the Cepheid spectra. A number of IAU standard stars were observed to calibrate the radial velocities obtained at MJUO to the IAU standard scale. The radial velocities from MJUO were found not to differ significantly from the IAU values. Binary Cepheids are particularly useful in the determination of Cepheid masses, which are still an active topic for astronomical research. The value of the MJUO data was that it provided a consistent set of data against which other sources of data could be compared. For 8 of the Cepheids new or improved orbital solutions were found. They are Y Car, YZ Car, AX Cir

  13. Relationship between femtosecond-picosecond dynamics to enzyme catalyzed H-transfer

    PubMed Central

    Cheatum, Christopher M.; Kohen, Amnon

    2015-01-01

    At physiological temperatures, enzymes exhibit a broad spectrum of conformations, which interchange via thermally activated dynamics. These conformations are sampled differently in different complexes of the protein and its ligands, and the dynamics of exchange between these conformers depends on the mass of the group that is moving and the length scale of the motion, as well as restrictions imposed by the globular fold of the enzymatic complex. Many of these motions have been examined and their role in the enzyme function illuminated, yet most experimental tools applied so far have identified dynamics at time scales of seconds to nanoseconds, which are much slower than the time scale for H-transfer between two heavy atoms. This chemical conversion and other processes involving cleavage of covalent bonds occur on picosecond to femtosecond time scales, where slower processes mask both the kinetics and dynamics. Here we present a combination of kinetic and spectroscopic methods that may enable closer examination of the relationship between enzymatic C-H→C transfer and the dynamics of the active site environment at the chemically relevant time scale. These methods include kinetic isotope effects and their temperature dependence, which are used to study the kinetic nature of the H-transfer, and 2D IR spectroscopy, which is used to study the dynamics of transition-state- and ground-state-analog complexes. The combination of these tools is likely to provide a new approach to examine the protein dynamics that directly influence the chemical conversion catalyzed by enzymes. PMID:23539379

  14. Radio-colouration of diamond: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Nasdala, Lutz; Grambole, Dieter; Wildner, Manfred; Gigler, Alexander M.; Hainschwang, Thomas; Zaitsev, Alexander M.; Harris, Jeffrey W.; Milledge, Judith; Schulze, Daniel J.; Hofmeister, Wolfgang; Balmer, Walter A.

    2013-05-01

    We have undertaken a study of the common green or orange-brown spots at the surface of rough diamond specimens, which are caused by alpha particles emanating from radioactive sources outside the diamond. Richly coloured haloes represent elevated levels of structural damage, indicated by strong broadening of the main Raman band of diamond, intense strain birefringence, and up-doming of spots due to their extensive volume expansion. Green radio-colouration was analogously generated through the irradiation of diamond with 8.8 MeV helium ions. The generation of readily visible radio-colouration was observed after irradiating diamond with ≥1015 He ions per cm2. The accumulation of such a high number of alpha particles requires irradiation of the diamond from a radioactive source over long periods of time, presumably hundreds of millions of years in many cases. In the samples irradiated with He ions, amorphisation was observed in volume areas where the defect density exceeded 5 × 10-3 Å-3 (or 0.03 dpa; displacements per target atom). In contrast, graphitisation as a direct result of the ion irradiation was not observed. The green colouration transformed to brown at moderate annealing temperatures (here 450 °C). The colour transformation is associated with only partial recovery of the radiation damage. The colour change is mainly due to the destruction of the GR1 centre, explained by trapping of vacancies at A defects to form the H3 centre. An activation energy of ~2.4 ± 0.2 eV was determined for the GR1 reduction. The H3 centre, in turn, causes intense yellowish-green photoluminescence under ultraviolet illumination. Radio-colouration and associated H3 photoluminescence are due to point defects created by the ions irradiated, whereas lattice ionisation is of minor importance. This is concluded from the depth distribution of the colouration and the photoluminescence intensity (which corresponds to the defect density but not the ionisation distribution pattern). The

  15. Lidar receivers for picosecond remote sensing

    NASA Technical Reports Server (NTRS)

    Stoyanov, D. V.; Dreischuh, T. N.

    1992-01-01

    The lidars of picosecond resolution are an attractive tool for remote probing of some highly dynamic objects like sea subsurface waters, small-scale turbulences in the atmosphere, etc. The picosecond lasers are suitable illuminating sources, but the main restrictions are due to the lack of proper receiving methods, combining the both high temporal and amplitude resolution, good sensitivity, short integration time, and wide dynamic range. The methods for short pulse measurements are not suitable for picosecond lidars, operating at low level, with highly dynamic signals. The streak-cameras are of high cost, lower sensitivity, and lower dynamic range (approximately 10(exp 3)). Because of the background, the single quantum regime in photomultipliers (PMT) is ineffective. The sampling of highly dynamic optical signals with resolution less than or equal to 1ns is a serious problem, limiting the application of the high speed PMT-MCP (microchannel plate) in the picosecond lidar systems. The goal of this work is to describe the use of a new photodetection technique which combines the picosecond resolution with the high amplitude resolution, dynamic range, and sensitivity.

  16. Lidar receivers for picosecond remote sensing

    NASA Astrophysics Data System (ADS)

    Stoyanov, D. V.; Dreischuh, T. N.

    1992-07-01

    The lidars of picosecond resolution are an attractive tool for remote probing of some highly dynamic objects like sea subsurface waters, small-scale turbulences in the atmosphere, etc. The picosecond lasers are suitable illuminating sources, but the main restrictions are due to the lack of proper receiving methods, combining the both high temporal and amplitude resolution, good sensitivity, short integration time, and wide dynamic range. The methods for short pulse measurements are not suitable for picosecond lidars, operating at low level, with highly dynamic signals. The streak-cameras are of high cost, lower sensitivity, and lower dynamic range (approximately 10(exp 3)). Because of the background, the single quantum regime in photomultipliers (PMT) is ineffective. The sampling of highly dynamic optical signals with resolution less than or equal to 1ns is a serious problem, limiting the application of the high speed PMT-MCP (microchannel plate) in the picosecond lidar systems. The goal of this work is to describe the use of a new photodetection technique which combines the picosecond resolution with the high amplitude resolution, dynamic range, and sensitivity.

  17. Vibrational and Raman Spectroscopic Study of Cubic Boron Nitride Under Pressure Using Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Pillai, Sharad Babu; Mankad, Venu; Jha, Prafulla K.

    2017-08-01

    Pressure-dependent mechanical, vibrational and Raman spectroscopic study of the cubic boron nitride in context of recent experimental Raman spectroscopic has been performed using the ab initio calculations based on density functional theory. Detailed analysis of the pressure-dependent mechanical and phonon properties shows that the pressure significantly affects the elastic constants and phonon frequencies. There is a systematic variation of elastic properties with pressure while a polynomial expression is used to fit the pressure dependence of the Raman shift. The longitudinal optical-transverse optical (LO-TO) splitting reduces with pressure, and the intensity of both LO and TO peaks start diminishing after 750 GPa. The phonon dispersion curves up to 1000 GPa indicate its dynamical stability. The lower slope of frequency versus pressure for the LO and TO modes at higher pressures suggests its use for pressure calibration at higher pressures.

  18. Picosecond and nanosecond studies of the photoreduction of benzophenone by 1,4-diazabicyclo(2. 2. 2)octane: Characterization of the transient

    SciTech Connect

    Devadoss, C.; Fessenden, R.W. )

    1990-05-31

    The transient that is produced in the quenching of triplet benzophenone by 1,4-diazabicyclo(2.2.2)octane (DABCO) has been examined by use of nano- and picosecond laser photolysis. The initial step in all solvents, both polar and nonpolar, is electron transfer to form a triplet contact ion pair. In nonpolar solvents, the ion pair remains in this form until it decays. For polar solvents, the spectra change somewhat over the first 100 ps showing that the solvation changes and the ion pair becomes solvent separated. The lifetime of the ion pair varies greatly with the solvent. In saturated hydrocarbons it is about 80 ps. Nonpolar solvents with either {pi} electrons or a lone pair of electrons stabilize the ion pair on the nanosecond to microsecond time scale. A small amount of alcohol in benzene also stabilizes the ion pair by hydrogen bonding. A shift in the peak position with time toward the blue accompanies the formation of hydrogen bonds in this case.

  19. Dynamics of charge recombination processes in the singlet electron-transfer state of pyrene-pyromellitic dianhydride systems in various solvents. Picosecond laser photolysis studies

    SciTech Connect

    Mataga, N.; Shioyama, H.; Kanda, Y.

    1987-01-15

    In order to elucidate the underlying mechanisms showing that no dissociated ion radicals are produced even in acetonitrile solution when some complexes of the strong electron donors and acceptors with CT absorption bands in the visible region are photoexcited, the authors have made detailed time-resolved transient absorption spectral measurements and time-resolved fluorescence measurements upon the pyrene-pyromellitic dianhydride (PMDA) system in various solvents with picosecond laser spectroscopy. A weakly fluorescent electron-transfer (ET) state with 400-ps lifetime is formed by photoexcitation in benzene solution, while nonfluorescent geminate ion pairs with much shorter lifetimes due to the charge recombination (CR) deactivation are formed in more polar solvents. In all solutions examined, dissociation into free ions from the geminate pair cannot compete with the CR deactivation which becomes faster in more polar solvents due to the decrease of the energy gap between the ion pair and neutral ground state. Moreover, it has been demonstrated that ion pairs produced by encounter between excited pyrene and unexcited PMDA in acetonitrile have more loose structure and show a smaller CR rate constant than those produced by exciting the ground-state complex.

  20. Hydrogen transfer dynamics in a photoexcited phenol/ammonia (1:3) cluster studied by picosecond time-resolved UV-IR-UV ion dip spectroscopy.

    PubMed

    Ishiuchi, Shun-ichi; Sakai, Makoto; Daigoku, Kota; Hashimoto, Kenro; Fujii, Masaaki

    2007-12-21

    The picosecond time-resolved IR spectra of phenol/ammonia (1:3) cluster were measured by UV-IR-UV ion dip spectroscopy. The time-resolved IR spectra of the reaction products of the excited state hydrogen transfer were observed. From the different time evolution of two vibrational bands at 3180 and 3250 cm(-1), it was found that two isomers of hydrogenated ammonia radical cluster .NH(4)(NH(3))(2) coexist in the reaction products. The time evolution was also measured in the near-IR region, which corresponds to 3p-3s Rydberg transition of .NH(4)(NH(3))(2); a clear wavelength dependence was found. From the observed results, we concluded that (1) there is a memory effect of the parent cluster, which initially forms a metastable product, .NH(4)-NH(3)-NH(3), and (2) the metastable product isomerizes successively to the most stable product, NH(3)-.NH(4)-NH(3). The time constant for OH cleaving, the isomerization, and its back reaction were determined by rate-equation analysis to be 24, 6, and 9 ps, respectively.

  1. Characterization of porcine skin as a model for human skin studies using infrared spectroscopic imaging.

    PubMed

    Kong, Rong; Bhargava, Rohit

    2011-06-07

    Porcine skin is often considered a substitute for human skin based on morphological and functional data, for example, for transdermal drug diffusion studies. A chemical, structural and temporal characterization of porcine skin in comparison to human skin is not available but will likely improve our understanding of this porcine skin model. Here, we employ Fourier transform infrared (FT-IR) spectroscopic imaging to holistically measure chemical species as well as spatial structure as a function of time to characterize porcine skin as a model for human skin. Porcine skin was found to resemble human skin spectroscopically and differences are elucidated. Cryo-prepared fresh porcine skin samples for spectroscopic imaging were found to be stable over time and small variations are observed. Hence, we extended characterization to the use of this model for dynamic processes. In particular, the capacity and stability of this model in transdermal diffusion is examined. The results indicate that porcine skin is likely to be an attractive tool for studying diffusion dynamics of materials in human skin.

  2. Picosecond LIBS diagnostics for Tokamak in situ plasma facing materials chemical analysis

    NASA Astrophysics Data System (ADS)

    Morel, Vincent; Pérès, Bastien; Bultel, Arnaud; Hideur, Ammar; Grisolia, Christian

    2016-02-01

    First results are presented in relation with experimental and theoretical studies performed at the CORIA laboratory in the general framework of the determination of the chemical analysis of Tokamak plasma facing materials by laser-induced breakdown spectroscopy (LIBS) in picosecond regime. Experiments are performed on W in a specific chamber. This chamber is equipped with a UV-visible-near IR spectroscopic device. Boltzmann plots are derived for typical laser characteristics. We show that the initial excitation temperature is close to 12 000 K followed by a quasi steady value close to 8500 K. The ECHREM (Euler code for CHemically REactive Multicomponent laser-induced plasmas) code is developed to reproduce the laser-induced plasmas. This code is based on the implementation of a Collisional-Radiative model in which the different excited states are considered as full species. This state-to-state approach is relevant to theoretically assess the departure from excitation and chemical equilibrium. Tested on aluminum, the model shows that the plasma remains close to excitation equilibrium.

  3. Exploring binding properties of sertraline with human serum albumin: Combination of spectroscopic and molecular modeling studies.

    PubMed

    Shahlaei, Mohsen; Rahimi, Behnoosh; Nowroozi, Amin; Ashrafi-Kooshk, Mohammad Reza; Sadrjavadi, Komail; Khodarahmi, Reza

    2015-12-05

    Human serum albumin (HSA)-drug binding is an important factor to determine half life and bioavailability of drugs. In the present research, the interaction of sertraline (SER) to HSA was investigated using combination of spectroscopic and molecular modeling techniques. Changes in the UV-Vis, CD and FT-IR spectra as well as a significant degree of tryptophan fluorescence quenching were observed upon SER-HSA interaction. Data obtained by spectroscopic methods along with the computational studies suggest that SER binds to residues located in subdomain IIA of HSA. Analysis of spectroscopic data represented the formation of 1:1 complex, significant binding affinity, negative values of entropy and enthalpy changes and the essential role of hydrophobic interactions in binding of SER to HSA. The binding models were demonstrated in the aspects of SER's conformation, active site interactions, important amino acids and hydrogen bonding. Computational mapping of the possible binding site of SER confirmed that the ligand to be bound in a large hydrophobic cavity of HSA. In accordance with experimental data, computational analyses indicated that SER binding does not alter the secondary structure of the protein. The results not only lead to a better understanding of interaction between SER and HSA but also provide useful data about the influence of SER on the protein conformation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Ultraviolet and optical spectroscopic studies of Lambda Andromedae - The chromosphere and interstellar medium

    NASA Technical Reports Server (NTRS)

    Baliunas, S. L.; Dupree, A. K.

    1979-01-01

    Chromospheric lines of, and interstellar lines toward, the spectroscopic binary Lambda And (primary component G7-G8 III-IV) have been observed in the ultraviolet with the spectrometer and telescope on board the Copernicus satellite. An extensive, high-resolution spectroscopic study of the Ca II H and K profiles has also been undertaken. Some of these optical spectra were obtained simultaneously with the ultraviolet data. The ultraviolet emission lines of Lamba And are compared to the sun and to stars of similar spectral type. The star Lamba And resembles the active sun in surface brightness of chromospheric emissions and in appearance of the Mg II and Ca II profiles. The largest variations in the integrated calcium emission cores amount to an 80% increase in the K core and a corresponding 40% increase in the H core between observations two years apart. Variations in the cores may show a dependence on spectroscopic phase, and may be contributed to by circumstellar matter in the binary system. Previously unreported, transient emission features have also been observed, at a velocity of -70 km/s with respect to the Ca II emission cores.

  5. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes.

    PubMed

    Adeniyi, Adebayo A; Ajibade, Peter A

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  6. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes

    NASA Astrophysics Data System (ADS)

    Adeniyi, Adebayo A.; Ajibade, Peter A.

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  7. Analysis of Picosecond Pulsed Laser Melted Graphite

    DOE R&D Accomplishments Database

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  8. Picosecond lasers with the dynamical operation control

    NASA Astrophysics Data System (ADS)

    Mikheev, N. G.; Morozov, V. B.; Olenin, A. N.; Yakovlev, D. V.

    2016-04-01

    Numerical model for simulation of generation process in advanced pulse-periodic high-peak-power picosecond diode-pumped Nd:YAG and Nd:YLF lasers has been developed. The model adequately describes picosecond pulse formation governed by active and passive mode-locking, negative feedback and adjustable loss level in the oscillator cavity. Optical jitter of output pulses attributed to laser generation development from spontaneous noise level was evaluated using statistical analysis of calculation results. In the presented laser scheme, minimal jitter value on the level ~40 ps was estimated.

  9. Picosecond dynamics from lanthanide chloride melts

    NASA Astrophysics Data System (ADS)

    Kalampounias, Angelos G.

    2012-12-01

    The picosecond dynamics of molten lanthanide chlorides is studied by means of vibrational spectroscopy. Polarized Raman spectra of molten LaCl3, NdCl3, GdCl3, DyCl3, HoCl3 and YCl3 are fitted to a model enabling to obtain the times of vibrational dephasing, tν and vibrational frequency modulation tω. Our aim is to find possible sensitive indicators of short-time dynamics. It has been found that all lanthanide chlorides exhibit qualitative similarities in the vibrational relaxation and frequency modulation times in the molten state. It appears that the vibrational correlation functions of all melts comply with the Rothschild approach assuming that the environmental modulation is described by a stretched exponential decay. The evolution of the dispersion parameter α indicates the deviation of the melts from the model simple liquid and the similar local environment in which the oscillator is placed and with which it is coupled. The "packing" of the anions around central La3+ cation seems to be the key factor for the structure and the dynamics of the melts. The results are discussed in the framework of the current phenomenological status of the field.

  10. Picosecond laser ablation of polyamide electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Götze, Marco; Krimig, Olaf; Kürbitz, Tobias; Henning, Sven; Heilmann, Andreas; Hillrichs, Georg

    2017-02-01

    Electrospun nanofibers mats have a great potential in tissue engineering and regenerative medicine. Their high porosity and enormous volume to surface ratio stimulate the growth and adhesion of mammalian cells and serve as a stable support structure. These suitable properties can be further optimized by structuring of the nanofibers. Ultrashort pulsed lasers can be used for modifying of the electrospun nanofibers without significant heat exposure. It seems also possible to generate very fine cuts from the fiber mats. In this study, polyamide electrospun nanofibers samples were processed with picosecond UV-laser irradiation (λ = 355 nm, τ = 15 ps). The samples were processed in dry, wet and immersed condition. To optimize cutting and structuring of nanofiber tissue flakes, the influence of different laser parameters on line widths, edge quality, heat-affected zone (HAZ) and the contamination of the fibers by ablated particles (debris) were examined. One additional aim was the minimization of the flake size. It was possible to generate nanofiber flakes in the sub-millimeter range. The quality of the nanofiber flakes could be improved by ablation near the ablation threshold of the material. For cutting under wet conditions shrinking of the flakes has to be taken into account.

  11. Dielectric breakdown induced by picosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

    1976-01-01

    The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger.

  12. Spectroscopic studies on the interaction of Ga3+-hypocrellin A with myoglobin.

    PubMed

    Xie, Wenli; Wei, Shaohua; Liu, Jihua; Ge, Xuefeng; Zhou, Lin; Zhou, Jiahong; Shen, Jian

    2014-01-01

    In this article, the interaction mechanism of Ga(3+)-hypocrellin A (Ga(3+)-HA) with myoglobin (Mb) is studied in detail through various spectroscopic technologies. UV-vis absorption and fluorescence spectra demonstrate the interaction process. The Stern-Volmer plot and the time-resolved fluorescence study suggest the fluorescence quenching mechanism of Mb by Ga(3+)-HA is a static quenching procedure, and the electronic transfer forces play a major role in binding Ga(3+)-HA to Mb. Furthermore, synchronous fluorescence studies and circular dichroism (CD) spectra reveal that the conformation of Mb is changed after its conjugation with Ga(3+)-HA.

  13. Spectroscopic studies on the interaction of Ga3+-hypocrellin A with myoglobin

    NASA Astrophysics Data System (ADS)

    Xie, Wenli; Wei, Shaohua; Liu, Jihua; Ge, Xuefeng; Zhou, Lin; Zhou, Jiahong; Shen, Jian

    2014-03-01

    In this article, the interaction mechanism of Ga3+-hypocrellin A (Ga3+-HA) with myoglobin (Mb) is studied in detail through various spectroscopic technologies. UV-vis absorption and fluorescence spectra demonstrate the interaction process. The Stern-Volmer plot and the time-resolved fluorescence study suggest the fluorescence quenching mechanism of Mb by Ga3+-HA is a static quenching procedure, and the electronic transfer forces play a major role in binding Ga3+-HA to Mb. Furthermore, synchronous fluorescence studies and circular dichroism (CD) spectra reveal that the conformation of Mb is changed after its conjugation with Ga3+-HA.

  14. Synthesis, structural and spectroscopic studies of two new benzimidazole derivatives: A comparative study

    NASA Astrophysics Data System (ADS)

    Saral, Hasan; Özdamar, Özgür; Uçar, İbrahim

    2017-02-01

    In the present work, structural and spectroscopic studies on 1-Methyl-2-(2‧-hydroxy-4‧-chlorophenyl)benzimidazole (1) and 1-Methyl-2-(2‧-hydroxy-4‧-methoxyphenyl)benzimidazole (2), have been carried out extensively by X-ray diffraction, HRMS, UV-Vis, FT-IR and 1H and 13C NMR spectroscopy. The crystal structure of both compounds is stabilized by Osbnd H⋯N hydrogen bond and π-π interactions. Contrary to compound 1, the skeleton of compound 2 is considerably deviated from the planarity probably caused by intermolecular hydrogen bonding. The experimental results were compared to the theoretical ones, obtained at DFT level. Ground state geometry, electronic structure, vibrational and NMR spectra have been performed using the B3LYP functional with the 6-31 G(d,p) basis set. It was observed that the bond distances and angles in the both compounds were in good with those of the experiment. The energetic behaviors of the both compounds in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). Isotropic chemical shifts (13C and 1H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. The HOMO and LUMO analyses were used to elucidate information regarding charge transfer within the molecule.

  15. Study of spectroscopic and thermal characteristics of nonlinear optical molecular crystals based on 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Pavlovetc, I. M.; Fokina, M. I.

    2016-08-01

    The paper presents the results of study of spectroscopic and thermal characteristics of molecular co-crystals: 2-aminopyridine-4-nitrophenol-4-mtrophenolate (2AP4N) and 2,6- diaminopyridine-4-nitrophenol-4nitrophenolate (26DAP4N). Crystals were successfully grown by slow evaporation technique. Optical transparency in the region of 190-1100 was found to be suitable for applications with cut off wavelengths 420 and 430 nm respectively. Thermogravimetric and differential thermal analysis show good quality and thermal stability for studied crystals. Kurtz and Perry powder technique proves that the crystals are acentric and have significant nonlinear optical response.

  16. Spectroscopic study of sub-barrier quasi-elastic nuclear reactions

    SciTech Connect

    Pass, C.N.; Evans, P.M.; Smith, A.E.; Stuttge, L.; Betts, R.R.; Lilley, J.S.; Connell, K.A.; Simpson, J.; Smith, J.R.; James, A.N.

    1988-01-01

    The technique developed in this paper is particularly well suited to the detailed spectroscopic study of low energy quasi-elastic nuclear reactions and by overcoming the limitations of conventional procedure, the prospect of detailed studies of inclusive reaction mechanism may be realised. With only limited statistics we find evidence for strong multistep character in the transfer of a single nucleon from spherical vibrational target to spherical projectile nuclei. The suggestive measurements reported here may be made definitive through extended runs based on this technique and experiments planned for the future offer the real prospect of developing a quantified interpretation of the reaction process. 9 refs. 5 figs.

  17. Fourier transform Raman spectroscopic studies of a novel wood pulp bleaching system

    NASA Astrophysics Data System (ADS)

    Weinstock, Ira A.; Atalla, Rajai H.; Agarwal, Umesh P.; Minor, James L.; Petty, Chris

    1993-06-01

    The use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy for the study of lignocellulosic materials is discussed. An application utilizing NIR FT-Raman spectroscopy to study a novel chlorine-free process for the bleaching of wood pulps is presented in detail. The new process, still under development, entails the oxidation of residual lignin in wood pulps by vanadium-substituted polyoxometalates, and reoxidation of the reduced polyoxometalates by chlorine-free oxidants such as air, dioxygen, peroxides or ozone. Results from FT-Raman measurements of polyoxometalate-treated pulps are compared with those from chemical, spectroscopic and optical techniques commonly used in the pulp and paper industry.

  18. High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

    SciTech Connect

    Ng, Cheuk-Yiu

    2016-04-25

    The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

  19. Fluorophore conjugated silver nanoparticles: a time-resolved fluorescence correlation spectroscopic study

    NASA Astrophysics Data System (ADS)

    Ray, Krishanu; Zhang, Jian; Lakowicz, Joseph R.

    2009-02-01

    Fluorescence detection is a central component in biological research. In recent years there has been a growing interest in the interactions of fluorophores with metallic surfaces or particles. A single-stranded oligonucleotide was chemically bound to a single 50 nm diameter silver particle and a Cy5-labeled complementary single-stranded oligonucleotide was hybridized with the particle-bound oligonucleotide. The bound Cy5 molecules on the silver particles were spatially separated from the silver surface by the hybridized DNA duplex chains, which were about 8 nm in length, to reduce the competitive quenching. We use fluorescence lifetime correlation spectroscopy (FLCS) with picosecond time-resolved detection to separate the fluorescence correlation spectroscopy (FCS) contributions from fluorophores and metal-conjugated fluorophores. The single Cy5-labeled 50 nm silver particles displayed a factor of 15-fold increase in emission signal and 5-fold decrease in emission lifetimes in solution relative to the Cy5-DNA in the absence of metal. Lifetime measurements support the near-field interaction mechanism between the fluorophore and silver nanoparticle. In this study, FLCS is being applied to a system where the brightness and the fluorescent lifetime of the emitting species are significantly different. Our measurements suggest that FLCS is a powerful method for investigating the metal-fluorophore interaction at the single molecule level and to separate two different species from a mixture solution emitting at the same wavelength. Additionally, the highly bright Cy5-DNA-Ag molecules offer to be excellent probes in high background biological samples.

  20. Tomographic reconstruction of picosecond acoustic strain propagation

    NASA Astrophysics Data System (ADS)

    Tomoda, Motonobu; Matsuda, Osamu; Wright, Oliver B.; Li Voti, Roberto

    2007-01-01

    By means of an ultrafast optical technique, picosecond acoustic strain pulses in a transparent medium are tomographically visualized. The authors reconstruct strain pulses in Au-coated glass from time-domain reflectivity changes as a function of the optical angle of incidence, with ˜1ps temporal and ˜100nm spatial resolutions.

  1. Picosecond Time-Resolved - and Energy Relaxation Study of Rotons in Solid Parahydrogen and of Neutral INDIUM(1) and Neutral GALLIUM(1) Defects in Potassium Chloride

    NASA Astrophysics Data System (ADS)

    Sierens, Christiaan

    Picosecond laser pulses are used to investigate the ultrafast dynamic processes in solids with the time -resolved stimulated Raman gain and induced transparency techniques. First, a description of these techniques and the characteristics of the obtained decay curves in these cases are presented, and distinct solutions to the specific problems of these methods are compared with each other. We measured at low temperatures the dephasing of three distinct J = 2 rotons in para-H_2 crystals. Excellent exponential fits were obtained for the decay curves, indicating little or no inhomogeneous broadening processes. The resulting T_2 times exhibit no temperature dependence between 5 and 10 K and are in good agreement with recent high resolution spectral measurements. In the explored range of ortho -H_2 impurity concentration of up to five percent, a linear increase is found for the relaxation rate T_sp {2}{-1} with nearly equal slopes for the different | M_{J}| rotons. The linear increase is attributed to the scattering of the rotons by the impurities which act as independent scattering centers. If we extrapolate our results to pure para-H_2 , we obtain T_2 times in the neighborhood of 100 ps which agree quite well with those of a recent microscopic calculation. However, in the experiments, unpredicted and significant differences (up to 30%) are evident between T_2 times for different | M_{J }| values. The Ga^0(1) and In ^0(1) defects in KCl possess the laser-active type structure. A subnanosecond recovery was measured of the ground state population of Ga^0(1) and In^0(1) after laser pulse excitation in their third optical transition (OT3) about 615 nm. The relaxation times at 7K are (260 +/- 15)ps and (90 +/- 15)ps for Ga ^0(1) and In^0(1), respectively. For the Ga^0(1) defect an Arrhenius-fit of the temperature dependence of the decay time between 50K and 150K yields an activation energy of (60 +/- 10) cm^{ -1}. It is argued that this radiationless electronic deexcitation

  2. Thermal Physical, and Infrared Spectroscopic Studies on Glasses Prepared by Microwave Route

    SciTech Connect

    Jagadeesha, N.; Gowda, V. C. Veeranna; Chakradhar, R. P. S.; Reddy, C. Narayana

    2011-07-15

    This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO{sub 4/2}]{sup -} and [B{sub 2}V{sub 2}O{sub 9}]{sup 2-}) groups are confirmed by Infrared Spectroscopy of investigated glasses.

  3. HeI photoelectron spectroscopic studies on the electronic structure of alkyl nitrosamines

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Qian, Ximei; Li, Chunhui; Qiao, Chunhua; Wang, Dianxun

    1997-10-01

    HeI photoelectron spectroscopic (PES) studies on the electronic structure of alkyl nitrosamines R 2N 2O (R = CH 3-, CH 3CH 2-, and CH 3CH 2CH 2-) are reported. The assignment of the PES bands for this series of compounds has been made with the aid of the band shapes, the band intensity and ab initio SCF MO calculations based on the 631 ∗ G basis sets. Both PES experiment and the ab initio SCF MO calculations show that the detoxification ability of nitrosamine with longer alkyl chain is stronger.

  4. Fourier transform Raman spectroscopic studies of encrustations formed at the lichen-substratum interface

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G.; Farwell, Dennis W.; Lewis, Ian R.; Seaward, Mark R.

    1994-01-01

    FT-Raman microscope spectra of lichen-substratum samples of Xanthoria parietina and Ochrolechia parella growing in situ on sandstone have been obtained. The presence of small amounts of calcium oxalate and evidence for biodeterioration by lichen metabolic by-products is confirmed spectroscopically. Comparisons are made with similar studies of aggressive colonization by the high oxalate-producing lichen Dirina massiliensis forma sorediata on Renaissance frescoes. Spatial discrimination of the Raman microprobe technique for high and low oxalate-producing lichens is demonstrated.

  5. On-line separator for {gamma}-spectroscopic studies at FLNR JINR

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2007-05-22

    A JINR - IN2P3 collaboration project named 'GABRIELA' aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  6. On-line separator for γ-spectroscopic studies at FLNR JINR

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2007-05-01

    A JINR — IN2P3 collaboration project named "GABRIELA" aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  7. Infrared Spectroscopic Study of C12/02 Co-Adsorption on Al(111)

    DTIC Science & Technology

    1988-08-01

    adsorbed 0 and Cl leading to an enhancement of 6 the Al -O dynamic dipole moment. The situation is more complicated in other exposure regimes [e.g., Figs...Include Security Classification) Unclassified Technical Report No. 6 . "Infrared Spectroscopic Study of C12/02 Co-Adsorption on Al (111). 12 PERSONAL...IRRARS) has been used to observe the effects of C12 (02 ) pre-adsorption on the vibrational modes of 0 (Cl) formed by exposure of Al (111) to 0 ’ (C12

  8. Quantitative carbon-13 nuclear magnetic resonance spectroscopic study of mobile residues in bacteriorhodopsin

    SciTech Connect

    Bowers, J.L.; Oldfield, E.

    1988-07-12

    The authors have used quantitative carbon-13 nuclear magnetic resonance (NMR) spectroscopy to study the dynamic structure of the backbone of bacteriorhodopsin in the purple membrane of Halobacterium halobium R/sub 1/ and JW-3. NMR experiments were performed using an internal sucrose quantitation standard on purple membranes in which one of the following /sup 13/C'-labeled amino acids had been biosynthetically incorporated: glycine, isoleucine, lysine, phenylalanine, and valine. The results suggest that the C-terminus of the polypeptide chain backbone, and possibly one of the connecting loops, undergoes rapid, large angle fluctuations. The results are compared with previous NMR and fluorescence spectroscopic data obtained on bacteriorhodopsin.

  9. Dielectric properties of WS2-coated multiwalled carbon nanotubes studied by energy-loss spectroscopic profiling

    NASA Astrophysics Data System (ADS)

    Stolojan, Vlad; Silva, S. R. P.; Goringe, Michael J.; Whitby, R. L. D.; Hsu, Wang K.; Walton, D. R. M.; Kroto, Harold W.

    2005-02-01

    We investigate experimentally the electronic properties of the coating for multiwalled carbon nanotubes covered in tungsten disulfide (WS2) of various thicknesses. Coatings of thicknesses between 2 and 8 monolayers (ML) are analyzed using energy-loss spectroscopic profiling (ELSP), by studying the variations in the plasmon excitations across the coated nanotube, as a function of the coating thickness. We find a change in the ELSP for coatings above 5 ML thickness, which we interpret in terms of a change in its dielectric properties.

  10. Laser ablation of iron: A comparison between femtosecond and picosecond laser pulses

    SciTech Connect

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2013-08-28

    In this study, a comparison between femtosecond (fs) and picosecond (ps) laser ablation of electrolytic iron was carried out in ambient air. Experiments were conducted using a Ti:sapphire laser that emits radiation at 785 nm and at pulse widths of 110 ps and 130 fs, before and after pulse compression, respectively. Ablation rates were calculated from the depth of craters produced by multiple laser pulses incident normally to the target surface. Optical and scanning electron microscopy showed that picosecond laser pulses create craters that are deeper than those created by the same number of femtosecond laser pulses at the same fluence. Most of the ablated material was ejected from the ablation site in the form of large particles (few microns in size) in the case of picosecond laser ablation, while small particles (few hundred nanometers) were produced in femtosecond laser ablation. Thermal effects were apparent at high fluence in both femtosecond and picosecond laser ablation, but were less prevalent at low fluence, closer to the ablation threshold of the material. The quality of craters produced by femtosecond laser ablation at low fluence is better than those created at high fluence or using picosecond laser pulses.

  11. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    NASA Astrophysics Data System (ADS)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  12. A spectroscopic study of the radial velocity variations and accretion disks found in four dwarf novae

    NASA Astrophysics Data System (ADS)

    Stover, R. J.

    Time resolved spectroscopic observations of the four dwarf novae SS Cyg, EM Cyg, U Gem, and RU Peg are presented. Although these systems were studied previously, all of the spectroscopic studies were done photographically. A linear response, digital detector is employed. Analytic techniques to the study of the radial velocity variations and emission line profiles found in dwarf novae are applied. In the study of SS Cyg cross-correlation techniques were used for the first time to measure the radial velocity variations of the secondary star absorption lines. In the study of U Gem, analysis of the accretion disk emission lines showed that the motion of the material in the disk cannot be described accurately by orbits defined within the three-body approximation. The observations of EM Cyg reveal an unstable accretion disk, with emission lines that vary erratically on timescales of minutes to days. New measurements of the radial velocity variations of the emission and absorption lines found in the spectrum of RU Peg agree with previous measurements but have a higher accuracy.

  13. Fast drying and film formation of latex dispersions studied with FTIR spectroscopic imaging.

    PubMed

    Kimber, James A; Gerst, Matthias; Kazarian, Sergei G

    2014-11-18

    Drying of thin latex films (∼20 μm) at high drying speeds (of the order of seconds) has been studied by fast chemical imaging. ATR-FTIR spectroscopic imaging combined with a fast "kinetic" mode was used to acquire spectral images without coaddition, enabling the amount of water and homogeneity of the drying film to be studied over time. Drying profiles, constructed from analyzing the water content in each image, show two stages of drying, a fast and a slow region. The formulation of latex dispersions affects the onset of slow drying and the volume fraction of water remaining at the onset of slow drying. In this work, the effect of physical properties, film thickness and glass transition temperature (Tg), were investigated, as well as the effect of monomer composition where two monomoers, 2-ethylhexyl acrylate and n-butyl acrylate, and the amount of hydrophilic comonomer, methyl methacrylate (MMA), were varied. It was found that thicker films produced slower overall drying and that the formulation with a Tg above the minimum film formation temperature did not dry evenly, exhibiting cracking. However, the drying kinetics of high and low Tg films were similar, highlighting the advantage of using a spatially-resolved spectroscopic approach. Formulations containing more MMA dried faster than those with less. This was due to the hydrophilicity of MMA and the increase in Tg of the dispersion from the addition of MMA. Overall, FTIR spectroscopic imaging was shown to be a suitable approach in measuring film drying at high speeds as both chemical changes and chemical distribution could be analyzed over time.

  14. Infrared and Raman spectroscopic studies on alkali borate glasses: evidence of mixed alkali effect.

    PubMed

    Padmaja, G; Kistaiah, P

    2009-03-19

    A lithium-potassium-borate glass system containing manganese and iron cations has been thoroughly investigated in order to obtain information about the mixed alkali effect and the structural role of both the manganese and iron in such glass hosts. Mixed alkali borate glasses of the (30 - x)Li(2)O - xK(2)O - 10CdO/ZnO - 59B(2)O(3) (x = 0, 10, 15, 20, and 30) doped with 1MnO(2)/1Fe(2)O(3) system were prepared by a melt quench technique. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. The spectroscopic properties of glass samples were studied using infrared (IR) and Raman spectroscopic techniques. The density of all the prepared glasses was measured using Archimedes principle. Molar volumes were estimated from the density data. IR spectra of these glasses revealed a dramatic variation of three- and four-coordinated boron structures as a function of mixed alkali concentration. The vibrations due to Li-O, K-O, and MnO(4)/FeO(4) arrangements are consistent in all the compositions and show a nonlinear variation in the intensity with alkali content. Raman spectra of different alkali combinations with CdO and ZnO present drastic changes in the intensity of various Raman bands. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO(3) units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition.

  15. Majorana Neutrino Masses by Spectroscopic Studies of Double Beta Decays and Moon

    NASA Astrophysics Data System (ADS)

    Ejiri, Hiroyasu

    This is a brief review of spectroscopic studies of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. It aims at studying the Majorana nature of neutrinos and the mass spectrum by spectroscopic studies of 0νββ with ν-mass sensitivity of ≈ 30 meV. The solid scintillator option of the MOON detector is a super ensemble of multi-layer modules, each being composed by a scintillator plate and two tracking detector planes. Thin ββ source films are interleaved between the detector planes. High localization of the two β tracks enables one to select true signals and reject BG ones by spatial and time correlation analyses. MOON with detector ≠ ββ source is used for studying 0νββ decays from 100Mo, 82Se and other ββ isotopes with large nuclear sensitivity (large Qββ). Real-time exclusive measurements of low energy solar neutrinos can also be made by observing inverse β rays from solar-ν captures of 100Mo in delayed coincidence with the subsequent β decay of 100Tc.

  16. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies.

    PubMed

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-05

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298 K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.

  18. Optical studies on picoseconds response of optical switching 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile organic NLO material.

    PubMed

    Bharath, D; Kalainathan, S

    2014-01-24

    An organic push-pull chromophores 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile(MOT2) was synthesized. The third order nonlinear optical property of MOT2 crystal was studied by using Z-scan technique with He-Ne laser (632.8 nm). The magnitude of nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ(3)) have found to be in the range of 10(-14) m(2)/W, 10(-7) m/W and 10(-8) esu respectively. The multiphoton absorption and self defocusing effect were observed in z-scan open and closed aperture methods respectively. The response time of MOT2 crystal has found to be in the order of picoseconds, which is the essential requirement for the fabrication of optical switching. The optical transparency of MOT2 crystal was studied using UV-Vis-NIR spectroscopy and the reflectance, optical band gap (2.159 ev), extinction coefficient, optical conductivity were calculated. The refractive index of MOT2 crystal was measured using Abbe's refractometer and it is found to be 1.661. Photoluminescence study was carried out using Xenon lamp in a wavelength range of 450-700 nm. Laser optical damage threshold of MOT2 crystal was calculated using pulsed Nd-YAG laser of 1064 nm repetition rate of 10 ns. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Optical studies on picoseconds response of optical switching 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile organic NLO material

    NASA Astrophysics Data System (ADS)

    Bharath, D.; Kalainathan, S.

    2014-01-01

    An organic push-pull chromophores 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile(MOT2) was synthesized. The third order nonlinear optical property of MOT2 crystal was studied by using Z-scan technique with He-Ne laser (632.8 nm). The magnitude of nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ3) have found to be in the range of 10-14 m2/W, 10-7 m/W and 10-8 esu respectively. The multiphoton absorption and self defocusing effect were observed in z-scan open and closed aperture methods respectively. The response time of MOT2 crystal has found to be in the order of picoseconds, which is the essential requirement for the fabrication of optical switching. The optical transparency of MOT2 crystal was studied using UV-Vis-NIR spectroscopy and the reflectance, optical band gap (2.159ev), extinction coefficient, optical conductivity were calculated. The refractive index of MOT2 crystal was measured using Abbe's refractometer and it is found to be 1.661. Photoluminescence study was carried out using Xenon lamp in a wavelength range of 450-700 nm. Laser optical damage threshold of MOT2 crystal was calculated using pulsed Nd-YAG laser of 1064 nm repetition rate of 10 ns.

  20. The Distance to the Massive Galactic Cluster Westerlund 2 from a Spectroscopic and HST Photometric Study

    NASA Astrophysics Data System (ADS)

    Vargas Álvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P.

    2013-05-01

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters RV and AV for O-type stars in Wd2. We find average values langRV rang = 3.77 ± 0.09 and langAV rang = 6.51 ± 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance langdrang = 4.16 ± 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  1. THE DISTANCE TO THE MASSIVE GALACTIC CLUSTER WESTERLUND 2 FROM A SPECTROSCOPIC AND HST PHOTOMETRIC STUDY

    SciTech Connect

    Vargas Alvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P. E-mail: chipk@uwyo.edu E-mail: sheila@physics.unc.edu E-mail: rcool@obs.carnegiescience.edu

    2013-05-15

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters R{sub V} and A{sub V} for O-type stars in Wd2. We find average values (R{sub V} ) = 3.77 {+-} 0.09 and (A{sub V} ) = 6.51 {+-} 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance (d) = 4.16 {+-} 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2.

  2. Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V. K.; Singh, Bachcha; Singh, Ranjan K.

    2016-02-01

    Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

  3. Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

    PubMed

    Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V K; Singh, Bachcha; Singh, Ranjan K

    2016-02-05

    Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Laser-induced back-ablation of aluminum thin films using picosecond laser pulses

    SciTech Connect

    BULLOCK, A B

    1999-05-26

    Experiments were performed to understand laser-induced back-ablation of Al film targets with picosecond laser pulses. Al films deposited on the back surface of BK-7 substrates are ablated by picosecond laser pulses propagating into the Al film through the substrate. The ablated Al plume is transversely probed by a time-delayed, two-color sub-picoseond (500 fs) pulse, and this probe is then used to produce self-referencing interferograms and shadowgraphs of the Al plume in flight. Optical emission from the Al target due to LIBA is directed into a time-integrated grating spectrometer, and a time-integrating CCD camera records images of the Al plume emission. Ablated Al plumes are also redeposited on to receiving substrates. A post-experimental study of the Al target and recollected deposit characteristics was also done using optical microscopy, interferometry, and profilometry. In this high laser intensity regime, laser-induced substrate ionization and damage strongly limits transmitted laser fluence through the substrate above a threshold fluence. The threshold fluence for this ionization-based transmission limit in the substrate is dependent on the duration of the incident pulse. The substrate ionization can be used as a dynamic control of both transmitted spatial pulse profile and ablated Al plume shape. The efficiency of laser energy transfer between the laser pulse incident on the Al film and the ablated Al plume is estimated to be of order 5% and is a weak function of laser pulsewidth. The Al plume is highly directed. Low plume divergence ({theta}{sub divergence} < 5{sup o}) shows the ablated plume temperature to be very low at long time delays ( T << 0.5 eV at delays of 255 ns). Spectroscopic observations and calculations indicate that, in early time (t < 100 ps), the Al film region near the substrate/metal interface is at temperatures of order 0.5 eV. Interferograms of Al plumes produced with 0.1 {micro}m films show these plumes to be of high neutral atom

  5. X-ray spectroscopic study of the largest X-ray selected spectroscopic AGN sample in the XMM-XXL north

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Merloni, A.; Georgakakis, A.; Menzel, M.; Buchner, J.; Nandra, K.

    2014-07-01

    The XMM-XXL survey is a large public XMM survey which covers two ˜25 deg^2 sky regions with rich multi-wavelength coverage. In the northern field, we have extracted about ˜8000 unique point-like sources, identified their optical counterparts in SDSS imaging, and obtained spectroscopic redshift for ˜2400 AGN (with high completeness down to r-band optical magnitude of r˜22) thanks to a dedicated ancillary program of the SDSS-III/BOSS survey. This is to date the largest contiguous X-ray selected AGN sample with spectroscopic redshift information. Here we present the overall X-ray spectral properties of these ˜2400 reliable AGN. We fitted each X-ray spectrum with a simple power law model, modified by Galactic and intrinsic absorption. By dividing the sample into different redshift and luminosity bins, it possible to study the average X-ray spectrum properties of AGN in different cosmic epoch. We can also study the correlations between the X-ray spectrum and the optical spectrum parameters, and how those correlations change with redshift and the other physical parameters of the source (e.g. BH mass, accretion disc luminosity, broad emission line shapes etc.). Using the X-ray spectrum stacking method, we also study the properties of the iron K line in different redshift and luminosity bins.

  6. Laser spectroscopic and theoretical studies of the structures and encapsulation motifs of functional molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-01-22

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) 'hosts' interacting with N{sub 2}, acetylene, water, and ammonia 'guest' molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes.

  7. Laser Spectroscopic and Theoretical Studies of the Structures and Encapsulation Motifs of Functional Molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-02-01

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) "hosts" interacting with N2, acetylene, water, and ammonia "guest" molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes

  8. Spectroscopic Study on Ultrafast Carrier Dynamics and Terahertz Amplified Stimulated Emission in Optically Pumped Graphene

    NASA Astrophysics Data System (ADS)

    Otsuji, Taiichi; Boubanga-Tombet, Stephane; Satou, Akira; Suemitsu, Maki; Ryzhii, Victor

    2012-08-01

    This paper reviews recent advances in spectroscopic study on ultrafast carrier dynamics and terahertz (THz) stimulated emission in optically pumped graphene. The gapless and linear energy spectra of electrons and holes in graphene can lead to nontrivial features such as negative dynamic conductivity in the THz spectral range, which may lead to the development of new types of THz lasers. First, the non-equilibrium carrier relaxation/recombination dynamics is formulated to show how photoexcited carriers equilibrate their energy and temperature via carrier-carrier and carrier-phonon scatterings and in what photon energies and in what time duration the dynamic conductivity can take negative values as functions of temperature, pumping photon energy/intensity, and carrier relaxation rates. Second, we conduct time-domain spectroscopic studies using an optical pump and a terahertz probe with an optical probe technique at room temperature and show that graphene sheets amplify an incoming terahertz field. Two different types of samples are prepared for the measurement; one is an exfoliated monolayer graphene on SiO2/Si substrate and the other is a heteroepitaxially grown non-Bernal stacked multilayer graphene on a 3C-SiC/Si epi-wafer.

  9. Theoretical study of spectroscopic constants and anharmonic force field of SiF2.

    PubMed

    Li, Jing; Wang, Meishan; Yang, Chuanlu; Ma, Meizhong; Tong, Dianmin

    2015-05-01

    The equilibrium structure, spectroscopy constants, and anharmonic force field of SiF2 have been investigated at MP2, B3LYP, and B3PW91 levels of theory employing two basis sets cc-pVQZ and cc-pVTZ, respectively. The obtained equilibrium geometries, rotational constants, fundamental vibrational wave numbers, and centrifugal distortion constants are compared with the available experimental data or the previous theoretical values. The MP2/cc-pVQZ results of SiF2 are in excellent agreement with the available experimental data and afford a marked improvement over B3LYP/cc-pVQZ and B3PW91/cc-pVQZ in the calculation of spectroscopic constants and force constants of SiF2. The basis set enhancement beyond cc-pVQZ does not lead to a major improvement so that the cc-pVQZ basis set is sufficient for SiF2. The MP2/cc-pVQZ results may provide useful data for the spectroscopic experiment studies of SiF2. The used DFT method is also an advisable choice to study anharmonic force field of SiF2.

  10. Vibrational spectroscopic study of newly developed self-forming lipids and nanovesicles.

    NASA Astrophysics Data System (ADS)

    Bista, Rajan; Bruch, Reinhard

    2009-03-01

    We present the first experimental study of self-forming synthetic nanovesicles, trademarked as QuSomes, using vibrational spectroscopic techniques namely near-infrared (NIR) and laser tweezers Raman spectroscopy. Raman spectra of these new artificial nanovesicles suspended in Phosphate Buffered Saline (PBS) have been obtained by using an inverted confocal laser-tweezers-Raman-microscopy system in the spectral range of 3100 to 500 cm-1. This spectrometer works with an 80 mW diode-pumped solid-state laser, operating at a wavelength of 785 nm in the TEM00 mode. The laser is used both for optical trapping and Raman excitation. Similarly, NIR absorption spectra of these novel nanovesicles have been recorded in the spectral range of 9000-4800 cm-1 by using a new miniaturized micro-mirror spectrometer based on micro-optical-electro-mechanical systems (MOEMS) technology. In this work, we have found that the most prominent bands in the studied spectral region of Raman spectra are dominated by vibrational modes arising from C-C and CH2 bonds. Similarly, NIR spectra are primarily assigned as first and second overtone of C-H stretching mode and second overtone of C=O stretching mode. These spectroscopic techniques have proven to be an excellent tool to establish the fingerprint region revealing the molecular structure and conformation of QuSomes nanoparticles.

  11. Theoretical DFT study on spectroscopic signature and molecular dynamics of neurotransmitter and effect of hydrogen removal

    NASA Astrophysics Data System (ADS)

    Mukherjee, V.; Singh, N. P.; Yadav, R. A.

    2013-04-01

    Vibrational spectroscopic study has been made for the serotonin molecule and its deprotonated form. The Infrared and Raman spectra in optimum geometry of these two molecules are calculated using density functional theorem and the normal modes are assigned using potential energy distributions (PEDs) which are calculated using normal coordinate analysis method. The vibrational frequencies of these two molecules are reported and a comparison has been made. The effect of removal of the hydrogen atom from the serotonin molecule upon its geometry and vibrational frequencies are studied. Electronic structures of these two molecules are also studied using natural bond orbital (NBO) analysis. Theoretical Raman spectrum of serotonin at different exciting laser frequencies and at different temperatures are obtained and the results are discussed. Present study reveals that some wrong assignments had been made for serotonin molecule in earlier study.

  12. Spectroscopic study of honey from Apis mellifera from different regions in Mexico

    NASA Astrophysics Data System (ADS)

    Frausto-Reyes, C.; Casillas-Peñuelas, R.; Quintanar-Stephano, JL; Macías-López, E.; Bujdud-Pérez, JM; Medina-Ramírez, I.

    2017-05-01

    The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks. Using UV-Vis-NIR, spectroscopy, a characteristic spectrum profile of transmittance was obtained for each honey type. In addition, to have an objective characterization of color, a CIE Yxy and CIE L*a*b* colorimetric register was realized for each honey type. Applying the principal component analysis and their correlation with chromaticity coordinates allowed classifying the honey samples in one plot as: cutoff wavelength, maximum transmittance, tones and lightness. The results show that it is possible to obtain a spectroscopic record of honeys with specific characteristics by reducing the effects of fluorescence.

  13. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  14. Spectroscopic study of honey from Apis mellifera from different regions in Mexico.

    PubMed

    Frausto-Reyes, C; Casillas-Peñuelas, R; Quintanar-Stephano, J L; Macías-López, E; Bujdud-Pérez, J M; Medina-Ramírez, I

    2017-05-05

    The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks. Using UV-Vis-NIR, spectroscopy, a characteristic spectrum profile of transmittance was obtained for each honey type. In addition, to have an objective characterization of color, a CIE Yxy and CIE L*a*b* colorimetric register was realized for each honey type. Applying the principal component analysis and their correlation with chromaticity coordinates allowed classifying the honey samples in one plot as: cutoff wavelength, maximum transmittance, tones and lightness. The results show that it is possible to obtain a spectroscopic record of honeys with specific characteristics by reducing the effects of fluorescence. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Electron spectroscopic study (ESI, EELS) of Nanoplast-embedded mammalian lung.

    PubMed

    Fehrenbach, H; Richter, J; Schnabel, P A

    1992-06-01

    The potential of Nanoplast melamine resin embedding for the study of mammalian lung parenchyma was examined by means of electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). Samples were either fixed with glutaraldehyde-paraformaldehyde or glutaraldehyde-tannic acid, or were directly transferred to the embedding medium without prior fixation. Organic dehydrants, as well as fixatives containing heavy metals and stains, were omitted. A very high level of ultrastructural detail of chromatin, ribosomes, mitochondria and plasma membranes was achieved by ESI from the Nanoplast-embedded samples. The most prominent gain in ultrastructural detail was achieved when moving from an energy loss just below the L2,3 edge of phosphorus at 132 eV to an energy loss just beyond this edge. This reflects the prominent P L2,3 edge observed by EELS of Nanoplast-embedded samples in comparison with conventionally processed samples. Thus, taking into account possible sectioning artefacts, excellent heterochromatin images which rely on the phosphorus distribution can be obtained from Nanoplast-embedded samples by computer-assisted analysis of electron spectroscopic images. In this respect glutaraldehyde-paraformaldehyde fixation is preferable to glutaraldehyde-tannic acid fixation because the presence of silicon, revealed by EELS, in tannic-acid-fixed samples may introduce artefacts in phosphorus distribution images obtained by the three-window method because of the close proximity of the L2,3 edges of silicon and phosphorus.

  16. Glucose Oxidase Adsorption on Sequential Adsorbed Polyelectrolyte Films Studied by Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tristán, Ferdinando; Solís, Araceli; Palestino, Gabriela; Gergely, Csilla; Cuisinier, Frédéric; Pérez, Elías

    2005-04-01

    The adsorption of Glucose Oxidase (GOX) on layers of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) deposited on Sequentially Adsorbed Polyelectrolyte Films (SAPFs) were studied by three different spectroscopic techniques. These techniques are: Optical Wave Light Spectroscopy (OWLS) to measure surface density; Fluorescence Resonance Energy Transfer (FRET) to verify the adsorption of GOX on the surface; and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection mode (FTIR-HATR) to inspect local structure of polyelectrolytes and GOX. Two positive and two negative polyelectrolytes are used: Cationic poly(ethyleneimine) (PEI) and poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrene sulfonate) (PSS) and poly(acrylic acid) (PAA). These spectroscopic techniques do not require any labeling for GOX or SAPFs, specifically GOX and PSS are naturally fluorescent and are used as a couple donor-acceptor for the FRET technique. The SAPFs are formed by a (PEI)-(PSS/PAH)2 film followed by (PAA/PAH)n bilayers. GOX is finally deposited on top of SAPFs at different values of n (n=1..5). Our results show that GOX is adsorbed on positive ended SAPFs forming a monolayer. Contrary, GOX adsorption is not observed on negative ended film polyelectrolyte. GOX stability was tested adding a positive and a negative polyelectrolyte after GOX adsorption. Protein is partially removed by PAH and PAA, with lesser force by PAA.

  17. Copper(II) complexes of prion protein PEG11-tetraoctarepeat fragment: spectroscopic and voltammetric studies.

    PubMed

    Bonomo, Raffaele P; Di Natale, Giuseppe; Rizzarelli, Enrico; Tabbì, Giovanni; Vagliasindi, Laura I

    2009-04-14

    Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All the copper atoms occupy similar coordination sites formed by imidazole, peptidic nitrogen atoms and carbonyl oxygen atoms in a square base pyramidal geometry. Voltammetric measurements on these systems point out the cooperativity in the electron transfer processes among the copper(II) sites during their reduction. NO interaction with these polynuclear copper species is characterized by the reduction of the copper sites through the formation of two different intermediate complex species. When an excess of the Ac-PEG11-(PHGGGWGQ)4-NH2 ligand is considered, frozen solution EPR parameters and UV-Vis spectroscopic data identify the [Cu(N(im))4]2+ chromophore, which does not interact with NO.

  18. A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS

    SciTech Connect

    Allers, K. N.; Liu, Michael C.

    2013-08-01

    We present a near-infrared (0.9-2.4 {mu}m) spectroscopic study of 73 field ultracool dwarfs having spectroscopic and/or kinematic evidence of youth ( Almost-Equal-To 10-300 Myr). Our sample is composed of 48 low-resolution (R Almost-Equal-To 100) spectra and 41 moderate-resolution spectra (R {approx}> 750-2000). First, we establish a method for spectral typing M5-L7 dwarfs at near-IR wavelengths that is independent of gravity. We find that both visual and index-based classification in the near-IR provides consistent spectral types with optical spectral types, though with a small systematic offset in the case of visual classification at J and K band. Second, we examine features in the spectra of {approx}10 Myr ultracool dwarfs to define a set of gravity-sensitive indices based on FeH, VO, K I, Na I, and H-band continuum shape. We then create an index-based method for classifying the gravities of M6-L5 dwarfs that provides consistent results with gravity classifications from optical spectroscopy. Our index-based classification can distinguish between young and dusty objects. Guided by the resulting classifications, we propose a set of low-gravity spectral standards for the near-IR. Finally, we estimate the ages corresponding to our gravity classifications.

  19. Lanthanide and transition metal complexes of bioactive coumarins: molecular modeling and spectroscopic studies.

    PubMed

    Georgieva, I; Mihaylov, Tz; Trendafilova, N

    2014-06-01

    The present paper summarizes theoretical and spectroscopic investigations on a series of active coumarins and their lanthanide and transition metal complexes with application in medicine and pharmacy. Molecular modeling as well as IR, Raman, NMR and electronic spectral simulations at different levels of theory were performed to obtain important molecular descriptors: total energy, formation energy, binding energy, stability, conformations, structural parameters, electron density distribution, molecular electrostatic potential, Fukui functions, atomic charges, and reactive indexes. The computations are performed both in gas phase and in solution with consideration of the solvent effect on the molecular structural and energetic parameters. The investigations have shown that the advanced computational methods are reliable for prediction of the metal-coumarin binding mode, electron density distribution, thermodynamic properties as well as the strength and nature of the metal-coumarin interaction (not experimentally accessible) and correctly interpret the experimental spectroscopic data. Known results from biological tests for cytotoxic, antimicrobial, anti-fungal, spasmolytic and anti-HIV activities on the studied metal complexes are reported and discussed.

  20. Studying the dwarf galaxies in nearby groups of galaxies: Spectroscopic and photometric data

    NASA Astrophysics Data System (ADS)

    Hopp, U.; Vennik, J.

    2014-11-01

    Galaxy evolution by interaction-driven transformation is probably highly efficient in groups of galaxies. Dwarf galaxies with their shallow potential are expected to reflect the interaction most prominently in their observable structure. The major aim of this series of papers is to establish a data base which allows to study the impact of group interaction onto the morphology and star-forming properties of dwarf galaxies. Firstly, we present our selection rules for target groups and the morphological selection method of target dwarf member candidates. Secondly, the spectroscopic follow-up observations with the HET are presented. Thirdly, we applied own reduction methods based on adaptive filtering to derive surface photometry of the candidates. The spectroscopic follow-up indicate a dwarf identification success rate of roughly 55 %, and a group member success rate of about 33 %. A total of 17 new low surface-brightness members is presented. For all candidates, total magnitudes, colours, and light distribution parameters are derived and discussed in the context of scaling relations. We point out short comings of the SDSS standard pipeline for surface photometry for these dim objects. We conclude that our selection strategy is rather efficient to obtain a sample of dim, low surface brightness members of groups of galaxies within the Virgo super-cluster. The photometric scaling relation in these X-ray dim, rather isolated groups does not significantly differ from those of the galaxies within the local volume.

  1. Design of and Studies with a Novel One Meter Multi - Spectroscopic Telescope

    NASA Astrophysics Data System (ADS)

    Barry, Donald James

    1996-01-01

    A traditional one-meter imaging telescope costs 250,000 and weighs several tons. A novel multi -element spectroscopic telescope is described which trades imaging ability and monolithic size for low cost and weight, producing the same light gathering power at under one-tenth the cost. A complete spectroscopic facility consisting of one-meter equivalent-aperture telescope, fiber optical feed, Newtonian-Ebert spectrograph, and automated processing software has been prototyped, constructed, and placed into operation. The total cost of materials is under 85,000. A variety of science observations have been conducted with this facility including a tomographic reconstruction of the component spectra of the massive binary Plaskett's star components, a measurement of the line-profile variability of the Be stars lambda Eridani and BK Camelopardalis, and a dynamical study of the orbit of the triple star system 55 Ursae Majoris. The instrument performs well and is now in regular use as a scheduled telescope at the Georgia State University Hard Labor Creek Observatory. Improvements continue, and the telescope continues to serve a valuable role in the GSU Astronomy program's scientific programs and pedagogical mission.

  2. An investigation on the hole quality during picosecond laser helical drilling of stainless steel 304

    NASA Astrophysics Data System (ADS)

    Zhang, Hongyu; Di, Jianke; Zhou, Ming; Yan, Yu; Wang, Rong

    2015-05-01

    Precision drilling with ultra-short pulse lasers (e.g., picosecond and femtosecond) has been advocated to significantly improve the quality of the micro-holes with reduced recast layer thickness and no heat-affected zone. However, a combination of high-power picosecond laser with helical drilling strategy in laser drilling has rarely been reported in previous studies. In the present study, a series of micro-holes with circular, triangular, rectangular, and rhombic shapes (diameter 0.6 mm) were manufactured on stainless steel 304 using a newly developed laser drilling system which incorporated a picosecond laser and a high-speed laser beam rotation apparatus into a five-axis positioning platform. The quality of the helical drilled holes, e.g., recast layer, micro-crack, circularity, and conicity, were evaluated using an optical microscope, an optical interferometer, and a scanning electron microscope. In addition, the microstructure of the samples was investigated following etching treatment. It was demonstrated that the entrance ends, the exit ends, and the side walls of the micro-holes were quite smooth without accumulation of spattering material and formation of recast layer and micro-crack. No tapering phenomenon was observed, and the circularity of the holes was fairly good. There was no distinctive difference with regard to the microstructure between the edges of the holes and the bulk material. Picosecond laser helical drilling can be an effective technique for manufacturing of micro-holes with very high quality. The development of high-power picosecond laser would promote picosecond laser drilling to be more industrial relevance in the future.

  3. X-ray photoelectron and Raman spectroscopic studies of MeV proton irradiated graphite

    NASA Astrophysics Data System (ADS)

    Mathew, S.; Joseph, B.; Sekhar, B. R.; Dev, B. N.

    2008-07-01

    Poly-crystalline graphite samples were irradiated using 2.25 MeV H + ions with a fluence of 2 × 10 17 ions/cm 2. Magnetic ordering in highly oriented pyrolytic graphite samples have been reported earlier under the similar irradiation conditions [Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201]. In that study, the authors attribute the observed irradiation induced magnetic ordering to the formation of a mixed sp 2-sp 3 hybridized carbon atoms. In the present study, we report the X-ray photoelectron and Raman spectroscopic studies on pristine and irradiated samples. Irradiated samples are found to show an increased number of sp 3 hybridized carbon atoms. However, the Raman spectrum, specially the second order data, do indicate that the nature of the graphene lattice structure has been preserved in the irradiated samples. The mechanisms for the irradiation induced enhancement in sp 3 hybridization are discussed.

  4. Spectroscopic study of N-acetylcysteine and N-acetylcystine/hydrogen peroxide complexation

    NASA Astrophysics Data System (ADS)

    Picquart, Michel; Abedinzadeh, Zohreh; Grajcar, Lydie; Baron, Marie Héléne

    1998-03-01

    A spectroscopic study of N-acetylcysteine (RSH) and N-acetylcystine (RSSR) has been performed using infrared absorption and Raman scattering in order to pinpoint the sites of complexation of these two species with H 2O 2. Molecules of RSH and RSSR were studied in KBr pellets, and in aqueous solutions of H 2O, D 2O and H 2O with H 2O 2 (1 mol l -1) to characterize the specific influence of the solvent molecules. A time-resolved Raman study was performed for RSH-H 2O 2 in aqueous solution at 1:1 molar ratio in order to observe the formation of RSSR and to discuss the mechanism of this redox reaction.

  5. In vitro drug interaction of levocetirizine and diclofenac: Theoretical and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Abo Dena, Ahmed S.; Abdel Gaber, Sara A.

    2017-06-01

    Levocetirizine dihydrochloride is known to interact with some anti-inflammatory drugs. We report here a comprehensive integrated theoretical and experimental study for the in vitro drug interaction between levocetirizine dihydrochloride (LEV) and diclofenac sodium (DIC). The interaction of the two drugs was confirmed by the molecular ion peak obtained from the mass spectrum of the product. Moreover, FTIR and 1HNMR spectra of the individual drugs and their interaction product were inspected to allocate the possible sites of interaction. In addition, quantum mechanical DFT calculations were performed to search for the interaction sites and to verify the types of interactions deduced from the spectroscopic studies such as charge-transfer and non-bonding π-π interactions. It was found that the studied drugs interact with each other in aqueous solution via four types of interactions, namely, ion-pair formation, three weak hydrogen bonds, non-bonding π-π interactions and charge-transfer from DIC to LEV.

  6. Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

    The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

  7. Spectroscopic Studies on Eu{sup 3+} Doped Boro-Tellurite Glasses

    SciTech Connect

    Selvaraju, K.; Marimuthu, K.

    2011-07-15

    Eu{sup 3+} doped boro-tellurite glasses have been synthesized and its optical behavior have been studied and reported. The presence of varying tellurium dioxide content results changes in spectroscopic behavoir were explored through UV-VIS, and Luminescence spectra. The bonding parameters have been calculated based on the observed band positions of the absorption spectra. The Judd-Ofelt intensity parameters {Omega}{sub {lambda}} ({lambda} = 2, 4 and 6) have been determined through the luminescence spectra without applying any constraints and the results are presented. The Judd-Ofelt parameters have been used to determine various optical properties corresponding to {sup 5}D{sub 0}{yields}{sup 7}F{sub J}(J = 1,2,3 and 4) transitions of Eu{sup 3+} ions. The varying optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar studies.

  8. Spectroscopic and thermodynamic studies of light harvesting perylenediimide derivative - zinc porphyrin complex in aqueous media.

    PubMed

    El-Refaey, Ahmed; Shaban, Shaban Y; El-Kemary, Maged; El-Khouly, Mohamed E

    2017-11-05

    Self-assembly of perylene derivative such as N,N'-bis(2(trimethylammonium iodide) ethylene)perylene-3,4,9,10-tetracarboxyldiimide (TAIPDI) can produce one-dimensional form (1D) in an aqueous media. The ability of one-dimensional TAIPDI to form light harvesting complex with water-soluble zinc porphyrin (ZnTPPS4) via the π-π and electrostatic interactions has been described. Owing to electronic interactions between the π-systems, the complex formation is accompanied by pronounced absorption spectral changes in the UV/Vis absorption bands. The formation constant of the ZnTPPS4-TAIPDI complex has been determined as 2.60×10(4)M(-1) suggests a moderately stable complex. The steady-state fluorescence measurements exhibited fluorescence quenching of both the singlet TAIPDI and ZnTPPS4 because of the electron transfer process from the electron-donating ZnTPPS4 to the electron-accepting TAIPDI. Based on the picosecond time-resolved fluorescence, the rate and quantum yield of the electron transfer were found to be 2.47×10(10)s(-1) and 0.99, respectively, indicating fast and efficient electron transfer. The thermodynamic parameters of the complex formation have been determined from the stopped-flow measurements. The interaction between ZnTPPS4 and TAIPDI occurs in two steps, a fast and reversible step followed by a slow and irreversible one. The activation parameters for the complex formation (ΔH(#)=22±5kJmol(-1) and ΔS(#)=-123±18JK(-1)mol(-1)), (ΔH(#)=133±4kJmol(-1) and ΔS(#)=167±13Jmol(-1)K(-1)) were determined from variable temperature studies for the "on" and the "off" of the first step and ΔS(#)=246±37.89Jmol(-1)K(-1) and ΔH(#)=130±11kJmol(-1) for the second step. The negative and positive ΔS(#) values found for the interaction reactions are consistent with an associative interaction for the first step followed by dissociative mechanism for both the "off" and the second step. Copyright © 2017. Published by Elsevier B.V.

  9. Picosecond pulsed diode ring laser gyroscope

    SciTech Connect

    Rosker, M.J.; Christian, W.R.; McMichael, I.C.

    1994-12-31

    An external ring cavity containing as its active medium a pair of InGaAsP diodes is modelocked to produce picosecond pulses. In such a laser, a small frequency difference proportional to the nonreciprocal phase shift (resulting from, e.g., the Sagnac effect) can be observed by beating together the counter propagating laser arms; the device therefore acts as a rotating sensor. In contrast to a conventional (cw) ring laser gyroscope, the pulsed gyroscope can avoid gain competition, thereby enabling the use of homogeneously broadened gain media like semiconductor diodes. Temporal separation of the pulses within the cavity also discriminates against frequency locking of the lasers. The picosecond pulsed diode ring laser gyroscope is reviewed. Both active and passive modelocking are discussed.

  10. Direct fluorescence characterisation of a picosecond seeded optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Stuart, N. H.; Bigourd, D.; Hill, R. W.; Robinson, T. S.; Mecseki, K.; Patankar, S.; New, G. H. C.; Smith, R. A.

    2015-02-01

    The temporal intensity contrast of high-power lasers based on optical parametric amplification (OPA) can be limited by parametric fluorescence from the non-linear gain stages. Here we present a spectroscopic method for direct measurement of unwanted parametric fluorescence widely applicable from unseeded to fully seeded and saturated OPA operation. Our technique employs simultaneous spectroscopy of fluorescence photons slightly outside the seed bandwidth and strongly attenuated light at the seed central wavelength. To demonstrate its applicability we have characterised the performance of a two-stage picosecond OPA pre-amplifier with 2.8×105 gain, delivering 335 μJ pulses at 1054 nm. We show that fluorescence from a strongly seeded OPA is reduced by ~500× from the undepleted to full pump depletion regimes. We also determine the vacuum fluctuation driven noise term seeding this OPA fluorescence to be 0.7±0.4 photons ps-1 nm-1 bandwidth. The resulting shot-to-shot statistics highlights a 1.5% probability of a five-fold and 0.3% probability of a ten-fold increase of fluorescence above the average value. Finally, we show that OPA fluorescence can be limited to a few-ps pedestal with 3×10-9 temporal intensity contrast 1.3 ps ahead of an intense laser pulse, a level highly attractive for large scale chirped-pulse OPA laser systems.

  11. Batch sorption and spectroscopic speciation studies of neptunium uptake by montmorillonite and corundum

    NASA Astrophysics Data System (ADS)

    Elo, O.; Müller, K.; Ikeda-Ohno, A.; Bok, F.; Scheinost, A. C.; Hölttä, P.; Huittinen, N.

    2017-02-01

    Detailed information on neptunium(V) speciation on montmorillonite and corundum surfaces was obtained by batch sorption and desorption studies combined with surface complexation modelling using the Diffuse Double-Layer (DDL) model, in situ time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and X-ray absorption (XAS) spectroscopies. The pH-dependent batch sorption studies and the spectroscopic investigations were conducted under carbonate-free conditions in 10 mM NaClO4 or 10 mM NaCl. Solid concentrations of 0.5 g/l and 5 g/l were used depending on the experiment. The neptunium(V) desorption from the two mineral surfaces was investigated at pH values ranging from 8 to 10, using the replenishment technique. Neptunium(V) was found to desorb from the mineral surface, however, the extent of desorption was dependent on the solution pH. The desorption of neptunium(V) was confirmed in the ATR FT-IR spectroscopic studies at pH 10, where all of the identified inner-sphere complexed neptunium(V), characterized by a vibrational band at 790 cm-1, was desorbed from both mineral surfaces upon flushing the mineral films with a blank electrolyte solution. In XAS investigations of neptunium(V) uptake by corundum, the obtained structural parameters confirm the formation of an inner-sphere complex adsorbed on the surface in a bidentate fashion. As the inner-sphere complexes found in the IR-studies are characterized by identical sorption bands on both corundum and montmorillonite, we tentatively assigned the neptunium(V) inner-sphere complex on montmorillonite to the same bidentate complex found on corundum in the XAS investigations. Finally, the obtained batch sorption and spectroscopic results were modelled with surface complexation modelling to explain the neptunium(V) speciation on montmorillonite over the entire investigated pH range. The modelling results show that cation exchange in the interlayer space as well as two pH-dependent surface complexes

  12. High-power picosecond laser pulse recirculation.

    PubMed

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J

    2010-07-01

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  13. High Power Picosecond Laser Pulse Recirculation

    SciTech Connect

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  14. Preferential binding of fisetin to the native state of bovine serum albumin: spectroscopic and docking studies.

    PubMed

    Singha Roy, Atanu; Pandey, Nitin Kumar; Dasgupta, Swagata

    2013-04-01

    We have investigated the binding of the biologically important flavonoid fisetin with the carrier protein bovine serum albumin using multi-spectroscopic and molecular docking methods. The binding constants were found to be in the order of 10(4) M(-1) and the number of binding sites was determined as one. MALDI-TOF analyses showed that one fisetin molecule binds to a single bovine serum albumin (BSA) molecule which is also supported by fluorescence quenching studies. The negative Gibbs free energy change (∆G°) values point to a spontaneous binding process which occurs through the presence of electrostatic forces with hydrophobic association that results in a positive entropy change (+51.69 ± 1.18 J mol(-1) K(-1)). The unfolding and refolding of BSA in urea have been studied in absence and presence of fisetin using steady-state fluorescence and lifetime measurements. Urea denaturation studies indicate that fisetin is gradually released from its binding site on the protein. In the absence of urea, an increase in temperature that causes denaturation of the protein results in the release of fisetin from its bound state indicating that fisetin binds only to the native state of the protein. The circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic studies showed an increase in % α-helix content of BSA after binding with fisetin. Site marker displacement studies in accordance with the molecular docking results suggested that fisetin binds in close proximity of the hydrophobic cavity in site 1 (subdomain IIA) of the protein. The PEARLS (Program of Energetic Analysis of Receptor Ligand System) has been used to estimate the interaction energy of fisetin with BSA and the results are in good correlation with the experimental findings.

  15. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    NASA Astrophysics Data System (ADS)

    Moral, Mónica; García, Gregorio; Peñas, Antonio; Garzón, Andrés; Granadino-Roldán, José M.; Melguizo, Manuel; Fernández-Gómez, Manuel

    2012-10-01

    This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph2Tz) and some oligomeric derivatives. Ph2Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  16. Spectroscopic study of antileishmanial drug incubated in the promastigotes of Leishmania mexicana

    NASA Astrophysics Data System (ADS)

    Hung, J.; Castillo, J.; Jiménez, G.; Hasegawa, M.; Rodriguez, M.

    2003-11-01

    In this work we present spectroscopic study of Boldine (aporphine alkaloid) that possesses important biological activities, in particular, in interaction with the promastigotes of Leishmania mexicana. The results show the applicability of autofluorescence of this drug to determinate the possible mechanism of its biological action. The blue shift and hyperchromic effect in the emission spectrum of the drug in interaction with the parasite cells indicate an energy transference process between them. The morphological change of cell shape of the promastigotes treated with the drug is observed using confocal microscopy. This morphological cell-shape transformation evidences an important interaction between the drug studied and some protein of the parasite cell. Here we describe for the first time the fluorescence properties of the Boldine in the promastigotes of L. mexicana.

  17. Dielectric studies of boron sub phthalocyanine chloride thin films by admittance spectroscopic techniques

    SciTech Connect

    Kalia, Sameer; Neerja; Mahajan, Aman Sharma, Anshul Kumar; Kumar, Sanjeev; Bedi, R. K.

    2016-05-06

    The dielectric properties of Boron Sub Phthalocyanine Chloride (Cl-SubPc) thermally deposited on ITO substrate have been studied using admittance spectroscopic techniques. The I-V and capacitance –frequency (C-F) studies at various bias voltages reveal that the mobility of charge carriers decrease with bias voltage, however the conduction phenomenon still remain hopping in nature. From the differential susceptance curve, the contribution of the Schottky barrier contact in the charge carrier concentration was found to be absent. The mobility of charge carriers have been determined using differential susceptance variation and from the phase of admittance curve. The values obtained in two cases have been found to be in agreement with each other.

  18. Synthesis, Spectroscopic, ac Conductivity and Thermal Studies on Co(III) Acetylacetonate-Iodine Complex

    NASA Astrophysics Data System (ADS)

    Hashem, H. A.; Refat, M. S.

    A spectrophotometric study of 1:1 donor-acceptor complex, cobalt (III) acetylacetonate (donor) and iodine (σ-acceptor) has been preformed. The equilibrium constants, (K) and the absorpitivity (ɛ) for the formation of the iodine complex have been calculated. The predicted structure of the solid triiodide charge-transfer complex reported in this study is further supported by thermal, far and mid infrared spectroscopic measurements. Electron transfer from Co (acac = 2, 4-pentanedionate)3 to iodine leads to the formation of an organic semiconductor with the formula of [Co(acac)3]_2 I+. I3-. The kinetic parameters (nonisothermal method) for their decomposition have been evaluated by graphical methods using the equations of Freeman-Carroll (FC), Horowitz-Metzger (HM) and Coats-Redfern (CR). The ac conductivity and dielectric properties of [Co(acac)3]_2 I+. I3- have been measured over the frequency 50-106 Hz at temperature 298 K.

  19. Interaction between serum albumins and sonochemically synthesized cadmium sulphide nanoparticles: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Naveenraj, Selvaraj; Asiri, Abdullah M.; Anandan, Sambandam

    2013-05-01

    Cadmium Sulphide nanoparticles approximately 5-10 nm in size range were synthesized by sonochemical technique, which follows acoustic cavitation phenomenon and generates nanoparticles with a smaller size range and higher surface area. The in vitro binding interaction of these sonochemically synthesized CdS nanoparticles with serum albumins (SA) were investigated using UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques since CdS nanoparticles has biological applications such as cellular labelling and deep-tissue imaging. UV-Vis absorption and fluorescence studies confirm that CdS nanoparticles bind with SA through ground state complex formation (static quenching mechanism). The results suggest that sonochemically synthesized CdS nanoparticles interact with HSA more than that of BSA and these nanoparticles can be easily transported and rapidly released to the targets by serum albumins. CD studies confirmed the conformational change of serum albumins on the interaction of CdS nanoparticles.

  20. Defect study in ZnO related structures—A multi-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Ling, C. C.; Cheung, C. K.; Gu, Q. L.; Dai, X. M.; Xu, S. J.; Zhu, C. Y.; Luo, J. M.; Zhu, C. Y.; Tam, K. H.; Djurišić, A. B.; Beling, C. D.; Fung, S.; Lu, L. W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H. C.

    2008-10-01

    ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

  1. Infrared Spectroscopic Studies with the Stratospheric Observatory for Infrared Astronomy (sofia)

    NASA Astrophysics Data System (ADS)

    Gehrz, R. D.; Becklin, E. E.

    2011-06-01

    The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA) will be a premier facility for studying the physics and chemistry of the interstellar medium and the stellar evolution process for many decades. SOFIA's first-generation instrument complement includes broadband imagers, moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km/s resolution. SOFIA spectroscopic science applications will be discussed, with special emphasis on investigations related to infrared spectroscopy of astrophysical gas, grains, and ices. First light images and early science results related to these topics will be presented.

  2. Electrochemical and spectroscopic studies of the oxidation mechanism of the herbicide propanil.

    PubMed

    Garrido, E M; Lima, J L F C; Delerue-Matos, C; Borges, F; Silva, A M S; Piedade, J A P; Oliveira Brett, A M

    2003-02-12

    Electrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil occurs, leading to the appearance of another species in solution which oxidizes at +0.60 V. The anodic peak found at +0.79 V vs Ag/AgCl in deuterated basic solutions is related to the presence of an anionic species in which a negative charge is on the nitrogen atom. The electrochemical data were confirmed by the identification of all the species formed in acidic and basic deuterated solutions by means of NMR spectroscopy. The results are supported by electrochemical and spectroscopic studies of acetanilide in deuterated solutions.

  3. A picosecond high pressure gas switch

    SciTech Connect

    Cravey, W.R.; Poulsen, P.P.; Pincosy, P.A.

    1992-06-01

    Work is being done to develop a high pressure gas switch (HPGS) with picosecond risetimes for UWB applications. Pulse risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at high pressures and higher electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With these high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized on the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with lab data.

  4. Accurate molecular structure and spectroscopic properties for nucleobases: A combined computational - microwave investigation of 2-thiouracil as a case study

    PubMed Central

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2015-01-01

    The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier Transform Microwave spectrometers. The joint experimental – computational study allowed us to determine accurate molecular structure and spectroscopic properties for the title molecule, but more important, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules. PMID:24002739

  5. SPECTROSCOPIC STUDIES OF THE ANAEROBIC ENZYME-SUBSTRATE COMPLEX OF CATECHOL 1,2-DIOXYGENASE

    PubMed Central

    Horsman, Geoff P.; Jirasek, Andrew; Vaillancourt, Frédéric H.; Barbosa, Christopher J.; Jarzecki, Andrzej A.; Xu, Changliang; Mekmouche, Yasmina; Spiro, Thomas G.; Lipscomb, John D.; Blades, Michael W.; Turner, Robin F.B.; Eltis, Lindsay D.

    2008-01-01

    The basis of the respective regiospecificities of intradiol and extradiol dioxygenase is poorly understood and may be linked to the protonation state of the bidentate-bound catechol in the enzyme:substrate complex. Previous ultraviolet resonance Raman (UVRR) and UV-visible (UV-vis) difference spectroscopic studies demonstrated that in extradiol dioxygenases, the catechol is bound to the Fe(II) as a monoanion. In this study, we use the same approaches to demonstrate that in catechol 1,2-dioxygenase (C12O), an intradiol enzyme, the catechol binds to the Fe(III) as a dianion. Specifically, features at 290 nm and 1550 cm−1 in the UV-vis and UVRR difference spectra, respectively, are assigned to dianionic catechol based on spectra of the model compound, ferric tris(catecholate). The UVRR spectroscopic band assignments are corroborated by density functional theory (DFT) calculations. In addition, negative features at 240 nm in UV-vis difference spectra and at 1600, 1210, and 1175 cm−1 in UVRR difference spectra match those of a tyrosinate model compound, consistent with protonation of the axial tyrosinate ligand when it is displaced from the ferric ion coordination sphere upon substrate binding. The DFT calculations ascribe the asymmetry of the bound dianionic substrate to the trans donor effect of an equatorially ligated tyrosinate ligand. In addition, the computations suggest that trans donation from the tyrosinate ligand may facilitate charge-transfer from the substrate to yield the iron-bound semiquinone transition state, which is capable of reacting with dioxygen. In illustrating the importance of ligand trans effects in a biological system, the current study demonstrates the power of combining difference UVRR and optical spectroscopies to probe metal ligation in solution. PMID:16316234

  6. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    NASA Astrophysics Data System (ADS)

    Harde, G. B.; Muley, G. G.

    2016-05-01

    Borate glasses of the system xNd2O3-(1-x) La2O3-SrCO3-10H3BO3 (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition 4I9/2 → 4G5/2 + 2G7/2 has found more prominent than the other transitions. Optical band gap energies of glasses have been determined and found less for Nd doped glass.

  7. Thermal dependence of optical properties of silver thin films studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Sundari, S. Tripura; Dash, S.; Tyagi, A. K.

    2012-06-01

    The thermal dependence of the dielectric constants of silver thin films were investigated between 300 K and 650 K by spectroscopic ellipsometer in the energy range 1.5 to 5 eV. The studies showed an increase in the imaginary part (ɛ2) of the dielectric function, a shift of ˜300 meV in the onset of the main absorption (L3-L2'(EF)), appearance of additional absorption above 500 K which is attributed to (L2'- L1) and increased broadening of the absorption spectra owing to smearing of Fermi level. It was found that the unscreened plasma frequency ωpu associated with resonant oscillations of conduction electrons increased while the relaxation time decreased with increase in temperature.

  8. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    NASA Astrophysics Data System (ADS)

    Kurhekar, Anil Sudhakar; Apte, Prakash R.

    2013-02-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces.

  9. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga).

    PubMed

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  10. A dielectric spectroscopic study of the disperse structure of asphaltene solutions at high pressures

    SciTech Connect

    Syunyaev, R.Z.; Sh. Abid, R.

    1994-03-01

    The disperse structure of oil asphaltenes in benzene and toluene solutions at different temperatures and concentrations were studied at pressures up to 1.0 GPa. The polarity of the asphaltene molecules allows the dielectric spectroscopic method to be used. A sharp increase in the relaxation time and the sizes of the asphaltene aggregates, calculated according to the Debye model near the phase transition point, were found in the benzene solution. The pressure value corresponding to crystallization is much higher in the toluene solution, and only the border region can be investigated. An explanation of the pressure dependences of the relaxation times are presented. The activation energies and the coefficients of isothermal compressibility are calculated.

  11. Study of targeted-treatment on colon cancer cell via spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chan, Ching-Hsiang; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2017-04-01

    We present the enhancement of targeted treatment on colon cancer cell via microscopic imaging ellipsometry (MIE). All spectroscopic MIE signals on 5μm×5μm area in visible range are captured within the modified Optrel MULTISKOP system. Colon cancer cells are cultured in Bottom-up Millicell EZ SLIDE 4-well structure under the environment (37°C, 10% CO2). Original single colon cancer cell, single colon cancer cell under untargeted-treatment, and single colon cancer cell under targeted-treatment are studied by specular-reflective mode and off-specular scattering mode in this experiment. Some polarization-related and phase-related MIE images are analyzed to reveal the improvement of targeted-treatment by observing changes in specular and off-specular reflectance and absorption.

  12. Molecular spectroscopic study on the interaction of tetracyclines with serum albumins.

    PubMed

    Bi, Shuyun; Song, Daqian; Tian, Yuan; Zhou, Xin; Liu, Zhongying; Zhang, Hanqi

    2005-02-01

    A molecular spectroscopic investigation of the interaction between tetracyclines antibiotics and human serum albumin or bovine serum albumin was reported. The influences of some metal ions on the interaction were also studied. When tetracyclines drugs were added into the solution containing serum albumins, the fluorescence intensity of serum albumins decreased with the increasing of the drugs concentrations, which is due to the formation of new non-fluorescence complexes of drug-serum albumin. The tetracyclines acted as quenchers and quenched the fluorescence of the serum albumins. The binding constants and the number of the binding sites of the reaction of tetracyclines and serum albumins were obtained. The main sorts of acting force between the drugs and serum albumins were found and the action distances and the energy transfer efficiencies between donor-acceptor were calculated based on the Foster energy transference.

  13. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; El-Mallah, H. M.; Atwee, T.; El-Damhogi, D. G.

    2017-05-01

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57 eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q2), and oscillator strength (f), of the principal optical transitions have also been evaluated.

  14. Laser Raman and ac impedance spectroscopic studies of PVA: NH 4NO 3 polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Hema, M.; Selvasekarapandian, S.; Hirankumar, G.; Sakunthala, A.; Arunkumar, D.; Nithya, H.

    2010-01-01

    Ion conducting polymer electrolyte PVA:NH 4NO 3 has been prepared by solution casting technique and characterized using XRD, Raman and ac impedance spectroscopic analyses. The amorphous nature of the polymer films has been confirmed by XRD and Raman spectroscopy. An insight into the deconvoluted Raman peaks of υ1 vibration of NO 3- anion for the polymer electrolyte reveals the dominancy of ion aggregates at higher NH 4NO 3 concentration. From the ac impedance studies, the highest ion conductivity at 303 K has been found to be 7.5 × 10 -3 S cm -1 for 80PVA:20NH 4NO 3. The conductivity of the polymer electrolytes has been found to depend on the degree of dissociation of the salt in the host polymer matrix. The combination of the above-mentioned analyses has proven worth while and in fact necessary in order to achieve better understanding of these complex systems.

  15. Raman spectroscopic study of “The Malatesta”: A Renaissance painting?

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.; Vandenabeele, Peter; Benoy, Timothy J.

    2015-02-01

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

  16. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  17. The study of interaction between PFOA/PFOS and uracil by topology quality and spectroscopic analysis

    NASA Astrophysics Data System (ADS)

    Xu, Hui-Ying; Zhu, Jian-Qing; Wang, Wei; Xu, Xiao-Lu; Lu, Yin

    2014-02-01

    It has been established that perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) can be considered as emerging persistent organic pollutants. In recent years, there was increasing distribution of PFOA/PFOS in environmental systems, and accumulation and toxic effects of PFOA/PFOS in human body. In this paper, quantum chemistry methods were employed to study the interaction between perfluorinated organic pollutants and base (uracil). The results showed that there were four stable binding modes between the two perfluorinated compounds with uracil, especially the second mode which caused the most detrimental physiological functional response. NBO analysis showed that reactive hydrogen in the two perfluorinated compounds had the greatest effect on the hydrogen bond. The nature of the hydrogen bond formed between the two perfluorinated compounds and base was investigated using the AIM theory. The changes of spectroscopic properties in complexes were analyzed by IR and NMR spectra.

  18. Inhibitory effect of morin on tyrosinase: insights from spectroscopic and molecular docking studies.

    PubMed

    Wang, Yajie; Zhang, Guowen; Yan, Jiakai; Gong, Deming

    2014-11-15

    Tyrosinase is a key enzyme in the production of melanin in the human body, excessive accumulation of melanin can lead to skin disorders. Morin is an important bioactive flavonoid compound widely distributed in plants and foods of plant origin. In this study, the inhibitory kinetics of morin on tyrosinase and their binding mechanism were determined using spectroscopic and molecular docking techniques. The results indicate that morin reversibly inhibited tyrosinase in a competitive manner through a multi-phase kinetic process. Morin was found to bind to tyrosinase at a single binding site mainly by hydrogen bonds and van der Waals forces. Analysis of circular dichroism spectra revealed that the binding of morin to tyrosinase induced rearrangement and conformational changes of the enzyme. Moreover, molecular docking results suggested that morin competitively bound to the active site of tyrosinase with the substrate levodopa. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique.

    PubMed

    Zeyada, H M; El-Mallah, H M; Atwee, T; El-Damhogi, D G

    2017-05-15

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q(2)), and oscillator strength (f), of the principal optical transitions have also been evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Molecular spectroscopic study on the interaction of tetracyclines with serum albumins

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Song, Daqian; Tian, Yuan; Zhou, Xin; Liu, Zhongying; Zhang, Hanqi

    2005-02-01

    A molecular spectroscopic investigation of the interaction between tetracyclines antibiotics and human serum albumin or bovine serum albumin was reported. The influences of some metal ions on the interaction were also studied. When tetracyclines drugs were added into the solution containing serum albumins, the fluorescence intensity of serum albumins decreased with the increasing of the drugs concentrations, which is due to the formation of new non-fluorescence complexes of drug-serum albumin. The tetracyclines acted as quenchers and quenched the fluorescence of the serum albumins. The binding constants and the number of the binding sites of the reaction of tetracyclines and serum albumins were obtained. The main sorts of acting force between the drugs and serum albumins were found and the action distances and the energy transfer efficiencies between donor-acceptor were calculated based on the Föster energy transference.

  1. Study of biological reaction in cancer cell with spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2016-09-01

    We present experimental studies of live cancer cells via microscopic imaging ellipsometry (MIE). The Rotating Compensator Ellipsometry (RCE) is used for our measurements. Ellipsometry spectra with signals integrated over a 20μm×20μm area in visible range (450nm to 750nm) are obtained with the Optrel MULTISKOP system for both specular reflection and off-specular scattering. The microscopic ellipsometry (ME) images at a few fixed wavelengths within the same range were also analyzed. Dielectric constants for glass slide, culture fluid, and glass cover plate were firstly characterized by spectroscopic ellipsometry measurements, which can be used in the simulation for MIE measurements of cancer cells embedded in the culture fluid and sandwiched between a glass slide and cover plate. The measured ME spectra and images of cancer cells before and after medicine injection are measured and analyzed.

  2. FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix.

    PubMed

    Rerek, Mark E; Van Wyck, Dina; Mendelsohn, Richard; Moore, David J

    2005-03-01

    IR spectroscopic studies are reported for N-stearyl-D-erythro-phytosphingosine (Cer NP) and N-stearyl-2-hydroxy-D-erythro-phytosphingosine (Cer AP) in a hydrated model of the skin lipid barrier comprised of equimolar mixtures of each ceramide with cholesterol and d(35)-stearic acid. Examination of the methylene stretching, rocking and bending modes reveal some rotational freedom and hexagonal packing in both the ceramide and stearic acid chains. Analysis of the acid carbonyl stretch and the ceramide Amide I modes show both shift to higher frequencies, indicating weaker hydrogen bonding, in the mixed systems compared to the pure materials. For both systems, the fatty acid chain disordering temperatures are significantly increased from those of the pure acids. The observed behaviors of these phytosphingosine ceramide systems are fundamentally different from the previously reported analogous sphingosine ceramide systems. The implications of these observations for lipid organization in the stratum corneum are briefly discussed.

  3. Spectroscopic and theoretical study of the o-vanillin hydrazone of the mycobactericidal drug isoniazid

    NASA Astrophysics Data System (ADS)

    González-Baró, Ana C.; Pis-Diez, Reinaldo; Parajón-Costa, Beatriz S.; Rey, Nicolás A.

    2012-01-01

    A complete and detailed study of the hydrazone obtained from condensation of antituberculous isoniazid (hydrazide of the isonicotinic acid, INH) and o-vanillin (2-hydroxy-3-methoxybenzaldehyde, o-HVa) is performed. It includes structural and spectroscopic analyses, comparing experimental and theoretical results. The compound was obtained as a chloride of the pyridinic salt (INHOVA +Cl -) but it will be referred as INHOVA for the sake of simplicity. The conformational space was searched and optimized geometries were determined both in gas phase and including solvent effects. Vibrational (IR and Raman), electronic and NMR spectra were registered and assigned with the help of computational methods based on the Density Functional Theory. Isoniazid hydrazones are good candidates for therapeutic agents against tuberculosis with conserved efficiency and lower toxicity and resistance than parent INH.

  4. Molecular interactions of flavonoids to pepsin: Insights from spectroscopic and molecular docking studies.

    PubMed

    Zeng, Hua-Jin; Yang, Ran; Liang, Huili; Qu, Ling-Bo

    2015-01-01

    In the work described on this paper, the inhibitory effect of 10 flavonoids on pepsin and the interactions between them were investigated by a combination of spectroscopic and molecular docking methods. The results indicated that all flavonoids could bind with pepsin to form flavonoid-pepsin complexes. The binding parameters obtained from the data at different temperatures revealed that flavonoids could spontaneously interact with pepsin mainly through electrostatic forces and hydrophobic interactions with one binding site. According to synchronous and three-dimensional fluorescence spectra and molecular docking results, all flavonoids bound directly into the enzyme cavity site and the binding influenced the microenvironment and conformation of the pepsin activity site which resulted in the reduced enzyme activity. The present study provides direct evidence at a molecular level to understand the mechanism of digestion caused by flavonoids.

  5. Growth of vacuum evaporated ultraporous silicon studied with spectroscopic ellipsometry and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kaminska, Kate; Amassian, Aram; Martinu, Ludvik; Robbie, Kevin

    2005-01-01

    Using a combination of variable-angle spectroscopic ellipsometry and scanning electron microscopy, we investigated the scaling behavior of uniaxially anisotropic, ultraporous silicon manufactured with glancing angle deposition. We found that both the diameter of the nanocolumns and the spacing between them increase with film thickness according to a power-law relationship consistent with self-affine fractal growth. An ellipsometric model is proposed to fit the optical properties of the anisotropic silicon films employing an effective medium approximation mixture of Tauc-Lorentz oscillator and void. This study shows that the optical response of silicon films made at glancing incidence differs significantly from that of amorphous silicon prepared by other methods due to highly oriented nanocolumn formation and power-law scaling.

  6. Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature

    SciTech Connect

    Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

    2011-11-22

    Room temperature IR and Raman spectra of rubidium lithium tungstate and sodium lithium tungstates belonging to double alkali tungstate family are investigated using group theoretical methods. Observed internal and lattice modes in both systems studied are assigned. Analysis of spectral behavior reveals that the effect of site potential around tungstates ion is weak and the factor group splitting is operative. Differences in the lattice mode mixing and splitting of internal modes is influenced by the statistical ordering between two alkali ions having large and small ionic radii and is explained using size and charge effect observed earlier in scheelite type of structure. Thus, vibrational spectroscopic analysis may be a tool to understand the alkali ion ordering in double alkali systems.

  7. Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

    SciTech Connect

    Sowińska, Małgorzata Henkel, Karsten; Schmeißer, Dieter; Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gruska, Bernd; Gargouri, Hassan

    2016-01-15

    The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.

  8. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    PubMed Central

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2014-01-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  9. Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

    NASA Astrophysics Data System (ADS)

    Chang, J.-K.; Hsu, C.-C.; Liu, S.-Y.; Wu, C.-I.; Gharib, M.; Yeh, N.-C.

    2016-06-01

    The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H2O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

  10. Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

    SciTech Connect

    Chang, J.-K.; Hsu, C.-C.; Liu, S.-Y.; Wu, C.-I.; Gharib, M.; Yeh, N.-C.

    2016-06-21

    The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H{sub 2}O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

  11. Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, Carle M.; Edwards, J. O.; Coyne, L. M.; Chang, S.

    1991-01-01

    Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.

  12. Biosorption of cadmium by live and dead Spirulina: IR spectroscopic, kinetics, and SEM studies.

    PubMed

    Doshi, Hiren; Ray, Arabinda; Kothari, I L

    2007-03-01

    Cadmium is an important environmental pollutant and a potent toxicant to bacteria, algae, and fungi. Mechanisms of Cd+2 toxicity and resistance are variable, depending on the organism. The present work reports the use of live and dead Spirulina sp. for sorption of Cd+2. This investigation shows that this biomass takes up substantial amount of Cd+2 ions. IR spectroscopic study, kinetics models, Langmuir & Freundlich adsorption isotherms, scanning electron microscopic analysis of Spirulina sp., and the Spirulina sp. treated with different metal ions have been employed to understand the sorption mechanism. Infrared spectra of live Spirulina treated with Cd+2 ions for different lengths of time have been taken to understand the time dependency of metal interaction.

  13. Raman spectroscopic study of high-pressure behavior of Ag3[Co(CN)6

    NASA Astrophysics Data System (ADS)

    Rao, Rekha; Achary, S. N.; Tyagi, A. K.; Sakuntala, T.

    2011-08-01

    In situ Raman spectroscopic studies have been carried out on Ag3[Co(CN)6] at high pressures up to 16 GPa. From the pressure dependence of the Raman frequencies, the mode Grüneisen parameters in the trigonal and the monoclinic phases are obtained. Besides the reported trigonal-to-monoclinic transition at 0.2 GPa, it is observed that the compound shows pressure-induced amorphization above 13 GPa. The recovered sample shows features characteristic of amorphous carbon nitride, indicating the decomposition of the parent compound in the pressure-reducing cycle. Temperature dependence of the mode frequencies over the range 80-290 K is also investigated, from which the modes that are more anharmonic than other modes are identified.

  14. Study of gamma detection capabilities of the REWARD mobile spectroscopic system

    NASA Astrophysics Data System (ADS)

    Balbuena, J. P.; Baptista, M.; Barros, S.; Dambacher, M.; Disch, C.; Fiederle, M.; Kuehn, S.; Parzefall, U.

    2017-07-01

    REWARD is a novel mobile spectroscopic radiation detector system for Homeland Security applications. The system integrates gamma and neutron detection equipped with wireless communication. A comprehensive simulation study on its gamma detection capabilities in different radioactive scenarios is presented in this work. The gamma detection unit consists of a precise energy resolution system based on two stacked (Cd,Zn)Te sensors working in coincidence sum mode. The volume of each of these CZT sensors is 1 cm3. The investigated energy windows used to determine the detection capabilities of the detector correspond to the gamma emissions from 137Cs and 60Co radioactive sources (662 keV and 1173/1333 keV respectively). Monte Carlo and Technology Computer-Aided Design (TCAD) simulations are combined to determine its sensing capabilities for different radiation sources and estimate the limits of detection of the sensing unit as a function of source activity for several shielding materials.

  15. Biophysical influence of coumarin 35 on bovine serum albumin: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bayraktutan, Tuğba; Onganer, Yavuz

    2017-01-01

    The binding mechanism and protein-fluorescence probe interactions between bovine serum albumin (BSA) and coumarin 35 (C35) was investigated by using UV-Vis absorption and fluorescence spectroscopies since they remain major research topics in biophysics. The spectroscopic data indicated that a fluorescence quenching process for BSA-C35 system was occurred. The fluorescence quenching processes were analyzed using Stern-Volmer method. In this regard, Stern-Volmer quenching constants (KSV) and binding constants were calculated at different temperatures. The distance r between BSA (donor) and C35 (acceptor) was determined by exploiting fluorescence resonance energy transfer (FRET) method. Synchronous fluorescence spectra were also studied to observe information about conformational changes. Moreover, thermodynamics parameters were calculated for better understanding of interactions and conformational changes of the system.

  16. Spectroscopic study of floating zone technique-grown Nd3+-doped CaMoO4

    NASA Astrophysics Data System (ADS)

    Andrade, L. H. C.; Reyes Ardila, D.; Barbosa, L. B.; Andreeta, J. P.; Li, M. Siu; Brenier, A.; Guyot, Y.; Boulon, G.

    2005-01-01

    Optical spectroscopy studies of Nd3+-doped scheelite calcium molybdate (CaMoO{4}) single crystal grown by a floating zone-like technique was performed using Judd-Ofelt analysis, besides luminescence data and lifetime measurements in the visible and near infrared domains. The excited state absorption in cross section units of this material was measured by two different methods for all expected infrared emission. By using calculated intensity parameters Ω t (t=2, 4, 6), it were determined branching ratios, emission cross-sections, and lifetimes for all related transitions. The observed single excited state absorption calibrated in absorption cross-section units was found too small to disturb the laser efficiency in the 1030 1100 nm spectral range. A comparison of main spectroscopic parameters of this material with those of other Nd3+-doped crystals is presented.

  17. Wrapping Together Galactic Archaeology and Interstellar Medium Studies in Large Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Kos, J.

    2016-10-01

    The cold interstellar medium (ISM) in our galaxy is usually observed at wavelengths other than optical. But optical spectroscopic surveys of stars give unprecedented information that is valuable also for ISM studies because they cover millions of lines-of-sight penetrating regions in and out of the Galactic plane that most all-sky surveys. Big advantages are distances to observed stars from which we infer distances to clumps of the ISM. The ISM is detected as scarce absorptions of several atoms and simple molecules and also as diffuse interstellar bands (DIBs), weak but numerous absorption features at visible and near IR wavelengths. With the enormous amount of information the surveys provide we can start doing galactic archaeology from the ISM point of view. Even though the principles are very different for star and gas dynamics, the starting points are the same. Here we present some results that are the first steps toward the galactic archaeology of the ISM.

  18. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    SciTech Connect

    Harde, G. B.; Muley, G. G.

    2016-05-06

    Borate glasses of the system xNd{sub 2}O{sub 3}-(1-x) La{sub 2}O{sub 3}-SrCO{sub 3}-10H{sub 3}BO{sub 3} (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition {sup 4}I{sub 9/2} → {sup 4}G{sub 5/2} + {sup 2}G{sub 7/2} has found more prominent than the other transitions. Optical band gap energies of glasses have been determined and found less for Nd doped glass.

  19. Fe-complex of a tetraamido macrocyclic ligand: Spectroscopic characterization and catalytic oxidation studies

    NASA Astrophysics Data System (ADS)

    Sullivan, Shane Z.; Ghosh, Anindya; Biris, Alexandru S.; Pulla, Sharon; Brezden, Anna M.; Collom, Samulel L.; Woods, Ross M.; Munshi, Pradip; Schnackenberg, Laura; Pierce, Brad S.; Kannarpady, Ganesh K.

    2010-10-01

    This work presents the spectroscopic characterization and reaction studies of a Fe III-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment ( μeff = 3.87 BM), EPR spectroscopy of 2 shows signals consistent with S = 3/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV/vis spectroscopy and cyclic voltammetry were used to further characterize 2. 2 is soluble in water and activates hydrogen peroxide under ambient conditions. 2 catalytically bleaches dyes, pulp and paper effluents and oxidizes several amines to their corresponding N-oxides with high turnover number and good yields.

  20. Photometric and spectroscopic study of the new FUor star V2493 Cyg

    NASA Astrophysics Data System (ADS)

    Semkov, Evgeni H.; Peneva, Stoyanka P.; Ibryamov, Sunay I.

    2017-01-01

    The recent results from photometric and spectroscopic study of the FUor star V2493 Cyg (HBC 722) are presented in the paper. The outburst of V2493 Cyg was registered during the summer of 2010 before the brightness of the star reached the maximum value. V2493 Cyg is the first FUor object, whose outburst was observed from its very beginning in all spectral ranges. The recent photometric data show that the star keeps its maximum brightness during the period September 2013 - Ocober 2016 and the recorded amplitude of the outburst is ΔV=5.1 mag. Consequently, the outburst of V2493 Cyg lasts for more than six years. Our spectral observations showed strong variability in the profiles and the intensity of emission lines especially for Hα line. We expect that the interest in this object will increase in the coming years and the results will help to explore the nature of young stars.