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Sample records for moessbauer spectroscopic study

  1. Moessbauer spectroscopic studies of iron-doped rutile.

    NASA Technical Reports Server (NTRS)

    Stampfl, P. P.; Travis, J. C.; Bielefeld, M. J.

    1973-01-01

    Moessbauer spectra were obtained of single crystal and powdered samples of rutile (TiO2) doped to about one percent by weight in isotopically enriched iron. It is shown that the oxidation state may be reversibly altered in situ. After reduction, the oxygen neighbors of the dopant ion are apparently shifted to accomodate the larger ferrous ion. The agreement of calculated quadrupole splittings with experimental results suggests that impurities and oxygen vacancies are uniformly distributed in powdered samples, giving the dopant ions an 'ideal lattice' local environment. The differences between the single crystal and powder sample hyperfine parameters are attributed to variations in stoichiometry, charge compensation mechanisms, or other diffusion related parameters.

  2. Moessbauer spectroscopic studies of iron compounds in coal and related materials

    SciTech Connect

    Twardowska, H.

    1980-01-01

    A selection of Illinois coals, related materials, and coal process residues were investigated by means of Moessbauer spectroscopy. The purpose of the study is to characterize the iron compounds in the materials and the iron chemistry which occurs when the coal is processed. The predominant iron mineral occurring in the coals was pyrite. Marcasite also occurred in the coals although it was frequently obscured by pyrite. Jarosite was found in the weathered coals. The study also considered pyrrhotite. An important chemical process in the charring and liquefaction of coal is the conversion of pyrite to pyrrhotite. (JMT)

  3. Moessbauer effect: Study of disordered magnetic systems

    SciTech Connect

    Chang, Xiao Sha.

    1989-01-01

    This dissertation describes Moessbauer spectroscopy studies of two chemically disordered binary, crystalline alloys having the composition A{sub 1-x}B{sub x}. Both systems are random 3d Heisenberg ferromagnets. In each case both A and B atoms carry a magnetic moment. The first study concerns a Moessbauer absorber experiment on Fe{sub 1-x} V{sub x}, in which the disorder in the critical region is of the annealed random exchange type. To eliminate the effect of concentration inhomogeneity, the measurement of the critical exponent {beta} was done on the alloy with x = 0.125, where dT{sub C}/dx = 0, yielding {beta} = 0.362(8) over the reduced temperature range 1.4 {times} 10{sup {minus}3} < t < 4.88 {times} 10{sup {minus}1}. This result confirms the theoretical prediction that the annealed disorder is irrelevant to critical behavior in this case. As expected the critical exponent {beta} is consistent with the expectation for the 3d Heisenberg model as well as the measured exponent of pure Fe. The second study involves a Moessbauer source experiment on {sup 57} CoPd{sub 0.80}Co{sub 0.20}, in which disorder is of the quenched random exchange type perturbed by a very weak random anisotropy interaction. The critical exponent {beta} deduced over the range 1 {times} 10{sup {minus}2} < t < 2 {times} 10{sup {minus}1} is 0.385(20), and is consistent with the theoretical prediction for quenched disordered 3d Heisenberg systems: the disorder is irrelevant to the critical behavior. However, because of the restricted range of reduced temperature, the result is insufficiently asymptotic to serve as a conclusive test of the theory. Outside the critical region the distribution of Fe{sup 57} hyperfine field in Pd{sub 0.80}Co{sub 0.20} is observed to have an anomalous temperature dependence characterized by a linear increase in the width of the field distribution for T/T{sub C} {ge} 0.6.

  4. Fe-57 Moessbauer study of tektites

    NASA Technical Reports Server (NTRS)

    Evans, B. J.; Leung, L. K.

    1976-01-01

    Moessbauer measurements were made on selected moldavite, australite, philippinite, and Georgia tektites. The spectra consist of two apparent lines, but at least two quadrupole doublets can be fitted to these spectra. The Moessbauer parameters for these doublets indicate that they arise from Fe2+ ions with local environments, which are relatively rich and relatively poor in calcium, respectively, similar to those in clinopyroxenes. No evidence for Fe3+/Fe2+ ratios above 0.01 (estimated detection limit) have been found in any tektite. Tektites are considerably more reduced than previously believed, and the extent of the reduction shows little or no variation among different types of tektites. These results limit the source materials of tektites to minerals in which the iron is uniformly highly reduced and in which the iron is contained clinopyroxene-like phases.

  5. Moessbauer spectroscopic study of the initial stages of iron-core formation in horse spleen apoferritin: Evidence for both isolated Fe(III) atoms and oxo-bridged Fe(III) dimers as early intermediates

    SciTech Connect

    Bauminger, E.R.; Nowik, I. ); Harrison, P.M.; Treffry, A. )

    1989-06-27

    Ferritin stores iron within a hollow protein shell as a polynuclear Fe(III) hydrous oxide core. Although iron uptake into ferritin has been studied previously, the early stages in the creation of the core need to be clarified. These are dealt with in this paper by using Moessbauer spectroscopy, a technique that enables several types of Fe(II) and Fe(III) to be distinguished. Systematic Moessbauer studies were performed on samples prepared by adding {sup 57}Fe(II) atoms to apoferritin as a function of pH (5.6-7.0), n (the number of Fe/molecule (4-480)), and t{sub f} (the time the samples were held at room temperature before freezing). Four different Fe(III) species were identified: solitary Fe(III) atoms giving relaxation spectra, which can be identified with the species observed before by EPR and UV difference spectroscopy; oxo-bridged dimers giving doublet spectra with large splitting, observed for the first time in ferritin; small Fe(III) clusters giving doublets of smaller splitting and larger antiferromagnetically coupled Fe(III) clusters, similar to those found previously in larger ferritin iron cores, which, for samples with n {ge} 40, gave magnetically split spectra at 4.1 K. Both solitary Fe(III) and dimers diminished with time, suggesting that they are intermediates in the formation of the iron core. Two kinds of divalent iron were distinguished for n = 480, which may correspond to bound and free Fe(II).

  6. Moessbauer Study of Soil Profiles in Industrial Region of Ukraine

    SciTech Connect

    Kopcewicz, B.; Jelenska, M.; Hasso-Agopsowicz, A.; Kopcewicz, M.

    2005-04-26

    Moessbauer spectroscopy was applied to study the influence of industrial activity on soil composition. Comparing the Moessbauer spectra of separate layers for the Mariupol sampling site (highly polluted industrial region of South -- East Ukraine) we observed: i) appearance of the Fe3O4 compound at top soil layers: 16.6% of relative spectral area (RA) at (0 - 10 cm) layer, 5.3% of RA at (30 - 40 cm) layer and no magnetite component at deeper layers, ii) a significant increase of the contribution of the magnetically split spectral components: from 10.9% of RA for (120 - 130 cm) layer to 32.8% of RA for (0-10 cm) layer. The differences in RA of the magnetically split spectral components between top soil layer and the (120 - 130 cm) layer at the Homutovski steppe sampling site (non-polluted area) are much smaller, 13.7% and 9.8%, respectively. From the temperature dependence of the Moessbauer spectra it was concluded that part of the iron-containing compounds appears in the form of ultra fine particles in the superparamagnetic state. The observed increase of total concentration of the magnetic minerals for polluted sampling sites is caused by an increase of the content of coarse fraction of the magnetic particles.

  7. Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Moessbauer Spectroscopy

    SciTech Connect

    Oshtrakh, M. I.; Novikov, E. G.; Semionkin, V. A.; Dubiel, S. M.

    2010-07-13

    A study of several samples of vitamins and dietary supplements containing ferrous fumarate and ferrous sulfate was carried out using Moessbauer spectroscopy with a high velocity resolution. A presence of ferrous and ferric impurities was revealed. Small variations of Moessbauer hyperfine parameters were found for both ferrous fumarates and ferrous sulfates in the investigated medicines.

  8. Moessbauer studies of two-electron centers with negative correlation energy in crystalline and amorphous semiconductors

    SciTech Connect

    Bordovsky, G. A.; Nemov, S. A.; Marchenko, A. V.; Seregin, P. P.

    2012-01-15

    The results of the study of donor U{sup -}-centers of tin and germanium in lead chalcogenides by Moessbauer emission spectroscopy are discussed. The published data regarding the identification of amphoteric U{sup -}-centers of tin in glassy binary arsenic and germanium chalcogenides using Moessbauer emission spectroscopy, and in multicomponent chalcogenide glasses using Moessbauer absorption spectroscopy are considered. Published data concerning the identification of two-atom U{sup -}-centers of copper in lattices of semimetal copper oxides by Moessbauer emission spectroscopy are analyzed. The published data on the detection of spatial inhomogeneity of the Bose-Einstein condensate in superconducting semiconductors and semimetal compounds, and on the existence of the correlation between the electron density in lattice sites and the superconducting transition temperature are presented. The principal possibility of using Moessbauer U{sup -}-centers as a tool for studying the Bose-Einstein condensation of electron pairs during the superconducting phase transition in semiconductors and semimetals is considered.

  9. Moessbauer studies of complex materials: Energy versus time domain

    SciTech Connect

    Planckaert, N.; Callens, R.; Demeter, J.; Temst, K.; Vantomme, A.; Laenens, B.; Meersschaut, J.; Sturhahn, W.; Kharlamova, S.

    2009-06-01

    We present a critical comparison between conventional Moessbauer spectroscopy on the one hand and energy and time resolved nuclear resonant scattering on the other hand. The three Moessbauer techniques are evaluated by the characterization of the complex magnetic structure of an Fe{sub 3}Al alloy. It is shown how the different scattering processes and detection schemes, which are involved in the respective configurations, determine the specific strengths of the three techniques and how they are optimally suited for the characterization of materials of varying complexity and reduced sizes.

  10. SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

    NASA Technical Reports Server (NTRS)

    Housley, R. M.

    1982-01-01

    New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

  11. SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

    NASA Astrophysics Data System (ADS)

    Housley, R. M.

    New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

  12. TEM and Moessbauer Study of Nano Sized Fe{sub 2}MnAl Flakes

    SciTech Connect

    Vinesh, A.; Sudheesh, V. D.; Lakshmi, N.; Venugopalan, K.

    2011-07-15

    Magnetic and structural properties of L21 ordered Fe{sub 2}MnAl Heusler alloy have been studied by X-ray diffraction, Transmission electron microscopy (TEM), Moessbauer spectroscopy and DC magnetization. Structural texturing induced by ball milling is destroyed on heating while Moessbauer and DC magnetization studies show magnetic texturing persists after thermal treatment. TEM shows large distribution in particle size with an average size of 27 nm. Thermal annealing of ball milled sample results L2{sub 1} ordering and the needle shaped particle contributes spin texturing.

  13. Antiferromagnetism in Co-57-doped La2CuO(4-y) studied by Moessbauer spectroscopy

    NASA Technical Reports Server (NTRS)

    Jha, S.; Mitros, C.; Lahamer, Amer; Yehia, Sherif; Julian, Glenn M.

    1989-01-01

    Moessbauer effect studies of Co-57-doped La2CuO(4-y) were performed at temperatures between 4.2 K and room temperature. These confirm the antiferromagnetic ordering of these compounds below room temperature. Temperature dependence of the quadrupole splitting shows that the hyperfine field is at an angle with the c-axis.

  14. Moessbauer study in thin films of FeSi2 and FeSe systems

    NASA Technical Reports Server (NTRS)

    Escue, W. J.; Aggarwal, K.; Mendiratta, R. G.

    1978-01-01

    Thin films of FeSi2 and FeSe were studied using Moessbauer spectroscopy information regarding dangling bond configuration and nature of crystal structure in thin films was derived. A significant influence of crystalline aluminum substrate on film structure was observed.

  15. Use of Moessbauer spectroscopy to study reaction products of polyphenols and iron compounds

    SciTech Connect

    Gust, J. ); Suwalski, J. )

    1994-05-01

    Moessbauer spectroscopy was used to study parameters of the reaction products of iron compounds (Fe[sup III]) and polyphenols with hydroxyl (OH) groups in ortho positions. Polyphenols used in the reaction were catechol, pyrogallol, gallic acid, and oak tannin. The Fe-containing compounds were hydrated ferric sulfate (Fe[sub 2][SO[sub 4

  16. 57Fe Moessbauer Spectroscopic Investigations on the Brownmillerite Series Ca2(Fe2-xAlx)O5

    SciTech Connect

    Redhammer, G.J.; Roth, G.

    2005-04-26

    Several compounds along the Brownmillerite solid solution series Ca2Fe2-xAlxO5 with 0.0 {<=} x {<=} 1.34 have been synthesized by slow cooling from the melt and subsequent quenching. These samples were studied by Moessbauer spectroscopy at different absorber temperatures. Samples up to x = 1.00 are antiferromagnetically ordered at room temperature and can be evaluated by one octahedral and one tetrahedral magnetically split subspectra. With increasing temperature or increasing Al3+-content, respectively, the local magnetic fields decrease and finally collapse (TN = 518 K for x = 0.0 and TN = 298 K for x = 1.06, respectively). Despite the change of space group symmetry, quadrupole splittings at both positions increase almost linearly with increasing Al3+-content. This can be referred to structural changes reported. Even at low Al3+-contents, there always is a distribution of Fe3+ and Al3+ over the tetrahedral and octahedral positions in contrast to earlier results. Fe3+ prefers the octahedral and Al3+ prefers the tetrahedral positions.

  17. Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

    SciTech Connect

    Kuzmann, E.; Homonnay, Z.; Klencsar, Z.; Vertes, A.; Lakatos-Varsanyi, M.; Miko, A.; Varga, L.K.; Kalman, E.; Nagy, F.

    2005-04-26

    Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to {gamma}-FeOOH in addition to the dominant sextet of {alpha}-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of {alpha}-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies.

  18. Bulk and thin films of FeTe: A Moessbauer study

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Aggarwal, K.; Mendiratta, R. G.

    1977-01-01

    Studies of bulk and thin films of FeTe using Moessbauer spectroscopy showed that FeTe has one noncubic Fe (+2) site which is 3d2 4s 4p3 hybridized. The presence of dangling bands was indicated in spectra of FeTe thin films. The films showed a tendency of texture formation. The substrate was observed to influence the film structure and nature of bonds in films.

  19. A hydrogen bond study in tobacco mosaic virus using Moessbauer spectroscopy.

    PubMed

    Haffner, H; Appel, H; Holmes, K C

    1986-01-01

    The Moessbauer method was applied to obtain information on a suggested hydrogen bond in tobacco mosaic virus (TMV), between the hydroxyl group of Tyr 139 and a carboxyl oxygen of Glu 22 in a neighbouring subunit. Spectra of 129I were taken of 3,5-di-iodo-L-tyrosine as a free amino acid and in situ in TMV. The increase of the pK value of 3,5-di-iodo-L-tyrosine by 0.8 units at position 139 in TMV compared to the free value is a strong argument in favour of the existence of a hydrogen bond via the relevant hydroxyl group. The reported study demonstrates the surprising sensitivity of the observable Moessbauer parameters to details of the electronic configuration in the neighbourhood of the probe nucleus. PMID:3816698

  20. Moessbauer spectroscopy studies of carbon-encapsulated magnetic nanoparticles obtained by different routes

    SciTech Connect

    Bystrzejewski, M.; Huczko, A.; Lange, H.; Grabias, A.; Borysiuk, J.

    2008-09-01

    Carbon-encapsulated magnetic nanoparticles (CEMNPs) are nanomaterials with a core-shell structure. Their intrinsic properties result both from the unique nature of the encapsulated magnetic phases and the high chemical stability of the external carbon shells. CEMNPs may find many prospective applications, e.g., in magnetic data storage, catalysis, xerography, magnetic resonance imaging, and in biomedical applications. Herein, we present detailed structural studies of such nanostructures by Moessbauer spectroscopy, x-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy. CEMNPs have been obtained by three different techniques: carbon arc, combustion synthesis, and radio frequency thermal plasma. The evaluation of the phase composition of the products was strongly limited due to the broadening and overlapping of the lines in XRD diffraction patterns. The presence of the semicrystalline phases, which could not been identified by XRD, was established by Moessbauer spectroscopy. Furthermore, the magnetic core phase composition was evaluated quantitatively. The products were purified before structural analyses to remove the nonencapsulated particles. The purification caused significant changes in the mass and the saturation magnetization. The Moessbauer spectra of the purified products were compared with the literature data concerning the as-produced CEMNPs.

  1. Synthesis and Moessbauer-spectroscopic investigation of coordination compounds of tin(IV) with ligands based on thiosemicarbazide

    SciTech Connect

    Gerbeleu, N.V.; Rochev, V.Ya.; Turte, K.I.; Bologa, O.A.; Bobkova, S.A.; Lozan, V.I.; Lavrinyuk, I.P.

    1987-03-01

    Coordination compounds of Sn(IV) of the type SnX/sub 4/L/sub 2/, where X = Cl and Br, and L stands for pyruvic acid thiosemicarbazone (pyth), carboxybenzaldehyde thiosemicarbazone (beth), and thiosemicarbazidediacetic acid (thda), respectively, have been investigated by Moessbauer spectroscopy. The gamma-resonance spectra have the form of unbroadened singlet lines with values of the isomer shifts at 92/sup 0/K equal to 0.56 for SnCl/sub 4/ (pyth)/sub 2/, 0.52 for SnCl/sub 4/ (beth)/sub 2/, 0.65 for SnCl/sub 4/ (thda)/sub 2/, 0.78 for SnBr/sub 4/ (pyth)/sub 2/, and 0.91 mm/sec for SnBr/sub 4/ (thda)/sub 2/. An analysis of the IR spectra and Moessbauer spectra led to the conclusion that in all the compounds synthesized L acts as a neutral monodentate ligand, in which the sulfur atom is the donor site.

  2. Constraints on the oxidation state of the mantle: An electrochemical and sup 57 Fe Moessbauer study of mantle-derived ilmenites

    SciTech Connect

    Virgo, D.; Luth, R.W. ); Moats, M.A.; Ulmer, G.C. )

    1988-07-01

    Ilmenite samples from four kimberlite localities were studied using electrochemical, Moessbauer spectroscopic, and microprobe analytical techniques in order to infer the oxidation state of their source regions in the mantle. The values of Fe{sup 3+}/{Sigma}Fe calculated from analyses, using three different electron microanalytical instruments assuming ilmenite stoichiometry, are consistently higher than those derived from the Moessbauer data, by as much as 100%. Furthermore, the range in Fe{sup 3+}/{Sigma}Fe calculated using the analyses from different instruments and/or different correction schemes is nearly as large. Thus Fe{sup 3+}/{Sigma}Fe calculated from microprobe analyses should be taken with caution, even if the precision appears high. {sup 57}Fe Moessbauer spectroscopy on the electrochemical experiment run products demonstrates that Fe{sup 3+}/{Sigma}Fe is significantly lower than it is for the natural C-bearing ilmenites. In contrast, the ilmenite that lacked C did not change Fe{sup 3+}/{Sigma}Fe during the electrochemical experiment. Examination of the reduced samples with SEM established that the natural, single-phase ilmenites exsolved during the electrochemical experiment to form ilmenite{sub ss} + spinel{sub ss}. The initial, reduced trends in the electrochemical experiments for the C-bearing ilmenites are attributed to disequilibrium interactions between the decomposing sample and the evolved gas in the electrochemical cell and do not represent the quenched mantle memory nor the intrinsic f{sub O{sub 2}} of the sample prior to reduction. Furthermore, the oxidized f{sub O{sub 2}} trend is interpreted, for the carbon-bearing samples, are representing the f{sub O{sub 2}} of the ilmenite{sub ss} + spinel{sub ss} assemblage and not the intrinsic f{sub o{sub 2}} of the mantle-derived ilemnite{sub ss}.

  3. Spectroscopic study of sprites

    NASA Astrophysics Data System (ADS)

    Kanmae, Takeshi

    Optical emissions from sprites--large electric discharges in the mesosphere caused by intense lightning strokes--have been studied for decades. Studies have identified that sprite emissions are primarily composed of molecular band emissions of nitrogen and notably identified the near ultraviolet and blue emission from the N2+ First Negative system, which provided direct evidence of ionization in sprites. This implies that further evidence of the ionization may be provided by the visible and near infrared emission from the N2+ Meinel system, which is more accessible from ground-based platforms, though anticipated strong quenching in the mesosphere and below have made the presence of the emission somewhat controversial. To investigate the presence of the Meinel emission along the vertical extent of sprites, we made ground-based spectral observations in 2005. The observed spectra were mainly composed of the N2 First Positive system, and no or little indication of the Meinel bands were found. This study suggests that the quenching is indeed severe at sprite altitude, and it is difficult to study the ionization process in sprites via the Meinel emission. In addition, the data allowed us to investigate details of the First Positive emission from sprites. The observed First Positive spectra showed that the vibrational distribution of the upper state varies along the vertical extent of sprites, which is in agreement with previous reports, and furthermore this study indicates that the variation is associated with altitude, implying that collisional energy transfer processes play roles in exciting the First Positive emission, particularly at lower altitudes. Recent high-speed imaging observations have revealed the very dynamic nature of sprites: they develop within a few to 10 ms in forms of streamers and columnar glows. The underlying electron energies in these features have been inferred from their emissions in previous measurements, but they lacked either sufficient

  4. 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.

  5. {sup 57}Fe and {sup 119}Sn Moessbauer Effect Study of Fe-Sn-B Amorphous Alloys

    SciTech Connect

    Miglierini, M.; Rusakov, V. S.

    2010-07-13

    Ribbons of Fe{sub 100-x}Sn{sub 5}B{sub x} (x = 15, 17, 20) metallic glass are studied using {sup 57}Fe and {sup 119}Sn Moessbauer spectrometry. The obtained Moessbauer spectra are evaluated by distributions of hyperfine magnetic fields in addition to crystalline components. The as-quenched alloys are XRD amorphous for x =15 and 17 whereas for x =20, traces of quenched-in crystallites are revealed. Progress of crystallization is followed on samples annealed for 30 min at temperatures that cover the first crystallization peak. The evolution of crystalline fraction as well as average values of hyperfine magnetic fields and isomer shifts are discussed as a function of the alloy composition and temperature of annealing.

  6. Moessbauer spectroscopy study on the corrosion resistance of plasma nitrided ASTM F138 stainless steel in chloride solution

    SciTech Connect

    Souza, S.D. de; Olzon-Dionysio, M.; Basso, R.L.O.; Souza, S. de

    2010-10-15

    Plasma nitriding of ASTM F138 stainless steel samples has been carried out using dc glow discharge under 80% H{sub 2}-20% N{sub 2} gas mixture, at 673 K, and 2, 4, and 7 h time intervals, in order to investigate the influence of treatment time on the microstructure and the corrosion resistance properties. The samples were characterized by scanning electron microscopy, glancing angle X-ray diffraction and conversion electron Moessbauer spectroscopy, besides electrochemical tests in NaCl aerated solution. A modified layer of about 6 {mu}m was observed for all the nitrided samples, independent of nitriding time. The X-ray diffraction analysis shows broad {gamma}{sub N} phase peaks, signifying a great degree of nitrogen supersaturation. Besides {gamma}{sub N,} the Moessbauer spectroscopy results indicated the occurrence of {gamma}' and {epsilon} phases, as well as some other less important phases. Corrosion measurements demonstrate that the plasma nitriding time affects the corrosion resistance and the best performance is reached at 4 h treatment. It seems that the {epsilon}/{gamma}' fraction ratio plays an important role on the resistance corrosion. Additionally, the Moessbauer spectroscopy was decisive in this study, since it was able to identify and quantify the iron phases that influence the corrosion resistance of plasma nitrided ASTM F138 samples.

  7. Moessbauer and Electron Microprobe Studies of Density Separates of Martian Nakhlite Mil03346: Implications for Interpretation of Moessbauer Spectra Acquired by the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; McKay, G. A.; Agresti, D. G.; Li, Loan

    2008-01-01

    Martian meteorite MIL03346 is described as an augite-rich cumulate rock with approx.80%, approx.3%, and approx.21% modal phase proportions of augite (CPX), olivine and glassy mesostasis, respectively, and is classified as a nakhlite [1]. The Mossbauer spectrum for whole rock (WR) MIL 03346 is unusual for Martian meteorites in that it has a distinct magnetite subspectrum (7% subspectral area) [2]. The meteorite also has products of pre-terrestrial aqueous alteration ("iddingsite") that is associated primarily with the basaltic glass and olivine. The Mossbauer spectrometers on the Mars Exploration Rovers have measured the Fe oxidation state and the Fe mineralogical composition of rocks and soils on the planet s surface since their landing in Gusev Crater and Meridiani Planum in January, 2004 [3,4]. The MIL 03346 meteorite provides an opportunity to "ground truth" or refine Fe phase identifications. This is particularly the case for the so-called "nanophase ferric oxide" (npOx) component. NpOx is a generic name for a ferric rich product of oxidative alteration. On Earth, where we can take samples apart and study individual phases, examples of npOx include ferrihydrite, schwertmannite, akagaaneite, and superparamagnetic (small particle) goethite and hematite. It is also possible for ferric iron to be associated to some unknown extent with igneous phases like pyroxene. We report here an electron microprobe (EMPA) and Moessbauer (MB) study of density separates of MIL 03346. The same separates were used for isotopic studies by [5]. Experimental techniques are described by [6,7].

  8. Moessbauer study of iron-carbide growth and Fischer-Tropsch activity

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-31

    There is a need to establish a correlation between the Fischer-Tropsch (FT) activity of an iron-based catalyst and the catalyst phase during FT synthesis. The nature of iron phases formed during activation and FT synthesis is influenced by the gas used for activation. Moessbauer investigations of iron-based catalysts subjected to pretreatment in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been carried out. Studies on UCI 1185-57 catalyst indicate that activation of the catalyst in CO leads to the formation of 100% magnetite and the magnetite formed gets rapidly converted to at least 90% of x-Fe{sub 5}C{sub 2} during activation. The x-Fe{sub 5}C{sub 2} formed during activation gets partly (= 25%) converted back to Fe{sub 3}O{sub 4} during FT synthesis and both x-Fe{sub 5}C{sub 2} and Fe{sub 3}O{sub 4} reach constant values. On the other hand, activation of the catalyst in synthesis gas leads to formation of Fe{sub 3}O{sub 4} and which is slowly converted to x-Fe{sub 5}C{sub 2} and e-Fe{sub 2.2}C during activation, and both carbide phases increase slowly during FT synthesis. FT synthesis activity is found to give rise to {approx} 70% (H2+CO) conversion in the case of CO activated catalyst as compared to {approx} 20% (H2+CO) conversion in the case of synthesis gas-activated catalyst.

  9. Study of excess Fe metal in the lunar fines by magnetic separation, Moessbauer spectroscopy, and microscopic examination.

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Grant, R. W.; Abdel-Gawad, M.

    1972-01-01

    A simple and convenient method of making quantitative magnetic separations has been applied to the lunar fines. The fractions obtained form groups containing distinctively different particle types; thus, it appears that magnetic separation in itself many be a useful way of characterizing lunar fines. Moessbauer studies of fines 10084 show that the metal cannot contain more than about 1.5% Ni, implying that by far the bulk of the metal results from reduction rather than from direct meteoritic addition. Microscopic examination of magnetic separates from 15101 fines suggests that reduction of Fe accompanies every major impact event on the moon.

  10. Moessbauer studies on LaNi(4.7)Sn(0.3) and its hydride

    NASA Technical Reports Server (NTRS)

    Oliver, F. W.; Morgan, W.; Hammond, E. C.; Wood, S.; May, L.

    1985-01-01

    Moessbauer measurements were made on LaNi(4.7)Sn(0.3) at room and liquid nitrogen temperatures. Experimental data yielded a singlet at room temperature and a doublet at liquid-nitrogen temperature. Spectra of the hydrided sample yielded a doublet at liquid-nitrogen temperature with an increase in the quadrupole splitting compared to the unhydrided spectra, but no change in the isomer shift. These data indicate that there is no significant interaction between the tin and the hydrogen. The magnetic character remained the same down to liquid-nitrogen temperature as evidenced by the Moessbauer data. X-ray diffraction measurements on the hydride showed an expanded lattice with the same structure as found for the unhydrided sample. A decrease in particle size was observed upon hydriding.

  11. Structural properties of magnetite under high pressure studied by Moessbauer spectroscopy

    SciTech Connect

    Kobayashi, Hisao; Isogai, Ichiro; Kamimura, Takashi; Hamada, Noriaki; Onodera, Hideya; Todo, Sakae; Mori, Nobuo

    2006-03-01

    We have measured the Moessbauer spectra of magnetite (Fe{sub 3}O{sub 4}) under a pressure of up to 18 GPa at room temperature using nonenriched high-quality samples. An analysis of the observed Moessbauer spectra confirms that Fe{sub 3}O{sub 4} does not undergo a magnetic or crystalline structural transition up to 18 GPa at room temperature. In the pressure dependences of the refined hyperfine interaction parameters, however, small but distinct anomalies are found at 7.0 GPa in the center shifts of two crystallographically nonequivalent Fe sites, which are caused by the discontinuous decrease of an oxygen internal coordinate in the cubic inverse spinel structure. We believe that the pressure-induced discontinuous change of the Fe-O bond length is related to the absence of a metal-insulator transition above 7.5 GPa.

  12. A {sup 151}Eu Moessbauer spectroscopic and magnetic susceptibility investigation of the intermetallic compounds EuTIn (T = Zn, Pd, Pt, Au)

    SciTech Connect

    Muellmann, R.; Mosel, B.D.; Eckert, H.; Kotzyba, G.; Poettgen, R.

    1998-04-01

    The title compounds were investigated by magnetic susceptibility measurements and {sup 151}Eu Moessbauer spectroscopy. EuZnIn and EuPtIn show Curie-Weiss behavior above 60 K with experimental magnetic moments of 7.80(5) and 8.0(1) {mu}{sub B}/Eu, respectively, indicating divalent europium. The zinc compound orders antiferromagnetically at T{sub N} = 8.0(5) k and two metamagnetic transitions are detected at the critical field strengths B{sub C1} = 1.1(1) T and B{sub C2} = 2.6(2) T. At 5 K the saturation magnetic moment amounts to 7.0(1) {mu}{sub B}/Eu, suggesting a full parallel spin alignment. EuPdIn and EuAuIn order antiferromagnetically at 13.0(5) and 21.0(5) K in low external magnetic fields, respectively. The four compounds are metallic conductors. The Moessbauer measurements of the EuTIn compounds show {sup 151}Eu isomer shifts typical of divalent europium. The isomer shifts are found to linearly correlated with the closest Eu-Eu distance in the structure. Based on the Moessbauer data the onset of magnetic order is observed at T{sub N}(EuZnIn) = 9.5(5) K, T{sub N}(EuPdIn) = 15.5(5) K, T{sub N}(EuAuIn) = 20.0(5) K, and T{sub N}(EuPtIn) = 20.0(5) K, respectively. The magnetically split spectrum of EuZnIn reveals evidence of Eu site inequivalence.

  13. Moessbauer study of iron-carbide growth and Fischer-Tropsch activity

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-31

    There is a need to establish a correlation between the Fischer-Tropsch (FT) activity of an iron-based catalyst and the catalyst phase during FT synthesis. The nature of iron phases formed during activation and FT synthesis is influenced by the nature of the gas and pressure apart from other parameters like temperature, flow rate etc., used for activation. Moessbauer investigations of iron-based catalysts subjected to pretreatment at two different pressures in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been carried out. Studies on UCI 1185-57 (64%Fe{sub 2}O{sub 3}/5%CuO/1%K{sub 2}O/30% Kaolin) catalyst indicate that activation of the catalyst in CO at 12 atms. leads to the formation of 100% magnetite and the magnetite formed gets rapidly converted to at least 90% of {chi}-Fe{sub 5}C{sub 2} during activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation. The FT activity was found to be good at 70-80% of (H{sub 2}+CO) conversion. On the other hand, activation of the catalyst in synthesis gas at 12 atms. leads to formation of Fe{sub 3}O{sub 4} and it gets sluggishly converted to {chi}-Fe{sub 5}C{sub 2} and {epsilon}-Fe{sub 2.2}C during activation and both continue to grow slowly during FT synthesis. FT activity is found to be poor. Pretreatment of the catalyst, 100fe/3.6Si/0.71K at a low pressure of 1 atms. in syngas gave rise to the formation of {chi}-Fe{sub 5}C{sub 2} and good FT activity. On the other hand, pretreatment of the catalyst, 100Fe/3.6Si/0.71K at a relatively high pressure of 12 atms. in syngas did not give rise to the formation any carbide and FT activity was poor.

  14. Photoelectron, nuclear gamma-ray and infrared absorption spectroscopic studies of neptunium in sodium silicate glass

    SciTech Connect

    Veal, B.W.; Carnall, W.T.; Dunlap, B.D.; Mitchell, A.W.; Lam, D.J.

    1986-04-01

    The valence state of neptunium ions in sodium silicate glasses prepared under reducing and oxidizing conditions has been investigated by the x-ray photoelectron, Moessbauer and optical absorption spectroscopic techniques. Results indicate that the Np ions are tetravalent in glasses prepared under reducing conditions and pentavalent in glasses prepared under oxidizing conditions.

  15. Moessbauer and SANS Studies of Anti-Invar Fe-Ni-C Alloy under Magnetic Field

    SciTech Connect

    Nadutov, V. M.; Kosintsev, S. G.; Svystunov, Ye. O.; Garamus, V. M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

    2010-07-13

    Anti-Invar effect in the f.c.c.-Fe-25.3%Ni-C alloy was revealed, i.e., enhanced thermal expansion coefficient (TEC)({approx}20x10{sup -6} K{sup -1}) which was accompanied by almost temperature-insensitive behavior in a temperature range of 122-525 K that was considerably expanded to the low temperature range due to alloying with carbon. The Moessbauer and small-angle neutron scattering (SANS) experiments with the varying temperature and in an external magnetic field of 1.5-5 T have revealed an existence of inhomogeneous magnetic order in anti-Invar alloy below and above the magnetic transition point. The anti-Invar behavior correlates with the thermally induced change in the magnetic order and interspin interaction.

  16. Moessbauer studies of pressure-induced amorphization in the molecular crystal SnBr{sub 4}

    SciTech Connect

    Hearne, G.R.; Pasternak, M.P. |; Taylor, R.D.

    1995-10-01

    A single line spectrum is characteristic of the Moessbauer data obtained in the 0--5 GPa range, indicating the preservation of fourfold symmetry of the SnBr{sub 4} molecule in the crystal. Above 5 GPa, near {ital P}{sub {ital c}}, a {ital quadruple} {ital interaction} takes place concurrent with a dramatic increase in the {ital recoil{minus}free} {ital fraction} $({ital f})---. The value of the quadrupole splitting reaches a maximum of 0.9 mm/s at {ital P}{similar_to}15 GPa and remains constant thereafter. By {similar_to}9 GPa the absorption area, which is proportional to {ital f}, increases by 30--40 % over the lowest pressure value and then remains constant at higher pressure. These results are consistent with the formation of a molecular species, e.g., a (SnBr{sub 4}){sub 2} dimer, lacking the {ital T}{sub {ital d}} symmetry at the original Sn{sup 4+} site and having optical phonons {ital hard} enough not to be excited by the nuclear recoil process. Molecular association into (SnBr{sub 4}){sub 2} dimers, the building block of the high-pressure disordered state, also explains many of the experimental features of the Raman data. Upon decompression, Moessbauer (and Raman) data suggest that these dimers dissociate into monomers at {similar_to}5 GPa; however, a disordered structure of SnBr{sub 4} persists as pressure is decreased further. Crystallization is fully recovered below 1 GPa. The nature of the pressure-induced amorphization of the insulator SnBr{sub 4} is discussed in terms of the structural and valence properties of the analogous metallic SnI{sub 4}.

  17. Moessbauer and magnetic study of Mn, Zr and Cd substituted W-type hexaferrites prepared by co-precipitation

    SciTech Connect

    Iqbal, Muhammad Javed; Khan, Rafaqat Ali; Mizukami, Shigemi; Miyazaki, Terunobu

    2011-11-15

    Highlights: {yields} Zr and Cd ions substitute tetrahedral 4e and 4f{sub IV} sites while Mn ions occupy octahedral 6g and 4f sites. {yields} Doping of W-type hexaferrites with Mn, Zr and Cd improves the values of M{sub s} and M{sub r}. {yields} The enhancement of magnetic characteristic togetherwith the formation of rice shaped W-type hexaferrites nanoparticles is promising for imaging and sensing devices. {yields} The synthesized materials are suitable for magnetic data storage with high density. -- Abstract: BaCo{sub 2-x}Mn{sub x}Fe{sub 16-2y}(Zr-Cd){sub y}O{sub 27} (x = 0-0.5 and y = 0-1.0) hexaferrite nanocrystallites of average sizes in the range of 33-42 nm are synthesized by the chemical co-precipitation method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), energy dispersive X-ray florescence (ED-XRF), scanning electron microscope (SEM), Moessbauer spectrometer and vibrating-sample magnetometer (VSM). Based on analysis of the data obtained from Moessbauer spectral studies, doping is believed to have occurred preferably in the vicinity of 12k sub-lattice, i.e. f{sub IV} (4e, 4f{sub IV}), 2b (6g, 4f) and 2d site. Variations in the saturation magnetization (77.1-60.9 emu g{sup -1}), remanent magnetization (22.08-31.23 emu g{sup -1}) and coercivity (1570.1-674.7 Oe) exhibit tunable behavior with dopant content and therefore can be useful for application in various magnetic devices.

  18. 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.

  19. Spectroscopic studies of copper enzymes

    SciTech Connect

    Dooley, D.M.; Moog, R.; Zumft, W.; Koenig, S.H.; Scott, R.A.; Cote, C.E.; McGuirl, M.

    1986-05-01

    Several spectroscopic methods, including absorption, circular dichroism (CD), magnetic CD (MCD), X-ray absorption, resonance Raman, EPR, NMR, and quasi-elastic light-scattering spectroscopy, have been used to probe the structures of copper-containing amine oxidases, nitrite reductase, and nitrous oxide reductase. The basic goals are to determine the copper site structure, electronic properties, and to generate structure-reactivity correlations. Collectively, the results on the amine oxidases permit a detailed model for the Cu(II) sites in these enzymes to be constructed that, in turn, rationalizes the ligand-binding chemistry. Resonance Raman spectra of the phenylhydrazine and 2,4-dinitrophenyl-hydrazine derivatives of bovine plasma amine oxidase and models for its organic cofactor, e.g. pyridoxal, methoxatin, are most consistent with methoxatin being the intrinsic cofactor. The structure of the Cu(I) forms of the amine oxidases have been investigated by X-ray absorption spectroscopy (XAS); the copper coordination geometry is significantly different in the oxidized and reduced forms. Some anomalous properties of the amine oxidases in solution are explicable in terms of their reversible aggregation, which the authors have characterized via light scattering. Nitrite and nitrous oxide reductases display several novel spectral properties. The data suggest that new types of copper sites are present.

  20. Moessbauer Footprint in the Soil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D image taken by the microscopic imager onboard the Mars Exploration Rover Opportunity shows a circular imprint left in the Meridiani Planum soil by the rover's Moessbauer spectrometer, an instrument located on its arm that detects iron-bearing minerals. Scientists are studying the curiously rounded grains for clues about the soil's history. The observed area is 3 centimeters (1.2 inches) across.

  1. Moessbauer Nose Print

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by the microscopic imager, an instrument located on the Mars Exploration Rover Opportunity 's instrument deployment device, or 'arm.' The image shows the imprint of the donut-shaped plate on the rover's Moessbauer spectrometer instrument, also located on the 'arm.' The Moessbauer spectrometer was deployed within the trench to investigate the fine-grained soil for iron-bearing minerals. The area in this image measures approximately 3 centimeters (1.2 inches) across.

  2. Magnetic and Moessbauer studies of Apollo 16 rock chips 60315,51 and 62295,27

    NASA Technical Reports Server (NTRS)

    Brecher, A.; Vaughan, D. J.; Burns, R. G.

    1973-01-01

    Analysis of the Moessbauer spectra of two Apollo 16 rocks showed that 60315,51 is much richer in iron metal and troilite, but poorer in olivine, than 62295,27. The values of magnetic parameters, derived from hysteresis loops at 175 and 300 K, indicate the high metal contents and the predominance of coarse multidomain grains in both rocks. These coexist with a superparamagnetic grain fraction in 60315 and with a small single-domain grain fraction in 62295. The high Fe(0)/Fe(2+) ratios, the nonlinear acquisition of laboratory thermoremanence, and the drastic changes in magnetic parameters upon heating support the proposed formation of both rocks from the lunar regolith, with incorporation of shocked meteoritic metal grains during high-temperature impact events and simultaneous acquisition of magnetic remanence. Values estimated for ancient lunar magnetic fields by comparing the natural remanence with laboratory thermoremanence acquired in fields of 0.05 and 0.5 Oe, range from 0.01 to more than 1 Oe.

  3. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

  4. 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.

  5. 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.

  6. Effects of time and temperature of firing on Fe-rich ceramics studied by Moessbauer spectroscopy and two-dimensional {sup 1}H-nuclear magnetic resonance relaxometry

    SciTech Connect

    Casieri, Cinzia; De Luca, Francesco; Nodari, Luca; Russo, Umberto; Terenzi, Camilla; Tudisca, Valentina

    2012-10-15

    The combined effects of firing temperature and soaking time on the microstructure of iron-rich porous ceramics have been studied by {sup 57}Fe-Moessbauer spectroscopy and 2D {sup 1}H nuclear magnetic resonance (NMR) relaxometry using a single-sided probe. Examining water-saturated ceramics using the relaxation correlation method, where longitudinal (T{sub 1}) and transverse (T{sub 2}) relaxation times are measured concurrently, provides information about firing-induced changes in both porosity (related to T{sub 1}) and magnetic properties (related to T{sub 2}). Comparing the information obtained from {sup 1}H-NMR analyses with that obtained from Moessbauer spectroscopy (which characterizes changes in iron-bearing species) shows that the T{sub 1}-T{sub 2} NMR correlation technique is very sensitive to even subtle modifications in the magnetic behavior of Fe-bearing species. Moreover, the single-sided NMR approach allows us to perform millimeter-scale depth-resolved measurements, which can be used to non-invasively study the microstructural heterogeneities associated with non-uniform firing effects inside ceramics. This is in contrast to Moessbauer spectroscopy, which requires that the ceramic samples be ground.

  7. The Use of Moessbauer Spectroscopy in Metallurgy

    SciTech Connect

    Forder, S.D.

    2005-04-26

    This review will present examples of the varied way in which Moessbauer spectroscopy has been used, with complementary analytical techniques, to gain information about metals and alloys, with cases chosen to illustrate how this information can be valuable to industry.The Moessbauer investigations reviewed have been divided into three categories:1) Monitoring the effect of deliberate modification of the metal by processing, either at the pre-treatment stage, e.g. metal ion etching of steel surfaces prior to coating or during the modification of structure and properties, such as the formation of Al-Fe surface alloys formed by ion implantation of Fe in Al.2) Monitoring changes in the metal not caused deliberately, i.e. the side-effects of processing. Examples reviewed include Moessbauer studies of reactor steels, and phase transformation during intensive plastic deformation. Also the Moessbauer Effect has helped to determine the cause of staining occurring on electrogalvanized steel.3) Obtaining information to enable fundamental understanding of metals and alloys. These examples include Moessbauer spectroscopy used to study the formation of intermetallic phases in industrial alloys, the influence of metal ions on iron oxide rusts and the study of quasi-crystalline alloys.The information gained has helped the improvement of properties, the monitoring of changes in structures, as well as the development of fundamental understanding of metals and alloys.

  8. Moessbauer studies of Sr{sub 2}FeO{sub 4} to pressures of 20 GPa

    SciTech Connect

    Hearne, G.R. |; Pasternak, M.P.; Rozenberg, G.

    1995-09-01

    The transport and magnetic properties of the antiferromagnetic semiconductor Sr{sub 2}FeO{sub 4} (Fe{sup 4+}, d{sup 4}) were probed by resistance studies and {sup 57}Fe Moessbauer spectroscopy to 20 GPa using a diamond-anvil cell. The main conclusions of this work are that beyond the onset of the semiconductor-metal transition at {approx}17(1) GPa determined in the resistance studies: (1) the compound is still magnetic and, (2) there is no charge disproportionation of the form: 2Fe{sup 4+} {yields} Fe{sup 3+} + Fe{sup 5+}. The quadrupole splitting ({delta}E{sub Q}) at room temperature (RT) decreases from 0.42 mm/s at ambient pressure to a minimum of 2.2 mm/s at {approx}5.5 GPa. Beyond 5.5 GPa {delta}E{sub Q} at RT increases monotonically reaching 0.5 mm/s at 20 GPa. In the 0-10 GPa pressure range the Neel temperature T{sub N}, is pinned at 60-70 K reaching values of 135(5) K at 19 GPa where the compound is metallic. At 19 GPa and T {much_lt} T{sub N} a simplified magnetic spectrum having an internal magnetic field of {approx}25 T and a substantial quadrupole interaction is obtained.

  9. NGC 6067: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Alonso-Santiago, J.; Negueruela, I.; Marco, A.; Dorda, R.

    2015-05-01

    NGC 6067 is a young open cluster in the Norma Cloud. Its age is around 100 Ma. It hosts a large population of evolved stars: 14 luminous red stars (most of which K Ib supergiants and late-G/early-K giants), 6--8 B giants, two A/F supergiants and two Cepheids (F/G supergiants). All this would imply that NGC 6067 represent one of the best laboratories in the Galaxy to study the evolution of intermediate-mass stars. Thackeray et al. (1962, MNRAS 124, 445T) performed the first complete study of this cluster but it has been poorly studied since then. We obtained high resolution echelle spectra (R=48000) using FEROS (Fiber Extended Range Optical Spectrograph) mounted on the ESO 2.2 m telescope at La Silla Observatory (Chile) in May 2011. Here we present preliminary results based on this spectroscopy and the UBV photometry listed in Terndrup & Pinsonneault (2007, ApJ 671, 1640).

  10. 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.

  11. 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).

  12. 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.

  13. 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.

  14. Spectroscopic Studies of Classical Cepheids.

    NASA Astrophysics Data System (ADS)

    Gauthier, Robert Paul

    The extent and nature of the distortions of the emergent flux spectrum of cepheids due to the effects of the pulsation as a function of period and amplitude are not clearly understood. A multiphase classification study of a sample of 26 cepheids from the southern hemisphere at the relatively high dispersion of 67(ANGSTROM)/mm has been undertaken and complemented with the recent high quality photometric data for Pel (1976) in order to observe the results of increasing period and amplitude of pulsation on the line spectrum. The original framework of such investigations set up by Struve (1944) and Code (1947) has been enlarged upon principally through the use of modern MK standard supergiant sequences. It has been found that, while the spectrum of weak metal lines (in cepheids with periods less than forty days) can always be found to match that of a non-variable supergiant, anomalies in the strengths of the strong metal lines and Balmer H(delta) and H(gamma) lines increase both in number and intensity with increasing period and amplitude. The consequences of this on the line blanketing of the atmosphere are seen to be significant when comparing the color-spectrum relations of different period bins, indicating the inappropriateness of extending intrinsic color relations established with short period variables to the longer period ones. It has also been found that the effects of the amplitude of the pulsation are more directly felt by the atmosphere near the extrema of the physical displacement as evidenced by the sudden widening of the period-spectrum relation at the mid-descending and mid-rising branch phases. Following the suggestions by Sorvari (1974) that the luminosity sensitive OI 7773(ANGSTROM) triplet is responding to the dynamical effects of the pulsation on the atmosphere, a moderate dispersion (27(ANGSTROM)/mm) study of a small sample of cepheids (4) and supergiant standards has been undertaken. It has been found that the strength of this feature throughout

  15. 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.

  16. Moessbauer on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken at Meridiani Planum, Mars, by the panoramic camera on the Mars Exploration Rover Opportunity shows the rover's Moessbauer spectrometer (circular device in center), located on its instrument deployment device, or 'arm.' The image was acquired on the ninth martian day or sol of the rover's mission.

  17. Mark of the Moessbauer

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image, taken by an instrument called the microscopic imager on the Mars Exploration Rover Spirit, reveals an imprint left by another instrument, the Moessbauer spectrometer. The imprint is at a location within the rover wheel track named 'Middle of Road.' Both instruments are located on the rover's instrument deployment device, or 'arm.'

    Not only was the Moessbauer spectrometer able to gain important mineralogical information about this site, it also aided in the placement of the microscopic imager. On hard rocks, the microscopic imager uses its tiny metal sensor to determine proper placement for best possible focus. However, on the soft martian soil this guide would sink, prohibiting proper placement of the microscopic imager. After the Moessbauer spectrometer's much larger, donut-shaped plate touches the surface, Spirit can correctly calculate where to position the microscopic imager.

    Scientists find this image particularly interesting because of the compacted nature of the soil that was underneath the Moessbauer spectrometer plate. Also of interest are the embedded, round grains and the fractured appearance of the material disturbed within the hole. The material appears to be slightly cohesive. The field of view in this image, taken on Sol 43 (February 16, 2004), measures approximately 3 centimeters (1.2 inches) across.

  18. 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.

  19. Elementary diffusion jump of iron atoms in intermetallic phases studied by Moessbauer spectroscopy; 1: Fe-Al close to equiatomic stoichiometry

    SciTech Connect

    Vogl, G.; Sepiol, B. . Inst. fuer Festkoerperphysik)

    1994-09-01

    The authors have studied the quasielastic broadening of the [sup 57]Fe Moessbauer resonance in the intermetallic compound FeAl in order to determine the diffusion jump mechanism of the Fe atoms. From the angular dependence of the line broadening relative to an oriented single crystal they deduce that the Fe atoms jump effectively to different neighbor sites on the Fe sublattice. The jump is, however, not a direct one, but rather a combination of a jump into a nearest neighbor vacancy--leading to short-time occupation of an antistructure site on the Al sublattice--and a jump into a vacancy back on the Fe sublattice.

  20. Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, {sup 57}Fe Moessbauer spectroscopy and thermal studies

    SciTech Connect

    Travnicek, Zdenek; Herchel, Radovan; Mikulik, Jiri; Zboril, Radek

    2010-05-15

    Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN){sub 5}NO].H{sub 2}O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN){sub 5}NO].2H{sub 2}O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]octadecane and [Cu(nme){sub 2}Fe(CN){sub 5}NO].H{sub 2}O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, {sup 57}Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, {sup 57}Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe{sub 2}O{sub 4} and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN){sub 5}NO].xH{sub 2}O, where L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and {sup 57}Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.

  1. Moessbauer study of microstructural and chemical changes in Fe-9Ni steel during two-phase tempering

    SciTech Connect

    Fultz, B.; Morris, J.W. Jr.

    1980-11-01

    Two-phase tempering of martensitic Fe-9Ni steel serves to enhance the low temperature toughness and forms austenite precipitates in this material. Hyperfine field effects in Fe-Ni alloys were systematized so that tempering induced chemical composition changes in the martensite could be quantified by Moessbauer spectrometry. The kinetics of segregation of alloy elements from the martensite into the fresh austenite can be determined simultaneously with the amount of austenite which was formed.

  2. Moessbauer Study and Macroscopic/Global Magnetic Behavior of Powdered Ilmenite (FeTiO{sub 3}) Sample

    SciTech Connect

    Cuda, J.; Prochazka, V.; Zboril, R.; Tucek, J.; Maslan, M.

    2010-07-13

    In this article, the commercial synthetic powdered sample of ilmenite (FeTiO{sub 3}) has been re-examined by Moessbauer spectroscopy in the paramagnetic regime from 77 K to 280 K and in a magnetically ordered state below 57 K. The effective vibrating mass and the Debye temperature was found to be (78{+-}3) amu and (359{+-}27) K, respectively. The two sextet components were used for correct fitting of the Moessbauer spectra recorded at 5 K and 45 K in an external magnetic field of 5 T. Moreover, the macroscopic magnetic measurements were carried out by an MPMS XL-7 magnetometer to determine a temperature dependence of the molar susceptibility and hysteresis loops of this sample. The Moessbauer spectra and magnetization measurements confirm that below the ordering temperature of ilmenite, it behaves as a non-ideal antiferromagnetic material with a significant magnetic hardening at low temperatures. In addition, the magnetic molar susceptibility follows a Curie-Weiss law with C{sub m=5.8x10{sup -5}Km{sup 3}/mol}, and Weiss temperature {theta}{sub p} = 30.6 K.

  3. Moessbauer Close-Up

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This close-up image of the Mars Exploration Rover Spirit's instrument deployment device, or 'arm,' shows the donut-shaped plate on the Moessbauer spectrometer. This image makes it easy to recognize the imprint left by the instrument in the martian soil at a location called 'Peak' on sol 43 (February 16, 2004). This image was taken by the rover's panoramic camera on sol 39 (February 11, 2004).

  4. Spectroscopic study of solar twins and analogues

    NASA Astrophysics Data System (ADS)

    Datson, Juliet; Flynn, Chris; Portinari, Laura

    2015-02-01

    Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims: This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48 000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods: The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar analogues versus a reference solar reflection spectrum. Results: We derive spectroscopic parameters for 148 solar analogues (about 70 are new entries to the literature) and verify with a-posteriori differential tests that our values are well-centred on the solar values. We use our dataset to assess the two alternative calibrations of the GCS parameters; our methods favour the latest revision. We show that the choice of spectral line list or the choice of asteroid or time of observation does not affect the results. We also identify seven solar twins in our sample, three of which are published here for the first time. Conclusions: Our methods provide an independent means to differentially test the calibration of stellar catalogues around the values of a well-known benchmark star, which makes our work interesting for calibration tests of upcoming Galactic surveys. Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D

  5. Moessbauer spectroscopy study of iron-based catalysts used in Fischer-Tropsch synthesis

    SciTech Connect

    Rao, K.R.P.M.; Huggins, F.E.; Huffman, G.P.

    1995-12-01

    Mossbauer investigations of iron-based catalysts containing the promoters K, and Cu, and binders consisting of oxides of Al, Si and Zr were carried out. Catalysts subjected to pretreatment in gas atmospheres containing mixtures of CO, H{sub 2}, and He have been studied. It is shown that the nature of binders, promoters and pretreatment of a catalyst influence the iron-phases formed during pretreatment and FT synthesis. Activation of the catalysts in CO leads to rapid and almost complete formation of {chi}-Fe{sub 5}C{sub 2} during activation and gives rise to high (H{sub 2}+CO) conversion. On the other hand, activation of the catalysts in synthesis gas leads to slow and incomplete formation of carbides and low (H{sub 2}+CO) conversion.

  6. Map of Moessbauer Placement

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This elevation map of a soil target called 'Peak' was created from images taken by the microscopic imager located on the Mars Exploration Rover Spirit's instrument deployment device or 'arm.' The image reveals the various high and low points of this spot of soil after the Moessbauer spectrometer, another instrument on the rover's arm, was gently placed down on it. The blue areas are farthest away from the instrument; the red areas are closest. The variation in distance between blue and red areas is only 2 millimeters, or .08 of an inch. The images were acquired on sol 39 (February 11, 2004).

  7. 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.

  8. Moessbauer spectroscopy study of the aging and tempering of high nitrogen quenched Fe-N alloys: Kinetics of formation of Fe{sub 16}N{sub 2} nitride by interstitial ordering in martensite

    SciTech Connect

    Fall, I.; Genin, J.M.R. |

    1996-08-01

    The distribution of nitrogen atoms in austenite and during the different stages of aging and tempering of martensite is studied by Moessbauer spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). Transmission Moessbauer spectroscopy (TMS) and conversion electron Moessbauer spectroscopy (CEMS) are used for studying the austenite phase where the distribution of nitrogen atoms is found to depend on the nitriding method, gas nitriding in the authors` case, or ion implantation. Conversion electron Moessbauer spectroscopy, which concerns a depth predominantly less than 200 nm, reveals a nitrogen atom distribution different from that found in the bulk by TMS. The identification and kinetics of the stages of aging and tempering of martensite are followed by TMS measurements, and the phase characterization is confirmed by X-ray diffraction and TEM. The major stages are the early ordering of nitrogen atoms, which leads to small coherent precipitates of {alpha}-Fe{sub 16}N{sub 2}; the passage by thickening to semicoherent precipitates of {alpha}-Fe{sub 16}N{sub 2}; the dissolution of {alpha}-Fe{sub 16}N{sub 2} with the concomitant formation of {gamma}-Fe{sub 4}N; and the decomposition of retained austenite by tempering. The three first stages correspond to activation energies of 95, 126, and 94 kJ/mole, respectively, consistent with the nitrogen diffusion for the first and third stages and the dislocation pipe diffusion of iron for the second.

  9. 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.

  10. Spectroscopic studies of superconductors. Part B: Tunneling, photoelectron, and other spectra

    SciTech Connect

    Bozovic, I.; Marel, D. van der

    1996-12-31

    Part B is divided into the following sections: (1) tunneling, photoelectron, and other spectra; (2) tunneling spectra: theoretical studies; (3) photoelectron spectra; and (4) other spectra (XAFS, RBS, ESR, Moessbauer, thermoreflectance, etc.). Separate abstracts were prepared for most papers in this volume.

  11. A Moessbauer-effect study of a series of R sub 2 Fe sub 14 C hard magnetic materials

    SciTech Connect

    Long, G.J.; Pringle, O.A.; Marasinghe, G.K. Department of Physics, University of Missouri-Rolla, Rolla, Missouri 65401 ); Grandjean, F. ); Buschow, K.H.J. )

    1991-04-15

    The {sup 57}Fe Moessbauer-effect spectra of the series of hard magnetic materials, R{sub 2}Fe{sub 14}C, where R is Nd, Gd, Tb, Dy, Ho, and Lu, have been measured at 295 K. All of these carbides exhibit uniaxial magnetic anisotropy. The spectra resemble those obtained for the related R{sub 2}Fe{sub 14}B compounds and have been fit with the model used earlier for Nd{sub 2}Fe{sub 14}B. The magnitude of the hyperfine field on each site, as a function of rare earth, parallels the Curie temperature; the maximum hyperfine fields and the maximum Curie temperature are observed for Gd{sub 2}Fe{sub 14}C. A linear correlation is observed between the hyperfine fields on the six sites in the analogous borides and carbides; however, these fields are systematically smaller in the carbides. The decrease in the tetragonal unit cell {ital c}-axis length in the carbides apparently reduces the exchange interactions between the 8{ital j} and 16{ital k} iron layers and hence reduces the moments. The isomer shift on each site decreases as the atomic number of the rare earth increases, whereas the quadrupole interactions are independent of rare earth.

  12. Fe-57 and Sn-119 Moessbauer study of La2CuO(4-y), YBa2Cu3O(7-y) and SmBa2Cu3O(7-y)

    NASA Technical Reports Server (NTRS)

    Jha, S.; Mitros, C.; Yehia, S.; Lahamer, Amer; Julian, Glenn M.

    1988-01-01

    Moessbauer studies reveal antiferromagnetic order in doped La2CuO(4-7): at 77 K, H = 476 kOe at Fe-57 and H is less that 10 kOe at Sn-119. Split-source and conventional absorber experiments on RBa2Cu3O(7-y) (R = Y, Sm) are consistent with occupation of 3 sites by Fe-57, the relative population depending on sample preparation and Fe concentration.

  13. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  14. Fourier transform infrared spectroscopic study of truffles

    NASA Astrophysics Data System (ADS)

    Zhao, Dezhang; Liu, Gang; Song, Dingshan; Liu, Jian-hong; Zhou, Yilan; Ou, Jiaming; Sun, Shizhong

    2006-01-01

    Truffles are rare wild growing edible mushrooms belonging to Ascomycetes. In this paper, Fourier transform infrared (FTIR) spectroscopy was used to obtain vibrational spectra of truffles. The results show that the mushrooms exhibit characteristic spectra. The two strongest absorption bands appear at about 1077cm -1 and 1040 cm -1, which were described as C-O stretching in carbohydrate. The vibrational spectra indicate that the main compositions of the truffles are polysaccharide and protein. According to the characteristics bands and absorption ratios of spectra, different species of truffles can be discriminated. It is also found the great changes between moldy and healthy truffles, which the major differences are observed in the bands of protein. In addition, FTIR spectral differences are observed between the same species of truffles from different producing areas. It is showed that the FTIR spectroscopic method is valuable tool for rapid and nondestructive analysis of truffles prior to any extraction method used.

  15. Phase evolution in {sup 57}Fe/Al multilayers studied through dc magnetization, conversion electron Moessbauer spectroscopy, and transmission electron microscopy

    SciTech Connect

    Jani, Snehal; Lakshmi, N.; Venugopalan, K.; Sebastian, Varkey; Reddy, V. R.; Gupta, Ajay; Lalla, N. P.

    2008-12-15

    Fe/Al multilayer thin films with an overall atomic concentration ratio of Fe:Al=1:2 have been prepared by ion-beam sputtering. Phase formation and microstructural evolution with thermal annealing have been studied by x-ray reflectivity, cross-sectional transmission electron microscopy, dc magnetization, and conversion electron Moessbauer spectroscopy. These studies show that although the starting composition is Al rich, the intermixing of Fe and Al at the interfaces leads to the formation of a magnetic Fe{sub 3}Al-like region at the interface. Thus, the magnetic contribution in the as-deposited multilayer structure (MLS) is not only from pure Fe but also from an Fe{sub 3}Al-like region formed at the interface. On annealing the MLS, a stable nonmagnetic MLS consisting of intermetallic B2Fe{sub 50}Al{sub 50} separated by thin Al layers is formed. Further annealing only induces better ordering of Fe{sub 50}Al{sub 50} and does not destroy the MLS.

  16. Moessbauer spectroscopy studies of iron-catalysts used in Fischer-Tropsch (FT) processes. Quarterly technical progress report, January--March, 1995

    SciTech Connect

    Huffman, G.P.; Rao, K.R.P.M.

    1995-10-01

    Moessbauer spectroscopy investigations were carried out on 14 iron-based catalysts during the period under review. The catalyst 100Fe/4.4Si/0.71K (all atomic ratios) was subjected to activation first in syngas and subsequently in CO gas atmosphere. Fischer-Tropsch (FT) synthesis was carried out on the above catalyst. Another catalyst 100Fe/4.4Si/2.6Cu/0.71K (all atomic ratios) activated in syngas and subjected to FT synthesis was also studied to understand the effect of added Cu on the phase distribution and its effect on the FT activity. The following trends were observed: (1) activation of the catalyst in syngas, H{sub 2}/CO, lead to the formation of Fe{sub 3}O{sub 4} and no carbides were formed, the FT activity was found to be low at 9--12% (H{sub 2}+CO) conversion; (2) activation of the catalyst in CO for 22hrs lead to the formation of 33% of {chi}-carbide and the FT activity was found to be high at 88% maximum; (3) addition of copper to the catalyst has improved the FT activity for those catalysts pretreated in syngas at elevated pressures.

  17. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  18. The Miniaturized Moessbauer Spectrometer MIMOS II for the Asteroid Redirect Mission(ARM): Quantative Iron Mineralogy And Oxidation States

    NASA Technical Reports Server (NTRS)

    Schroeder, C.; Klingelhoefer, G; Morris, R. V.; Yen, A. S.; Renz, F.; Graff, T. G.

    2016-01-01

    The miniaturized Moessbauer spectrometer MIMOS II is an off-the-shelf instrument with proven flight heritage. It has been successfully deployed during NASA’s Mars Exploration Rover (MER) mission and was on-board the UK-led Beagle 2 Mars lander and the Russian Phobos-Grunt sample return mission. A Moessbauer spectrometer has been suggested for ASTEX, a DLR Near-Earth Asteroid (NEA) mission study, and the potential payload to be hosted by the Asteroid Redirect Mission (ARM). Here we make the case for in situ asteroid characterization with Moessbauer spectroscopy on the ARM employing one of three available fully-qualified flight-spare Moessbauer instruments.

  19. Spectroscopic study of low-lying {sup 16}N levels

    SciTech Connect

    Bardayan, D. W.; Nesaraja, C. D.; Pain, S. D.; Smith, M. S.; O'Malley, P. D.; Cizewski, J. A.; Hatarik, R.; Peters, W. A.; Blackmon, J. C.; Chae, K. Y.; Jones, K. L.; Moazen, B. H.; Paulauskas, S.; Pittman, S. T.; Schmitt, K. T.; Chipps, K. A.; Kozub, R. L.; Shriner, J. F. Jr.; Matei, C.

    2008-11-15

    The magnitude of the {sup 15}N(n,{gamma}){sup 16}N reaction rate in asymptotic giant branch stars depends directly on the neutron spectroscopic factors of low-lying {sup 16}N levels. A new study of the {sup 15}N(d,p){sup 16}N reaction is reported populating the ground and first three excited states in {sup 16}N. The measured spectroscopic factors are near unity as expected from shell model calculations, resolving a long-standing discrepancy with earlier measurements that had never been confirmed or understood. Updated {sup 15}N(n,{gamma}){sup 16}N reaction rates are presented.

  20. Halo Nucleus Be11: A Spectroscopic Study via Neutron Transfer

    NASA Astrophysics Data System (ADS)

    Schmitt, K. T.; Jones, K. L.; Bey, A.; Ahn, S. H.; Bardayan, D. W.; Blackmon, J. C.; Brown, S. M.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hahn, K. I.; Kolata, J. J.; Kozub, R. L.; Liang, J. F.; Matei, C.; Matoš, M.; Matyas, D.; Moazen, B.; Nesaraja, C.; Nunes, F. M.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Roberts, A.; Shapira, D.; Shriner, J. F., Jr.; Smith, M. S.; Spassova, I.; Stracener, D. W.; Villano, A. N.; Wilson, G. L.

    2012-05-01

    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 Be11, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the Be10(d,​p) reaction has been used in inverse kinematics at four beam energies to study the structure of Be11. 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 nℓj=2s1/2 state coupled to the ground state of Be10 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.

  1. Features of the Quantitative Analysis in Moessbauer Spectroscopy

    SciTech Connect

    Semenov, V. G.; Panchuk, V. V.; Irkaev, S. M.

    2010-07-13

    The results describing the effect of different factors on errors in quantitative determination of the phase composition of studied substances by Moessbauer spectroscopy absorption are presented, and the ways of using them are suggested. The effectiveness of the suggested methods is verified by an example of analyzing standard and unknown compositions.

  2. Synchrotron-Radiation-Based Moessbauer Spectroscopy

    SciTech Connect

    Seto, Makoto; Masuda, Ryo; Mitsui, Takaya; Higashitaniguchi, Satoshi; Kitao, Shinji; Kobayashi, Yasuhiro; Inaba, Chika; Yoda, Yoshitaka

    2009-05-29

    We have developed a new method that yields Moessbauer absorption spectra using synchrotron radiation (SR); this method is applicable for almost all Moessbauer nuclides including those that cannot be measured by previous methods using radioisotope (RI) sources. The Moessbauer spectrum of the 68.752 keV excited state of {sup 73}Ge, which cannot be measured using a RI source, was measured using SR. Our results show that this method can be used to perform advanced Moessbauer spectroscopy measurements owing to the excellent features of SR.

  3. 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.

  4. Spectroscopic study of bituminous oxidative stress.

    PubMed

    Masmoudi, H; Rebufa, C; Raffi, J; Permanyer, A; Kister, J

    2004-05-01

    Bitumen, as each organic substance, is a product which alters over time. Indeed, roads deteriorate under the effect of several phenomena. A number of studies have been undertaken to increase the quality of road's coating, mostly by adding polymer to bitumen. This work was based on the study, by electron paramagnetic resonance (EPR), FTIR and Synchronous UV fluorescence, of different base and modified bitumens after different treatments used to simulate the ageing (gamma irradiation, thermal treatment). Our purpose was to compare and correlate the results obtained by different techniques to improve the knowledge of bitumen's reactivity and evolution submitted to ageing phenomena. PMID:15134733

  5. 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.

  6. 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.

  7. Spectroscopic studies of lead halo borate glasses

    NASA Astrophysics Data System (ADS)

    Sekhar, K. Chandra; Hameed, Abdul; Chary, M. Narasimha; Shareefuddin, Md.

    2015-06-01

    Glasses in the system xPbF2-(30-x) PbO-69B2O3-1CuO (x=5, 10, 15, 20, & 25 mole %) were prepared by melt quenching method and they are characterized by XRD to confirm the glassy nature. Electron Paramagnetic Resonance (EPR) studies at room temperature in the X-band frequencies and FTIR studies on prepared glass systems were reported. The non-linear variation of spin-Hamiltonian parameters with PbF2 content indicated the change in the ligand field strength around Cu2+ ions in the host glass. The ground state of Cu2+ ions in the glass is designated as dx2-y2 orbital (2B1g) while the observed symmetry around it is tetragonally distorted octahedral. The molecular orbital coefficients α2, β2 and β12 are evaluated for Cu2+ doped samples. From the FTIR studies it was observed that the glass made up of BO3 and BO4 units.

  8. Spectroscopic and quantum chemical studies of isocytosine

    SciTech Connect

    Tulub, A.A.; Semenov, S.G.; Stetsenko, A.I.; Yudovich, E.E.

    1988-07-01

    The methods of electronic and vibrational (IR) spectroscopy were used to study the spectral properties of isocytosine in H/sub 2/O, D/sub 2/O, chloroform, and hexane in a wide concentration interval. Quantum chemical calculations of tautomeric forms and dimers of isocytosine were carried out. The bands of the calculated and experimental spectra were assigned. The results of the quantum calculations were compared with the experimental data. The spectral bands were classified according to the type of tautomer or dimer to which they belong.

  9. 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.

  10. 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.

  11. Spectroscopic studies of solutes in aqueous solution.

    PubMed

    Chai, Bing-hua; Zheng, Jian-ming; Zhao, Qing; Pollack, Gerald H

    2008-03-20

    Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structure distinct from that of bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). Absorption peaks at approximately 270 nm similar to those observed in the exclusion zone were seen in solutions of the following substances: salts, Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose. To determine the fate of the absorbed energy, we studied the fluorescence properties of these solutions. The salts showed fluorescence emission around 480-490 nm under different excitation wavelengths. The fluorescence intensity of LiCl was higher than NaCl, which was in turn higher than KCl-the same ordering as the absorption intensities. Fluorescence of Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose were observed as well, with multiple excitation wavelengths. Hence, at least some of the absorbed energy is released as fluorescence. The results show features closely similar to those observed in the exclusion zone, implying that the aqueous region around the solutes resembles the aqueous zone adjacent to hydrophilic surfaces. Both may be more extensively ordered than previously thought. PMID:18298105

  12. 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

  13. 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.

  14. Spectroscopic and quantum chemical studies on bromopyrazone

    NASA Astrophysics Data System (ADS)

    Gökce, Halil; Bahçeli, Semiha

    2014-12-01

    In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data.

  15. 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.

  16. Ultrafast spectroscopic studies of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Min

    An important aim of nanoparticle research is to understand how the properties of materials depend on their size and shape. In this thesis, time-resolved spectroscopy has been used to measure the physical properties of nanometer sized objects, such as the characteristic time scale for heat dissipation and their elastic moduli. In our experiments, metal nanoparticles are excited with a sub-picosecond laser pulse, which causes a rapid increase in the lattice temperature. In the first project, the rate of heat dissipation from Au nanoparticles to their surroundings was examined for different size gold nanospheres in aqueous solution. Laser induced lattice heating can also impulsively excite the phonon modes of the particle that correlate with the expansion co-ordinates. For spherical Au particles the symmetric breathing mode is excited. Experimental results for ˜50 nm diameter Au particles were compared to a model calculation where the expansion coordinate is treated as a damped harmonic oscillator. This gives information about the excitation mechanism. In the second project, the extensional and breathing modes of cylindrical gold nanorods were studied by time-resolved spectroscopy. These experiments yield values for the elastic constants for the rods. Both the extensional mode and the breathing mode results show that gold nanorods produced by wet chemical techniques have a smaller elastic moduli than bulk gold. HR-TEM and SAED studies show that the rods have a 5-fold twinned structure with growth along the [110] crystal direction. However, neither the growth direction nor the twinning provide a simple explanation for the reduced elastic moduli measured in the experiments. In a final project, polydisperse silver nanoparticle samples were investigated. A signal due to coherently excited vibrational motion was observed. The analysis shows that the observed signal arises from the triangular-shaped particles, rather than the rods or spheres that are present in the sample

  17. Raman spectroscopic studies of disordered ferroelectric oxides

    NASA Astrophysics Data System (ADS)

    Savvinov, Alexey A.

    Relaxational properties of compositionally disordered AB03 perovskite oxides were studied. These oxides are the prototypical soft ferroelectric (FE) mode systems, and their interesting dipolar relaxational properties are determined by their long, strongly temperature-dependent correlation lengths for the dipolar interactions. The simple cases involve dilute chemical substitutions in the incipient ferroelectrics KTaO3 and SrTiO3, which exhibit relatively weak, low-temperature Debye-type relaxations. More complicated dipolar interactions are seen in B-site disordered Nb-doped KTaO3, which exhibits glass-like relaxor and relaxor-to-ferroelectric crossover behaviors at low temperatures. Finally, there is a class of more complex perovskites represented by PMN, PZN-PT and the PLT that exhibit strong, high-temperature relaxor and/or ferroelectric properties. The renewed interest in the KTa1-xNbxO (KTN) mixed perovskite materials, especially in high quality thin films, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak, up to 20 times in comparison with the pure KTaO3 and KNbO3. The effects of the substrate and the symmetry-breaking defects on their vibration spectra were studied by micro-Raman spectroscopy. An anomalous residual intensity of the forbidden first-order scattering modes in the cubic paraelectric phase of the KTN films was connected with the formation of polar microregions even far above the bulk Tc. On the whole, the KTN film behavior shows the existence of specific defects enhancing the perovskite unit cell in the film so that the activity of off-center Nb ions increases in producing larger electric dipoles and extending the precursor phase above Tc. In diluted compositions with low Nb concentrations KTN materials exhibit formation of polar nano regions and relaxor like behavior. This behavior is analogous with

  18. 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.

  19. 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.

  20. 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.

  1. DAO Spectroscopic Study of Nova Cygni 1992

    NASA Astrophysics Data System (ADS)

    Garnavich, Peter M.

    1992-12-01

    The spectral development of Nova Cygni 1992 is being monitored at the Dominion Astrophysical Observatory. The brightest nova in over 15 years provides a rare opportunity to study, in detail, nova evolution from maximum to the late nebular stages. Our spectra during the early phases of the outburst had a resolution of 0.6 Angstroms while in the nebular phase the resolution ranged from 2 Angstroms to 4 Angstroms . The nova was observed at DAO on more than 40 nights in 1992. Our first spectrum was obtained near maximum light on February 22, 1992. It showed weak Hβ and Fe II emission lines with P-Cygni absorption components at -910 and -1670 km/s (IAUC 5457). During the early decline, the P-Cygni absorption complex spread blueward, eventually reaching -2900 km/s by the ides of March. Observations by IUE showed absorption troughs of UV lines extending to -2800 km/s even before maximum (IAUC 5456). This suggests that the apparent increase in the velocity of the diffuse-enhanced absorption is due to opacity effects, not a physical acceleration of the gas or the changing geometry of the expanding shells. The transition to the nebular phase occurred in late April, 1992. The emission lines were broad (FWHM of 2200 km/s) and contained as many as 10 velocity components. The temperature and density evolution of the major velocity components are estimated from diagnostic line ratios during the nebular stage. The similarity between Nova Cygni 1992 and V1500 Cyg suggested that the coronal line, [Fe X] 6374 Angstroms , might be present in the early nebular phase. The unusual shape and strength of the [O I] line at 6363 Angstroms added to this suspicion. In spectra taken 90 days after outburst, the [O I] 6300 Angstroms line was used to deconvolve the emission, but the contamination was found to be due to the Si II doublet 6347/71 Angstroms . Infrared observations indicated the onset of a coronal phase 200 days after maximum (IAUC 5612), and our data from this period are analyzed

  2. 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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Allamandola, L. J.

    1997-12-01

    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.

  5. 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.

  6. Indentation device for in situ Raman spectroscopic and optical studies

    NASA Astrophysics Data System (ADS)

    Gerbig, Y. B.; Michaels, C. A.; Forster, A. M.; Hettenhouser, J. W.; Byrd, W. E.; Morris, D. J.; Cook, R. F.

    2012-12-01

    Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.

  7. Moessbauer studies in zinc-manganese ferrites for use in measuring small velocities and accelerations with great precision

    NASA Technical Reports Server (NTRS)

    Escue, W. T.; Gupta, R. G.; Mendiratta, R. G.

    1975-01-01

    Mossbauer spectroscopy was used for a systematic study of the magnetic behavior of manganese and zinc in mixed ferrites. It was observed that Zn2+ has preference to substitute Mn2+ at interstitial sites where the metal ions are tetrahedrally coordinated with four oxygen neighbors. The internal magnetic hyperfine field at the tetrahedral iron site is larger than that at the octahedral site. The relaxation effects were observed to play an important role as the zinc contents were increased, while the spin-correlation time and the magnetic field were observed to decrease in strength. It is concluded that Mossbauer effect data on complex materials, when used in conjunction with other data, can provide useful insight into the origin of the microscopic properties of magnetic materials.

  8. 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.

  9. The first spectroscopic study of southern binary:HD 53570

    NASA Astrophysics Data System (ADS)

    Sürgit, D.

    2016-03-01

    In this study, I present the first analysis of spectroscopic observations of southern detached eclipsing binary star HD 53570. The spectroscopic observations of HD 53570 was made at the Sutherland Station of the South African Astronomical Observatory (SAAO) in 2013 and 2014. Radial velocities (RVs) of the components of HD 53570 were determined by cross-correlation technique (CCT). The Hβ (4861.36 Å) lines of the components of HD 53570 were chosen as the most suitable lines for reliable RV measurements. The resulting orbital elements of HD 53570 is calculated as, a1 sin i = 0.0258±0.0005 AU, a2 sin i = 0.0228±0.0005 AU, M1 sin3i = 1.035±0.046 M⊙ and M2 sin3i = 1.167±0.050 M⊙. The radial velocity models of HD 53570 give the close binaries mass ratio as 1.13±0.07.

  10. 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.

  11. [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. PMID:15766067

  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. Material Research Using Moessbauer Spectroscopy With Exotic Nuclei

    SciTech Connect

    Kobayashi, Y.

    2009-05-04

    We have succeeded to obtain in-beam Moessbauer spectra using a short-lived {sup 57}Mn (T{sub 1/2} = 1.45 min) probes implanted into some different types of samples, in order to study the chemical states of the excited atoms produced just after nuclear decays and/or the dynamic behaviors of isolated single atoms in a semiconductor. {sup 57}Mn was produced as a radioactive beam following a nuclear projectile-fragmentation reaction of {sup 58}Fe{sup 21+} beams (E = 63 MeV/nucleon) with Be production target, and separated by the in-flight isotope separator at the accelerators in RIKEN Nishina Center. From the temperature dependence of obtained Moessbauer parameters of the isomer shift (I.S.), the quadrupole splitting (Q.S.), and the linewidth (I), the chemical species and the dynamic behavior of the isolated atoms could be discussed. The in-beam Moessbauer technique combined with a short-lived RI beam is a very powerful tool to investigate the products after nuclear transformations and the dynamics of dilute impurities in solids.

  14. 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.

  15. 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.

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

    PubMed

    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. PMID:22225606

  17. 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.

  18. 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. PMID:25194320

  19. Spectroscopic and quantum chemical studies on 4-acryloyl morpholine

    NASA Astrophysics Data System (ADS)

    Arjunan, V.; Rani, T.; Santhanalakshmi, K.; Mohan, S.

    2011-09-01

    Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and an extensive spectroscopic investigations have been carried out on 4-acryloyl morpholine (4AM). Theoretical quantum chemical studies have also been performed. From the ab initio and DFT analysis using HF, B3LYP and B3PW91 methods with 6-31G(d,p) and 6-311G++(d,p) basis sets the energies, structural, thermodynamical and vibrational characteristics of the compound were determined. The energy difference between the chair equatorial and chair axial conformers of 4AM have been calculated by density functional theory (DFT) method. The optimized geometrical parameters, theoretical wavenumbers and thermodynamic properties of the molecule are compared with the experimental values. The effect of acryloyl group on the characteristic frequencies of the morpholine ring has been analysed. The mixing of the fundamental modes with the help of potential energy distribution (PED) through normal co-ordinate analysis has been discussed.

  20. Infrared spectroscopic study of sputtered tungsten oxide films

    SciTech Connect

    Paul, J.L.; Lassegues, J.C. )

    1993-10-01

    Recent infrared and Raman spectroscopic studies of various tungsten oxide films concluded either the formation of W=O terminal bonds or the transformation of such bonds into W-OH groups upon proton insertion. The infrared transmission and reflection spectra of bleached and colored sputtered films were reinvestigated in order to resolve the previous contradictory interpretations and for better insight into the mechanism of electrochromism at the molecular level. The new results confirm the first interpretation and allow us to show that H[sup +] or Li[sup +] insertion creates shorter ([approximately]1.7[angstrom]) and longer ([approximately]2 [angstrom]) W-O bonds around the W[sup 5+] centers. These results are in agreement with the concepts of small polaron and of intervalence charge transfer mechanism. They illustrate the local lattice distortion around a W[sup 5+] site. Aging of the initial films has also been followed and characterized by H/D in situ isotopic exchange.

  1. 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.

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

    DOE PAGESBeta

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

    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

  3. 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.

  4. 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.

  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. Moessbauer Effect Study of Bi2O3. Na2O. B2O3. Fe2O3 Glass System

    SciTech Connect

    Salah, S.H.; Kashif, I.; Salem, S.M.; Mostafa, A.G.; El-Manakhly, K.A.

    2005-04-26

    Sodium-tetra-borate host glass containing both bismuth and iron cations were prepared obeying the composition (Na2B4O7)0.75 (Fe2O3)0.25-x (Bi2O3)x [where x = 0.0, 0.05, 0.10, 0.15, 0.20, and 0.25 mol.%]. X-ray diffraction indicated that all samples were in a homogeneous glassy phase. Moessbauer effect results showed that all iron ions appeared as Fe3+ ions occupying tetrahedral coordination state. The covalency of the Fe-O bond increased as bismuth oxide was gradually increased. IR measurements indicated the presence of some non-bridging oxygens and confirmed that iron ions occupy the tetrahedral coordination state. It was found also that, as Bi2O3 was gradually increased both magnetic susceptibility and specific volume decreased, while both density and molar volume increased.

  7. Metal valences in electron-doped (Sr,La){sub 2}FeTaO{sub 6} double perovskite: A {sup 57}Fe Moessbauer spectroscopy study

    SciTech Connect

    Rautama, E.-L.; Linden, J.; Yamauchi, H.; Karppinen, M.

    2007-02-15

    Substitution of divalent Sr by trivalent La is found to affect the valence states of both of the two B-site cations, Fe and Ta, in the double perovskite oxide (Sr{sub 1-} {sub x} La {sub x} ){sub 2}FeTaO{sub 6}. Moreover, it improves the degree of order of these cations. From {sup 57}Fe Moessbauer spectra the average Fe valence was found to decrease with increasing La substitution level, x. However, the valence of Fe decreased less than expected if the valence of Ta was assumed to remain constant. Hence, we conclude that also the valence of Ta decreases. - Graphical abstract: Both the degree of order and the valence states of Fe and Ta are controlled in the (Sr{sub 1-} {sub x} La {sub x} ){sub 2}FeTaO{sub 6} double perovskite oxide through aliovalent La{sup III}-for-Sr{sup II} substitution.

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

    PubMed Central

    Suess, Daniel L. M.

    2015-01-01

    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 57Fe 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. PMID:26508821

  9. Spectroscopic study of sorption of nitrogen heterocyclic compounds on phyllosilicates

    SciTech Connect

    Chattopadhyay, S.; Traina, S.J.

    1999-03-02

    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 this article show that the degree of sorption of NHCs on phyllosilicates was dependent on the nature of the participating sorbates and sorbents. Sorption of the selected NHCs was pH-dependent, with maximum sorption occurring at low pH conditions, especially at pH < pK{sub a} of the NHC. Though sorption of the cationic forms of the NHCs on clays was preferred, neutral, zwitterionic, and anionic species of NHCs also sorbed on the clay surfaces. Spectroscopic studies have shown that sorbed NHC molecules formed clusters on clay surfaces, which acted as templates for molecular aggregation. Finally, the authors have also found that the clay surfaces promoted protonation of neutral AcN molecules at low sorbate concentrations.

  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. 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

  12. 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

  13. 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. PMID:23130955

  14. 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. PMID:26493066

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

    PubMed

    Maurya, Anju; Rastogi, Shantanu

    2015-12-01

    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. PMID:26117194

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

    PubMed

    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 488nm and 785nm 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. PMID:27372511

  17. Fluorination of graphene: a spectroscopic and microscopic study.

    PubMed

    Wang, Bei; Wang, Junjie; Zhu, Jun

    2014-02-25

    Since the advent of graphene, there has been intense interest in exploring the possibility of incorporating fluorinated graphene (FG), an ultrathin insulator, into graphene electronics as barriers, gate dielectrics, and optoelectronic elements. Here we report on the synthesis of FG from single-layer graphene sheets grown by chemical vapor deposition (CVD) using CF4 plasma. We examine its properties systematically via microscopic and spectroscopic probes. Our studies show that, by controlling the conditions of the plasma, FG of varying fluorine coverage can be produced; however, the resulting material contains a mixture of CFx (x = 1-3) bonds. Existing grain boundaries and lattice defects of CVD graphene play an important role in controlling its rate of fluorination and the damage of the sheet. Combining topography and current mapping, we demonstrate that the spatial distribution of fluorine on CVD graphene is highly inhomogeneous, where multilayer islands and structural features such as folds, wrinkles, and ripples are less fluorinated and consequently form a conductive network through which charge transport occurs. It is the properties of this network that manifest in the electrical transport of FG sheets. Our experiments reveal the many challenges of deriving electronics-quality FG from current CVD graphene while at the same time point to the possible solutions and potential of FG in graphene electronics and optoelectronics. PMID:24471932

  18. 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.

  19. Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD)

    NASA Astrophysics Data System (ADS)

    Barnes, S. E.; Brown, E. C.; Corrigan, N.; Coates, P. D.; Harkin-Jones, E.; Edwards, H. G. M.

    2005-10-01

    The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

  20. New homotrinuclear lanthanide complexes: synthesis, characterization and spectroscopic study.

    PubMed

    Silva, Wagner E; Belian, Mônica Freire; Freire, Ricardo O; de Sá, Gilberto F; Alves, Severino

    2010-09-23

    This work presents the synthesis and spectroscopic study of new homotrinuclear (TRI) systems for photonics applications. The luminescence spectroscopy shows characteristics transitions of Eu(III) and Tb(III) ions. For the Gd(III) complexes, the triplets states were determined by phosphorescence measurement. The complexes’ coordination geometries were calculated using the Sparkle/AM1 model. For the europium systems, the Sparkle/AM1 geometries were used to calculate all details involved in the energy transfer process, and the theoretical quantum yields were determined. From an energy diagram, that estimates triplet levels, it was possible to understand some experimental phenomenon, such as weak luminescence for precursor complex (without heterocyclics ligands), and ligands emission in terbium complexes. Some of these observations can also be explained by the Jablonski diagrams that describe, based on theoretical calculations, all luminescent process. The synthesized complexes showed high values of quantum yield in ethanolic environment: 50% for EuTRIDipy, 26% EuTRITerpy, and 56% for EuTRIPhen complexes. PMID:20738128

  1. 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.

  2. Moessbauer Spectroscopy on the Martian Surface: Predictions

    NASA Technical Reports Server (NTRS)

    Schaefer, M. W.; Dyar, M. D.

    2003-01-01

    Moessbauer spectrometers will be used on the upcoming MER/Athena and Mars Express/ Beagle 2 landers to identify and quantify relative amounts of iron-bearing minerals and determine Fe3+/Fe2+ ratios, allowing more realistic modeling of Martian mineralogy and geochemistry. To properly interpret the spectra acquired by these instruments, we must understand the Mossbauer parameters of minerals that we might expect to find on Mars. We present here a summary of predicted Fe-bearing minerals that might be observed by the MER Moessbauer spectrometers, based upon previous and our own on-going work.

  3. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Not Available

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  4. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  5. Moessbauer spectroscopy studies of iron-catalysts used in Fischer-Tropsch (FT) processes. Quarterly technical progress report, October 1, 1996--December 31, 1996

    SciTech Connect

    Huffman, G.P.; Rao, K.R.P.M.

    1996-12-31

    The U.S. Department of Energy has currently a program to develop Fischer-Tropsch catalysts which are active at low H{sub 2}/Co ratio of 0.67. The Center for Applied Energy Research, University of Kentucky and Texas A&M University have been developing Fischer- Tropsch catalysts which are active at a low H{sub 2}/Co ratio of 0.67. It is of interest to find out any relationships that may exist between the iron phases that are produced during activation and FT synthesis and the activity of the catalysts. Moessbauer spectroscopy investigations were carried out on 32 iron-base catalysts during the period under review. Eleven catalysts withdrawn from slurry type of reactors during and at the end of FT synthesis were received from the University of Kentucky. Twenty one catalysts withdrawn at the end of the run from both the slurry and fixed-bed reactors were received from Texas A&M University.

  6. 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.

  7. Raman spectroscopic studies of amorphous carbon and buckminsterfullerene

    SciTech Connect

    Sinha, K.

    1992-01-01

    Raman spectroscopic techniques have been applied to investigate a variety of carbon systems. Using resonance Raman spectroscopy as a probe for optical transitions in a system, a careful quantitative estimate of the Raman cross-section of graphite in the pre-resonance regime has been made. Raman and resonance Raman spectroscopy have been used to correlate the structural and electronic properties of amorphous carbon materials. The low optical gaps and e-2e spectroscopy measurements on evaporated carbon films suggests a structure close to graphite. Raman measurements, however, reveal a great amount of disorder in the material. This apparent contradiction has been resolved through the use of a phenomenological model for the electronic density of states for amorphous carbon systems. Raman spectroscopy has also been used to study the vibrational and the electronic properties of the recently discovered third allotrope of carbon, C[sub 60]. The vibrational modes of this molecule have been studied in great detail. The observed vibrational spectra confirms earlier work in this material. Furthermore, the mode frequencies have been found to be in reasonably good agreement with theoretical predictions. Resonance Raman studies of solid C[sub 60] and C[sub 60] dissolved in solvents has revealed, in the solid phase, the existence of optical transitions well below the symmetry allowed transitions for the isolated molecules. Loss of inversion symmetry in the solid state has been proposed to account for the resonance observed in the Raman excitation profile. Original Raman measurements on C[sub 60] revealed a strong peak at 1469 cm[sup [minus]1]. The peak was found to obey the correct selection rule for symmetric A[sub g] mode and was assigned to the [open quotes]pentagonal pinch[close quotes] mode of the molecule.

  8. 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.

  9. 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.

  10. Fe-57 Moessbauer Spectroscopy of Fulgurites: Implications for Chemical Reduction

    NASA Technical Reports Server (NTRS)

    Sheffer, A. A.; Dyar, M. D.

    2004-01-01

    The high temperature (superliquidus) processing of silicates often results in very reduced products, such as Si-bearing Fe metal in type-1 chondrules and in lunar regolith agglutinates. Previous work on fulgurites (the glassy products of the lightning strike fusion of sand, soil, or rock) found silicon metal and iron-silicon alloys inside the silicate glass. The mechanism for this extreme reduction is not yet understood. In this work, we begin a Fe-57 Moessbauer spectroscopy study as well as continuing a microprobe study of several fulgurites in order to better constrain the extent and process of Fe reduction.

  11. 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...

  12. 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

  13. Time-differential perturbed-angular-correlation and emission Moessbauer studies on {sup 99}Ru dispersed in YBa{sub 2}Cu{sub 3}O{sub 6.8} and YBa{sub 2}Cu{sub 3}O{sub 6}

    SciTech Connect

    Ohkubo, Y.; Kobayashi, Y.; Harasawa, K.; Ambe, S.; Okada, T.; Ambe, F.; Asai, K.; Shibata, S.

    1995-06-29

    The hyperfine interactions at {sup 99}Ru({sup $IMP@99}Rh) dispersed in YBa{sub 2}Cu{sub 3}O{sub 6.8} and YBa{sub 2}Cu{sub 3}O{sub 6} were studied by means of time-differential perturbed-angular-correlation (TDPAC) and emission Moessbauer spectroscopy. The TDPAC and Moessbauer measurements show that Ru ions are in the tetravalent state and exclusively occupy the Cu-1 sites, which form one-dimensional Cu-O chains in the orthorhombic phase. The oxygen coordinations around the Ru ions are discussed on the basis of the observed electric field gradients at {sup 99}Ru in YBa{sub 2}Cu{sub 3}O{sub 6.8} and YBa{sub 2}Cu{sub 3}O{sub 6}. 35 refs., 6 figs., 1 tab.

  14. Structure and oscillational motion of /sup 57/Fe atoms in interstitial sites in Al as determined from interference of Moessbauer. gamma. radiation

    SciTech Connect

    Pauling, L.

    1981-12-01

    The first excited site of the /sup 57/Fe atom entrapped in an interstitial site in aluminum, as reported by W. Petry, G. Vogl, and W. Mansel (Phys. Rev. Lett. 45, 1862 (1980)) from a Moessbauer spectroscopic study of a single crystal, is analyzed by consideration of the value of the Hooke's law constant of the Fe-Al bonds obtained from the values for elemental Fe and Al. The eight wavefunctions for the eightfold nearly degenerate excited state are described as 2s1p1d1f hybrids of three-dimensional harmonic oscillator wavefunctions relative to the center of the undistorted Al/sub 6/ octahedron or as localized 1s functions relative to the center of the distorted octahedron. These considerations provide a qualitative understanding of the observations on this system.

  15. 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

  16. Analysis of Moessbauer Data from Mars: A Database and Artificial Neural Network for Identification of Iron-bearing Phases

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; deSouza, P. A.; Morris, R. V.; Klingelhoefer, G.

    2003-01-01

    The exploration of the planet Mars is one of the major goals within the Solar system exploration programs of the US-American space agency NASA and the European Space Agency ESA. In particular the search for water and life and understanding of the history of the surface and atmosphere will be the major tasks of the upcoming space missions to Mars. The miniaturized Moessbauer spectrometer MIMOS II has been selected for the NASA Mars-Exploration-Rover twin-mission to Mars in 2003 and the ESA 2003 Mars-Express Beagle 2 mission. Reduced in size and weight, in comparison to ordinary laboratory setup, the sensor head just weights approximately 400 g, with a volume of (50x50x90) cu mm, and holds two gamma-ray sources: the stronger for experiments and the weaker for calibrations. The collimator (in sample direction) also shields the primary radiation off the detectors. Around the drive four detectors are mounted. The detectors are made of Si-PIN-photodiodes in chip form (100 sq mm, thickness of 0.5 mm). The control unit is located in a separate electronics board. This board is responsible for the power supply, generation of the drive's velocity reference signal, read of the detector pulses to record the spectrum, data storage and communication with the host computer. After more than four decades from the discovery of the Moessbauer effect, more than 400 minerals were studied at different temperatures. Their Moessbauer parameters were reported in the literature, and have been recently collected in a data bank. Previous Mars-missions, namely Viking and Mars Pathfinder, revealed Si, Al, Fe, Mg, Ca, K, Ti, S and Cl to be the major constituents in soil and rock elemental composition of the red planet. More than 200 minerals already studied by Moessbauer spectroscopy contain significant amounts of these elements. A considerable number of Moessbauer studies were also carried out on meteorites and on Moon samples. Looking backward in the studies of the whole Moessbauer community

  17. 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.

  18. Magnetic properties and Moessbauer analyses of glass from the K-T boundary, Beloc, Haiti

    NASA Technical Reports Server (NTRS)

    Senftle, F. E.; Thorpe, A. N.; May, L.; Barkatt, A.; Adel-Hadadi, M. A.; Marbury, G. S.; Izett, G.; Sigurdsson, H.; Maurasse, F. J.-M. R.

    1993-01-01

    The experimental magnetic susceptibility, the temperature-independent component of the magnetic susceptibility, the magnetization, and the Curie constant have been measured for a number of specimens of glass from the K-T boundary found at Beloc, Haiti, and the results are compared with those of similar measurements of tektites. Because the Fe(3+)/Fe(2+) ratio is needed to calculate the magnetic parameters, Moessbauer spectroscopic measurements were also made. The data were consistent with the classification of the Beloc glasses as tektites.

  19. Electron Spin Resonance Spectroscopic Studies of Radical Cation Reactions.

    NASA Astrophysics Data System (ADS)

    Dai, Sheng

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra in this work is derived by using the general effective Hamiltonian theory in the usual Schrodinger 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 is derived through the use of 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 syn-sesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl_3 matrix at low temperature. The ESR spectra of the former radical cation exhibit a novel alternating linewidth effect arising from an internal relation between the coupling constants for the four equivalent pairs of hydrogens. 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 shown to be the 3-iminiopropyl distonic species(3-iminium-1-propyl radical) resulting from a symmetry-allowed 1,2-hydrogen shift in the parent radical cation. The nucleophilic endocyclization 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-hexadiyne have resulted in the first spectroscopic characterization of the radical cation Cope rearrangement, the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5 -hexatetraene radical cation. ESR studies show that the symmetric(C_{rm 2v}) bicyclo (3.3.0) -octa-2,6-diene-4,8-diyl(a bridged 1,4 -bishomobenzene species) radical cation is

  20. Photometric and spectroscopic study of cD galaxies

    NASA Astrophysics Data System (ADS)

    Kemp, S. N.; Pérez-Hernández, Ernesto; Ramírez-Siordia, Víctor Hugo

    2016-02-01

    We have carried out photometry and spectroscopy on a sample of 10 cD galaxies. The photometry shows, in general, fairly flat and red profile colours, implying an envelope with the same stellar population as the central galaxy. This may indicate a possible primordial origin for both structures, consistent with ideas of downsizing. Preliminary spectroscopic results are generally in agreement with the photometry, with for example younger populations at large radii for A2199, but A2589 has only younger populations.

  1. Spectroscopic ellipsometry study of novel nanostructured transparent conducting oxide structures

    NASA Astrophysics Data System (ADS)

    Khosroabadi, Akram A.; Norwood, R. A.

    2013-02-01

    Spectroscopic ellipsometry has been used to find the optical constants, including refractive index, extinction coefficient, thickness and volume fraction of nanostructured transparent conducting oxides including indium tin oxide (ITO) and indium zinc oxide (IZO). We observed sharp features in the ellipsometry data, with the spectral peaks and positions depending on the nanostructure dimensions and material. A superposition of Lorentzian oscillators and the effective medium approximation has been applied to determine the volume ratio of voids and nanopillars, thereby providing the effective optical constants.

  2. 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

  3. 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

  4. Spectroscopic studies of gas-phase molecular clusters

    NASA Astrophysics Data System (ADS)

    Wong, Chi-Kin

    Spectroscopic investigations of hydrogen-bonding and van der Waals' interactions in molecular clusters were studied by the techniques of infrared predissociation and resonance-enhanced multiphoton ionization spectroscopies (REMPI). Ab initio calculations were applied in conjunction for data interpretation. The infrared predissociation spectroscopy of CN-·(H 2O)n (n = 2--6) clusters was reported in the region of 2950--3850 cm-1. The hydrogen bondings for the C-site and N-site binding, and among the water molecules were identified for n = 2 to 4. A spectral transition was observed for n = 5 and 6, implying that the anion was surface-bound onto the water aggregates in larger clusters. The infrared predissociation spectroscopy of Br-·(NH 3) and I-·(NH3) n (n = 1--3) clusters was reported in the region of 3050--3450 cm-1. For the Br -·(NH3) complex, a dominating ionic NH stretch appeared at 3175 cm-1, and the weaker free NH stretch appeared at 3348 cm-1. The observed spectrum was consistent to the structure in which there was one nearly linear hydrogen bond between Br- and the NH3 moiety. For the I- ·(NH3) complex, five distinct IR absorption bands were observed in the spectrum. The spectrum was not consistent with basic frequency patterns of three geometries considered in the ab initio calculations---complex with one, two and three hydrogen bondings between I- and the NH3 moiety. Substantial inhomogenous broadening were displayed in the spectra for I- ·(NH3)n (n = 2--3), suggesting the presence of multiple isomers. The REMPI spectroscopy of the bound 4p 2pi 1/2 and 2pi3/2 states, and the dissociative 3d 2Sigma+1/2 state in the Al·Ar complex was reported. The dissociative spectrum at Al+ channel suggested the coupling of the 4p 2pi 1/2,3/2 states to the repulsive 3d 2Sigma+1/2 state. The spin-electronic coupling was further manifested in the dissociative Al+ spectrum of the 3d 2Sigma+1/2 state. Using the potential energy curves obtained from ab initio

  5. 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.

  6. Mineralogical and Geochemical Analyses of Antarctic Lake Sediments: A Reflectance and Moessbauer Spectroscopy Study with Applications for Remote Sensing on Mars

    NASA Technical Reports Server (NTRS)

    Froeschl, Heinz; Lougear, Andre; Trautwein, Alfred X.; Newton, Jason; Doran, Peter T.; Koerner, Wilfried; Koeberl, Christian; Bishop, Janice (Technical Monitor); DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Lakebottom sediments from the Dry Valleys region of Antarctica have been analyzed here in order to study the influence of water chemistry on the mineralogy and geochemistry of these sediments, as well as to evaluate techniques for remote spectral identification of potential biomarker minerals on Mars. Lakes from the Dry Valleys region of Antarctica have been investigated as possible analogs for extinct lake environments on early Mars. Sediment cores were collected in the present study from perennially ice-covered Lake Hoare in the Taylor Valley. These sediments were taken from a core in an oxic region of the lake and another core in an anoxic zone. Differences between the two cores were observed in the sediment color, Fe(II)/Fe(III) ratio, the presence of pyrite, the abundance of Fe, S and some trace elements, and the C, N and S isotope fractionation patterns. The results of visible-infrared reflectance spectroscopy (0.3-25 microns) Mossbauer spectroscopy (77 and 4 K) and X-ray diffraction are combined to determine the mineralogy and composition of these samples. The sediments are dominated by plagioclase, K-feldspar, quartz and pyroxene. Algal mats grow on the bottom of the lake and organic material has been found throughout the cores. Calcite is abundant in some layers of the aerobic core (shallow region) and pyrite is abundant in some layers of the anaerobic core (deep region). Analysis of the spectroscopic features due to organics and carbonates with respect to the abundance of organic C and carbonate contents was performed in order to select optimal spectral bands for remote identification of these components in planetary regoliths. Carbonate bands near 4 and 6.8 microns (approx.2500 and 1500/cm) were detected for carbonate abundances as low as 0.1 wt.% CO2. Organic features at 3.38, 3.42 and 3.51 microns (2960, 2925 and 2850/cm) were detected for organic C abundances as low as 0.06 wt.% C. The d13C trends show a more complex organic history for the anaerobic

  7. {sup 57}Fe Moessbauer and x-ray magnetic circular dichroism study of magnetic compensation of the rare-earth sublattice in Nd{sub 2-x}Ho{sub x}Fe{sub 14}B compounds

    SciTech Connect

    Chaboy, J.; Piquer, C.; Plugaru, N.; Bartolome, F.; Laguna-Marco, M. A.

    2007-10-01

    We present here a study of the magnetic properties of the Nd{sub 2-x}Ho{sub x}Fe{sub 14}B series. The macroscopic properties of these compounds evolve continuously from those of Nd{sub 2}Fe{sub 14}B to those of Ho{sub 2}Fe{sub 14}B as Ho gradually replaces Nd. The system shows a compensation of the rare-earth sublattice magnetization for a critical concentration, x{sub c}=0.55, that is reflected into the anomalous behavior of both macroscopic and microscopic magnetic probes. The combined analysis of magnetization, {sup 57}Fe Moessbauer spectroscopy and Fe K-edge x-ray magnetic circular dichroism (XMCD) measurements suggests that the origin of the anomalous magnetic behavior found at x{sub c}=0.55 is mainly due to the Ho sublattice. Moreover, the analysis of the Fe K-edge XMCD signals reveal the presence of a rare-earth contribution, reflecting the coupling of the rare-earth and Fe magnetic moments, which can lead to the possibility of disentangling the magnetic behavior of both Fe and R atoms using a single absorption edge.

  8. IR spectroscopic study of the chemical composition of epiphytic lichens

    NASA Astrophysics Data System (ADS)

    Meysurova, A. F.; Khizhnyak, S. D.; Pakhomov, P. M.

    2011-11-01

    Changes in the chemical composition of lichens exposed to pollutants are investigated by means of FTIR spectroscopy. According to model experiments, alkyl nitrates, ammonium salts, amines, and sulfones develop in the lichen thallus through the action of ammonia and nitric and sulfuric acids. Spectroscopic data of modeling experiments enabled nitrogen- and sulfur-containing substances to be identified as the main air pollutants in the vicinity of a pig-breeding complex and information to be obtained on the content of the pollutants and their impact on the lichens.

  9. 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.

  10. Resonance Raman spectroscopic studies of enzymesubstrate intermediates at 5 K

    NASA Astrophysics Data System (ADS)

    Kim, Munsok; Carey, Paul R.

    1991-01-01

    A simple and versatile system for resonance Raman (RR) spectroscopic analysis of enzymesubstrate complexes at liquid helium temperatures is described. The system allows us to record high-quality RR spectra for dithioacyl papain intermediates (MeO-Phe-Gly- and MeO-Gly-Gly-Phe-Gly-C (dbnd S)S-papain) in ice matrices at 5 K. Based on established structure-spectra correlations, it is concluded that the active-site conformation of the intermediates about the φ', ψ' glycinic linkages and cysteine-25 side chain is B-G+-PH both in ice matrices at 5 K and in solution at room temperature.

  11. 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.

  12. Spectroscopic study of carbonaceous dust particles grown in benzene plasma

    SciTech Connect

    Lee, Szetsen; Chen, H.-F.; Chin, C.-J.

    2007-06-01

    Carbonaceous dust particles have been synthesized from benzene using an rf glow discharge. Scanning electron microscope inspection revealed that the plasma-synthesized dust particles can be classified into two types. Shell-structured dust particles showed a wide size distribution from 3 to40 {mu}m. The other type, with different degrees of aggregation, appeared to be dense and spherical with a very distinctive yellow color and size distribution from 100 nm to 2 {mu}m. Analyses using micro-Raman and Fourier transform infrared microscopy indicated that the main components of the dust particles are polyphenyls and hydrogenated amorphous carbon (HAC). The luminescence background in Raman spectra and the infrared C-H stretching vibrational features observed around 3.4 {mu}m for the dust particles are attributed to HAC. The formation mechanisms and spectroscopic characterization of carbonaceous dust particles are discussed.

  13. Spectroscopic intravascular photoacoustic imaging of neovasculature: phantom studies

    NASA Astrophysics Data System (ADS)

    Su, Jimmy L.; Wang, Bo; Emelianov, Stanislav Y.

    2009-02-01

    An acceleration of angiogenesis in the adventitial vasa-vasorum is usually associated with vulnerable, thin-cap fibroatheroma in atherosclerotic plaques. Angiogenesis creates microvasculature too small to be detected and differentiated using conventional imaging techniques. However, by using spectroscopic photoacoustic imaging, we take advantage of the wavelength-dependent optical absorption properties of blood. We used a vessel-mimicking phantom with micro blood vessels. The phantom was imaged with intravascular photoacoustic imaging across a range of wavelengths. The image intensities were cross-correlated with the known absorption spectra of blood. The resulting cross-correlation image was able to reveal the location of the artificial blood vessels differentiated from non-blood vessel components.

  14. Spectroscopic studies of superconductors. Part A: Infrared and Raman spectra

    SciTech Connect

    Bozovic, I.; Marel, D. van der

    1996-12-31

    During the ten years that followed the discovery of superconductivity above 30 K in lanthanum barium cuprate by Bednorz and Mueller, the condensed matter physics community has been engaged in an unprecedented worldwide effort in materials processing, characterization of physical properties, and theoretical modeling of superconductors. The present conference has brought together a group of researchers who are actively involved in the experimental determination of the physical properties of high-{Tc} superconductors, the quest for the microscopic mechanism (or mechanisms) of superconductivity, the search for new physical phenomena in these materials, or the search for new classes of superconducting materials. The distinguishing feature and the unifying theme of this conference was the use of spectroscopic techniques as the primary tools in pursuing these goals. Separate abstracts were prepared for 32 papers in this conference.

  15. A spectroscopic study of uranium(VI) interaction with magnetite

    NASA Astrophysics Data System (ADS)

    Aamrani, S. El; Giménez, J.; Rovira, M.; Seco, F.; Grivé, M.; Bruno, J.; Duro, L.; de Pablo, J.

    2007-08-01

    The uranium sorbed onto commercial magnetite has been characterized by using two different spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS). Magnetite samples have been put in contact with uranium(VI) solutions in conditions in which a high uranium uptake is expected. After several days, the magnetite surface has been analysed by XPS and EXAFS. The XPS results obtained are not conclusive regarding the uranium oxidation state in the magnetite surface. On the other hand, the results obtained with the EXAFS technique show that the uranium-magnetite sample spectrum has characteristics from both the UO 2 and schoepite spectra, e.g. a relatively high coordination number of equatorial oxygens and two axial oxygens, respectively. These results would indicate that the uranium sorbed onto magnetite would be a mixture of uranium(IV) and uranium(VI).

  16. In-situ spectroscopic studies of electrochromic tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Ozer, Nilgun; Demirbas, Muharrem; Ozyurt, Secuk

    2001-11-01

    Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl6) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO3 structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO3/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm2/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

  17. Charge Transfer in FeOCl Intercalation Compounds and its Pressure Dependence: An X-ray Spectroscopic Study

    SciTech Connect

    I Jarrige; Y Cai; S Shieh; H Ishii; N Hiraoka; S Karna; W Li

    2011-12-31

    We present a study of charge transfer in Na-intercalated FeOCl and polyaniline-intercalated FeOCl using high-resolution x-ray absorption spectroscopy and resonant x-ray emission spectroscopy at the Fe-K edge. By comparing the experimental data with ab initio simulations, we are able to unambiguously distinguish the spectral changes which appear due to intercalation into those of electronic origin and those of structural origin. For both systems, we find that about 25% of the Fe sites are reduced to Fe{sup 2+} via charge transfer between FeOCl and the intercalate. This is about twice as large as the Fe{sup 2+} fraction reported in studies using Moessbauer spectroscopy. This discrepancy is ascribed to the fact that the charge transfer occurs on the same time scale as the Moessbauer effect itself. Our result suggests that every intercalated atom or molecule is involved in the charge-transfer process, thus making this process a prerequisite for intercalation. The Fe{sup 2+} fraction is found to increase with pressure for polyaniline-FeOCl, hinting at an enhancement of the conductivity in the FeOCl intercalation compounds under pressure.

  18. Inelastic scattering in condensed matter with high intensity Moessbauer radiation. Final technical report, December 1, 1989--November 30, 1992

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1993-02-01

    The QUEGS facility at MURR has produced a number of new results and demonstrated the range of potential applications of high resolution, high intensity Moessbauer scattering. This work has been carried out by both MU and Purdue researchers and includes published results on Na, W, pentadecane, polydimethylsiloxane and other systems, manuscripts submitted on alkali halides (Phys. Rev. B) and accurate Moessbauer lineshape measurements (Phys. Rev. C), and manuscripts in preparation on glycerol, NiAl and Moessbauer spectra obtained by modulating a scattering crystal. Recently, new collaborations have been initiated which will substantially enhance our efforts. These are with W. Steiner (Vienna), G. Coddens (Saclay), and R. D. Taylor (Los Alamos). Steiner is experienced with Fe-57 Moessbauer scattering, while Coddens specializes in quasielastic neutron scattering; both of these areas naturally complement our work. R. D. Taylor has pioneered Moessbauer spectroscopy from the time of its discovery and has already made important contributions to our study of lattice dynamics and superconductivity for lead alloyed with small quantities of tin. At the same time, a significant instrument upgrade is underway, funded in part by the DOE-URIP program.

  19. 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.

  20. 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 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.

  1. Studies of Two Massive Eclipsing Double-lined Spectroscopic Binaries

    NASA Astrophysics Data System (ADS)

    Williams, Stephen J.; Gies, D. R.; Hillwig, T. C.; McSwain, M. V.; Huang, W.

    2013-06-01

    As part of an ongoing investigation into the spectroscopic variability of massive stars, we present preliminary results for two double-lined eclipsing binary systems, HD 130146 (VZ Cen) and LS 3052 (V 1176 Cen). In our analysis we used archival Hipparcos photometry for HD 103146 and All Sky Automated Survey V-band photometry for LS 3052. All spectra were obtained from the Cerro Tololo Inter-American Observatory 1.5-m telescope. The systems were analyzed using the Eclipsing Light Curve code (ELC; Orosz & Hauschildt 2000). A combined analysis of these data yields masses, radii, effective temperatures, gravities, and estimates for the ages and distances of each system. HD 103146 is a 4.9 day binary with a slightly evolved primary (T_{eff} 28000 K and log g 3.75) while the secondary nearly fills its Roche lobe. LS 3052 has an eccentric orbit with a period of 31 days and contains both an evolved primary and secondary. Preliminary solutions indicate the primary's mass to be 33 Mo with a 21 Mo secondary.

  2. 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.

  3. 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.

  4. 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.

  5. 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

    2015-12-01

    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. PMID:26151435

  6. Spectroscopic studies of the small-amplitude Cepheid SU Cas

    NASA Astrophysics Data System (ADS)

    Usenko, I. A.; Klochkova, V. G.; Tavolzhanskaya, N. S.

    2013-09-01

    A new set of 16 high-resolution spectra for the small-amplitude Cepheid SU Cas obtained in 2007-2009 has allowed us to determine its atmospheric parameters ( T eff = 6345 ± 30 K, log g = 2.40, V t = 3.25 km s-1) and to measure its radial velocities. The latter were added to the general list of radial velocities (375 estimates) obtained in the last 90 years. Using a frequency analysis, we have refined the pulsation and orbital periods of the Cepheid. Apart from the well-known fundamental pulsation period [Figure not available: see fulltext.], we have detected a possible secondary period of [Figure not available: see fulltext.]. Their ratio of 0.96 suggests the existence of nonradial pulsations in the Cepheid's atmosphere. Based on photoelectric photometry in the last 60 years, we have shown that the effective temperature undergoes cyclic secular changes of ±200 K with an unknown period. The mean effective temperature T eff = 6395 ± 52 K estimated from photometric data agrees well with our estimate from spectroscopic data. The variations of the mean color index, effective temperature, and γ-velocity (in 90 years of observations) point to a possible orbital motion of the well-known hot companion with the most probable periods of [Figure not available: see fulltext.], [Figure not available: see fulltext.], and [Figure not available: see fulltext.]. The elemental abundances in the atmosphere of SU Cas confirm the conclusion that this Cepheid is a typical yellow supergiant after the first dredge-up. Our T eff estimate gives a radius of 32 R ⊙ and a distance of 455 pc for it, which is inconsistent with its membership in the open cluster Alessi 95. The question about the pulsation mode of SU Cas still remains open.

  7. Pump probe based Raman spectroscopic studies of PTFE under laser driven shock compression

    NASA Astrophysics Data System (ADS)

    Rastogi, Vinay; Rao, Usha; Chaurasia, S.; Mishra, A. K.; Poswal, H. K.; Deo, M. N.; Sharma, S. M.

    2016-05-01

    High pressure spontaneous Raman spectroscopic studies of poly tetra fluro ethylene (PTFE) have been carried out under laser driven shock compression in confinement geometry target. The Raman modes under shock compression as a function of pressure were measured and compared with the corresponding Raman modes in static pressure experiments. Our results indicate that PTFE undergoes transition to phase III across this pressure.

  8. Moessbauer spectrometer for mineralogical analysis of the Mars surface: Moessbauer source considerations

    NASA Technical Reports Server (NTRS)

    Evlanov, E. N.; Frolov, V. A.; Prilutskii, O. F.; Veselova, G. V.; Rodin, A. M.; Klingelhoefer, G.

    1993-01-01

    Development of space rocketry and cosmic instrument making has made it possible to create interplanetary stations to be sent to the solar system bodies. In the last decade of the century the planet Mars will be in the focus of planetary science problems. Russia, USA (the NASA) and Europe (the ESA) plan to do a new step in the study of the planetary system by spacecraft missions to Mars. One part of the programs of these missions is Martian surface measurements of iron, which is a dominant element in both the Martian soil and rocks (about 13 percent by weight). The chemistry of iron in space is strongly coupled to the chemistry of abundant elements (to begin with hydrogen, carbon, oxygen) and it is this coupling of chemical cycles of abundant elements that gives us the possibility of understanding some features of the chemical evolution of matter. In this connection of extremely great importance for the understanding of the evolution of the solar system are the oxidation state of the iron and its mineral composition of the Mars surface. Being highly successful, the Viking landers had no instrumentation to answer these questions. Such instrumentation has to be specifically sensitive to mineralogy. For this purpose the back scattering Moessbauer spectrometer (MS-96) was proposed to be installed on a rover to be launched on board the Russian spacecraft Mars-96 mission to Mars. Due to power and mass restrictions three systems of the device MS-96 (velocity transducer, detector and electronic components) have been extremely miniaturized in comparison to a standard system. In this paper we intend to place for consideration a radioactive source to find out what characteristics it should have to be suitable for purposes of the experiment.

  9. XRD and {sup 119}Sn Moessbauer spectroscopy characterization of SnSe obtained from a simple chemical route

    SciTech Connect

    Bernardes-Silva, Ana Claudia . E-mail: anaclaudiabs2000@yahoo.com.br; Mesquita, A.F.; Moura de Neto, E.; Porto, A.O. . E-mail: arilzaporto@yahoo.com.br; Ardisson, J.D.; Lameiras, F.S.

    2005-09-01

    Crystalline tin selenide semiconductor was synthesized by a chemical route. Selenium powder reacted with potassium boronhydride, giving a soluble selenium species potassium seleniumhydride. The reaction of potassium seleniumhydride with tin chloride produced crystalline tin selenide, which was characterized by X-ray diffraction, {sup 119}Sn Moessbauer spectroscopy and scanning electronic microscopy. The material was thermally treated, in nitrogen flow, at 300 and 600 deg. C for 2 h and the particle size evolution was studied by X-ray diffraction. The X-ray diffraction and {sup 119}Sn Moessbauer results showed that a mixture of tin oxides and orthorhombic tin selenide was obtained.

  10. 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

    2005-08-01

    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. PMID:15856523

  11. 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.

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

    SciTech Connect

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

    1990-01-01

    The formyl radical and the acetylene molecule were chosen for these studies. The visible and fluorescence spectra of the formyl radical were recorded, and the spectral results are used as a basis to explain the electronic structure. Optical-optical double resonance studies of acetylene were recorded, and the spectral results are interpreted. The results of Zeeman and Stark anticrossing and quantum beat studies of acetylene are reported, and they provide an unusually detailed view of both Intersystem Crossing and Internal Conversion in small polyatomic molecules. 22 references are cited as resulting from Department of Energy sponsorship of this project.

  13. Spectroscopic study of the humification process during sewage sludge treatment

    NASA Astrophysics Data System (ADS)

    Pajączkowska, J.; Sułkowska, A.; Sułkowski, W. W.; Jędrzejczyk, M.

    2003-06-01

    The aim of this work was to study the free radical transition of organic materials during the sewage treatment process. Investigations of sludge from biologic-mechanical sewage treatment plant in Sosnowiec Zagórze were carried out. The course of the humification processes during sewage treatment was studied by electron paramagnetic resonance (EPR) technique. The concentration of free radicals at each process stage and the value g were determined. Sludge samples and extracted fractions of humic acids were examined. Humic acids were extracted from sludge by means of conventional methods elaborated by Stevenson. For study of humic acids structures, besides EPR, the UV-Vis and IR spectroscopy were used.

  14. Laser-induced breakdown spectroscopic study of ammonium nitrate plasma

    SciTech Connect

    Hanif, M.; Salik, M.; Baig, M. A.

    2013-12-15

    We present the optical emission studies of the ammonium nitrate plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser. The target material was placed in front of the laser beam in an open atmospheric air. The spectrum reveals numerous transitions of neutral nitrogen. We have studied the spatial behavior of the plasma temperature (T{sub e}) and electron number density (N{sub e}) determined using the Boltzmann plot method and Stark broadened line profiles, respectively. Besides, we have studied the variation of the plasma parameters as a function of the laser irradiance.

  15. 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.

  16. 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...

  17. Moessbauer analysis of heat affected zones of an SA 508 steel weld

    SciTech Connect

    Kwon, S.J.; Oh, S.J.; Kim, S.; Lee, S.; Kim, J.H.

    1998-12-18

    Microstructure of a heat affected zone (HAZ) in a weld is influenced by many factors such as chemical composition, welding condition, and peak temperature. It is more complex under multi-pass welding because of the repeated heat input. For the analysis of the HAZ microstructure, optical microscope, electron microscope, and X-ray diffraction techniques have been widely used. However, their application is limited since they can hardly make quantitative analysis of HAZ where numerous phases such as martensite, bainite, ferrite, pearlite, austenite, and carbides are co-existing. Moessbauer spectroscopy, in such a case, is particularly useful due to the capability of quantitative analysis on the fraction of each phase. In this study, phases present in the HAZ of an SA 508 steel were identified, and their fractions were quantitatively determined by Moessbauer spectroscopy in conjunction with microscopic observations.

  18. Moessbauer search for ferric oxide phases in lunar materials and simulated lunar materials

    NASA Technical Reports Server (NTRS)

    Forester, D. W.

    1973-01-01

    Moessbauer studies were carried out on lunar fines and on simulated lunar glasses containing magnetic-like precipitates with the primary objective of determining how much, if any, ferric oxide is present in the lunar soils. Although unambiguous evidence of lunar Fe(3+) phases was not obtained, an upper limit was estimated from different portions of the Moessbauer spectra to be between 0.1 and 0.4 wt.% (as Fe3O4). A smaller than 62 microns fraction of 15021,118 showed 0.5 wt.% ferromagnetic iron at 300 K in as-returned condition. After heating to 650 C in an evacuated, sealed quartz tube for 1400 hours, the same sample exhibited 1 wt.% ferromagnetic iron at room temperature. An accompanying decrease in excess absorption area near zero velocity was noted. Thus, the result of the vacuum heat treatment was to convert fine grained iron to larger particles, apparently without the oxidation effects commonly reported.

  19. Sum frequency generation vibrational spectroscopic studies on buried heterogeneous biointerfaces.

    PubMed

    Zhang, Chi; Jasensky, Joshua; Leng, Chuan; Del Grosso, Chelsey; Smith, Gary D; Wilker, Jonathan J; Chen, Zhan

    2014-05-01

    A sum frequency generation (SFG) vibrational micro-spectroscopy system was developed to examine buried heterogeneous biointerfaces. A compact optical microscope was constructed with total-internal reflection (TIR) SFG geometry to monitor the tightly focused SFG laser spots on interfaces, providing the capability of selectively probing different regions on heterogeneous biointerfaces. The TIR configuration ensures and enhances the SFG signal generated only from the sample/substrate interfacial area. As an example for possible applications in biointerfaces studies, the system was used to probe and compare buried interfacial structures of different biological samples attached to underwater surfaces. We studied the interface of a single mouse oocyte on a silica prism to demonstrate the feasibility of tracing and studying a single live cell and substrate interface using SFG. We also examined the interface between a marine mussel adhesive plaque and a CaF2 substrate, showing the removal of interface-bonded water molecules. This work also paves the way for future integration of other microscopic techniques such as TIR-fluorescence microscopy or nonlinear optical imaging with SFG spectroscopy for multimodal surface or interface studies. PMID:24784085

  20. Photoemission Spectroscopic Study of Cesium Telluride Thin Film Photocathode

    SciTech Connect

    Sugiyama, Harue; Ogawa, Koji; Azuma, Junpei; Takahashi, Kazutoshi; Kamada, Masao

    2009-08-04

    The photoemission spectroscopy using synchrotron radiation has been carried out to study the high quantum efficiency and long working lifetime of cesium telluride (Cs{sub x}Te{sub y}) thin film photocathode. The electron affinity derived from the observed energy-distribution curves provides an important hint for long persistency of the photocathode.

  1. 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 ...

  2. Structural, Magnetic and Spectroscopic Studies of Thin Manganite Films

    NASA Astrophysics Data System (ADS)

    Tyson, T. A.

    2003-03-01

    Starting from early experiments [1], evidence has been found for a close coupling of strain and the magnetotransport properties of manganite films. The characteristic feature found is that the metal to insulator transition temperature (TMI) is suppressed in very thin films [2]. In addition, studies show that the magnetic transition temperature (Tc) and TMI decouple in ultrathin films [3]. Systematic magnetization studies reveal that strain induces strong magnetic anisotropy [4]. Theoretical work also points to the sensitivity of Tc to biaxial strain [5]. Most studies have focused on single bulk properties. In order to understand the correlations between strain and the transport and magnetic properties we have examined the structure of films on multiple length scales. The local structure of films have been studies by x-ray absorption spectroscopy. The long -range structure has been studied by high-resolution x-ray diffraction and the microstructure has been studied by AFM measurements. These measurements are correlated with bulk magnetization and transport studies. Insight is gained on the evolution of lattice strain and Jahn-Teller distortions with thickness. Direct evidence is found for the arrest of charge ordering with strain and the existence of strain induced insulating regions of films. The magnetic ordering and transport properties as a function of strain as compared with bandstructure calculations. This work is supported by NSF Career Grant DMR-9733862 and DMR-0209243. Collaborators: Q. Qian, M. Deleon (NJIT), C. Dubourdiu (CNRS), J. Bai (ORNL), W. Prellier, A. Biswas, R. L. Greene (U. Maryland) [1] S. Jin et al., Appl. Phys. Lett. 67, 557 (1995). [2] (a) J. Z. Sun et al. Appl. Phys. Lett. 74, 3017 (1999). (b) F. S. Razi et al., Appl. Phys. Lett 76, 155 (2000) [3] J. Aarts et al., Appl. Phys. Lett. 72, 2975 (1998). (b) R. A. Rao et al., J. Appl. Phys. 85, 4794 (1999). [4] (a) X. W. Wu et al., Phys. Rev. B 61, 501 (2000). (b) J. O'Donnell et al., Appl. Phys

  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. Spectroscopic studies of laser ablation plumes of artwork materials

    NASA Astrophysics Data System (ADS)

    Oujja, M.; Rebollar, E.; Castillejo, M.

    2003-04-01

    Studies on the plasma plume created during KrF laser (248 nm) ablation of dosimeter tempera samples in vacuum have been carried out to investigate the basic interactions of the laser with paint materials. Time resolved optical emission spectroscopy (OES) was used to measure the translational velocity of electronically excited transients in the plasma plume. Laser-induced fluorescence (LIF) studies using a probe dye laser, allowed to determine the velocities of non-emitting species. The propagation velocities of C 2 in the a 3π u and d 3π g electronic states and of excited atomic species are indicative of a high translational temperature. Differences between the velocities of organic and inorganic species and between emissions from the tempera systems and from the pigments as pellets allow to discuss the participation of photochemical mechanisms in the laser irradiation of the paint systems.

  5. Thiosaccharine disulfide: Synthesis, crystal structure, spectroscopic characterization and theoretical study

    NASA Astrophysics Data System (ADS)

    Ferullo, Ricardo M.; Granados, Alejandro; Lanterna, Anabel; Güida, Jorge A.; Piro, Oscar E.; Castellano, Eduardo E.; Dennehy, Mariana

    2013-01-01

    The title compound, (thiosaccharine disulfide), bis[1,1'dioxide-2,3-dihidro-1,2-benzoisothiazol]disulfide, (tsac)2 has been synthesized and fully characterized by UV-Visible, IR, Raman, 1H and 13C NMR spectroscopy elemental analysis and structural X-ray crystallography. A DFT theoretical study has been performed and good agreement between experimental and theoretical values of structural parameters and vibration frequencies have been achieved.

  6. 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.

  7. 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.

  8. Raman microprobe spectroscopic studies of solid DNA-CTMA films

    NASA Astrophysics Data System (ADS)

    Yaney, Perry P.; Ahmad, Faizan; Grote, James G.

    2008-08-01

    Extensive studies have been carried out on developing the new biopolymer, deoxyribonucleic acid (DNA) derived from salmon, that has been complexed with a surfactant to make it water insoluble for application to bioelectronic and biophotonic devices. One of the key issues associated with the properties and behavior of solid films of this material is the extreme size of the >8 MDa molecular weight of the virgin, as-received material. Reduction of this molecular weight by factors of up to 40 is achieved by high power sonication. To support the various measurements that have been made to confirm that the sonicated material is still double strand DNA and to look for other effects of sonication, Raman studies were carried out to compare the spectra over a wide range of molecular weights and to develop baseline data that can be used in intercolation studies where various dopants are added to change the electrical, mechanical or optical properties. Raman microprobe spectra from solid, dry thin films of DNA with molecular weights ranging from 200 kDa to >8 MDa complexed with cetyltrimethyl-ammonium chloride (CTMA) are reported and compared to the as-received spectrum and to published DNA spectra in aqueous solutions. In addition, microscopy and measurements on macro-molecular structures of DNA-CTMA are reported.

  9. Moessbauer studies in Zn(2+)0.3 Mn(2+)0.7 Mn(3+) (2-y) Fe(3+) (2-y) O4

    NASA Technical Reports Server (NTRS)

    Gupta, R. G.; Mendiratta, R. G.; Escue, W. T.

    1975-01-01

    The Mossbauer effect has proven to be effective in the study of nuclear hyperfine interactions. Ferrite systems having the formula (Zn(2+)0.3)(Mn(2+)0.7)(Mn(3+)y)(Fe(3+)2-y)(O4) were prepared and studied. These systems can be interpreted as mangacese-doped zinc and a part of iron ions. A systematic study of these systems is presented to promote an understanding of their microstructure for which various theories were proposed.

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

    SciTech Connect

    WISHART,J.F.

    2007-11-30

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate

  11. 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

  12. Infrared micro-spectroscopic studies of epithelial cells

    PubMed Central

    Romeo, Melissa; Mohlenhoff, Brian; Jennings, Michael; Diem, Max

    2009-01-01

    We report results from a study of human and canine mucosal cells, investigated by infrared micro-spectroscopy, and analyzed by methods of multivariate statistics. We demonstrate that the infrared spectra of individual cells are sensitive to the stage of maturation, and that a distinction between healthy and diseased cells will be possible. Since this report is written for an audience not familiar with infrared micro-spectroscopy, a short introduction into this field is presented along with a summary of principal component analysis. PMID:16797481

  13. Photoelectron spectroscopic study of the ethyl cyanoacrylate anion

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Tang, Xin; Bowen, Kit

    2013-09-01

    Anion photoelectron spectroscopy and density functional theory have been utilized to study the parent, ethyl cyanoacrylate molecular anion, ECA-. The measured electron affinity (0.9 ± 0.2 eV), vertical detachment energy (1.3 ± 0.1 eV), and anion-to-triplet neutral, photodetachment transition energies (4.0 ± 0.1 eV and 4.5 ± 0.1 eV) all compare well with their calculated values. The relatively high electron affinity of the ECA monomer is responsible for the fact that its “anionic” polymerization mechanism proceeds even with weak nucleophiles, such as water.

  14. Chemical and spectroscopic studies of Cercidium praecox gum exudate.

    PubMed

    León de Pinto, G; Martínez, M; Rivas, C

    1994-07-01

    The structure of the polysaccharide from Cercidium praecox (R&P) Harms gum exudate has been studied by Smith degradation, by sugar and methylation analyses, and by 13C NMR spectroscopy. The results showed a (1-->4)-xylan core. Some xylose residues are substituted at O-2 by alpha-D-glucuronic acid and 4-O-methyl-alpha-D-glucuronic acid residues. beta-D-Glucuronic acid is present, probably as terminal residues. The arabinose is present as alpha-L-furanose and beta-L-pyranose. PMID:8062287

  15. Spectroscopic, thermal and structural studies on manganous malate crystals

    SciTech Connect

    Thomas, J. Lincy, A. Mahalakshmi, V.; Saban, K. V.

    2013-01-15

    Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal X-ray diffraction. The crystals are orthorhombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG-DTA studies is in conformity with the single crystal XRD data.

  16. 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.

  17. 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

    2015-10-01

    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. PMID:25956330

  18. Rotational Spectroscopic Studies and Observational Searches for HO3

    NASA Astrophysics Data System (ADS)

    Widicus Weaver, Susanna

    Interstellar chemistry is largely driven by reactions of unstable molecules that serve as reaction intermediates in terrestrial chemistry. One such class of compounds are weakly-bound clusters. These clusters could form in interstellar environments through radiative association reactions, but their identification and characterization in interstellar environments is limited by a lack of rotational spectral information. One such species is HO3, which could be formed in the interstellar medium from O2 and OH. HO3 has been studied extensively in the infrared, and there are a few microwave spectral studies that have also been reported. However, no millimeter or submillimeter spectral information is available to guide astronomical observations. In this talk, we will present the laboratory characterization of trans -HO3 and trans -DO3 from 70 to 450 GHz using our newly developed fast sweeping technique. The molecular constants have been significantly refined, and additional higher order centrifugal distortion constants have been determined. We will also present an initial observational search for HO3 in 32 star forming regions. Although no HO3 lines have been detected thus far, strict upper limits can be placed on the HO3 column density in these sources based on this analysis. Additional Authors: Luyao Zou, Brian M. Hays.

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

    PubMed

    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. PMID:16165029

  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. Thermo-active polymer nanocomposites: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Winter, A. Douglas; Larios, Eduardo; Jaye, Cherno; Fischer, Daniel A.; Omastová, Mária; Campo, Eva M.

    2014-09-01

    Photo- and thermo-mechanical actuation behaviour in specific polymer-carbon nanotube composites has been observed in recent years and studied at the macroscale. These systems may prove to be suitable components for a wide range of applications, from MOEMs and nanotechnology to neuroscience and tissue engineering. Absence of a unified model for actuation behaviour at a molecular level is hindering development of such smart materials. We observed thermomechanical actuation of ethylene-vinyl acetate | carbon nanotube composites through in situ near-edge X-ray absorption fine structure spectroscopy to correlate spectral trends with macroscopic observations. This paper presents spectra of composites and constituents at room temperature to identify resonances in a building block model, followed by spectra acquired during thermo-actuation. Effects of strain-induced filler alignment are also addressed. Spectral resonances associated with C=C and C=O groups underwent synchronised intensity variations during excitation, and were used to propose a conformational model of actuation based on carbon nanotube torsion. Future actuation studies on other active polymer nanocomposites will verify the universality of the proposed model.

  2. 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. PMID:25252174

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Theoretical spectroscopic studies on chemical and electronic structures of arginylglycine.

    PubMed

    Li, Hongbao; Li, Leilei; Jiang, Jun; Lin, Zijing; Luo, Yi

    2015-10-14

    The energy differences between canonical and zwitterionic isomers of arginylglycine (ArgGly) at the CCSD/aug-cc-pVDZ level are too small (less than 1 kcal mol(-1)) to determine the dominant form in the gas phase from the energetic point of view. First-principles simulations have been performed for near-edge X-ray absorption fine-structure (NEXAFS) spectra and X-ray photoelectron spectra (XPS) at C, N and O K-edges, as well as for infrared (IR) spectra of neutral ArgGly. Noticeable spectral differences were found which enable the unambiguous identification of different neutral groups. We thus demonstrate X-ray spectroscopy as a powerful technique to study the conformation dependent chemical and electronic properties of neutral ArgGly. PMID:26266331

  9. 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.

  10. High resolution spectroscopic study of Be10Lambda;

    NASA Astrophysics Data System (ADS)

    Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; Baturin, P.; Badui, R.; Boeglin, W.; Bono, J.; Brash, E.; Carter, P.; Chiba, A.; Christy, E.; Danagoulian, S.; de Leo, R.; Doi, D.; Elaasar, M.; Ent, R.; Fujii, Y.; Fujita, M.; Furic, M.; Gabrielyan, M.; Gan, L.; Garibaldi, F.; Gaskell, D.; Gasparian, A.; Han, Y.; Hashimoto, O.; Horn, T.; Hu, B.; Hungerford, Ed. V.; Jones, M.; Kanda, H.; Kaneta, M.; Kato, S.; Kawai, M.; Khanal, H.; Kohl, M.; Liyanage, A.; Luo, W.; Maeda, K.; Margaryan, A.; Markowitz, P.; Maruta, T.; Matsumura, A.; Maxwell, V.; Mkrtchyan, A.; Mkrtchyan, H.; Nagao, S.; Nakamura, S. N.; Narayan, A.; Neville, C.; Niculescu, G.; Niculescu, M. I.; Nunez, A.; Nuruzzaman, Okayasu, Y.; Petkovic, T.; Pochodzalla, J.; Qiu, X.; Reinhold, J.; Rodriguez, V. M.; Samanta, C.; Sawatzky, B.; Seva, T.; Shichijo, A.; Tadevosyan, V.; Tang, L.; Taniya, N.; Tsukada, K.; Veilleux, M.; Vulcan, W.; Wesselmann, F. R.; Wood, S. A.; Yamamoto, T.; Ya, L.; Ye, Z.; Yokota, K.; Yuan, L.; Zhamkochyan, S.; Zhu, L.; Hksjlab E05-115 Collaboration

    2016-03-01

    Spectroscopy of a Be10Lambda; hypernucleus was carried out at JLab Hall C using the (e ,e'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 p (e ,e'K+)Λ ,Σ0 reactions allowed us to determine the energy levels; and the binding energy of the ground-state peak (mixture of 1- and 2- states) was found to be BΛ=8.55 ±0.07 (stat . ) ±0.11 (sys . ) MeV. 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 the charge symmetry breaking effect in the Λ N interaction.

  11. 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.

  12. 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.

  13. In-beam spectroscopic studies of the 44S nucleus

    NASA Astrophysics Data System (ADS)

    Cáceres, L.; Sohler, D.; Grévy, S.; Sorlin, O.; Dombrádi, Zs.; Bastin, B.; Achouri, N. L.; Angélique, J. C.; Azaiez, F.; Baiborodin, D.; Borcea, R.; Bourgeois, C.; Buta, A.; Bürger, A.; Chapman, R.; Dalouzy, J. C.; Dlouhy, Z.; Drouard, A.; Elekes, Z.; Franchoo, S.; Gaudefroy, L.; Iacob, S.; Laurent, B.; Lazar, M.; Liang, X.; Liénard, E.; Mrazek, J.; Nalpas, L.; Negoita, F.; Nowacki, F.; Orr, N. A.; Penionzhkevich, Y.; Podolyák, Zs.; Pougheon, F.; Poves, A.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Stanoiu, M.; Stefan, I.

    2012-02-01

    The structure of the 44S nucleus has been studied at GANIL through the one proton knock-out reaction from a 45Cl secondary beam at 42 A·MeV. The γ rays following the de-excitation of 44S were detected in flight using the 70 BaF2 detectors of the Château de Cristal array. An exhaustive γγ-coincidence analysis allowed an unambiguous construction of the level scheme up to an excitation energy of 3301 keV. The existence of the spherical 22+ state is confirmed and three new γ-ray transitions connecting the prolate deformed 21+ level were observed. Comparison of the experimental results to shell model calculations further supports a prolate and spherical shape coexistence with a large mixing of states built on the ground state band in 44S.

  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. 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.

  16. 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. PMID:16839805

  17. 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.

  18. Phosphonic drugs: Experimental and theoretical spectroscopic studies of fosfomycin

    NASA Astrophysics Data System (ADS)

    Chruszcz-Lipska, Katarzyna; Zborowski, Krzysztof K.; Podstawka-Proniewicz, Edyta; Liu, Shaoxuan; Xu, Yizhuang; Proniewicz, Leonard M.

    2011-02-01

    pH and time-dependant changes of fosfomycin molecular structure in an aqueous solution are studied by Raman, NMR, and generalized 2D correlation spectroscopies. Interpretation of the experimental spectra is based on the assumption of formation of different species running on applied physicochemical conditions. Geometries of all possible structures were entirely optimized with the 6-311++G(2df,p) basis set at the B3LYP theoretical level using procedures implemented in the Gaussian '03 set of programs. Harmonic frequency calculations verified the nature of the studied structures and allowed to simulate obtained Raman spectra. The theoretical NMR shielding was calculated using the GIAO method at the same computational level. In addition, in some cases PCM model was used to monitor the influence of water molecules on the NMR spectra. It is shown that in the pH range of 1-2 of fosfomycin aqueous solution oxirane ring is open sequent to nucleophilic attack and forms 1,2-dihydroxyphosphonic acid with small content of its monodeprotonated species. On the other hand, in pH 7 and higher it appears either as 1,2-epoxypropylphosphonic or 1,2-dihydroxyphosphonic dianion depending upon whether hydrolysis took place or not. It is also discussed that Raman marker bands originating from the individual species of fosfomycin can be used to detect and/or to monitor this antibiotic in an aqueous medium (for example urine samples). Hence, depending upon the structure found in urine one can tell about metabolic processes of this antibiotic in the body.

  19. Acidic properties of sulfated zirconia: An infrared spectroscopic study

    SciTech Connect

    Babou, F.; Coudurier, G.; Vedrine, J.C.

    1995-04-01

    Sulfated zirconia with S content of 2 wt.% equivalent to complete coverage of its surface was studied by infrared spectroscopy. At least four sulfated species were identified and exhibited an important and reversible sensitivity to water. These equilibria were demonstrated to exist by the study of adsorption of incremental amounts of water. D{sub 2}O and H{sub 2}{sup 18}O isotopically enriched water molecules were used to assist interpretation of IR spectra. To characterize acidity features, the probe molecules butane, CO, and H{sub 2}O (as weak bases) or pyridine (as a strong base) were adsorbed. Two Lewis acid sites (L{sub 1} and L{sub 2}) were observed and one Bronsted site (B) related to the zirconia support (L{sub 1}) and the sulfated species (L{sub 2}, B). They were evidenced by pyridine adsorption which was shown to partly displace adsorbed sulfate species. With the help of previous theoretical calculations using an ab initio method and representing the zirconia surface by a mononuclear zirconium complex, it is emphasized that the sulfated zirconia can be visualized as a H{sub 2}SO{sub 4} compound grafted onto the surface of zirconia in a way which makes it very sensitive to water but in a reversible way. Its acidity is similar to that of sulfuric acid but it is not really superacidic. Comparison with other oxides leads us to suggest that the cationic charge borne by the metallic cation is of prime importance for the acidity strength. The role of water on the acidic and catalytic properties for n-butane isomerization reaction is emphasized. 33 refs., 11 figs., 2 tabs.

  20. Spectroscopic and HPLC studies of photodegradation of nilvadipine.

    PubMed

    Augustyniak, W; Mielcarek, J; Milewski, M; Szamburska, O

    2001-11-01

    Photochemical decomposition of nilvadipine (NV), a derivative of 1,4-dihydropyridine (DHP), was studied. Photodegradation was carried out in the conditions recommended in the first version of the document issued by the International Conference on Harmonization (ICH), currently in force in the studies of photochemical stability of drugs and therapeutic substances. Methanol solutions of NV were irradiated with a high-pressure mercury arc lamp, type HBO 200 (300-400 nm). The maximum absorption of radiation at 365 nm was achieved by applying the interference filter and Wood's filter. The assessment of NV photodegradation was made on the basis of the UV spectrophotometric and high-performance liquid chromatographic (HPLC) methods. Quantitatively, the process was described with the calculated rate constants of decomposition k, time of decomposition of 50% of the compound to 5, and time of decomposition of 10% of the compound t(0.1). The two methods applied allowed a determination of the kinetic parameters of NV photodegradation from the relationship ln c = f(t). Using the Reinecke salt as a chemical actinometer, apparent quantum yields of photodegradation were obtained; after extrapolation to the time of irradiation zero, these gave the actual quantum yield (phi = 7.3 10(-5)). The quantum yield of fluorescence at lambda(exc) = 375 nm was about 9.3 x 10(-4) The methods used for evaluation of NV photodegradation were subjected to validation, and results of the analytical methods were statistically assessed by Snedecor F and Student t tests. The former test revealed no statistically significant difference between the variances obtained by the HPLC and UV spectrophotometric methods. Also, verification of the zero hypothesis of the Student t test on equality of means of the results obtained gave no significant diferences between the two methods. PMID:11794805

  1. 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.

  2. Effect of nanocrystallization on the electrical conductivity enhancement and Moessbauer hyperfine parameters of iron based glasses

    SciTech Connect

    El-Desoky, M.M.; Ibrahim, F.A.; Mostafa, A.G.; Hassaan, M.Y.

    2010-09-15

    Selected glasses of Fe{sub 2}O{sub 3}-PbO{sub 2}-Bi{sub 2}O{sub 3} system have been transformed into nanomaterials by annealing at temperature close to crystallization temperature (T{sub c}) for 1 h. The effects of the annealing of the present samples on its structural and electrical properties were studied by Moessbauer spectroscopy, transmission electron micrograph (TEM), differential scanning calorimeter (DSC) and dc conductivity ({sigma}). Moessbauer spectroscopy was used in order to determine the states of iron and its hyperfine structure. The effect of nanocrystalization on the Moessbauer hyperfine parameters did not exhibit significant modifications in present glasses. However, in case of glass ceramic nanocrystals show a distinct decrease in the quadrupole splitting ({Delta}) is observed, reflecting an evident decrease in the distortion of structural units like FeO{sub 4} units. In general, the Moessbauer parameters of the nano-crystalline phase exhibit tendency to increase with PbO{sub 2} content. TEM of as-quenched glasses confirm the homogeneous and essentially featureless morphology. TEM of the corresponding glass ceramic nanocrystals indicates nanocrystals embedded in the glassy matrix with average particle size of about 32 nm. The crystallization temperature (T{sub c}) was observed to decrease with PbO{sub 2} content. The glass ceramic nanocrystals obtained by annealing at T{sub c} exhibit improvement of electrical conductivity up to four orders of magnitude than the starting glasses. This considerable improvement of electrical conductivity after nanocrystallization is attributed to formation of defective, well-conducting phases 'easy conduction paths' along the glass-crystallites interfaces.

  3. Spectroscopic study of dinitrophenol herbicide sorption on smectite.

    PubMed

    Johnston, C T; Sheng, G; Teppen, B J; Boyd, S A; de Oliveira, M F

    2002-12-01

    Sorption of two dinitrophenolic herbicides, 4,6-dinitro-o-cresol (DNOC) and 4,6-dinitro-2-sec-butylphenol (DINOSEB) to smectite was studied using FTIR, HPLC, and quantum chemical methods. The high affinity of DNOC and DINOSEB for smectite surfaces was attributed to site-specific interactions with exchangeable cations and nonspecific van der Waals interactions with the siloxane surface. The positions of the nu(asym)(NO) and nu(sym)(NO) vibrational modes were perturbed by the exchangeable cations with similar changes occurring for both alkali and alkaline earth cations as a function of ionic potential. The cation-induced changes to the vibrational bands of the NO2 groups indicate that exchangeable metal cations are coordinated to -NO2 groups. Quantum chemical methods predicted a red-shift of the nu(asym)(NO) band and a corresponding blue-shift of the nu(sym)(NO) modes, as was observed experimentally. The nature of the smectite surface itself did not strongly influence the vibrational modes of sorbed DNOC or DINOSEB on the basis of a comparison of DNOC sorbed to three different smectites (K-SWy-2, K-SAz-1, and K-SHCa-1). FTIR spectra of DNOC and DINOSEB sorbed to a K-SWy-2 smectite were studied quantitatively using a modified form of Beers law. The FTIR-derived sorption isotherm of DNOC sorbed to K-SWy-2 was in good agreement with the isotherm derived from HPLC measurements. The molar absorptivity value of DNOC sorbed to K-SWy-2 smectite was 1.43 x 10(7) cm2/mol in good agreement with literature values for nitroaromatics (average value of 1.72 x 10(7) +/- 0.3 cm2/mol). On the basis of this value, the limit of detection using the FTIR method of approximately 5 microgDNOC g(clay) was determined. These two observations (sorption isotherms and molar absorptivity) provide a direct link between the macroscopic sorption results and the FTIR spectra. PMID:12523422

  4. Spectroscopic Studies of Azul Maya: Novel Organic/Inorganic Complexes

    NASA Astrophysics Data System (ADS)

    Reza, Layra; Manciu, Felicia; Torres, Brenda; Polette, Lori; Chianelli, Russell

    2006-10-01

    Maya pigments are novel organic/inorganic hybrid materials with multiple technological applications. The materials are surface compounds formed by heating an organic molecule such as indigo with an inorganic compound such as palygorskite, which is a common clay. The organic molecule upon heating forms a strong interaction with the clay surface stabilizing both entities. This strong interaction is exhibited through a color change from deep blue to the well-known Maya Blue indicating an exchange of electron density at the surface. Analysis by infrared absorption and Raman spectroscopy demonstrate the disappearance of nitrogen-hydrogen (N-H) bonding, as the indigo molecule incorporates into the inorganic palygorskite material. Infrared data confirm the loss of zeolitic water and a partial removal of structural water after the heating process. Carbon and oxygen studies at Stanford Synchrotron Radiation Laboratory by X-Ray photoemission spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS), respectively, suggest possible cationic (Al^+3) bonding of the organic molecule to palygorskite compound.

  5. 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.

  6. 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. PMID:24813273

  7. 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.

  8. 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.

  9. High resolution spectroscopic study of BeΛ10

    DOE PAGESBeta

    Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; et al

    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

  10. 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.