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Sample records for ir spectroscopy electronic

  1. Electron spectroscopy

    International Nuclear Information System (INIS)

    Hegde, M.S.

    1979-01-01

    An introduction to the various techniques in electron spectroscopy is presented. These techniques include: (1) UV Photoelectron spectroscopy, (2) X-ray Photoelectron spectroscopy, (3) Auger electron spectroscopy, (4) Electron energy loss spectroscopy, (5) Penning ionization spectroscopy and (6) Ion neutralization spectroscopy. The radiations used in each technique, the basis of the technique and the special information obtained in structure determination in atoms and molecules by each technique are summarised. (A.K.)

  2. Electronic processes in TTF-derived complexes studied by IR spectroscopy

    Science.gov (United States)

    Graja, Andrzej

    2001-09-01

    We focus our attention on the plasma-edge-like dispersion of the reflectance spectra of the selected bis(ethylenodithio)tetrathiafulvalene (BEDT-TTF)-derived organic conductors. The standard procedure to determine the electron transport parameters in low-dimensional organic conductors consists of fitting the appropriate theoretical models with the experimental reflectance data. This procedure provides us with basic information like plasma frequency, the optical effective mass of charge carriers, their number, mean free path and damping constant. Therefore, it is concluded that the spectroscopy is a powerful tool to study the electronic processes in conducting organic solids.

  3. IR Spectroscopy. An introduction

    International Nuclear Information System (INIS)

    Guenzler, H.; Gremlich, H.U.

    2002-01-01

    The following topics are dealt with: absorption and molecular design, spectrometers, sample preparation, qualitative spectral interpretation and assertions, near-infrared and far-infrared spectroscopy, reference spectra and expert systems

  4. Time-resolved photoelectron spectroscopy of IR-driven electron dynamics in a charge transfer model system.

    Science.gov (United States)

    Falge, Mirjam; Fröbel, Friedrich Georg; Engel, Volker; Gräfe, Stefanie

    2017-08-02

    If the adiabatic approximation is valid, electrons smoothly adapt to molecular geometry changes. In contrast, as a characteristic of diabatic dynamics, the electron density does not follow the nuclear motion. Recently, we have shown that the asymmetry in time-resolved photoelectron spectra serves as a tool to distinguish between these dynamics [Falge et al., J. Phys. Chem. Lett., 2012, 3, 2617]. Here, we investigate the influence of an additional, moderately intense infrared (IR) laser field, as often applied in attosecond time-resolved experiments, on such asymmetries. This is done using a simple model for coupled electronic-nuclear motion. We calculate time-resolved photoelectron spectra and their asymmetries and demonstrate that the spectra directly map the bound electron-nuclear dynamics. From the asymmetries, we can trace the IR field-induced population transfer and both the field-driven and intrinsic (non-)adiabatic dynamics. This holds true when considering superposition states accompanied by electronic coherences. The latter are observable in the asymmetries for sufficiently short XUV pulses to coherently probe the coupled states. It is thus documented that the asymmetry is a measure for phases in bound electron wave packets and non-adiabatic dynamics.

  5. Isolated Gramicidin Peptides Probed by IR Spectroscopy

    NARCIS (Netherlands)

    Rijs, A. M.; Kabelac, M.; Abo-Riziq, A.; Hobza, P.; de Vries, M. S.

    2011-01-01

    We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm(-1) to 1800 cm(-1) and the 2700 to 3750 cm(-1) region, allow structural analysis. By studying this broad IR range, various local

  6. Biochemical applications of FT-IR spectroscopy

    NARCIS (Netherlands)

    Pistorius, A.M.A.

    1996-01-01

    This thesis describes the use of (FT-)IR spectroscopy in general biochemical research. In chapter 3, IR spectroscopy is used in the quantitation of residual detergent after reconstitution of an integral membrane protein in a pre-defined lipid matrix. This chapter discusses the choice of the

  7. Visualizing Infrared (IR) Spectroscopy with Computer Animation

    Science.gov (United States)

    Abrams, Charles B.; Fine, Leonard W.

    1996-01-01

    IR Tutor, an interactive, animated infrared (IR) spectroscopy tutorial has been developed for Macintosh and IBM-compatible computers. Using unique color animation, complicated vibrational modes can be introduced to beginning students. Rules governing the appearance of IR absorption bands become obvious because the vibrational modes can be visualized. Each peak in the IR spectrum is highlighted, and the animation of the corresponding normal mode can be shown. Students can study each spectrum stepwise, or click on any individual peak to see its assignment. Important regions of each spectrum can be expanded and spectra can be overlaid for comparison. An introduction to the theory of IR spectroscopy is included, making the program a complete instructional package. Our own success in using this software for teaching and research in both academic and industrial environments will be described. IR Tutor consists of three sections: (1) The 'Introduction' is a review of basic principles of spectroscopy. (2) 'Theory' begins with the classical model of a simple diatomic molecule and is expanded to include larger molecules by introducing normal modes and group frequencies. (3) 'Interpretation' is the heart of the tutorial. Thirteen IR spectra are analyzed in detail, covering the most important functional groups. This section features color animation of each normal mode, full interactivity, overlay of related spectra, and expansion of important regions. This section can also be used as a reference.

  8. Characterization of banana peel by scanning electron microscopy and FT-IR spectroscopy and its use for cadmium removal.

    Science.gov (United States)

    Memon, Jamil R; Memon, Saima Q; Bhanger, M I; Memon, G Zuhra; El-Turki, A; Allen, Geoffrey C

    2008-10-15

    This study describes the use of banana peel, a commonly produced fruit waste, for the removal of Cd(II) from environmental and industrial wastewater. The banana peel was characterized by FT-IR and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis. The parameters pH, contact time, initial metal ion concentration and temperature were investigated and found to be rapid ( approximately 97% within 10 min). The Langmuir adsorption isotherm was used to describe partitioning behavior for the system at room temperature. The value of Q(L) was found to be (35.52 mg g(-1)) higher than the previously reported materials. The binding of metal ions was found to be pH-dependent with the optimal sorption occurring at pH 8. The retained species were eluted with 5 mL of 5 x 10(-3)M HNO(3) with the detection limit of 1.7 x 10(-3)mg L(-1). Kinetics of sorption followed the pseudo-first-order rate equation with the rate constant k, equal to 0.13+/-0.01 min(-1). Thermodynamic parameters such as Gibbs free energy at 303K (-7.41+/-0.13 kJ mol(-1)) and enthalpy (40.56+/-2.34 kJ mol(-1)) indicated the spontaneous and endothermic nature of the sorption process. The developed method was utilized for the removal of Cd(II) ions from environmental and industrial wastewater samples using flame atomic absorption spectrophotometer (FAAS).

  9. Isolated Gramicidin Peptides Probed by IR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Rijs, A. M.; Kabeláč, Martin; Abo-Riziq, A.; Hobza, Pavel; de Vries, M. S.

    2011-01-01

    Roč. 12, č. 10 (2011), s. 1816-1821 ISSN 1439-4235 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550808 Institutional research plan: CEZ:AV0Z40550506 Keywords : density functional calculations * gramicidin * IR spectroscopy * protein folding Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.412, year: 2011

  10. IR Cards: Inquiry-Based Introduction to Infrared Spectroscopy

    Science.gov (United States)

    Bennett, Jacqueline; Forster, Tabetha

    2010-01-01

    As infrared spectroscopy (IR) is frequently used in undergraduate organic chemistry courses, an inductive introduction to IR spectroscopy that uses index cards printed with spectra, structures, and chemical names is described. Groups of students are given an alphabetized deck of these "IR cards" to sort into functional groups. The students then…

  11. Electron Paramagnetic Resonance Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 11. Electron Paramagnetic Resonance Spectroscopy: Biological Applications. B G Hegde. General Article Volume 20 Issue 11 November 2015 pp 1017-1032. Fulltext. Click here to view fulltext PDF. Permanent link:

  12. Linearly Polarized IR Spectroscopy Theory and Applications for Structural Analysis

    CERN Document Server

    Kolev, Tsonko

    2011-01-01

    A technique that is useful in the study of pharmaceutical products and biological molecules, polarization IR spectroscopy has undergone continuous development since it first emerged almost 100 years ago. Capturing the state of the science as it exists today, "Linearly Polarized IR Spectroscopy: Theory and Applications for Structural Analysis" demonstrates how the technique can be properly utilized to obtain important information about the structure and spectral properties of oriented compounds. The book starts with the theoretical basis of linear-dichroic infrared (IR-LD) spectroscop

  13. Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Gopalaraman, C.P.

    1975-01-01

    General features of electron excited Auger electron spectroscopy (AES) which is a nondestructive technique for the analysis of surfaces upto about 15 Adeg depth with a detection limit of about 0.1% of a monolayer. Methods of measuring the Auger electron energies and recent improvements in the instrumentation are reviewed. Typical energy resolution is found to be about 0.5% which is specially suited for the detection of light elements. It is widely used in metallurgy, surface chemistry and thin film studies. (K.B.)

  14. Auger electron spectroscopy of alloys

    International Nuclear Information System (INIS)

    Kuijers, F.J.

    1978-01-01

    This thesis describes how the surface compositions of some alloys can be determined by Auger Electron Spectroscopy (AES). The motivation for this research and the reasons for the choice of alloy systems studied are formulated. The theoretical background of AES is briefly discussed and the apparatus used and the experimental procedures applied are described. Four alloy systems have been investigated in this thesis - Ni-Cu and Pd - Ag (consisting of a component active in most cataytic reactions - Ni and Pd; and a component which is almost inactive for a number of reactions - Cu and Ag) and Pt - Pd and Pt-Ir (consisting of two active components). Knowledge of the surface composition of the various alloy systems is shown to be essential for the interpretation of catalytic results. (Auth./C.F.)

  15. Conformational, IR spectroscopic and electronic properties of conium alkaloids and their adducts with C60 fullerene

    Science.gov (United States)

    Zabolotnyi, M. A.; Prylutskyy, Yu I.; Poluyan, N. A.; Evstigneev, M. P.; Dovbeshko, G. I.

    2016-08-01

    Conformational, IR spectroscopic and electronic properties of the components of Conium alkaloids (Conium maculatum) in aqueous environment were determined by model calculations and experiment. With the help of FT-IR spectroscopy the possibility of formation of an adduct between γ-coniceine alkaloid and C60 fullerene was demonstrated, which is important for further application of conium analogues in biomedical purposes.

  16. Characterization of Hydrogen Bonds by IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vojta, D.

    2012-05-01

    Full Text Available In the identification and quantification of hydrogen bond, as one of the most abundant non-covalent interactions in phenomena like self-assembly and molecular recognition, IR spectrosopy has been employed as the most sensitive method. The performance of the high dilution method enables determination of the stability constant of hydrogen-bonded complex as one of the most important thermodynamic quantities used in their characterization. However, the alleged experimental simplicity of the mentioned method is loaded with errors originating not only from researcher intervention but also independent from it. The second source of error is particularly emphasized and elaborated in this paper, which is designed as the recipe for the successful characterization of hydrogen bonds. Besides the enumeration of all steps in the determination of hydrogen-bonded stability constants, the reader can be acquainted with the most important ex perimental conditions that should be fulfilled in order to minimize the naturally occurring errors in this type of investigation. In the spectral analysis, the application of both uni- and multivariate approach has been discussed. Some computer packages, considering the latter, are mentioned, described, and recommended. KUI -10/2012Received August 1, 2011Accepted October 24, 2011

  17. Auger electron spectroscopy, ionization loss spectroscopy, appearance potential spectroscopy

    International Nuclear Information System (INIS)

    Riwan, R.

    1973-01-01

    The spectroscopy of surfaces using an incident electron beam is studied. The fundamental mechanisms are discussed together with the parameters involved in Auger emission: excitation of the atom, de-excitation by electron emission, and the migration of electrons towards the surface and their ejection. Some examples of applications are given (surface structures, metallurgy, chemical information). Two new techniques for analyzing surfaces are studied: ionization spectroscopy, and appearance potential spectroscopy [fr

  18. Molecular studies by electron spectroscopy

    International Nuclear Information System (INIS)

    Hansteen, J.M.

    1977-01-01

    Experience gained in experimental nuclear physics has played a large role in the development of electron spectroscopy as a powerful tool for studying chemical systems. The use of ESCA (Electron Spectroscopy for Chemical Analysis) for the mapping of molecular properties connected with inner as well as outer electron shells is reviewed, mainly from a phenomological point of view. Molecular Auger electron spectroscopy is described as a means of gaining information on details in molecular structure, simultaneously being extensively applied for surface studies. Future highly promising research areas for molecular electron spectroscopy are suggested to be (e,2e) processes as well as continued exploitation of synchrotron radiation from high energy nuclear devices. (Auth.)

  19. Laser Spark Formamide Decomposition Studied by FT-IR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk

    2011-01-01

    Roč. 115, č. 44 (2011), s. 12132-12141 ISSN 1089-5639 R&D Projects: GA AV ČR IAA400400705; GA AV ČR IAAX00100903; GA ČR GAP208/10/2302 Institutional research plan: CEZ:AV0Z40400503 Keywords : FT-IR spectroscopy * high-power laser * induced dielectric-breakdown Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  20. ESR spectroscopy and electron distribution

    International Nuclear Information System (INIS)

    Davies, A.G.

    1997-01-01

    EPR spectroscopy can map out the electron distribution in a molecule, in much the same way as proton NMR spectroscopy can map out the proton distribution, and it provides some of the most direct evidence for the principal concepts underlying the electronic theory of organic structure and mechanism. This is illustrated for phenomena of conjugation, hyper-conjugation, substituent effects in annulenes, Hueckel theory, ring strain, the Mills-Nixon effect, and ion pairing. (author)

  1. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  2. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  3. Study of the Pyrrol/Diphenylamine Copolymer by FT-IR spectroscopy and conductivity

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Perez

    2004-01-01

    Full Text Available The main goal of this study was to analyze the physical properties of the copolymer formed by the electrochemical deposition of the polydiphenylamine (PDPA on polypyrrole (Ppy and Ppy on PDPA, in different conditions, through the characterization of the materials formed by the resonant Raman, FT-IR and conductivity techniques. The interactions among the species which are present in the new copolymer structure and the changes in electronic conductivity, were verified. The copolymer was also synthesized electrochemically in the presence of iodide species and the material was characterized by FT-IR spectroscopy and conductivity. The role of the dopant was studied in the process of charge transfer between the copolymer-dopant, acting in the stabilization of the species in the polymer backbone and the increase of the electronic conductivity.

  4. electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Egerton, R.

    1997-01-01

    As part of a commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article describes the use of electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. 6 figs

  5. Electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Egerton, R.

    1997-01-01

    As part of the commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article discusses electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. (UK)

  6. Electron spectroscopy of crystals

    CERN Document Server

    Nemoshkalenko, V V

    1979-01-01

    This book is conceived as a monograph, and represents an up-to-date collection of information concerning the use of the method of X-ray photoelectron spec­ troscopy in the study of the electron structure of crystals, as well as a personal interpretation of the subject by the authors. In a natural way, the book starts in Chapter 1 with a recapitulation of the fundamentals of the method, basic relations, principles of operation, and a com­ parative presentation of the characteristics and performances of the most com­ monly used ESCA instruments (from the classical ones-Varian, McPherson, Hewlett Packard, and IEEE-up to the latest model developed by Professor Siegbahn in Uppsala), and continues with a discussion of some of the difficult problems the experimentalist must face such as calibration of spectra, prepara­ tion of samples, and evaluation of the escape depth of electrons. The second chapter is devoted to the theory of photoemission from crystal­ line solids. A discussion of the methods of Hartree-Fo...

  7. Study of the deuterated albumin by FT-IR spectroscopy

    International Nuclear Information System (INIS)

    Stoenescu, Daniela; Sahini, V.E.

    2000-01-01

    The albumin is a protein from the soluble or corpuscular protein class, which exists in cells, in dissolved state or in form of a hydrated gel. Proteins are essential constituents beside water, inorganic salts, lipids, carbon hydrates, vitamins, enzymes. The albumin is also a protein soluble in water and in diluted electrolyte solutions (acids, bases and salts). The investigation of the vibration isotopic effect has a great importance both for the diatomic molecules and for the polyatomic molecules. This paper is the first from a series of works which are intended to study the physico-chemical properties of the deuterated albumin and of the albumin solutions in heavy water by an isotopic exchange method. To put in evidence H-D exchange, the FT-IR spectroscopy is used when the deuterated albumin has different layer thickness. It is also of interest to elucidate the isotopic exchange between the hydrogen and oxygen atoms in bovine serum albumin macromolecules. (authors)

  8. Differentiation of Leishmania species by FT-IR spectroscopy

    Science.gov (United States)

    Aguiar, Josafá C.; Mittmann, Josane; Ferreira, Isabelle; Ferreira-Strixino, Juliana; Raniero, Leandro

    2015-05-01

    Leishmaniasis is a parasitic infectious disease caused by protozoa that belong to the genus Leishmania. It is transmitted by the bite of an infected female Sand fly. The disease is endemic in 88 countries Desjeux (2001) [1] (16 developed countries and 72 developing countries) on four continents. In Brazil, epidemiological data show the disease is present in all Brazilian regions, with the highest incidences in the North and Northeast. There are several methods used to diagnose leishmaniasis, but these procedures have many limitations, are time consuming, have low sensitivity, and are expensive. In this context, Fourier Transform Infrared Spectroscopy (FT-IR) analysis has the potential to provide rapid results and may be adapted for a clinical test with high sensitivity and specificity. In this work, FT-IR was used as a tool to investigate the promastigotes of Leishmaniaamazonensis, Leishmaniachagasi, and Leishmaniamajor species. The spectra were analyzed by cluster analysis and deconvolution procedure base on spectra second derivatives. Results: cluster analysis found four specific regions that are able to identify the Leishmania species. The dendrogram representation clearly indicates the heterogeneity among Leishmania species. The band deconvolution done by the curve fitting in these regions quantitatively differentiated the polysaccharides, amide III, phospholipids, proteins, and nucleic acids. L. chagasi and L. major showed a greater biochemistry similarity and have three bands that were not registered in L. amazonensis. The L. amazonensis presented three specific bands that were not recorded in the other two species. It is evident that the FT-IR method is an indispensable tool to discriminate these parasites. The high sensitivity and specificity of this technique opens up the possibilities for further studies about characterization of other microorganisms.

  9. Using Fourier transform IR spectroscopy to analyze biological materials

    Science.gov (United States)

    Baker, Matthew J; Trevisan, Júlio; Bassan, Paul; Bhargava, Rohit; Butler, Holly J; Dorling, Konrad M; Fielden, Peter R; Fogarty, Simon W; Fullwood, Nigel J; Heys, Kelly A; Hughes, Caryn; Lasch, Peter; Martin-Hirsch, Pierre L; Obinaju, Blessing; Sockalingum, Ganesh D; Sulé-Suso, Josep; Strong, Rebecca J; Walsh, Michael J; Wood, Bayden R; Gardner, Peter; Martin, Francis L

    2015-01-01

    IR spectroscopy is an excellent method for biological analyses. It enables the nonperturbative, label-free extraction of biochemical information and images toward diagnosis and the assessment of cell functionality. Although not strictly microscopy in the conventional sense, it allows the construction of images of tissue or cell architecture by the passing of spectral data through a variety of computational algorithms. Because such images are constructed from fingerprint spectra, the notion is that they can be an objective reflection of the underlying health status of the analyzed sample. One of the major difficulties in the field has been determining a consensus on spectral pre-processing and data analysis. This manuscript brings together as coauthors some of the leaders in this field to allow the standardization of methods and procedures for adapting a multistage approach to a methodology that can be applied to a variety of cell biological questions or used within a clinical setting for disease screening or diagnosis. We describe a protocol for collecting IR spectra and images from biological samples (e.g., fixed cytology and tissue sections, live cells or biofluids) that assesses the instrumental options available, appropriate sample preparation, different sampling modes as well as important advances in spectral data acquisition. After acquisition, data processing consists of a sequence of steps including quality control, spectral pre-processing, feature extraction and classification of the supervised or unsupervised type. A typical experiment can be completed and analyzed within hours. Example results are presented on the use of IR spectra combined with multivariate data processing. PMID:24992094

  10. IR Spectroscopy of Ethylene Glycol Solutions of Dimethylsulfoxide

    Science.gov (United States)

    Kononova, E. G.; Rodnikova, M. N.; Solonina, I. A.; Sirotkin, D. A.

    2018-07-01

    Features of ethylene glycol (EG) solutions of dimethylsulfoxide (DMSO) with low and moderate concentrations (from 2 to 50 mol % of DMSO) are studied by IR spectroscopy on a Bruker Tensor 37 FT-IR spectrometer in the wavenumber range of 400 to 4000 cm-1. The main monitored bands are the S=O stretching vibration band of DMSO (1057 cm-1) and the C-O (1086 and 1041 cm-1) and O-H (3350 cm-1) stretching vibration bands of EG. The obtained data show complex DMSO · 2EG to be present in all solutions with the studied concentrations due to formation of H-bonds between the S=O group of DMSO and the OH group of EG. In the concentration range of 6 to 25 mol % DMSO, the OH stretching vibration of EG is found to be broadened (by up to 70 cm-1), suggesting the strengthening of hydrogen bonds in the spatial network of the system due to the solvophobic effect of DMSO molecules and the formation of DMSO · 2EG. Starting from 25 mol % DMSO, narrowing of the OH stretching vibration is noted, and the bands of free DMSO appear along with the DMSO · 2EG complex, suggesting microseparation in the investigated system. At 50 mol % DMSO, the amounts of free and bound species in the system became comparable.

  11. Electron momentum spectroscopy

    International Nuclear Information System (INIS)

    McCarthy, I.E.

    1986-03-01

    For electron energies greater than a few hundred eV and recoil momenta less than a few atomic units, the differential cross section for the non-coplanar symmetric (e,2e) reaction on an atom or molecule depends on the target and ion structure only through the target-ion overlap. Experimental criteria for the energy and momentum are that the apparent structure information does not change when the energy and momentum are varied. The plane-wave impulse approximation is a sufficient description of the reaction mechanism for determining spherically-averaged squares of momentum-space orbitals for atoms and molecules and for coefficients describing initial and final state correlations

  12. Principles of electron tunneling spectroscopy

    CERN Document Server

    Wolf, E L

    2012-01-01

    Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

  13. Structural versus electronic distortions of symmetry-broken IrTe$_2$

    OpenAIRE

    Kim, Hyo Sung; Kim, Tae-Hwan; Yang, Junjie; Cheong, Sang-Wook; Yeom, Han Woong

    2014-01-01

    We investigate atomic and electronic structures of the intriguing low temperature phase of IrTe2 using high-resolution scanning tunneling microscopy and spectroscopy. We confirm various stripe superstructures such as $\\times$3, $\\times$5, and $\\times$8. The strong vertical and lateral distortions of the lattice for the stripe structures are observed in agreement with recent calculations. The spatial modulations of electronic density of states are clearly identified as separated from the struc...

  14. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

    Science.gov (United States)

    Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

    2017-03-01

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

  15. IL 6: 2D-IR spectroscopy: chemistry and biophysics in real time

    International Nuclear Information System (INIS)

    Bredenbeck, Jens

    2010-01-01

    Pulsed multidimensional experiments, daily business in the field of NMR spectroscopy, have been demonstrated only relatively recently in IR spectroscopy. Similar as nuclear spins in multidimensional NMR, molecular vibrations are employed in multidimensional IR experiments as probes of molecular structure and dynamics, albeit with femtosecond time resolution. Different types of multidimensional IR experiments have been implemented, resembling basic NMR experiments such as NOESY, COSY and EXSY. In contrast to one-dimensional linear spectroscopy, such multidimensional experiments reveal couplings and correlations of vibrations, which are closely linked to molecular structure and its change in time. The use of mixed IR/VIS pulse sequences further extends the potential of multidimensional IR spectroscopy, enabling studies of ultrafast non-equilibrium processes as well as surface specific, highly sensitive experiments. A UV/VIS pulse preceding the IR pulse sequence can be used to prepare the system under study in a non-equilibrium state. 2D-IR snapshots of the evolving non-equilibrium system are then taken, for example during a photochemical reaction or during the photo-cycle of a light sensitive protein. Preparing the system in a non-equilibrium state by UV/Vis excitation during the IR pulse sequence allows for correlating states of reactant and product of the light triggered process via their 2D-IR cross peaks - a technique that has been used to map the connectivity between different binding sites of a ligand as it migrates through a protein. Introduction of a non-resonant VIS pulse at the end of the IR part of the experiment allows to selectively up-convert the infrared signal of interfacial molecules to the visible spectral range by sum frequency generation. In this way, femtosecond interfacial 2D-IR spectroscopy can be implemented, achieving sub-monolayer sensitivity. (author)

  16. Characterization of Momordica charantia Ussing FT-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Attila Keseru

    2016-11-01

    In this paper, because earlier claim shows that the plant used as stomachic, carminative, tonic, antipyretic, antidiabetic, in rheumatoid arthritis and gout, the present investigation was carried to characterized a principal components of plant using FT-IR technique

  17. Nanomechanical IR spectroscopy for fast analysis of liquid-dispersed engineered nanomaterials

    OpenAIRE

    Andersen, Alina Joukainen; Yamada, Shoko; Ek, Pramod Kumar; Andresen, Thomas Lars; Boisen, Anja; Schmid, Silvan

    2016-01-01

    The proliferated use of engineered nanomaterials (ENMs), e.g. in nanomedicine, calls for novel techniques allowing for fast and sensitive analysis of minute samples. Here we present nanomechanical IR spectroscopy (NAM-IR) for chemical analysis of picograms of ENMs. ENMs are nebulized directly from dispersion and efficiently collected on nanomechanical string resonators through a non-diffusion limited sampling method. Even very small amounts of sample can convert absorbed IR light into a measu...

  18. IR-IR Conformation Specific Spectroscopy of Na+(Glucose) Adducts

    Science.gov (United States)

    Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

    2018-01-01

    We report an IR-IR double resonance study of the structural landscape present in the Na+(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na+(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctive Na+ coordination. [Figure not available: see fulltext.

  19. Fibre-Optic IR-Spectroscopy for Biomedical Diagnostics

    OpenAIRE

    Bindig, Uwe; Gersonde, Ingo; Meinke, Martina; Becker, Yukiyo; Müller, Gerhard

    2003-01-01

    The use of microscopy is a valuable means of gaining vital information for medical diagnostics. Due to a number of recent technological developments advances have been made in IR microscopy and in particular, rapid detection methods. Microscopic examination methods usually involve sampling followed by a method of sample purification or preparation. The advantages of the IR analytical method are that it is based on a direct, non‒destructive measurement of sample material and that the resulting...

  20. Nanomechanical IR spectroscopy for fast analysis of liquid-dispersed engineered nanomaterials

    DEFF Research Database (Denmark)

    Andersen, Alina Joukainen; Yamada, Shoko; Ek, Pramod Kumar

    2016-01-01

    The proliferated use of engineered nanomaterials (ENMs), e.g. in nanomedicine, calls for novel techniques allowing for fast and sensitive analysis of minute samples. Here we present nanomechanical IR spectroscopy (NAM-IR) for chemical analysis of picograms of ENMs. ENMs are nebulized directly from...

  1. Nanomechanical IR Spectroscopy for the fast analysis of picogram samples of engineered nanomaterials

    DEFF Research Database (Denmark)

    Andersen, Alina Joukainen; Ek, Pramod Kumar; Andresen, Thomas Lars

    2014-01-01

    The proliferation of engineered nanomaterials (ENMs), e.g. in nanomedicine, demands for novel sensitive techniques allowing for the analysis of minute samples. We present nanoelectromechanical system-based IR spectroscopy (NEMS-IR) of picograms of polymeric micelles. The micelles are nebulized...

  2. IR spectroscopy at the ITO-organic interface

    Energy Technology Data Exchange (ETDEWEB)

    Alt, Milan [Karlsruher Institut fuer Technologie, Karlsruhe (Germany); Shazada, Ahmad [Max-Planck Institut fuer Polymerforschung, Mainz (Germany); Tamanai, Akemi; Trollmann, Jens; Glaser, Tobias; Beck, Sebastian; Tengeler, Sven; Pucci, Annemarie [Kirchhoff-Institut fuer Physik, Heidelberg (Germany)

    2012-07-01

    Thin films of P3HT have been prepared by spin coating and electrooxidative polymerization on platinum- and ITO-coated substrates. Additionally, P3HT-films on silicon substrates have been prepared by spin coating only. The measured IR spectra of the spin coated films allowed for an elaboration of a detailed optical model for P3HT, which has been used to simulate IR reflection-absorption spectra on ITO and Pt substrates. Comparison of simulated spectra with measurements revealed no substrate influence on the IR spectra for the spincoated films. In case of spincoated P3HT-films on ITO-substrate, the obtained IR spectra correspond to simulation data very well up to 6000 wavenumbers. In the electropolymerized P3HT films we have identified residuals of the electrolyte ionic liquid, acting as dopand for P3HT. While IR spectra of the electropolymerized P3HT films on Pt substrate could be explained reasonably well as a superposition of chemically doped P3HT and the ionic electrolyte, the IR spectra of electropolymerized P3HT films on ITO substrates showed strongly deposition-time dependent deviations. These were most likely related to varying properties of the ITO surface between reference and sample measurement due to an interaction of ITO and the electrolyte at the film-substrate interface.

  3. Discrimination of Chinese Sauce liquor using FT-IR and two-dimensional correlation IR spectroscopy

    Science.gov (United States)

    Sun, Su-Qin; Li, Chang-Wen; Wei, Ji-Ping; Zhou, Qun; Noda, Isao

    2006-11-01

    We applied the three-step IR macro-fingerprint identification method to obtain the IR characteristic fingerprints of so-called Chinese Sauce liquor (Moutai liquor and Kinsly liquor) and a counterfeit Moutai. These fingerprints can be used for the identification and discrimination of similar liquor products. The comparison of their conventional IR spectra, as the first step of identification, shows that the primary difference in Sauce liquor is the intensity of characteristic peaks at 1592 and 1225 cm -1. The comparison of the second derivative IR spectra, as the second step of identification, shows that the characteristic absorption in 1400-1800 cm -1 is substantially different. The comparison of 2D-IR correlation spectra, as the third and final step of identification, can discriminate the liquors from another direction. Furthermore, the method was successfully applied to the discrimination of a counterfeit Moutai from the genuine Sauce liquor. The success of the three-step IR macro-fingerprint identification to provide a rapid and effective method for the identification of Chinese liquor suggests the potential extension of this technique to the identification and discrimination of other wine and spirits, as well.

  4. Supercontinuum based mid-IR imaging spectroscopy for cancer detection

    DEFF Research Database (Denmark)

    Bang, Ole; Møller, Uffe Visbech; Kubat, Irnis

    2014-01-01

    -power laser diodes, quantum cascade lasers and synchrotron radiation, have precluded mid-IR applications where the spatial coherence, broad bandwidth, high brightness and portability of a supercontinuum laser are all required. In an international collaboration in the EU project MINERVA [minerva...

  5. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

    Science.gov (United States)

    Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

    2017-03-05

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    Directory of Open Access Journals (Sweden)

    Simone Borri

    2016-02-01

    Full Text Available The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

  7. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing.

    Science.gov (United States)

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-02-17

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF₂ microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

  8. PAC spectroscopy of electronic ceramics

    International Nuclear Information System (INIS)

    Gardner, J.A.; Wang, R.; Schwenker, R.; Sommers, J.A.

    1991-01-01

    Dilute indium dopants in cerium oxides and YBa 2 Cu 3 O x have been studied by 111 In/Cd Perturbed Angular Correlation (PAC) spectroscopy. By controlling oxygen vacancy concentration in the cerium oxides through doping or high-temperature vacuum annealing, we have found that indium always forms a defect complex unless the sample is doped to reduce greatly the oxygen vacancy concentration. Three different vacancy-associated complexes are found with concentrations that depend on doping and oxygen stoichiometry. Another defect complex occurs in samples having negligible vacancy concentration. At low temperatures, evidence is found of interaction with an electronic hole trapped by 111 Cd after the radioactive decay of the 111 In parent. In YBa 2 Cu 3 O x the indium substitutes preferentially at the Y site but has measurable probability of substitution in at least one of the two copper sites. A symmetry change near 650 C is consistent with the well-documented orthorhombic/tetragonal transition for samples in air or oxygen. (author). 23 refs, 10 figs

  9. FT-IR spectroscopy of lipoproteins—A comparative study

    Science.gov (United States)

    Krilov, Dubravka; Balarin, Maja; Kosović, Marin; Gamulin, Ozren; Brnjas-Kraljević, Jasminka

    2009-08-01

    FT-IR spectra, in the frequency region 4000-600 cm -1, of four major lipoprotein classes: very low density lipoprotein (VLDL), low density lipoprotein (LDL) and two subclasses of high density lipoproteins (HDL 2 and HDL 3) were analyzed to obtain their detailed spectral characterization. Information about the protein domain of particle was obtained from the analysis of amide I band. The procedure of decomposition and curve fitting of this band confirms the data already known about the secondary structure of two different apolipoproteins: apo A-I in HDL 2 and HDL 3 and apo B-100 in LDL and VLDL. For information about the lipid composition and packing of the particular lipoprotein the well expressed lipid bands in the spectra were analyzed. Characterization of spectral details in the FT-IR spectrum of natural lipoprotein is necessary to study the influence of external compounds on its structure.

  10. Vibrational spectroscopy in the electron microscope.

    Science.gov (United States)

    Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

    2014-10-09

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

  11. Photothermal IR spectroscopy with perforated membrane micromechanical resonators

    DEFF Research Database (Denmark)

    Kurek, Maksymilian

    -IR method. In order to overcome them, string resonators were replaced by membranes. A reliable sampling technique was maintained by adding perforation to membranes and thereby essentially getting membrane porous filters. Membranes gave also access to fully integrated magnetic transduction that allowed...... for significant shrinkage and simplification of the system. An analytical model of a locally heated membrane was developed and confirmed through FEM simulations. Then, low stress silicon nitride perforated membranes were fabricated and characterized using two different experimental setups that employed optical...

  12. Study on Angelica and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

    Science.gov (United States)

    Liu, Hong-xia; Sun, Su-qin; Lv, Guang-hua; Chan, Kelvin K. C.

    2006-05-01

    In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy (2D-IR) to study the main constituents in traditional Chinese medicine Angelica and its different extracts (extracted by petroleum ether, ethanol and water in turn). The findings indicated that FT-IR spectrum can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can not only identify the main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. This analytical method is highly rapid, effective, visual and accurate for pharmaceutical research.

  13. Electronic structure, local magnetism, and spin-orbit effects of Ir(IV)-, Ir(V)-, and Ir(VI)-based compounds

    Energy Technology Data Exchange (ETDEWEB)

    Laguna-Marco, M. A.; Kayser, P.; Alonso, J. A.; Martínez-Lope, M. J.; van Veenendaal, M.; Choi, Y.; Haskel, D.

    2015-06-01

    Element- and orbital-selective x-ray absorption and magnetic circular dichroism measurements are carried out to probe the electronic structure and magnetism of Ir 5d electronic states in double perovskite Sr2MIrO6 (M = Mg, Ca, Sc, Ti, Ni, Fe, Zn, In) and La2NiIrO6 compounds. All the studied systems present a significant influence of spin-orbit interactions in the electronic ground state. In addition, we find that the Ir 5d local magnetic moment shows different character depending on the oxidation state despite the net magnetization being similar for all the compounds. Ir carries an orbital contribution comparable to the spin contribution for Ir4+ (5d(5)) and Ir5+ (5d(4)) oxides, whereas the orbital contribution is quenched for Ir6+ (5d(3)) samples. Incorporation of a magnetic 3d atom allows getting insight into the magnetic coupling between 5d and 3d transition metals. Together with previous susceptibility and neutron diffractionmeasurements, the results indicate that Ir carries a significant local magnetic moment even in samples without a 3d metal. The size of the (small) net magnetization of these compounds is a result of predominant antiferromagnetic interactions between local moments coupled with structural details of each perovskite structure

  14. Anisotropy in Bone Demineralization Revealed by Polarized Far-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Roman Schuetz

    2015-04-01

    Full Text Available Bone material is composed of an organic matrix of collagen fibers and apatite nanoparticles. Previously, vibrational spectroscopy techniques such as infrared (IR and Raman spectroscopy have proved to be particularly useful for characterizing the two constituent organic and inorganic phases of bone. In this work, we tested the potential use of high intensity synchrotron-based far-IR radiation (50–500 cm−1 to gain new insights into structure and chemical composition of bovine fibrolamellar bone. The results from our study can be summarized in the following four points: (I compared to far-IR spectra obtained from synthetic hydroxyapatite powder, those from fibrolamellar bone showed similar peak positions, but very different peak widths; (II during stepwise demineralization of the bone samples, there was no significant change neither to far-IR peak width nor position, demonstrating that mineral dissolution occurred in a uniform manner; (III application of external loading on fully demineralized bone had no significant effect on the obtained spectra, while dehydration of samples resulted in clear differences. (IV using linear dichroism, we showed that the anisotropic structure of fibrolamellar bone is also reflected in anisotropic far-IR absorbance properties of both the organic and inorganic phases. Far-IR spectroscopy thus provides a novel way to functionally characterize bone structure and chemistry, and with further technological improvements, has the potential to become a useful clinical diagnostic tool to better assess quality of collagen-based tissues.

  15. Inner-shell electron spectroscopy for microanalysis

    International Nuclear Information System (INIS)

    Joy, D.C.; Maher, D.M.

    1979-01-01

    The transmission electron energy-loss spectrum shows characteristic edges corresponding to the excitation of inner-shell electrons of atoms in a thin sample. Analysis of these edges provides detailed chemical, structural, and electronic data from the radiated volume. By combining electron spectroscopy and electron microscopy, this microanalytical technique can be performed in conjunction with high-resolution imaging of the sample. It is shown that this approach has advantages of sensitivity, spatial resolution, and convenience over other comparable techniques. 7 figures

  16. Electron attachment cross sections obtained from electron attachment spectroscopy

    International Nuclear Information System (INIS)

    Popp, P.; Baumbach, J.I.; Leonhardt, J.W.; Mothes, S.

    1988-01-01

    Electron capture detectors have a high sensitivity for substances with high thermal electron attachment cross sections. The electron attachment spectroscopy makes it possible to change the mean electron energy in such a way that the maximum for dissociative electron attachment is reached. Thus, best operation modes of the detection system as well as significant dependencies of electron attachment coefficients are available. Cross sections for electron attachment as a function of the electron energy are obtained with the knowledge of electron energy distribution functions from Boltzmann equation analysis by a special computer code. A disadvantage of this electron attachment spectroscopy is the superposition of space charge effects due to the decrease of the electron drift velocity with increasing mean electron energy. These influences are discussed. (author)

  17. Electron spectrometer for gas-phase spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.

  18. Electron-electron coincidence spectroscopies at surfaces

    International Nuclear Information System (INIS)

    Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

    2002-01-01

    In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

  19. Monitoring coal conversion processes by IR-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hobert, H.; Kempe, J.; Stephanowitz, H. (Friedrich-Schiller-Universitaet, Jena (German Democratic Republic))

    1990-01-01

    Explains application of infrared spectroscopy combined with multivariate data analysis by an on-line computer system for assessing coal quality and suitability of brown coal for conversion processes. Coal samples were pelletized under addition of KBr and analyzed using an IRF 180 Fourier transform spectrometer in the spectral range of 400 to 2,000 cm{sup -1}. Components of spectra are presented; the oil yield from coal hydrogenation is calculated by regression analysis. Covariance spectra of carbon, organic hydrogen and sulfur are shown. It is concluded that the field of application for the method includes industrial coal liquefaction, gasification as well as briquetting and coking. 8 refs.

  20. Narrow electron injector for ballistic electron spectroscopy

    International Nuclear Information System (INIS)

    Kast, M.; Pacher, C.; Strasser, G.; Gornik, E.

    2001-01-01

    A three-terminal hot electron transistor is used to measure the normal energy distribution of ballistic electrons generated by an electron injector utilizing an improved injector design. A triple barrier resonant tunneling diode with a rectangular transmission function acts as a narrow (1 meV) energy filter. An asymmetric energy distribution with its maximum on the high-energy side with a full width at half maximum of ΔE inj =10 meV is derived. [copyright] 2001 American Institute of Physics

  1. The study of the curing of the polyurethane coating by method of IR spectroscopy

    Directory of Open Access Journals (Sweden)

    N. A. Korshunova

    2016-12-01

    Full Text Available The results of the study of the curing process of polyurethane compositions with participation of two different catalysts by the method of IR spectroscopy are given. The time dependences of curing of polyurethane coatings from concentrations of catalysts were determined, on the basis of which the most effective catalyst was selected.

  2. Monitoring lipase-catalyzed interesterification for bulky fats modification with FT-IR/NIR spectroscopy

    DEFF Research Database (Denmark)

    Chang, Tinghong; Lai, Xuxin; Zhang, Hong

    2005-01-01

    This work demonstrates the application of FT-IR and FT-NIR spectroscopy to monitor the enzymatic interesterification process for bulky fat modification. The reaction was conducted between palm stearin and coconut oil (70/30, w/w) with the catalysis of Lipozyme TL IM at 70°C in a batch reactor...

  3. Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory

    Science.gov (United States)

    Pavel, John T.; Hyde, Erin C.; Bruch, Martha D.

    2012-01-01

    This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possible…

  4. Chapter 1.1 Crystallinity of Nanocellulose Materials by Near-IR FT-Raman Spectroscopy

    Science.gov (United States)

    Umesh P. Agarwal; Richard S. Reiner; Sally A. Ralph

    2013-01-01

    Considering that crystallinity is one of the important properties that influence the end use of cellulose nanomaterials, it is important that the former be measured accurately. Recently, a new method based on near-IR FTRaman spectroscopy was proposed to determine cellulose I crystallinity. It was reported that in the Raman spectrum of cellulose materials, the...

  5. Solid Acid-Catalyzed Cellulose Hydrolysis Monitored by In Situ ATR-IR Spectroscopy

    NARCIS (Netherlands)

    Zakzeski, J.; Grisel, R.J.H.; Smit, A.T.; Weckhuysen, B.M.

    2012-01-01

    The solid acid-catalyzed hydrolysis of cellulose was studied under elevated temperatures and autogenous pressures using in situ ATR-IR spectroscopy. Standards of cellulose and pure reaction products, which include glucose, fructose, hydroxymethylfurfural (HMF), levulinic acid (LA), formic acid, and

  6. Preliminary study of corrosion mechanisms of actinides alloys: calibration of FT-IR spectroscopy

    International Nuclear Information System (INIS)

    Magnien, Veronique; Cadignan, Marx; Faivret, Olivier; Rosa, Gaelle

    2008-01-01

    In situ analyzes of gaseous atmospheres could be performed by FT-IR spectroscopy in order to study the corrosion reactions of actinides. Nevertheless experimental conditions and the nature of studied species have a strong effect on IR absorption laws. Thus a prior calibration of our set-up is required to obtain an accurate estimation of gas concentration. For this purpose, the behavior of several air pure gases has been investigated according to their concentration from IR spectra. Reproducible results revealed subsequent increases of the most significant peak areas with gas pressure and small deviations from Beer Lambert's law. This preliminary work allowed to determine precise absorption laws for each studied pure gas in our in situ experimental conditions. Besides our FT-IR set-up was well suitable to quantitative analysis of gaseous atmosphere during corrosion reactions. Finally the effect of foreign gas will be investigated through more complex air mixtures to obtain a complete calibration network. (authors)

  7. Preliminary Discrimination of Cheese Adulteration by FT-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Lucian Cuibus

    2014-11-01

    Full Text Available The present work describes a preliminary study to compare some traditional Romanian cheeses and adulterated cheeses using Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR. For PLS model calibration (6 concentration levels and validation (5 concentration levels sets were prepared from commercial Dalia Cheese from different manufacturers by spiking it with palm oil at concentrations ranging 2-50 % and 5-40 %, respectively. Fifteen Dalia Cheese were evaluated as external set. The spectra of each sample, after homogenization, were acquired in triplicate using a FTIR Shimatsu Prestige 21 Spectrophotometer, with a horizontal diamond ATR accessory in the MIR region 4000-600 cm-1. Statistical methods as PLS were applied using MVC1 routines written for Matlab R2010a. As first step the optimal condition for PLS model were obtained using cross-validation on the Calibration set. Spectral region in 3873-652 cm-1, and 3 PLS-factors were stated as the best conditions and showed an R2 value of 0.9338 and a relative error in the calibration of 17.2%. Then validation set was evaluated, obtaining good recovery rates (108% and acceptable dispersion of the data (20%. The curve of actual vs. predicted values shows slope near to 1 and origin close to 0, with an R2 of 0.9695. When the external sample set was evaluated, samples F19, F21, F22 and F24, showed detectable levels of palm fats. The results proved that FTIR-PLS is a reliable non-destructive technique for a rapid quantification the level of adulteration in cheese.  The spectroscopic methods could assist the quality control authority, traders and the producers to discriminate the adulterated cheeses with palm oil.

  8. Conversion electron spectroscopy in transfermium nuclei

    International Nuclear Information System (INIS)

    Herzberg, R.D.

    2003-01-01

    Conversion electron spectroscopy is an essential tool for the spectroscopy of heavy deformed nuclei. The conversion electron spectrometer SACRED has been used in conjunction with the gas-filled recoil separator RITU to study conversion electron cascades in 254 No. The spectra reveal the ground state rotational bands down to low spin. A detailed analysis of the background seen for 254 No shows that approximately 40% of the decay path goes via excited high K bands which may be built on an isomer. (orig.)

  9. Probing Gas Adsorption in Zeolites by Variable-Temperature IR Spectroscopy: An Overview of Current Research.

    Science.gov (United States)

    Garrone, Edoardo; Delgado, Montserrat R; Bonelli, Barbara; Arean, Carlos O

    2017-09-15

    The current state of the art in the application of variable-temperature IR (VTIR) spectroscopy to the study of (i) adsorption sites in zeolites, including dual cation sites; (ii) the structure of adsorption complexes and (iii) gas-solid interaction energy is reviewed. The main focus is placed on the potential use of zeolites for gas separation, purification and transport, but possible extension to the field of heterogeneous catalysis is also envisaged. A critical comparison with classical IR spectroscopy and adsorption calorimetry shows that the main merits of VTIR spectroscopy are (i) its ability to provide simultaneously the spectroscopic signature of the adsorption complex and the standard enthalpy change involved in the adsorption process; and (ii) the enhanced potential of VTIR to be site specific in favorable cases.

  10. Investigation of the hydrated 7-hydroxy-4-methylcoumarin dimer by combined IR/UV spectroscopy

    International Nuclear Information System (INIS)

    Stamm, A.; Schwing, K.; Gerhards, M.

    2014-01-01

    The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S 0 ) and cationic (D 0 ) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC) 2 as well as its mono- and dihydrate (7H4MC) 2 (H 2 O) 1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction

  11. Remote Thermal IR Spectroscopy of our Solar System

    Science.gov (United States)

    Kostiuk, Theodor; Hewagama, Tilak; Goldstein, Jeffrey; Livengood, Timothy; Fast, Kelly

    1999-01-01

    Indirect methods to detect extrasolar planets have been successful in identifying a number of stars with companion planets. No direct detection of an extrasolar planet has yet been reported. Spectroscopy in the thermal infrared region provides a potentially powerful approach to detection and characterization of planets and planetary systems. We can use knowledge of our own solar system, its planets and their atmospheres to model spectral characteristics of planets around other stars. Spectra derived from modeling our own solar system seen from an extrasolar perspective can be used to constrain detection strategies, identification of planetary class (terrestrial vs. gaseous) and retrieval of chemical, thermal and dynamical information. Emission from planets in our solar system peaks in the thermal infrared region, approximately 10 - 30 microns, substantially displaced from the maximum of the much brighter solar emission in the visible near 0.5 microns. This fact provides a relatively good contrast ratio to discriminate between stellar (solar) and planetary emission and optimize the delectability of planetary spectra. Important molecular constituents in planetary atmospheres have rotational-vibrational spectra in the thermal infrared region. Spectra from these molecules have been well characterized in the laboratory and studied in the atmospheres of solar system planets from ground-based and space platforms. The best example of such measurements are the studies with Fourier transform spectrometers, the Infrared Interferometer Spectrometers (IRIS), from spacecraft: Earth observed from NIMBUS 8, Mars observed from Mariner 9, and the outer planets observed from Voyager spacecraft. An Earth-like planet is characterized by atmospheric spectra of ozone, carbon dioxide, and water. Terrestrial planets have oxidizing atmospheres which are easily distinguished from reducing atmospheres of gaseous giant planets which lack oxygen-bearing species and are characterized by spectra

  12. The discrimination of 72 nitrate, chlorate and perchlorate salts using IR and Raman spectroscopy

    Science.gov (United States)

    Zapata, Félix; García-Ruiz, Carmen

    2018-01-01

    Inorganic oxidizing energetic salts including nitrates, chlorates and perchlorates are widely used in the manufacture of not only licit pyrotechnic compositions, but also illicit homemade explosive mixtures. Their identification in forensic laboratories is usually accomplished by either capillary electrophoresis or ion chromatography, with the disadvantage of dissociating the salt into its ions. On the contrary, vibrational spectroscopy, including IR and Raman, enables the non-invasive identification of the salt, i.e. avoiding its dissociation. This study focuses on the discrimination of all nitrate, chlorate and perchlorate salts that are commercially available, using both Raman and IR spectroscopy, with the aim of testing whether every salt can be unequivocally identified. Besides the visual spectra comparison by assigning every band with the corresponding molecular vibrational mode, a statistical analysis based on Pearson correlation was performed to ensure an objective identification, either using Raman, IR or both. Positively, 25 salts (out of 72) were unequivocally identified using Raman, 30 salts when using IR and 44 when combining both techniques. Negatively, some salts were undistinguishable even using both techniques demonstrating there are some salts that provide very similar Raman and IR spectra.

  13. Depth sectioning using electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    D'Alfonso, A J; Findlay, S D; Allen, L J; Cosgriff, E C; Kirkland, A I; Nellist, P D; Oxley, M P

    2008-01-01

    The continued development of electron probe aberration correctors for scanning transmission electron microscopy has enabled finer electron probes, allowing atomic resolution column-by-column electron energy loss spectroscopy. Finer electron probes have also led to a decrease in the probe depth of focus, facilitating optical slicing or depth sectioning of samples. The inclusion of post specimen aberration corrected image forming lenses allows for scanning confocal electron microscopy with further improved depth resolution and selectivity. We show that in both scanning transmission electron microscopy and scanning confocal electron microscopy geometries, by performing a three dimensional raster scan through a specimen and detecting electrons scattered with a characteristic energy loss, it will be possible to determine the location of isolated impurities embedded within the bulk.

  14. Electron capture and energy-gain spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taulbjerg, K.

    1989-01-01

    The applicability of translation energy spectroscopy as a tool to determine individual reaction cross sections in atomic collisions is analyzed with special emphasis on the electron capture process in highly charged ion collisions. A condition is derived to separate between higher collision energies where translation energy spectroscopy is problem free and lower energies where strong overlap of individual spectra features prohibits an analysis of the total translation energy spectrum by means of a simple deconvolution procedure. 8 refs., 6 figs.

  15. Structural, phase stability, electronic, elastic properties and hardness of IrN{sub 2} and zinc blende IrN: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhaobo [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhou, Xiaolong, E-mail: kmzxlong@163.com [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhang, Kunhua [State Key Laboratory of Rare Precious Metals Comprehensive Utilization of New Technologies, Kunming Institute of Precious Metals, Kunming 650106 (China)

    2016-12-15

    First-principle calculations were performed to investigate the structural, phase stability, electronic, elastic properties and hardness of monoclinic structure IrN{sub 2} (m-IrN{sub 2}), orthorhombic structure IrN{sub 2} (o-IrN{sub 2}) and zinc blende structure IrN (ZB IrN). The results show us that only m-IrN{sub 2} is both thermodynamic and dynamic stability. The calculated band structure and density of states (DOS) curves indicate that o-IrN{sub 2} and ZB Ir-N compounds we calculated have metallic behavior while m-IrN{sub 2} has a small band gap of ~0.3 eV, and exist a common hybridization between Ir-5d and N-2p states, which forming covalent bonding between Ir and N atoms. The difference charge density reveals the electron transfer from Ir atom to N atom for three Ir-N compounds, which forming strong directional covalent bonds. Notable, a strong N-N bond appeared in m-IrN{sub 2} and o-IrN{sub 2}. The ratio of bulk to shear modulus (B/G) indicate that three Ir-N compounds we calculated are ductile, and ZB IrN possesses a better ductility than two types IrN{sub 2}. m-IrN{sub 2} has highest Debye temperature (736 K), illustrating it possesses strongest covalent bonding. The hardness of three Ir-N compounds were also calculated, and the results reveal that m-IrN{sub 2} (18.23 GPa) and o-IrN{sub 2} (18.02 GPa) are ultraincompressible while ZB IrN has a negative value, which may be attributed to phase transition at ca. 1.98 GPa.

  16. Rapid identification of Pterocarpus santalinus and Dalbergia louvelii by FTIR and 2D correlation IR spectroscopy

    Science.gov (United States)

    Zhang, Fang-Da; Xu, Chang-Hua; Li, Ming-Yu; Huang, An-Min; Sun, Su-Qin

    2014-07-01

    Since Pterocarpus santalinus and Dalbergia louvelii, which are of precious Rosewood, are very similar in their appearance and anatomy characteristics, cheaper Hongmu D. louvelii is often illegally used to impersonate valuable P. santalinus, especially in Chinese furniture manufacture. In order to develop a rapid and effective method for easy confused wood furniture differentiation, we applied tri-step identification method, i.e., conventional infrared spectroscopy (FT-IR), second derivative infrared (SD-IR) spectroscopy and two-dimensional correlation infrared (2DCOS-IR) spectroscopy to investigate P. santalinus and D. louvelii furniture. According to FT-IR and SD-IR spectra, it has been found two unconditional stable difference at 848 cm-1 and 700 cm-1 and relative stable differences at 1735 cm-1, 1623 cm-1, 1614 cm-1, 1602 cm-1, 1509 cm-1, 1456 cm-1, 1200 cm-1, 1158 cm-1, 1055 cm-1, 1034 cm-1 and 895 cm-1 between D. louvelii and P. santalinus IR spectra. The stable discrepancy indicates that the category of extractives is different between the two species. Besides, the relative stable differences imply that the content of holocellulose in P. santalinus is more than that of D. louvelii, whereas the quantity of extractives in D. louvelii is higher. Furthermore, evident differences have been observed in their 2DCOS-IR spectra of 1550-1415 cm-1 and 1325-1030 cm-1. P. santalinus has two strong auto-peaks at 1459 cm-1 and 1467 cm-1, three mid-strong auto-peaks at 1518 cm-1, 1089 cm-1 and 1100 cm-1 and five weak auto-peaks at 1432 cm-1, 1437 cm-1, 1046 cm-1, 1056 cm-1 and 1307 cm-1 while D. louvelii has four strong auto-peaks at 1465 cm-1, 1523 cm-1, 1084 cm-1 and 1100 cm-1, four mid-strong auto-peaks at 1430 cm-1, 1499 cm-1, 1505 cm-1 and 1056 cm-1 and two auto-peaks at 1540 cm-1 and 1284 cm-1. This study has proved that FT-IR integrated with 2DCOS-IR could be applicable for precious wood furniture authentication in a direct, rapid and holistic manner.

  17. Penning ionization processes studied by electron spectroscopy

    International Nuclear Information System (INIS)

    Yencha, A.J.

    1978-01-01

    The technique of measuring the kinetic energy of electrons ejected from atomic or molecular species as a result of collisional energy transfer between a metastable excited rare gas atom and an atom or molecule is known as Penning ionization spectroscopy. Like the analogous photoionization process of photoelectron spectroscopy, a considerable amount of information has been gained about the ionization potentials of numerous molecular systems. It is, in fact, through the combined analyses of photoelectron and Penning electron spectra that affords a probe of the particle-particle interactions that occur in the Penning process. In this paper a short survey of the phenomenon of Penning ionization, as studied by electron spectroscopy, will be presented as it pertains to the ionization processes of simple molecules by metastable excited atoms. (author)

  18. Detection of metanil yellow contamination in turmeric using FT-Raman and FT-IR spectroscopy

    Science.gov (United States)

    Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon; Schmidt, Walter; Chan, Dian

    2016-05-01

    Turmeric is well known for its medicinal value and is often used in Asian cuisine. Economically motivated contamination of turmeric by chemicals such as metanil yellow has been repeatedly reported. Although traditional technologies can detect such contaminants in food, high operational costs and operational complexities have limited their use to the laboratory. This study used Fourier Transform Raman Spectroscopy (FT-Raman) and Fourier Transform - Infrared Spectroscopy (FT-IR) to identify metanil yellow contamination in turmeric powder. Mixtures of metanil yellow in turmeric were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1% and 0.01% (w/w). The FT-Raman and FT-IR spectral signal of pure turmeric powder, pure metanil yellow powder and the 8 sample mixtures were obtained and analyzed independently to identify metanil yellow contamination in turmeric. The results show that FT-Raman spectroscopy and FT-IR spectroscopy can detect metanil yellow mixed with turmeric at concentrations as low as 1% and 5%, respectively, and may be useful for non-destructive detection of adulterated turmeric powder.

  19. Time-domain SFG spectroscopy using mid-IR pulse shaping: practical and intrinsic advantages.

    Science.gov (United States)

    Laaser, Jennifer E; Xiong, Wei; Zanni, Martin T

    2011-03-24

    Sum-frequency generation (SFG) spectroscopy is a ubiquitous tool in the surface sciences. It provides infrared transition frequencies and line shapes that probe the structure and environment of molecules at interfaces. In this article, we apply techniques learned from the multidimensional spectroscopy community to SFG spectroscopy. We implement balanced heterodyne detection to remove scatter and the local oscillator background. Heterodyning also separates the resonant and nonresonant signals by acquiring both the real and imaginary parts of the spectrum. We utilize mid-IR pulse shaping to control the phase and delay of the mid-IR pump pulse. Pulse shaping allows phase cycling for data collection in the rotating frame and additional background subtraction. We also demonstrate time-domain data collection, which is a Fourier transform technique, and has many advantages in signal throughput, frequency resolution, and line shape accuracy over existing frequency domain methods. To demonstrate time-domain SFG spectroscopy, we study an aryl isocyanide on gold, and find that the system has an inhomogeneous structural distribution, in agreement with computational results, but which was not resolved by previous frequency-domain SFG studies. The ability to rapidly and actively manipulate the mid-IR pulse in an SFG pules sequence makes possible new experiments and more accurate spectra. © 2011 American Chemical Society

  20. Photoelectron spectroscopy and Auger electron spectroscopy of solids and surfaces

    International Nuclear Information System (INIS)

    Kowalczyk, S.P.

    1976-01-01

    The use of photoelectron spectroscopy, primarily x-ray photoelectron spectroscopy, to obtain information on the electronic structure of a wide variety of solids (especially the bulk electronic structure of solids) is covered. Both valence band and core-level spectra, as well as a few cases of photon excited Auger electron spectroscopy, are employed in the investigations to derive information on N(E). The effect of several modulations inherent in the measured I(E)'s, such as final state band structure, cross section, and relaxation, is discussed. Examples of many-electron interactions in PES are given. Some experimental aspects of PES and AES studies are given with emphasis on sample preparation techniques. Multiple splitting of core levels is examined using the Mn levels in MnF 2 as a detailed case study. Core level splittings in transition metals, rare earth metals, transition metal halides and several alloys are also reported. The application of PES to the study of the chemical bond in some crystalline semiconductors and insulators, A/sup N/B/sup 8-N/ and A/sup N/B/sup 10-N/ compounds is treated, and a spectroscopic scale of ionicity for these compounds is developed from the measured ''s-band'' splitting in the valence band density of states

  1. Dynamical effects in electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jianqiang Sky, E-mail: jianqiang.zhou@polytechnique.edu; Reshetnyak, Igor; Giorgetti, Christine; Sottile, Francesco; Reining, Lucia [Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau (France); Kas, J. J.; Rehr, J. J. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Sponza, Lorenzo [Department of Physics, King’s College London, London WC2R 2LS (United Kingdom); Guzzo, Matteo [Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, D-12489 Berlin (Germany); Gatti, Matteo [Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau (France); Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette (France)

    2015-11-14

    One of the big challenges of theoretical condensed-matter physics is the description, understanding, and prediction of the effects of the Coulomb interaction on materials properties. In electronic spectra, the Coulomb interaction causes a renormalization of energies and change of spectral weight. Most importantly, it can lead to new structures, often called satellites. These can be linked to the coupling of excitations, also termed dynamical effects. State-of-the-art methods in the framework of many-body perturbation theory, in particular, the widely used GW approximation, often fail to describe satellite spectra. Instead, approaches based on a picture of electron-boson coupling such as the cumulant expansion are promising for the description of plasmon satellites. In this work, we give a unified derivation of the GW approximation and the cumulant expansion for the one-body Green’s function. Using the example of bulk sodium, we compare the resulting spectral functions both in the valence and in the core region, and we discuss the dispersion of quasi-particles and satellites. We show that self-consistency is crucial to obtain meaningful results, in particular, at large binding energies. Very good agreement with experiment is obtained when the intrinsic spectral function is corrected for extrinsic and interference effects. Finally, we sketch how one can approach the problem in the case of the two-body Green’s function, and we discuss the cancellation of various dynamical effects that occur in that case.

  2. Dynamical effects in electron spectroscopy

    International Nuclear Information System (INIS)

    Zhou, Jianqiang Sky; Reshetnyak, Igor; Giorgetti, Christine; Sottile, Francesco; Reining, Lucia; Kas, J. J.; Rehr, J. J.; Sponza, Lorenzo; Guzzo, Matteo; Gatti, Matteo

    2015-01-01

    One of the big challenges of theoretical condensed-matter physics is the description, understanding, and prediction of the effects of the Coulomb interaction on materials properties. In electronic spectra, the Coulomb interaction causes a renormalization of energies and change of spectral weight. Most importantly, it can lead to new structures, often called satellites. These can be linked to the coupling of excitations, also termed dynamical effects. State-of-the-art methods in the framework of many-body perturbation theory, in particular, the widely used GW approximation, often fail to describe satellite spectra. Instead, approaches based on a picture of electron-boson coupling such as the cumulant expansion are promising for the description of plasmon satellites. In this work, we give a unified derivation of the GW approximation and the cumulant expansion for the one-body Green’s function. Using the example of bulk sodium, we compare the resulting spectral functions both in the valence and in the core region, and we discuss the dispersion of quasi-particles and satellites. We show that self-consistency is crucial to obtain meaningful results, in particular, at large binding energies. Very good agreement with experiment is obtained when the intrinsic spectral function is corrected for extrinsic and interference effects. Finally, we sketch how one can approach the problem in the case of the two-body Green’s function, and we discuss the cancellation of various dynamical effects that occur in that case

  3. Combined IR-Raman vs vibrational sum-frequency heterospectral correlation spectroscopy

    Science.gov (United States)

    Roy, Sandra; Beutier, Clémentine; Hore, Dennis K.

    2018-06-01

    Vibrational sum-frequency generation spectroscopy is a valuable probe of surface structure, particularly when the same molecules are present in one of the adjacent bulk solid or solution phases. As a result of the non-centrosymmetric requirement of SFG, the signal generated is a marker of the extent to which the molecules are ordered in an arrangement that breaks the up-down symmetry at the surface. In cases where the accompanying changes in the bulk are of interest in understanding and interpreting the surface structure, simultaneous analysis of the bulk IR absorption or bulk Raman scattering is helpful, and may be used in heterospectral surface-bulk two-dimensional correlation. We demonstrate that, in such cases, generating a new type of bulk spectrum that combines the IR and Raman amplitudes is a better candidate than the individual IR and Raman spectra for the purpose of correlation with the SFG signal.

  4. Assessment of Azithromycin in Pharmaceutical Formulation by Fourier-transform Infrared (FT-IR Transmission Spectroscopy

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Mallah

    2011-12-01

    Full Text Available A simple, rapid and economical method for azithromycin quantification in solid tablet and capsule formulations has been developed by applying Fourier-transform Infrared (FT-IR transmission spectroscopy for regular quality monitoring. The newly developed method avoids the sample preparation, except grinding for pellet formation and does not involve consumption of any solvent as it absolutely eliminates the need of extraction. KBr pellets were employed for the appraisal of azithromycin while acquiring spectra of standards as well as samples on FT-IR. By selecting the FT-IR carbonyl band (C=O in the region 1,744–1,709 cm−1 the calibration model was developed based on simple Beer’s law. The excellent regression coefficient (R2 0.999 was accomplished for calibration set having standard error of calibration equal to 0.01 mg. The current work exposes that transmission FT-IR spectroscopy can definitely be applied to determine the exact amount of azithromycin to control the processing and quality of solid formulations with reduced cost and short analysis time.

  5. Characterization by Fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of a carbosilane dendrimer with peripheral ammonium groups

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, Maria-Cristina, E-mail: cpopescu@icmpp.ro [' Petru Poni' Institute of Macromolecular Chemistry (Romania); Gomez, Rafael; Mata, Fco Javier de la; Rasines, Beatriz [Universidad de Alcala, Departamento de Quimica Inorganica (Spain); Simionescu, Bogdan C. [' Petru Poni' Institute of Macromolecular Chemistry (Romania)

    2013-06-15

    Fourier transform infrared spectroscopy and 2D correlation spectroscopy were used to study the microstructural changes occurring on heating of a new carbosilane dendrimer with peripheral ammonium groups. Temperature-dependent spectral variations in the 3,010-2,710, 1,530-1,170, and 1,170-625 cm{sup -1} regions were monitored during the heating process. The dependence, on temperature, of integral absorptions and position of spectral bands was established and the spectral modifications associated with molecular conformation rearrangements, allowing molecular shape changes, were found. Before 180 Degree-Sign C, the studied carbosilane dendrimer proved to be stable, while at higher temperatures it oxidizes and Si-O groups appear. 2D IR correlation spectroscopy gives new information about the effect of temperature on the structure and dynamics of the system. Synchronous and asynchronous spectra indicate that, at low temperature, conformational changes of CH{sub 3} and CH{sub 3}-N{sup +} groups take place first. With increasing temperature, the intensity variation of the CH{sub 2}, C-N, Si-C and C-C groups from the dendritic core is faster than that of the terminal units. This indicates that, with increasing temperature, the segments of the dendritic core obtain enough energy to change their conformation more easily as compared to the terminal units, due to their internal flexibility.

  6. Characterization by Fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of a carbosilane dendrimer with peripheral ammonium groups

    International Nuclear Information System (INIS)

    Popescu, Maria-Cristina; Gómez, Rafael; Mata, Fco Javier de la; Rasines, Beatriz; Simionescu, Bogdan C.

    2013-01-01

    Fourier transform infrared spectroscopy and 2D correlation spectroscopy were used to study the microstructural changes occurring on heating of a new carbosilane dendrimer with peripheral ammonium groups. Temperature-dependent spectral variations in the 3,010–2,710, 1,530–1,170, and 1,170–625 cm −1 regions were monitored during the heating process. The dependence, on temperature, of integral absorptions and position of spectral bands was established and the spectral modifications associated with molecular conformation rearrangements, allowing molecular shape changes, were found. Before 180 °C, the studied carbosilane dendrimer proved to be stable, while at higher temperatures it oxidizes and Si–O groups appear. 2D IR correlation spectroscopy gives new information about the effect of temperature on the structure and dynamics of the system. Synchronous and asynchronous spectra indicate that, at low temperature, conformational changes of CH 3 and CH 3 –N + groups take place first. With increasing temperature, the intensity variation of the CH 2 , C–N, Si–C and C–C groups from the dendritic core is faster than that of the terminal units. This indicates that, with increasing temperature, the segments of the dendritic core obtain enough energy to change their conformation more easily as compared to the terminal units, due to their internal flexibility.

  7. Spectroscopy of two-electron atoms

    International Nuclear Information System (INIS)

    Desesquelles, J.

    1988-01-01

    Spectroscopy of heliumlike ions is discussed putting emphasis on mid and high Z atoms. Experimental aspects of ion charge, excitation production, clean spectra, and precise wavelength measurement are detailed. Recent results obtained at several laboratories including Lyon, Argonne, Notre-Dame, Oxford, Berkeley, Darmstadt, Paris, are used to test the QED contributions and higher order relativistic corrections to two-electron atom energies. (orig.)

  8. Molecular orientation in aligned electrospun polyimide nanofibers by polarized FT-IR spectroscopy.

    Science.gov (United States)

    Yang, Haoqi; Jiang, Shaohua; Fang, Hong; Hu, Xiaowu; Duan, Gaigai; Hou, Haoqing

    2018-07-05

    Quantitative explanation on the improved mechanical properties of aligned electrospun polyimide (PI) nanofibers as the increased imidization temperatures is highly required. In this work, polarized FT-IR spectroscopy is applied to solve this problem. Based on the polarized FT-IR spectroscopy and the molecular model in the fibers, the length of the repeat unit of PI molecule, the angle between the fiber axis and the symmetric stretching direction of carbonyl group on the imide ring, and the angle between the PI molecular axis and fiber axis are all investigated. The Mark-Howink equation is used to calculate the number-average molar mass of PI molecules. The orientation states of PI molecules in the electrospun nanofibers are studied from the number-average molar mass of PI molecules and the average fiber diameter. Quantitative analysis of the orientation factor of PI molecules in the electrospun nanofibers is performed by polarized FT-IR spectroscopy. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Proposals of electronic-vibrational energy relaxation studies by using laser pulses synchronized with IR-SR pulses

    International Nuclear Information System (INIS)

    Nakagawa, Hideyuki

    2000-01-01

    Synchrotron radiation is expected to be the sharp infrared light source for the advanced experiments on IR and FIR spectroscopy in wide research fields. Especially, synchronized use of SR with VIS and/or UV laser light is to be a promising technique for the research on the dynamical properties of the photo-excited states in condensed materials. Some proposals are attempted for high resolution IR spectroscopy to elucidate fine interaction of molecular ions in crystalline solids with their environmental field and for time-resolved IR spectroscopic studies on the electronic and vibrational energy relaxation by using laser pulses synchronized with IR-SR pulses. Several experimental results are presented in relevance to the subjects; on high-resolution FTIR spectra of cyanide ions and metal cyanide complexes in cadmium halide crystals, on the energy up-conversion process among the vibrational levels of cyanide ions in alkali halide crystals, and on the electronic-to-vibrational energy conversion process in metal cyanide complexes. (author)

  10. Application of Fourier transform infrared (FT-IR) spectroscopy in determination of microalgal compositions.

    Science.gov (United States)

    Meng, Yingying; Yao, Changhong; Xue, Song; Yang, Haibo

    2014-01-01

    Fourier transform infrared spectroscopy (FT-IR) was applied in algal strain screening and monitoring cell composition dynamics in a marine microalga Isochrysis zhangjiangensis during algal cultivation. The content of lipid, carbohydrate and protein of samples determined by traditional methods had validated the accuracy of FT-IR method. For algal screening, the band absorption ratios of lipid/amide I and carbo/amide I from FT-IR measurements allowed for the selection of Isochrysis sp. and Tetraselmis subcordiformis as the most potential lipid and carbohydrate producers, respectively. The cell composition dynamics of I. zhangjiangensis measured by FT-IR revealed the diversion of carbon allocation from protein to carbohydrate and neutral lipid when nitrogen-replete cells were subjected to nitrogen limitation. The carbo/amide I band absorption ratio had also been demonstrated to depict physiological status under nutrient stress in T. subcordiformis. FT-IR serves as a tool for the simultaneous measurement of lipid, carbohydrate, and protein content in cell. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Matrix isolation FT-IR spectroscopy and molecular orbital study of sarcosine methyl ester

    Science.gov (United States)

    Gómez-Zavaglia, A.; Fausto, R.

    2004-02-01

    N-methylglycine methyl ester (sarcosine-Me) has been studied by matrix isolation FT-IR spectroscopy and molecular orbital calculations undertaken at the DFT/B3LYP and MP2 levels of theory with the 6-311++G(d,p) and 6-31++G(d,p) basis set, respectively. Twelve different conformers were located in the potential energy surface of the studied compound, with the ASC conformer being the ground conformational state. This form is analogous to the dimethylglycine methyl ester most stable conformer and is characterized by a NH⋯O intramolecular hydrogen bond; in this form, the ester group assumes the cis configuration and the OC-C-N and Lp-N-C-C (where Lp is the nitrogen lone electron pair) dihedral angles are ca. -17.8 and 171.3°, respectively. The second most stable conformer ( GSC) differs from the ASC conformer essentially in the conformation assumed by the methylamino group, which in this case is gauche ( Lp-N-C-C dihedral angle equal to 79.4°). On the other hand, the third most stable conformer ( AAC) differs from the most stable form in the conformation of the OC-C-N axis (151.4°). These three forms were predicted to differ in energy by less than ca. 5 kJ mol -1 and represent ≈95% of the total conformational population at room temperature. FT-IR spectra were obtained for sarcosine-Me isolated in argon matrices (T=9 K) revealing the presence in the matrices of the three lowest energy conformers predicted by the calculations. The matrices were prepared by deposition of the vapour of the compound using two different nozzle temperatures, 25 and 60 °C. The relative populations of the three conformers trapped in the matrices were found to be consistent with occurrence of conformational cooling during matrix deposition and with a stabilization of the most polar GSC and AAC conformers in the matrices compared to the gas phase. Indeed, like it was previously observed for the methyl ester of dimethylglycine [Phys. Chem. Chem. Phys. 5 (2003) 52] the different

  12. Case study of chondrule alteration with IR spectroscopy in NWA 2086 CV3 meteorite

    Science.gov (United States)

    Kereszturi, A.; Gyollai, I.; Szabó, M.

    2015-02-01

    Analyzing the alteration in an olivine chondrule of the NWA 2086 CV3 meteorite, infrared spectral, electron microprobe and optical microscopic observations were correlated to each other. The intensity and wavelength positions of olivine peaks changed characteristically with the progression of alteration and related Fe/Mg substitution inward of the chondrule. Moderate to good correlations were identified between Fo% composition and positions of 830 and 860 cm-1 IR peaks. The disappearance of 1020 cm-1 peak by structural change happens already at a low level alteration without changing the optical appearance of the mineral. The existence of the 980 cm-1 peak is found to be an indicator of the intact phase of olivine. While profiles perpendicular to the chondrule's perimeter showed that the alteration progressed 15-20 μm distance inward without observable fractures (probablly by some diffusion related process), the "alteration distance" from various obvious fractures inside the chondrule was only 3-5 μm distance. These observations suggest that the substitution was more effective close to the matrix, and also related to some fluids that although were able to circulate along the large internal fractures too, did not produce such strong substitution there, like what happened close to the matrix. It was also demonstrated that the poorly exploited contact mode observations with ATR based reflection method in infrared spectroscopy provide a useful tool to analyze the alteration at micrometer scale without much sample preparation, and enable identifying alterations already at such a low level where the olivines still look optically intact.

  13. Single Molecule Spectroscopy of Electron Transfer

    International Nuclear Information System (INIS)

    Holman, Michael; Zang, Ling; Liu, Ruchuan; Adams, David M.

    2009-01-01

    The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

  14. ATR FT-IR spectroscopy on Vmh2 hydrophobin self-assembled layers for Teflon membrane bio-functionalization

    International Nuclear Information System (INIS)

    Portaccio, M.; Gravagnuolo, A.M.; Longobardi, S.; Giardina, P.; Rea, I.; De Stefano, L.; Cammarota, M.; Lepore, M.

    2015-01-01

    Graphical abstract: - Highlights: • Hydrophobin self-assembled layers on Teflon in different preparation conditions were investigated. • ATR collection data geometry allowed samples examination without any particular preparation. • Amide content, lipid/amide and carbohydrate/amide ratios of the protein layer were estimated. • Secondary structure of protein was determined for the examined samples. • FT-IR demonstrated to be of extreme relevance in monitoring hydrophobin self-assembled layers preparation. - Abstract: Surface functionalization by layers of hydrophobins, amphiphilic proteins produced by fungi offers a promising and green strategy for fabrication of biomedical and bioanalytical devices. The layering process of the Vmh2 hydrophobin from Pleurotus ostreatus on Teflon membrane has been investigated by Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) spectroscopy. In particular, protein layers obtained with hydrophobin purified with two different procedures and in various coating conditions have been examined. The layers have been characterized by quantifying the amide I and amide II band area together with the lipid/amide ratio and carbohydrate/amide ratio. This characterization can be very useful in evaluating the best purification strategy and coating conditions. Moreover the analysis of the secondary structure of the layered protein using the deconvolution procedure of amide I band indicate the prevalent contribution from β-sheet state. The results inferred by infrared spectroscopy have been also confirmed by scanning electron microscopy imaging

  15. ATR FT-IR spectroscopy on Vmh2 hydrophobin self-assembled layers for Teflon membrane bio-functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Portaccio, M., E-mail: marianna.portaccio@unina2.it [Dipartimento di Medicina Sperimentale – Seconda Università di Napoli, Via S.M. di Costantinopoli, 16-80134 Napoli (Italy); Gravagnuolo, A.M., E-mail: alfredomaria.gravagnuolo@unina.it [Dipartimento di Scienze Chimiche, Università “Federico II”, Via Cintia, 21- 80126 Napoli (Italy); Longobardi, S., E-mail: sara.longobardi@unina.it [Dipartimento di Scienze Chimiche, Università “Federico II”, Via Cintia, 21- 80126 Napoli (Italy); Giardina, P., E-mail: paola.giardina@unina.it [Dipartimento di Scienze Chimiche, Università “Federico II”, Via Cintia, 21- 80126 Napoli (Italy); Rea, I., E-mail: ilaria.rea@na.imm.cnr.it [Institute for Microelectronics and Microsystems, CNR, Via P. Castellino, 111-80131 Napoli (Italy); De Stefano, L., E-mail: luca.destefano@na.imm.cnr.it [Institute for Microelectronics and Microsystems, CNR, Via P. Castellino, 111-80131 Napoli (Italy); Cammarota, M., E-mail: marcella.cammarota@unina2.it [Dipartimento di Medicina Sperimentale – Seconda Università di Napoli, Via S.M. di Costantinopoli, 16-80134 Napoli (Italy); Lepore, M., E-mail: maria.lepore@unina2.it [Dipartimento di Medicina Sperimentale – Seconda Università di Napoli, Via S.M. di Costantinopoli, 16-80134 Napoli (Italy)

    2015-10-01

    Graphical abstract: - Highlights: • Hydrophobin self-assembled layers on Teflon in different preparation conditions were investigated. • ATR collection data geometry allowed samples examination without any particular preparation. • Amide content, lipid/amide and carbohydrate/amide ratios of the protein layer were estimated. • Secondary structure of protein was determined for the examined samples. • FT-IR demonstrated to be of extreme relevance in monitoring hydrophobin self-assembled layers preparation. - Abstract: Surface functionalization by layers of hydrophobins, amphiphilic proteins produced by fungi offers a promising and green strategy for fabrication of biomedical and bioanalytical devices. The layering process of the Vmh2 hydrophobin from Pleurotus ostreatus on Teflon membrane has been investigated by Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) spectroscopy. In particular, protein layers obtained with hydrophobin purified with two different procedures and in various coating conditions have been examined. The layers have been characterized by quantifying the amide I and amide II band area together with the lipid/amide ratio and carbohydrate/amide ratio. This characterization can be very useful in evaluating the best purification strategy and coating conditions. Moreover the analysis of the secondary structure of the layered protein using the deconvolution procedure of amide I band indicate the prevalent contribution from β-sheet state. The results inferred by infrared spectroscopy have been also confirmed by scanning electron microscopy imaging.

  16. Identification and characterization of salmonella serotypes using DNA spectral characteristics by fourier transform infrared (FT-IR) spectroscopy

    Science.gov (United States)

    Analysis of DNA samples of Salmonella serotypes (Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky) were performed using Fourier transform infrared spectroscopy (FT-IR) spectrometer by placing directly in contact with a diamond attenua...

  17. Mid IR-fiber spectroscopy in the 2-17μm range

    Science.gov (United States)

    Artyushenko, Viatcheslav G.; Bocharnikov, A.; Colquhoun, Gary; Leach, Clive A.; Lobachov, Vladimir; Pirogova, Lyudmila; Sakharova, Tatjana; Savitskij, Dmitrij; Ezhevskaya, Tatjana; Bublikov, Alexandr

    2007-10-01

    The latest development in IR-fibre optics enables us to expand the spectral range of process spectroscopy from 2μm out to 17μm (5000 to 600cm-1) i.e. into the most informative "finger-print" part of the spectrum. Mid-IR wavelength ranges from 2 to 6-10μm may be covered by Chalcogenide IR-glass CIR-fibres while Polycrystalline PIR-fibres made of Silver Halides solid solutions transmit 4-17 μm wavelength radiation. PIR-fibre immersion ATR probes and Transmission/Reflection probes had been manufactured and successfully tested with different FTIR spectrometers in the field of remote spectroscopy for forensic substances identification, chemical reaction control, and monitoring of exhaust or exhalation gases. Using these techniques no sample preparation is necessary for fibre probes to measure evanescent, reflection and transmission spectra, in situ and in real time. QCL spectrometer may be used as a portable device for multispectral gas analysis at 1ppb level of detectivity for various applications in environmental pollution monitoring.

  18. Collaborative Student Laboratory Exercise Using FT-IR Spectroscopy for the Kinetics Study of a Biotin Analogue

    Science.gov (United States)

    Leong, Jhaque; Ackroyd, Nathan C.; Ho, Karen

    2014-01-01

    The synthesis of N-methoxycarbonyl-2-imidazolidone, an analogue of biotin, was conducted by organic chemistry students and confirmed using FT-IR and H NMR. Spectroscopy students used FT-IR to measure the rate of hydrolysis of the product and determined the rate constant for the reaction using the integrated rate law. From the magnitude of the rate…

  19. Rapid identification of Chinese Sauce liquor from different fermentation positions with FT-IR spectroscopy

    Science.gov (United States)

    Li, Changwen; Wei, Jiping; Zhou, Qun; Sun, Suqin

    2008-07-01

    FT-IR and two-dimensional correlation spectroscopy (2D-IR) technology were applied to discriminate Chinese Sauce liquor from different fermentation positions (top, middle and bottom of fermentation cellar) for the first time. The liquors at top, middle and bottom of fermentation cellar, possessed the characteristic peaks at 1731 cm -1, 1733 cm -1 and 1602 cm -1, respectively. In the 2D correlation infrared spectra, the differences were amplified. A strong auto-peak at 1725 cm -1 showed in the 2D spectra of the Top Liquor, which indicated that the liquor might contain some ester compounds. Different from Top Liquor, three auto-peaks at 1695, 1590 and 1480 cm -1 were identified in 2D spectra of Middle Liquor, which were the characteristic absorption of acid, lactate. In 2D spectra of Bottom Liquor, two auto-peaks at 1570 and 1485 cm -1 indicated that lactate was the major component. As a result, FT-IR and 2D-IR correlation spectra technology provided a rapid and effective method for the quality analysis of the Sauce liquor.

  20. Attenuated total reflectance-FT-IR spectroscopy for gunshot residue analysis: potential for ammunition determination.

    Science.gov (United States)

    Bueno, Justin; Sikirzhytski, Vitali; Lednev, Igor K

    2013-08-06

    The ability to link a suspect to a particular shooting incident is a principal task for many forensic investigators. Here, we attempt to achieve this goal by analysis of gunshot residue (GSR) through the use of attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) combined with statistical analysis. The firearm discharge process is analogous to a complex chemical process. Therefore, the products of this process (GSR) will vary based upon numerous factors, including the specific combination of the firearm and ammunition which was discharged. Differentiation of FT-IR data, collected from GSR particles originating from three different firearm-ammunition combinations (0.38 in., 0.40 in., and 9 mm calibers), was achieved using projection to latent structures discriminant analysis (PLS-DA). The technique was cross (leave-one-out), both internally and externally, validated. External validation was achieved via assignment (caliber identification) of unknown FT-IR spectra from unknown GSR particles. The results demonstrate great potential for ATR-FT-IR spectroscopic analysis of GSR for forensic purposes.

  1. Auger electron spectroscopy of alloy surfaces

    International Nuclear Information System (INIS)

    Overbury, S.H.; Somorjai, G.A.

    1975-03-01

    Regular solution models are used to predict surface segregation of the constituent of lowest surface free energy in homogeneous multicomponent systems. Analysis of the Auger electron emission intensities from alloys yield the surface composition and the depth distribution of the composition near the surface. Auger Electron Spectroscopy (AES) studies of the surface composition of the Ag--Au and Pb--In systems have been carried out as a function of bulk composition and temperature. Although these alloys have very different regular solution parameters their surface compositions are predictable by the regular solution models. (U.S.)

  2. Photoelectron spectroscopy bulk and surface electronic structures

    CERN Document Server

    Suga, Shigemasa

    2014-01-01

    Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

  3. Application of FT-IR spectroscopy on breast cancer serum analysis

    Science.gov (United States)

    Elmi, Fatemeh; Movaghar, Afshin Fayyaz; Elmi, Maryam Mitra; Alinezhad, Heshmatollah; Nikbakhsh, Novin

    2017-12-01

    Breast cancer is regarded as the most malignant tumor among women throughout the world. Therefore, early detection and proper diagnostic methods have been known to help save women's lives. Fourier Transform Infrared (FT-IR) spectroscopy, coupled with PCA-LDA analysis, is a new technique to investigate the characteristics of serum in breast cancer. In this study, 43 breast cancer and 43 healthy serum samples were collected, and the FT-IR spectra were recorded for each one. Then, PCA analysis and linear discriminant analysis (LDA) were used to analyze the spectral data. The results showed that there were differences between the spectra of the two groups. Discriminating wavenumbers were associated with several spectral differences over the 950-1200 cm- 1(sugar), 1190-1350 cm- 1 (collagen), 1475-1710 cm- 1 (protein), 1710-1760 cm- 1 (ester), 2800-3000 cm- 1 (stretching motions of -CH2 & -CH3), and 3090-3700 cm- 1 (NH stretching) regions. PCA-LDA performance on serum IR could recognize changes between the control and the breast cancer cases. The diagnostic accuracy, sensitivity, and specificity of PCA-LDA analysis for 3000-3600 cm- 1 (NH stretching) were found to be 83%, 84%, 74% for the control and 80%, 76%, 72% for the breast cancer cases, respectively. The results showed that the major spectral differences between the two groups were related to the differences in protein conformation in serum samples. It can be concluded that FT-IR spectroscopy, together with multivariate data analysis, is able to discriminate between breast cancer and healthy serum samples.

  4. Matrix isolation FT-IR spectroscopy and molecular orbital study of sarcosine methyl ester

    OpenAIRE

    Gómez-Zavaglia, Andrea; Fausto, R.

    2004-01-01

    N-methylglycine methyl ester (sarcosine-Me) has been studied by matrix isolation FT-IR spectroscopy and molecular orbital calculations undertaken at the DFT/B3LYP and MP2 levels of theory with the 6-311++G(d,p) and 6-31++G(d,p) basis set, respectively. Twelve different conformers were located in the potential energy surface of the studied compound, with the ASC conformer being the ground conformational state. This form is analogous to the dimethylglycine methyl ester most stable conformer and...

  5. Study on high-silicon boron-containing zeolite by thermogravimetric and IR-spectroscopy techniques

    International Nuclear Information System (INIS)

    Chukin, G.D.; Nefedov, B.K.; Surin, S.A.; Polinina, E.V.; Khusid, B.L.; Sidel'kovskaya, V.G.

    1985-01-01

    The structure identity of initial Na-forms of boron-containing and aluminosilicate high-silicon zeolites is established by thermogravimetric and IR-spectroscopy methods. The presence of boron in Na-forms of high-silicon zeolites is shown to lead to reduction of structure thermal stability. It is noted that thermal stability of the H-form of both high-silicon boron-containing and boron-free zeolites is practically equal and considerably higher than that of Na-forms

  6. Using FT-IR Spectroscopy to Elucidate the Structures of Ablative Polymers

    Science.gov (United States)

    Fan, Wendy

    2011-01-01

    The composition and structure of an ablative polymer has a multifaceted influence on its thermal, mechanical and ablative properties. Understanding the molecular level information is critical to the optimization of material performance because it helps to establish correlations with the macroscopic properties of the material, the so-called structure-property relationship. Moreover, accurate information of molecular structures is also essential to predict the thermal decomposition pathways as well as to identify decomposition species that are fundamentally important to modeling work. In this presentation, I will describe the use of infrared transmission spectroscopy (FT-IR) as a convenient tool to aid the discovery and development of thermal protection system materials.

  7. Two-dimensional electronic spectroscopy with birefringent wedges

    Energy Technology Data Exchange (ETDEWEB)

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2014-12-15

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  8. Electron spectroscopy with fast heavy ions

    International Nuclear Information System (INIS)

    Schneider, D.

    1983-01-01

    Since about 1970 the spectroscopy of Auger-electrons and characteristic x-rays following energetic ion-atom collisions has received a great deal of attention. An increasing number of accelerators, capable of providing a large number of projectile ion species over a wide range of projectile energies, became available for studying ion-atom collision phenomena. Many charged particles from protons up to heavy ions like uranium can be accelerated to energies ranging over six orders of magnitude. This allows us to study systematically a great variety of effects accompanied by dynamic excitation processes of the atomic shells in either the projectile- or target-atoms. The studies yield fundamental information regarding the excitation mechanism (e.g., Coulomb and quasi-molecular excitation) and allow sensitive tests of atomic structure theories. This information in turn is valuable to other fields in physics like plasma-, astro-, or solid-state (surface) physics. It is a characteristic feature of fast heavy-ion accelerators that they can produce highly stripped ion species which have in turn the capability to highly ionize neutral target atoms or molecules in a single collision. The ionization process, mainly due to the strong electrical fields that are involved, allows us to study few-electron atoms with high atomic numbers Z. High resolution spectroscopy performed with these atoms allows a particularly good test of relativistic and QED effects. The probability of producing these few electron systems is determined by the charge state and the velocity of the projectile ions. In this contribution the possibilities of using electron spectroscopy as a tool to investigate fast ion-atom collisions is discussed and demonstrated with a few examples. 30 references

  9. ESR studies of electron irradiated K3Ir(CN)6 in KCl single crystals

    International Nuclear Information System (INIS)

    Vugman, N.V.; Pinhal, N.M.

    1983-01-01

    ESR studies of KCl single crystals doped with small amounts of K 3 Ir(CN) 6 and submitted to a prolongued 2 MeV electron irradiation at room temperature reveal the presence of the [IR(CN) 5 Cl] 4- and [Ir(CN) 4 Cl 2 ] 4- new molecular species. Ligand spin densities and ligand field parameters are calculated from the experimental hyperfine and superhyperfine interactions and compared to previous data on the [Ir(CN) 5 ] 4- species. (Author) [pt

  10. Structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7

    Science.gov (United States)

    Kumar, Harish; Chaurasia, Rachna; Kumari, Pratibha; Paramanik, A. K.

    2018-04-01

    We have studied the structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7. Structural investigation has been done using x-ray powder diffraction and Rietveld analysis. Pr2Ir2O7 crystallize in cubic crystallographic phase with Fd-3m space group. Temperature dependent magnetization data does not show magnetic bifurcation down to 2 K. Electrical resistivity data of Pr2Ir2O7 exhibits metallic behavior throughout temperature range. Below 50 K, a small rise in resistivity data of Pr2Ir2O7 is observed down to 12 K.

  11. Weak carbonyl-methyl intermolecular interactions in acetone clusters explored by IR plus VUV spectroscopy

    International Nuclear Information System (INIS)

    Guan, Jiwen; Hu, Yongjun; Xie, Min; Bernstein, Elliot R.

    2012-01-01

    Highlights: ► The carbonyl overtone of acetone clusters is observed by IR-VUV spectroscopy. ► Acetone molecules in the dimer are stacked with an antiparallel way. ► The structure of the acetone trimer and the tetramer are the cyclic structures. ► The carbonyl groups would interact with the methyl groups in acetone clusters. ► These weak interactions are further confirmed by H/D substitution experiment. -- Abstract: Size-selected IR–VUV spectroscopy is employed to detect vibrational characteristics in the region 2850 ∼ 3550 cm −1 of neutral acetone and its clusters (CH 3 COCH 3 ) n (n = 1–4). Features around 3440 cm −1 in the spectra of acetone monomer and its clusters are assigned to the carbonyl stretch (CO) overtone. These features red-shift from 3455 to 3433 cm −1 as the size of the clusters increases from the monomer to the tetramer. Based on calculations, the experimental IR spectra in the C=O overtone region suggest that the dominant structures for the acetone trimer and tetramer should be cyclic in the supersonic expansion sample. This study also suggests that the carbonyl groups interact with the methyl groups in the acetone clusters. These weak interactions are further confirmed by the use of deuterium substitution.

  12. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test

    Directory of Open Access Journals (Sweden)

    Tahereh-Sadat Jafarzadeh

    2015-12-01

    Full Text Available Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm. Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan was performed at the top and bottom (depth=2 mm surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

  13. Effect of Water on HEMA Conversion by FT-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    TS. Jafarzadeh Kashi

    2007-09-01

    Full Text Available Objective: The use of HEMA as a biocompatible material in dentin bonding systems and its potential for clinical applications has been well established. Excess water can affect conversion of bonding resins. The aim of this study was to survey the effect of water on the degree of conversion of HEMA by Fourier Transform Infra-red Spectroscopy (FT-IR.Materials and Methods: In this experimental study, distilled water was added in amounts of 0, 0.05, 0.1, 0.2, and 0.4 ml to 1 ml of curable HEMA solution. Six repetitions per wa-ter ratio were made and investigated. Each sample was polymerized for 60 seconds. De-gree of conversion was obtained from the absorbance IR-Spectrum of the materials before and after polymerization by FT-IR spectroscopy. One way ANOVA and Tukey-HSD were carried out to compare and detect any differences among groups.Results: Statistical analysis indicates highly significant difference between pairs of groups at level (P<0.001. The results showed a trend of decreasing in HEMA conversion with increasing water. Degree of conversion changes significantly within the 0.05 ml to 0.2 ml water range. However, degree of conversion did not change after reaching 0.02 ml and before 0.05.Conclusion: Degree of conversion of HEMA decreased by increasing water. The most dramatic effect of water on the polymerization process occurs within a range which exists under clinical conditions. The reason that the degree of conversion did not show signifi-cant result before 0.05 ml may be related to the hydrophilic nature of HEMA.

  14. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.

    Science.gov (United States)

    Jafarzadeh, Tahereh-Sadat; Erfan, Mohammad; Behroozibakhsh, Marjan; Fatemi, Mostafa; Masaeli, Reza; Rezaei, Yashar; Bagheri, Hossein; Erfan, Yasaman

    2015-01-01

    Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

  15. Implementation of the Electron conversion Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Hernandez, Torres, D.; Noriega Scull, C.

    1996-01-01

    In the present work has been exposed the principles of the Conversion Moessbauer Electron Spectroscopy and its possibilities of application. Is also described the operation of the parallel plate avalanche detector made at the CEADEN starting from modifications done to the Gancedo's model and is exposed examples of the use of this detector in the characterization of corroded surfaces, with chemical cleaning and in samples of welded joints. The experiences obtained of this work were extended to the National Polytechnic Institute of Mexico where a similar detector, made in our center, was installed there

  16. Spectroscopy of hexafluorides with an odd number of electrons

    International Nuclear Information System (INIS)

    Boudon, V.

    1995-05-01

    From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed us to write a simple model describing the vibronic structure of colored hexafluorides. Then, some applications of this formalism to the study of ro-vibronic couplings of XY 6 molecules in a fourfold degenerate electronic state have been considered, especially concerning operators associated to dynamic Jahn-Teller effect. From an experimental point of view, we have considered IrF 6 , for which we have mastered the synthesis, purification and conservation processes. A first study at low resolution (absorption and Raman scattering) has been performed for this molecule. We have then set up two high resolution spectroscopic devices in the visible region (saturated absorption - tested with an iodine cell- and simple absorption with multiple pass). These especially use a dye laser. They should now allow the spectroscopy of the visible band of IrF 6 in order to resolve for the first time its fine rotational structure. (author)

  17. Drift and transmission FT-IR spectroscopy of forest soils: an approach to determine decomposition processes of forest litter

    International Nuclear Information System (INIS)

    Haberhauer, G.; Gerzabek, M.H.

    1999-06-01

    A method is described to characterize organic soil layers using Fourier transformed infrared spectroscopy. The applicability of FT-IR, either dispersive or transmission, to investigate decomposition processes of spruce litter in soil originating from three different forest sites in two climatic regions was studied. Spectral information of transmission and diffuse reflection FT-IR spectra was analyzed and compared. For data evaluation Kubelka Munk (KM) transformation was applied to the DRIFT spectra. Sample preparation for DRIFT is simpler and less time consuming in comparison to transmission FT-IR, which uses KBr pellets. A variety of bands characteristics of molecular structures and functional groups has been identified for these complex samples. Analysis of both transmission FT-IR and DRIFT, showed that the intensity of distinct bands is a measure of the decomposition of forest litter. Interferences due to water adsorption spectra were reduced by DRIFT measurement in comparison to transmission FT-IR spectroscopy. However, data analysis revealed that intensity changes of several bands of DRIFT and transmission FT-IR were significantly correlated with soil horizons. The application of regression models enables identification and differentiation of organic forest soil horizons and allows to determine the decomposition status of soil organic matter in distinct layers. On the basis of the data presented in this study, it may be concluded that FT-IR spectroscopy is a powerful tool for the investigation of decomposition dynamics in forest soils. (author)

  18. A computer simulation of auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ragheb, M S; Bakr, M H.S. [Dept. Of Accellerators and Ion Sources, Division of Basic Nuclear Sciences, NRC, Atomic Energy Authority, (Egypt)

    1997-12-31

    A simulation study of Auger electron spectroscopy was performed to reveal how far the dependency between the different parameters governing the experimental behavior affects the peaks. The experimental procedure followed by the AC modulation technique were reproduced by means of a computer program. It generates the assumed output Auger electron peaks, exposes them to a retarding AC modulated field and collects the resulting modulated signals. The program produces the lock-in treatment in order to demodulate the signals revealing the Auger peaks. It analyzes the spectrum obtained giving the peak positions and energies. Comparison between results of simulation and the experimental data showed good agreement. The peaks of the spectrum obtained depend upon the amplitude, frequency and resolution of the applied modulated signal. The peak shape is effected by the rise time, the slope and the starting potential of the retarding field. 4 figs.

  19. Application of principal component and factor analyses in electron spectroscopy

    International Nuclear Information System (INIS)

    Siuda, R.; Balcerowska, G.

    1998-01-01

    Fundamentals of two methods, taken from multivariate analysis and known as principal component analysis (PCA) and factor analysis (FA), are presented. Both methods are well known in chemometrics. Since 1979, when application of the methods to electron spectroscopy was reported for the first time, they became to be more and more popular in different branches of electron spectroscopy. The paper presents examples of standard applications of the method of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). Advantages one can take from application of the methods, their potentialities as well as their limitations are pointed out. (author)

  20. The recent and prospective developments of cooled IR FPAs for double application at Electron NRI

    Science.gov (United States)

    Arutunov, V. A.; Vasilyev, I. S.; Ivanov, V. G.; Prokofyev, A. E.

    2003-09-01

    The recent and prospective developments of monolithic silicon IR-Schottky-barrier staring focal plane arrays (IR SB FPAs), photodetector assembly, and digital thermal imaging cameras (TICs) at Electron National Research Institute (Electron NRI) are considered. Basic parameters for IR SB FPAs with 256x256 and 512x512 pixels, and TICs based on these arrays are presented. The problems emerged while proceeding from the developments of IR SB FPAs for the wavelength range from 3 μm to 5 μm to the developments of those ones for xLWIR range are indicated (an abrupt increase in the level of background architecture). Possibility for further improvement in basic parameters of IR SB FPAs are discussed (a decrease in threshold signal power down to 0.5-1.0"1013 W/element with an increase in quantum efficiency, a decrease in output noise and proceeding to Schottky barriers of degenerated semiconductor/silicon heterojunction, and implementation of these array parameters in photodetector assembly with improved thermal background shielding taking into consideration an optical structure of TIC for concrete application). It is concluded that relative simplicity of the technology and expected low cost of monolithic silicon IR SB FPAs with basic parameters compared with hybrid IR FPAs for the wavelength ranges from 3 μm to 5 μm and from 8 μm to 12 μm maintain large monolithic IR SB FPAs as a basis for developments of double application digital TICs in the Russian Federation.

  1. Spectroscopy of hexafluorides with an odd number of electrons; Spectroscopie des hexafluorures a nombre impair d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Boudon, V

    1995-05-01

    From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed us to write a simple model describing the vibronic structure of colored hexafluorides. Then, some applications of this formalism to the study of ro-vibronic couplings of XY{sub 6} molecules in a fourfold degenerate electronic state have been considered, especially concerning operators associated to dynamic Jahn-Teller effect. From an experimental point of view, we have considered IrF{sub 6}, for which we have mastered the synthesis, purification and conservation processes. A first study at low resolution (absorption and Raman scattering) has been performed for this molecule. We have then set up two high resolution spectroscopic devices in the visible region (saturated absorption - tested with an iodine cell- and simple absorption with multiple pass). These especially use a dye laser. They should now allow the spectroscopy of the visible band of IrF{sub 6} in order to resolve for the first time its fine rotational structure. (author)

  2. Spectroscopy of hexafluorides with an odd number of electrons; Spectroscopie des hexafluorures a nombre impair d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Boudon, V

    1995-05-01

    From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed us to write a simple model describing the vibronic structure of colored hexafluorides. Then, some applications of this formalism to the study of ro-vibronic couplings of XY{sub 6} molecules in a fourfold degenerate electronic state have been considered, especially concerning operators associated to dynamic Jahn-Teller effect. From an experimental point of view, we have considered IrF{sub 6}, for which we have mastered the synthesis, purification and conservation processes. A first study at low resolution (absorption and Raman scattering) has been performed for this molecule. We have then set up two high resolution spectroscopic devices in the visible region (saturated absorption - tested with an iodine cell- and simple absorption with multiple pass). These especially use a dye laser. They should now allow the spectroscopy of the visible band of IrF{sub 6} in order to resolve for the first time its fine rotational structure. (author)

  3. Adding a dimension to the infrared spectra of interfaces: 2D SFG spectroscopy via mid-IR pulse shaping

    Science.gov (United States)

    Zanni, Martin

    2012-02-01

    Sum-frequency generation spectroscopy provides an infrared spectrum of interfaces and thus has widespread use in the materials and chemical sciences. In this presentation, I will present our recent work in developing a 2D pulse sequence to generate 2D SFG spectra of interfaces, in analogy to 2D infrared spectra used to measure bulk species. To develop this spectroscopy, we have utilized many of the tricks-of-the-trade developed in the 2D IR and 2D Vis communities in the last decade, including mid-IR pulse shaping. With mid-IR pulse shaping, the 2D pulse sequence is manipulated by computer programming in the desired frequency resolution, rotating frame, and signal pathway. We believe that 2D SFG will become an important tool in the interfacial sciences in an analogous way that 2D IR is now being used in many disciplines.

  4. Cold, Gas-Phase UV and IR Spectroscopy of Protonated Leucine Enkephalin and its Analogues

    Science.gov (United States)

    Burke, Nicole L.; Redwine, James; Dean, Jacob C.; McLuckey, Scott A.; Zwier, Timothy S.

    2014-06-01

    The conformational preferences of peptide backbones and the resulting hydrogen bonding patterns provide critical biochemical information regarding the structure-function relationship of peptides and proteins. The spectroscopic study of cryogenically-cooled peptide ions in a mass spectrometer probes these H-bonding arrangements and provides information regarding the influence of a charge site. Leucine enkephalin, a biologically active endogenous opiod peptide, has been extensively studied as a model peptide in mass spectrometry. This talk will present a study of the UV and IR spectroscopy of protonated leucine enkephalin [YGGFL+H]+ and two of its analogues: the sodiated [YGGFL+Na]+ and C-terminally methyl esterified [YGGFL-OMe+H]+ forms. All experiments were performed in a recently completed multi-stage mass spectrometer outfitted with a cryocooled ion trap. Ions are generated via nano-electrospray ionization and the analyte of interest is isolated in a linear ion trap. The analyte ions are trapped in a 22-pole ion trap held at 5 K by a closed cycle helium cryostat and interrogated via UV and IR lasers. Photofragments are trapped and isolated in a second LIT and mass analyzed. Double-resonance UV and IR methods were used to assign the conformation of [YGGFL+H]+, using the NH/OH stretch, Amide I, and Amide II regions of the infrared spectrum. The assigned structure contains a single backbone conformation at vibrational/rotational temperatures of 10 K held together with multiple H-bonds that self-solvate the NH3+ site. A "proton wire" between the N and C termini reinforces the H-bonding activity of the COO-H group to the F-L peptide bond, whose cleavage results in formation of the b4 ion, which is a prevalent, low-energy fragmentation pathway for [YGGFL+H]+. The reinforced H-bonding network in conjunction with the mobile proton theory may help explain the prevalence of the b4 pathway. In order to elucidate structural changes caused by modifying this H-bonding activity

  5. Phase-Sensitive Control Of Molecular Dissociation Through Attosecond Pump/Strong-Field Mid-IR Probe Spectroscopy

    Science.gov (United States)

    2016-04-15

    splitter (consisting of a thin, uncoated, silicon plate at brewsters angle) and the beams were focused onto the OPA crystal. For this work two...experiments in the future. These technologies include • Two-color driven (EUV/mid-IR) ion spectroscopy: we designed an interferometer combining EUV...isolated single-femtosecond EUV pulse generation: combining the use of low ionization threshold gas, an annual near-IR drive beam , polarization

  6. X-ray diffraction, IR spectroscopy and thermal characterization of partially hydrolyzed guar gum.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, B S

    2012-05-01

    Guar gum was hydrolyzed using cellulase from Aspergillus niger at 5.6 pH and 50°C temperature. Hydrolyzed guar gum sample was characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, dilute solution viscometry and rotational viscometry. Viscometry analysis of native guar gum showed a molecular weight of 889742.06, whereas, after enzymatic hydrolysis, the resultant product had a molecular weight of 7936.5. IR spectral analysis suggests that after enzymatic hydrolysis of guar gum there was no major transformation of functional group. Thermal analysis revealed no major change in thermal behavior of hydrolyzed guar gum. It was shown that partial hydrolysis of guar gum could be achieved by inexpensive and food grade cellulase (Aspergillus niger) having commercial importance and utilization as a functional soluble dietary fiber for food industry. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

    Science.gov (United States)

    Pereverzev, Sergey

    2017-02-01

    Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

  8. Monitoring wine aging with Fourier transform infrared spectroscopy (FT-IR

    Directory of Open Access Journals (Sweden)

    Basalekou Marianthi

    2015-01-01

    Full Text Available Oak wood has commonly been used in wine aging but recently other wood types such as Acacia and Chestnut, have attracted the interest of the researchers due to their possible positive contribution to wine quality. However, only the use of oak and chestnut woods is approved by the International Enological Codex of the International Organisation of Vine and Wine. In this study Fourier Transform (FT-mid-infrared spectroscopy combined with Discriminant Analysis was used to differentiate wines aged in barrels made from French oak, American oak, Acacia and Chestnut and in tanks with oak chips, over a period of 12 months. Two red (Mandilaria, Kotsifali and two white (Vilana, Dafni native Greek grape varieties where used to produce four wines. The Fourier Transform Infrared (FT-IR spectra of the samples were recorded on a Zinc Selenide (ZnSe window after incubation at 40 °C for 30 min. A complete differentiation of the samples according to both the type of wood used and the contact time was achieved based on their FT-IR spectra.

  9. Identification of forged Bank of England £20 banknotes using IR spectroscopy.

    Science.gov (United States)

    Sonnex, Emily; Almond, Matthew J; Baum, John V; Bond, John W

    2014-01-24

    Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm(-1) arising from νasym (CO3(2-)) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ν(OH) (ca. 3500 cm(-1)), ν(C-H) (ca. 2900 cm(-1)) and ν(C=O) (ca. 1750 cm(-1)) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Identification of forged Bank of England £20 banknotes using IR spectroscopy

    Science.gov (United States)

    Sonnex, Emily; Almond, Matthew J.; Baum, John V.; Bond, John W.

    2014-01-01

    Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm-1 arising from νasym (CO32-) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ν(OH) (ca. 3500 cm-1), ν(Csbnd H) (ca. 2900 cm-1) and ν(Cdbnd O) (ca. 1750 cm-1) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper.

  11. Development of a method for determination of fatty acid using FT-IR spectroscopy

    Directory of Open Access Journals (Sweden)

    Dimas Augusto Morozin Zaia

    2011-05-01

    Full Text Available In the present paper a new methodology has been developed for determination of fatty acids in biological systems using FT-IR spectroscopy. For this method is not necessary chromophore reagent or pre sample preparation. Palmitic acid was chosen as standard, because it is found in several biological systems. The FT-IR spectrum of palmitic acid showed two absorption bands in the region of 2852 and 2920 cm-1 attributed to CH stretching. The results for these bands showed that the Beer-Lambert Law was followed in wide range of concentration of palmitic acid (14 to 257 mmol L-1. Potassium ferricyanide (K3[Fe(CN6] was used as internal standard. Several interferents were tested and only cholesterol, ferric chloride (higher concentration, mixture of amino acids for the band at 2919 cm-1 (higher concentration and triglyceride could be interferent if they appear in high concentration. Thus, this new methodology has advantage to be not expensive and simple.

  12. Surface enhanced imaging and IR spectroscopy of the biological cells on the nanostructured gold film

    Directory of Open Access Journals (Sweden)

    G.I. Dovbeshko

    2017-07-01

    Full Text Available New approach for optical imaging, structural study and cell cultivation based on the effect of the enhancement of optical signals from biomolecules and biological cells near nanostructured rough gold surface is proposed. The surface enhanced IR absorption (SEIRA spectroscopy and confocal microscopy experiments were made using the culture of SPEV (porcine embryonic kidney epithelium transplantable line and fibroblast cells, cultivated and/or adsorbed on the gold substrate. The SEIRA spectra registered from monolayer of the SPEV cells cultivated on the rough gold showed a low frequency shift of about 2 to 7 cm 1 for the most characteristic IR vibrations, compared with those adsorbed from suspension on the same substrate. An enhancement factor of 15…30 was obtained for different molecular vibrations. The confocal microscopy contrast images of the SPEV cells on rough gold substrate were obtained in laser fluorescence mode. This approach opens new possibilities for visualization of the living cells in vivo without staining. The fluorescence of the rough gold surfaces and effects responsible for our findings have been discussed.

  13. FTIR spectroscopy of electron irradiated polymers

    International Nuclear Information System (INIS)

    Finch, D.S.

    1988-04-01

    The chemical changes in electron beam irradiated polymers, in particular PVC, are considered in order to relate the formation of conjugated structures to changes in the electrical properties. Infrared spectroscopy has been used to measure these changes. Fourier Transform techniques and computing facilities make better data processing possible. A method for base line interpretation is demonstrated whereby a shift parallel to the abscisal axis in a region of the polymer that is non absorbing is used to evaluate the baseline. This technique has proved to be highly reproducible providing that the polymer films to be examined are optically homogeneous. Evaluation of the rate of decay of the total area of the carbon chlorine region of the polymer has been compared with the chlorine decay curve analysed by the measurement of x-ray emission during irradiation of bulk samples. The significant reduction in the evolution of atomic chlorine through x-ray analysis has been attributed to the trapping of HCl within the polymer film and its subsequent slow diffusion out of the polymer. With PVC, one of the main products as a result of irradiation is the formation of conjugated sequences. These were studied by the use of uv-visible spectroscopy. (author)

  14. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea; Torre, Bruno; Allione, Marco; Perozziello, Gerardo; Candeloro, Patrizio; Di Fabrizio, Enzo M.

    2017-01-01

    This chapter includes a brief description of different laser coupling methods with guided surface plasmon polariton (SPP) modes at the surface of a cone. It shows some devices, their electromagnetic simulations, and their optical characterization. A theoretical section illustrates the optical and quantum description of the hot charge generation rate as obtained for the SPP propagation along the nanocone in adiabatic compression. The chapter also shows some experimental results concerning the application of the hot electron nanoscopy and spectroscopy (HENs) in the so-called Schottky configuration, highlighting the sensitivity and the nanoscale resolution of the technique. The comparison with Kelvin probe and other electric atomic force microscopy (AFM) techniques points out the intrinsic advantages of the HENs. In the end, some further insights are given about the possibility of exploiting HENs with a pulsed laser at the femtosecond time scale without significant pulse broadening and dispersion.

  15. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea

    2017-08-17

    This chapter includes a brief description of different laser coupling methods with guided surface plasmon polariton (SPP) modes at the surface of a cone. It shows some devices, their electromagnetic simulations, and their optical characterization. A theoretical section illustrates the optical and quantum description of the hot charge generation rate as obtained for the SPP propagation along the nanocone in adiabatic compression. The chapter also shows some experimental results concerning the application of the hot electron nanoscopy and spectroscopy (HENs) in the so-called Schottky configuration, highlighting the sensitivity and the nanoscale resolution of the technique. The comparison with Kelvin probe and other electric atomic force microscopy (AFM) techniques points out the intrinsic advantages of the HENs. In the end, some further insights are given about the possibility of exploiting HENs with a pulsed laser at the femtosecond time scale without significant pulse broadening and dispersion.

  16. An overview on the research of Sr2IrO4-based system probed by X-ray absorption spectroscopy

    Science.gov (United States)

    Cheng, Jie; Zhu, Chaomin; Ma, Jingyuan; Wang, Yu; Liu, Shengli

    2018-03-01

    Investigations of materials with 5d transition metal ions have opened up new paradigms in condensed-matter physics because of their large spin-orbit coupling (SOC) interactions. The typical compound is Sr2IrO4, which attracted much attention due to its similarities to the parent compound of high-Tc cuprate superconductor La2CuO4. Theoretical calculations predicted that the unconventional superconductivity can occur in carrier doped-Sr2IrO4 system. Until now, hundreds of experimental methods were devoted to investigate the carrier doping effect on Sr2IrO4. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) made great contributions to the local lattice and electronic structure, and also the intimate relationship between the local structure and physical properties induced by carrier doping. The aim of this review is a short introduction to the progress of research on Sr2IrO4-based system probed by the unique technique — XAS, including the strength of the SOC, valence changes upon doping and even local lattice structure with atomic level for this Sr2IrO4-based family.

  17. Gaz Phase IR and UV Spectroscopy of Neutral Contact Ion Pairs

    Science.gov (United States)

    Habka, Sana; Brenner, Valerie; Mons, Michel; Gloaguen, Eric

    2016-06-01

    Cations and anions, in solution, tend to pair up forming ion pairs. They play a crucial role in many fundamental processes in ion-concentrated solutions and living organisms. Despite their importance and vast applications in physics, chemistry and biochemistry, they remain difficult to characterize namely because of the coexistence of several types of pairing in solution. However, an interesting alternative consists in applying highly selective gas phase spectroscopy which can offer new insights on these neutral ion pairs. Our study consists in characterizing contact ion pairs (CIPs) in isolated model systems (M+, Ph-(CH2)n-COO- with M=Li, Na, K, Rb, Cs, and n=1-3), to determine their spectral signatures and compare them to ion pairs in solution. We have used laser desorption to vaporize a solid tablet containing the desired salt. Structural information for each system was obtained by mass-selective, UV and IR laser spectroscopy combined with high level quantum chemistry calculations1. Evidence of the presence of neutral CIPs was found by scanning the π-π* transition of the phenyl ring using resonant two-photon ionization (R2PI). Then, conformational selective IR/UV double resonance spectra were recorded in the CO2- stretch region for each conformation detected. The good agreement between theoretical data obtained at the BSSE-corrected-fullCCSD(T)/dhf-TZVPP//B97-D3/dhf-TZVPP level and experimental IR spectra led us to assign the 3D structure for each ion pair formed. Spectral signatures of (M+, Ph-CH2-COO-) pairs, were assigned to a bidentate CIPs between the alkali cation and the carboxylate group. In the case of (Li+, Ph-(CH2)3-COO-) pairs, the presence of a flexible side chain promotes a cation-π interaction leading to a tridentate O-O-π structure with its unique IR and UV signatures. IR spectra obtained on isolated CIPs were found very much alike the ones published on lithium and sodium acetate in solution2. However, in the case of sodium acetate, solution

  18. THE STUDY OF CLINOPTILOLITE MODIFIED WITH3d METALS HALIDES BY IR AND DIFFUSE REFLECTANCE SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    T. L. Rakitskaya

    2015-11-01

    Full Text Available The results of investigation of natural clinoptilolite (N-CLI and that modified with 3d metal halides (MeCl2/N-CLI, where Me are Cu, Co, and Mn by IR and diffuse reflectance spectroscopy are summarized. A band at 3437 cm-1 assigned to stretching vibrations of hydroxyl groups (nOH is found in the IR spectrum of the N-CLI sample. A location of the band was practically the same as for all above MeCl2/N-CLI samples. A band of middle intensity at 1638 cm-1 in the range of deformation vibrations of zeolite water observed in the IR spectrum of N-CLI slightly displays to lower frequencies in the case of the modified samples. An intensive wide band of a complex shape in the range from 1250 to 980 cm-1 assigned to Si–O–Si and Si–O–Al vibrations appears in IR spectra of all samples. A doublet band of middle intensity at 797 and 778 cm-1 is assigned to external symmetric stretching T-O vibrations and a band at 606 cm-1-to vibrations of a double ring. A location of the above bands is the same for all listed samples but their intensity is higher for MnCl2/N-CLI and CoCl2/N-CLI samples. After the reaction with ozone, significant changes in the IR spectra are observed only for MnCl2/N-CLI. They are due to MnO2 formation on the clinoptilolite surface resulting in a high frequency displacement of some bands. Based on UV-vi spectroscopy results, it is reasonable to make conclusions about the coordination and valence state of a central atom in the MeCl2/N-CLI samples under study. A location of charge transfer bands for these samples only slightly differs from that for N-CLI however the intensity of such bands increases for the MeCl2/N-CLI samples. The UV-vis spectrum of MnCl2/N-CLI changes after the reaction with ozone: the appearance of new bands of  charge transfer at 363 and 354 nm and also the two-fold increase in intensity of a charge transfer band at 272 nm in comparison with those of N-CLI and MnCl2/N-CLI are the evidence of change in both the

  19. Structure and properties of hydrocarbon radical cations in low-temperature matrices as studied by a combination of EPR and IR spectroscopy

    International Nuclear Information System (INIS)

    Feldman, V.I.

    1997-01-01

    Use of IR spectroscopy (as a supplement to EPR) may provide new insight into the problem of analysis of structure and properties of organic radical cations. In this work, the results of combined EPR/IR studies of the formation, structure and properties of hydrocarbon radical cations in halocarbon and solid rare gas matrices are discussed. Both IR and EPR studies were carried out with matrix deposited samples irradiated with fast electrons at 15 or 77 K. IR spectroscopic data were found to be helpful in three aspects: (i) characterization of the conformation and association and molecule-matrix interactions of the parent molecules; (ii) identification of diamagnetic products of the reactions of radical cations in ground and excited states; (iii) determining the characteristics of vibrational spectra of the radical cations, which are of primary interest for analysis of chemical bonding and reactivity of the radical cations. The applications of the combined approach are illustrated with examples of studies of several alkenes in Freon matrices and alkanes in solid rare gas matrices. The matrix effects on trapping and degradation of radical cations were interpreted as the result of variations in matrix electronic characteristics (IP, polarizability) and molecule-matrix interactions. (au) 48 refs

  20. Auger electron spectroscopy studies of boron carbide

    International Nuclear Information System (INIS)

    Madden, H.H.; Nelson, G.C.; Wallace, W.O.

    1986-01-01

    Auger electron spectroscopy has been used to probe the electronic structure of ion bombardment (IB) cleaned surfaces of B 9 C and B 4 C samples. The shapes of the B-KVV and C-KVV Auger lines were found to be relatively insensitive to the bulk stoichiometry of the samples. This indicates that the local chemical environments surrounding B and C atoms, respectively, on the surfaces of the IB cleaned samples do not change appreciably in going from B 9 C to B 4 C. Fracturing the sample in situ is a way of producing a clean representative internal surface to compare with the IB surfaces. Microbeam techniques have been used to study a fracture surface of the B 9 C material with greater spatial resolution than in our studies of IB surfaces. The B 9 C fracture surface was not homogeneous and contained both C-rich and B-rich regions. The C-KVV line for the C-rich regions was graphitic in shape. Much of the C-rich regions was found by IB to be less than 100 nm in thickness. The C-KVV line from the B-rich regions was carbidic and did not differ appreciably in shape from those recorded for the IB cleaned surfaces

  1. Chemical information from Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Madden, H.H.

    1981-01-01

    The nature of chemical information in Auger electron spectroscopy (AES) data is reviewed with special emphasis on data from solid surface systems. Two strategies are most frequently used to extract this information: (i) measuring and analyzing energy (chemical) shifts in Auger peaks; and (ii) making use of the shapes of Auger signals to determine the chemical environment at the site of the initial core hole. Chemical shift data are primarily illustrated by highlighting the interaction of oxygen with solids; and analyses of these data based on core-level binding-energy shifts, relaxation, and hole--hole interactions are outlined and discussed. Auger transitions that involve valence electrons are usually those for which lineshapes are taken as indications of the local chemistry at the initial core-hole site. Attempts at extracting valence band density-of-states information from lineshapes are proving successful and this approach to the surface chemical information in AES is illustrated with the aid of examples dealing with the interaction of silicon with hydrogen and with oxygen. The use of the AES lineshapes simply as ''fingerprints'' of the core-hole-site chemistry is examined and illustrated by examples which include studies of silicon nitride properties, of solid surface properties related to catalytic reactions, and of passive films on iron. Auger decay activated desorption processes are briefly examined and found to promise new and unique chemical information when combined with conventional AES. Some gas phase AES studies are also briefly reviewed

  2. NMR and IR Spectroscopy for the Structural Characterization of Edible Fats and Oils: An Instrumental Analysis Laboratory

    Science.gov (United States)

    Crowther, Molly W.

    2008-01-01

    This article describes an upper-level instrumental laboratory for undergraduates that explores the complementary nature of IR and NMR spectroscopy for analysis of several edible fats and oils that are structurally similar but differ in physical properties and health implications. Five different fats and oils are analyzed for average chain length,…

  3. Ultra-Broadband Infrared Pulses from a Potassium-Titanyl Phosphate Optical Parametric Amplifier for VIS-IR-SFG Spectroscopy

    Science.gov (United States)

    Isaienko, Oleksandr; Borguet, Eric

    A non-collinear KTP-OPA to provide ultra-broadband mid-infrared pulses was designed and characterized. With proper pulse-front and phase correction, the system has a potential for high-time resolution vibrational VIS-IR-SFG spectroscopy.

  4. Detection and classification of salmonella serotypes using spectral signatures collected by fourier transform infrared (FT-IR) spectroscopy

    Science.gov (United States)

    Spectral signatures of Salmonella serotypes namely Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky were collected using Fourier transform infrared spectroscopy (FT-IR). About 5-10 µL of Salmonella suspensions with concentrations of 1...

  5. Center Line Slope Analysis in Two-Dimensional Electronic Spectroscopy

    OpenAIRE

    ?anda, Franti?ek; Perl?k, V?clav; Lincoln, Craig N.; Hauer, J?rgen

    2015-01-01

    Center line slope (CLS) analysis in 2D infrared spectroscopy has been extensively used to extract frequency?frequency correlation functions of vibrational transitions. We apply this concept to 2D electronic spectroscopy, where CLS is a measure of electronic gap fluctuations. The two domains, infrared and electronic, possess differences: In the infrared, the frequency fluctuations are classical, often slow and Gaussian. In contrast, electronic spectra are subject to fast spectral diffusion and...

  6. Characterization of Paracoccidioides brasiliensis by FT-IR spectroscopy and nanotechnology

    Science.gov (United States)

    Ferreira, Isabelle; Ferreira-Strixino, Juliana; Castilho, Maiara L.; Campos, Claudia B. L.; Tellez, Claudio; Raniero, Leandro

    2016-01-01

    Paracoccidioides brasiliensis, the etiological agent of paracoccidioidomycosis, is a dimorphic fungus existing as mycelia in the environment (or at 25 °C in vitro) and as yeast cells in the human host (or at 37 °C in vitro). Because mycological examination of lesions in patients frequently is unable to show the presence of the fungus and serological tests can misdiagnose the disease with other mycosis, the development of new approach's for molecular identification of P. brasiliensis spurges is needed. This study describes the use of a gold nanoprobe of a known gene sequence of P. brasiliensis as a molecular tool to identify P. brasiliensis by regular polymerase chain reaction (PCR) associated with a colorimetric methods. This approach is suitable for testing in remote areas because it does not require any further step than gene amplification, being safer and cheaper than electrophoresis methods. The proposed test showed a color change of the PCR reaction mixture from red to blue in negative samples, whereas the solution remains red in positive samples. We also performed a Fourier Transform Infrared (FT-IR) Spectroscopy analysis to characterize and compare the chemical composition between yeast and mycelia forms, which revealed biochemical differences between these two forms. The analysis of the spectra showed that differences were distributed in chemical bonds of proteins, lipids and carbohydrates. The most prominent difference between both forms was vibration modes related to 1,3-β-glucan usually found in mycelia and 1,3-α-glucan found in yeasts and also chitin forms. In this work, we introduce FT-IR as a new method suitable to reveal overall differences that biochemically distinguish each form of P. brasiliensis that could be additionally used to discriminate biochemical differences among a single form under distinct environmental conditions.

  7. Cartilage ablation studies using mid-IR free electron laser

    Science.gov (United States)

    Youn, Jong-In; Peavy, George M.; Venugopalan, Vasan

    2005-04-01

    The ablation rate of articular cartilage and fibrocartilage (meniscus), were quantified to examine wavelength and tissue-composition dependence of ablation efficiency for selected mid-infrared wavelengths. The wavelengths tested were 2.9 um (water dominant absorption), 6.1 (protein and water absorption) and 6.45 um (protein dominant absorption) generated by the Free Electron Laser (FEL) at Vanderbilt University. The measurement of tissue mass removal using a microbalance during laser ablation was conducted to determine the ablation rates of cartilage. The technique can be accurate over methods such as profilometer and histology sectioning where tissue surface and the crater morphology may be affected by tissue processing. The ablation efficiency was found to be dependent upon the wavelength. Both articular cartilage and meniscus (fibrocartilage) ablations at 6.1 um were more efficient than those at the other wavelengths evaluated. We observed the lowest ablation efficiency of both types of cartilage with the 6.45 um wavelength, possibly due to the reduction in water absorption at this wavelength in comparison to the other wavelengths that were evaluated.

  8. Electronic resonances in broadband stimulated Raman spectroscopy

    Science.gov (United States)

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

  9. Evaluation of Salmon Adhesion on PET-Metal Interface by ATR, FT-IR, and Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    E. Zumelzu

    2015-01-01

    Full Text Available The material employed in this study is an ecoefficient, environmentally friendly, chromium (VI-free (noncarcinogenic metal polymer. The originality of the research lies in the study of the effect of new production procedures of salmon on metal packaging with multilayer polyethylene terephthalate (PET polymer coatings. Our hypothesis states that the adhesion of postmortem salmon muscles to the PET polymer coating produces surface and structural changes that affect the functionality and limit the useful life of metal containers, compromising therefore their recycling capacity as ecomaterials. This work is focused on studying the effects of the biochemical changes of postmortem salmon on the PET coating and how muscle degradation favors adhesion to the container. The experimental design considered a series of laboratory tests of containers simulating the conditions of canned salmon, chemical and physical tests of food-contact canning to evaluate the adhesion, and characterization of changes in the multilayer PET polymer by electron microscopy, ATR, FT-IR, and Raman spectroscopy analyses. The analyses determined the effect of heat treatment of containers on the loss of freshness of canned fish and the increased adhesion to the container wall, and the limited capability of the urea treatment to remove salmon muscle from the container for recycling purposes.

  10. Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Haertelt, M.; Meijer, G.; Fielicke, A.; Bakker, J. M.

    2013-01-01

    The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb-n (n = 5-20) over the 200-350 cm(-1)

  11. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    Science.gov (United States)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  12. Identification of Forged Bank of England 20 Gbp Banknotes Using IR Spectroscopy

    Science.gov (United States)

    Sonnex, Emily

    2014-06-01

    Bank of England notes of 20 GBP denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. A principal aim of this work was to develop a method so that a small, compact ATR FTIR instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 wn from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine 20 GBP notes were observed in the ν(OH) (ca. 3500 wn), ν(C-H) (ca. 2900 wn) and ν(C=O) (ca. 1750 wn) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper. Further to this, with an announcement by the Bank of England to produce polymer banknotes in the future, the work has been extended using Australian polymer banknotes to show that the method would be transferable.

  13. Forensic Hair Differentiation Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

    Science.gov (United States)

    Manheim, Jeremy; Doty, Kyle C; McLaughlin, Gregory; Lednev, Igor K

    2016-07-01

    Hair and fibers are common forms of trace evidence found at crime scenes. The current methodology of microscopic examination of potential hair evidence is absent of statistical measures of performance, and examiner results for identification can be subjective. Here, attenuated total reflection (ATR) Fourier transform-infrared (FT-IR) spectroscopy was used to analyze synthetic fibers and natural hairs of human, cat, and dog origin. Chemometric analysis was used to differentiate hair spectra from the three different species, and to predict unknown hairs to their proper species class, with a high degree of certainty. A species-specific partial least squares discriminant analysis (PLSDA) model was constructed to discriminate human hair from cat and dog hairs. This model was successful in distinguishing between the three classes and, more importantly, all human samples were correctly predicted as human. An external validation resulted in zero false positive and false negative assignments for the human class. From a forensic perspective, this technique would be complementary to microscopic hair examination, and in no way replace it. As such, this methodology is able to provide a statistical measure of confidence to the identification of a sample of human, cat, and dog hair, which was called for in the 2009 National Academy of Sciences report. More importantly, this approach is non-destructive, rapid, can provide reliable results, and requires no sample preparation, making it of ample importance to the field of forensic science. © The Author(s) 2016.

  14. Electronic structure and chemical bonding in LaIrSi-type intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Matar, Samir F. [Bordeaux Univ., Pessac (France). CNRS; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Nakhl, Michel [Univ. Libanaise, Fanar (Lebanon). Ecole Doctorale Sciences et Technologies

    2017-05-01

    The cubic LaIrSi type has 23 representatives in aluminides, gallides, silicides, germanides, phosphides, and arsenides, all with a valence electron count of 16 or 17. The striking structural motif is a three-dimensional network of the transition metal (T) and p element (X) atoms with TX{sub 3/3} respectively XT{sub 3/3} coordination. Alkaline earth or rare earth atoms fill cavities within the polyanionic [TX]{sup δ-} networks. The present work presents a detailed theoretical study of chemical bonding in LaIrSi-type representatives, exemplarily for CaPtSi, BaIrP, BaAuGa, LaIrSi, CeRhSi, and CeIrSi. DFT-GGA-based electronic structure calculations show weakly metallic compounds with itinerant small magnitude DOSs at E{sub F} except for CeRhSi whose large Ce DOS at E{sub F} leads to a finite magnetization on Ce (0.73 μ{sub B}) and induced small moments of opposite sign on Rh and Si in a ferromagnetic ground state. The chemical bonding analyses show dominant bonding within the [TX]{sup δ-} polyanionic networks. Charge transfer magnitudes were found in accordance with the course of the electronegativites of the chemical constituents.

  15. Probing Intermolecular Electron Delocalization in Dimer Radical Anions by Vibrational Spectroscopy

    International Nuclear Information System (INIS)

    Mani, Tomoyasu; Brookhaven National Laboratory; Grills, David C.

    2017-01-01

    Delocalization of charges is one of the factors controlling charge transport in conjugated molecules. It is considered to play an important role in the performance of a wide range of molecular technologies, including organic solar cells and organic electronics. Dimerization reactions are well-suited as a model to investigate intermolecular spatial delocalization of charges. And while dimerization reactions of radical cations are well investigated, studies on radical anions are still scarce. Upon dimerization of radical anions with neutral counterparts, an electron is considered to delocalize over the two molecules. By using time-resolved infrared (TRIR) detection coupled with pulse radiolysis, we show that radical anions of 4-n-hexyl-4'-cyanobiphenyl (6CB) undergo such dimerization reactions, with an electron equally delocalized over the two molecules. We have recently demonstrated that nitrile ν(C≡N) vibrations respond to the degree of electron localization of nitrile-substituted anions: we can quantify the changes in the electronic charges from the neutral to the anion states in the nitriles by monitoring the ν(C≡N) IR shifts. In the first part of this article, we show that the sensitivity of the ν(C≡N) IR shifts does not depend on solvent polarity. In the second part, we describe how probing the shifts of the nitrile IR vibrational band unambiguously confirms the formation of dimer radical anions, with K dim = 3 × 10 4 M –1 . IR findings are corroborated by electronic absorption spectroscopy and electronic structure calculations. We find that the presence of a hexyl chain and the formation of π–π interactions are both crucial for dimerization of radical anions of 6CB with neutral 6CB. Our study provides clear evidence of spatial delocalization of electrons over two molecular fragments.

  16. Photodissociation Spectroscopy of Cold Protonated Synephrine: Surprising Differences between IR-UV Hole-Burning and IR Photodissociation Spectroscopy of the O-H and N-H Modes.

    Science.gov (United States)

    Nieuwjaer, N; Desfrançois, C; Lecomte, F; Manil, B; Soorkia, S; Broquier, M; Grégoire, G

    2018-04-19

    We report the UV and IR photofragmentation spectroscopies of protonated synephrine in a cryogenically cooled Paul trap. Single (UV or IR) and double (UV-UV and IR-UV) resonance spectroscopies have been performed and compared to quantum chemistry calculations, allowing the assignment of the lowest-energy conformer with two rotamers depending on the orientation of the phenol hydroxyl (OH) group. The IR-UV hole burning spectrum exhibits the four expected vibrational modes in the 3 μm region, i.e., the phenol OH, C β -OH, and two NH 2 + stretches. The striking difference is that, among these modes, only the free phenol OH mode is active through IRPD. The protonated amino group acts as a proton donor in the internal hydrogen bond and displays large frequency shifts upon isomerization expected during the multiphoton absorption process, leading to the so-called IRMPD transparency. More interestingly, while the C β -OH is a proton acceptor group with moderate frequency shift for the different conformations, this mode is still inactive through IRPD.

  17. Differentiation of Body Fluid Stains on Fabrics Using External Reflection Fourier Transform Infrared Spectroscopy (FT-IR) and Chemometrics.

    Science.gov (United States)

    Zapata, Félix; de la Ossa, Ma Ángeles Fernández; García-Ruiz, Carmen

    2016-04-01

    Body fluids are evidence of great forensic interest due to the DNA extracted from them, which allows genetic identification of people. This study focuses on the discrimination among semen, vaginal fluid, and urine stains (main fluids in sexual crimes) placed on different colored cotton fabrics by external reflection Fourier transform infrared spectroscopy (FT-IR) combined with chemometrics. Semen-vaginal fluid mixtures and potential false positive substances commonly found in daily life such as soaps, milk, juices, and lotions were also studied. Results demonstrated that the IR spectral signature obtained for each body fluid allowed its identification and the correct classification of unknown stains by means of principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Interestingly, results proved that these IR spectra did not show any bands due to the color of the fabric and no substance of those present in daily life which were analyzed, provided a false positive. © The Author(s) 2016.

  18. Structural, electronic, and thermal properties of indium-filled InxIr4Sb12 skutterudites

    Science.gov (United States)

    Wallace, M. K.; Li, Jun; Subramanian, M. A.

    2018-06-01

    The "phonon-glass/electron-crystal" approach has been implemented through incorporation of "rattlers" into skutterudite void sites to increase phonon scattering and thus increase the thermoelectric efficiency. Indium filled IrSb3 skutterudites are reported for the first time. Polycrystalline samples of InxIr4Sb12 (0 ≤ x ≤ 0.2) were prepared by solid-state reaction under a gas mixture of 5% H2 and 95% Ar. The solubility limit of InxIr4Sb12 was found to be close to 0.18. Synchrotron X-ray diffraction refinements reveal all InxIr4Sb12 phases crystallized in body-centered cubic structure (space group : Im 3 bar) with ∼8% antimony site vacancy and with indium partially occupying the 16f site. Unlike known rattler filled skutterudites, under synthetic conditions employed, indium filling in IrSb3 significantly increases the electrical resistivity and decreases the Seebeck coefficient (n-type) while reducing the thermal conductivity by ∼30%. The resultant power factor offsets the decrease in total thermal conductivity giving rise to a substantial decrease in ZT. Principal thermoelectric properties of InxM4Sb12 (M = Co, Rh, Ir) phases are compared. As iridium is a 5d transition metal, zero field cooled (ZFC) magnetization were performed to unravel the effect of spin-orbit interaction on the electronic properties. These results serve to advance the understanding of filled skutterudites, and provide additional insight on the less explored smaller "rattlers" and their influence on key thermoelectric properties.

  19. Recent advances in ion and electron spectroscopy of polymer surfaces

    Science.gov (United States)

    Gardella, Joseph A.

    1988-01-01

    The structure of microdomains and bonding at multicomponent polymer material interfaces has been studied using a variety of surface sensitive spectroscopic techniques. In our laboratory, low energy ion scattering spectroscopy (ISS) and static secondary ion mass spectrometry (SIMS) serve to complement results from angular dependent X-ray photoelectron spectroscopy (XPS or ESCA), Fourier transform infrared (FTIR) with attenuated total reflectance (ATR) sampling and SEM techniques to provide a quantitative picture of the relationships between structure, bonding, morphology and microdomain formation in near surface regions of polymeric systems. The added surface sensitivity of ISS can yield quantitative information at a sampling depth of 3-5 Å, which, with ESCA and FTIR analysis yields a "non-destructive" depth profile of domain formation in copolymer and blend systems. These studies will be illustrated with results from siloxane and siloxane/polycarbonate copolymer systems, where a complete picture of surface domain formation and morphology as a function of composition and polymer crystallinity has been developed. ISS can also yield information regarding the orientation of surface functional groups which ESCA and FTIR do not have either sensitivity and/or sufficient detection limits to analyze. These studies will be illustrated by the analysis of plasma hydrolysis/oxidation of stereoregular poly(methyl-methacrylate). The effects of functional group orientation on reactivity will be explored using results from ISS, ESCA and FTIR for stereoregular (isotatic, syndiotactic) and random (atactic) PMMA. Electron energy loss spectroscopy at high resolution (HREELS) has recently been extended to the examination of polymer and organic surfaces. Vibrational information from this experiment can yield very precise results about surface functional groups (1-20 Å) but at much lower resolution than is typical from IR and Raman techniques. However, the promise of evaluating surface

  20. Electron beam effects in auger electron spectroscopy and scanning electron microscopy

    International Nuclear Information System (INIS)

    Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

    1979-01-01

    Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

  1. Electron-probe microanalysis: x-ray spectroscopy

    International Nuclear Information System (INIS)

    1987-01-01

    The main principles on X-ray, energy and wave length dispersive spectroscopy are reviewed. In order to allow the choice of the best operating conditions, the importance of the regulation and control systems is underlined. Emission theory, X-rays nature and its interaction with matter and electrons in the matter is shown. The structure, operating procedures and necessary electronics (single channel - analysis chain) automatic-control system for the threshold-energies discrimination and the energy distribution visualization) associated to the wavelength dispersive spectroscopy are described. The focusing control, resolution, influence of chemical bonds and multilayer-structure monochromators relaled to wavelength dispersive spectroscopy are studied. Concerning the energy-dispersive spectroscopy, the detector, preamplifier, amplifier, analog-digital converter, as well as the utilization and control of the spectrometer are described. Problems and instrumental progress on energy-dispersive spectroscopy related to the electronic-noise control, charge collection and light-elements detection are discussed [fr

  2. IR spectroscopy of synthetic glasses with Mercury surface composition: Analogs for remote sensing

    Science.gov (United States)

    Morlok, Andreas; Klemme, Stephan; Weber, Iris; Stojic, Aleksandra; Sohn, Martin; Hiesinger, Harald

    2017-11-01

    In a study to provide ground-truth data for mid-infrared observations of the surface of Mercury with the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument onboard the ESA/JAXA BepiColombo mission, we have studied 17 synthetic glasses. These samples have the chemical compositions of characteristic Hermean surface areas based on MESSENGER data. The samples have been characterized using optical microscopy, EMPA and Raman spectroscopy. Mid-infrared spectra have been obtained from polished thin sections using Micro-FTIR, and of powdered size fractions of bulk material (0-25, 25-63, 93-125 and 125-250 μm) in the 2.5-18 μm range. The synthetic glasses display mostly spectra typical for amorphous materials with a dominating, single Reststrahlen Band (RB) at 9.5-10.7 μm. RB Features of crystalline forsterite are found in some cases at 9.5-10.2 μm, 10.4-11.2 μm, and at 11.9 μm. Dendritic crystallization starts at a MgO content higher than 23 wt.% MgO. The Reststrahlen Bands, Christiansen Features (CF), and Transparency Features (TF) shift depending on the SiO2 and MgO contents. Also a shift of the Christiansen Feature of the glasses compared with the SCFM (SiO2/(SiO2+CaO+FeO+MgO)) index is observed. This shift could potentially help distinguish crystalline and amorphous material in remote sensing data. A comparison between the degree of polymerization of the glass and the width of the characteristic strong silicate feature shows a weak positive correlation. A comparison with a high-quality mid-IR spectrum of Mercury shows some moderate similarity to the results of this study, but does not explain all features.

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

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Heeyoung; Yuk, In-Soo; Park, Byeong-Gon; Park, Chan; Chun, Moo-Young; Kim, Kang-Min; Oh, Jae Sok; Jeong, Ueejeong; Yu, Young Sam; Lee, Jae-Joon; Kim, Hwihyun; Hwang, Narae; Lee, Sungho [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Pyo, Tae-Soo [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Pak, Soojong; Lee, Hye-In; Le, Huynh Anh Nguyen [School of Space Research and Institute of Natural Sciences, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104 (Korea, Republic of); Kaplan, Kyle; Pavel, Michael; Mace, Gregory, E-mail: hyoh@kasi.re.kr [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); and others

    2016-02-01

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

  4. Molecular orbital calculations of the unpaired electron distribution and electric field gradients in divalent paramagnetic Ir complexes

    International Nuclear Information System (INIS)

    Nogueira, S.R.; Vugman, N.V.; Guenzburger, D.

    1988-01-01

    Semi-empirical Molecular Orbital calculations were performed for the paramagnetic complex ions [Ir(CN) 5 ] 3- , [Ir(CN) 5 Cl] 4- and [Ir(CN) 4 Cl 2 ] 4- . Energy levels schemes and Mulliken-type populations were obtained. The distribution of the unpaired spin over the atoms in the complexes was derived, and compared to data obtained from Electron Paramagnetic Resonance spectra with the aid of a Ligand Field model. The electric field gradients at the Ir nucleus were calculated and compared to experiment. The results are discussed in terms of the chemical bonds formed by Ir and the ligands. (author) [pt

  5. Structural, electronic and magnetic properties of the series of double perovskites (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Bufaiçal, L., E-mail: lbufaical@ufg.br [Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia, GO (Brazil); Adriano, C. [Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859 Campinas, SP (Brazil); Lora-Serrano, R. [Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Duque, J.G.S. [Núcleo de Física, Universidade Federal de Sergipe, Campus Itabaiana, 49500-000 Itabaiana, SE (Brazil); Mendonça-Ferreira, L. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-170 Santo André, SP (Brazil); Rojas-Ayala, C.; Baggio-Saitovitch, E.; Bittar, E.M. [Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil); Pagliuso, P.G. [Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859 Campinas, SP (Brazil)

    2014-04-01

    Polycrystalline samples of the series of double perovskites Sr{sub 2−x}La{sub x}FeIrO{sub 6} were synthesized. Their structural, electronic and magnetic properties were investigated by X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, heat capacity and electrical resistivity experiments. The compounds crystallize in a monoclinic structure and were fitted in space group P2{sub 1}/n, with a significant degree of Fe/Ir cationic disorder. As in Ca{sub 2−x}La{sub x}FeIrO{sub 6} the Sr-based system seems to evolve from an antiferromagnetic ground state for the end members (x=0.0 and x=2.0) to a ferrimagnetic order in the intermediate regions (x∼1). Since Mössbauer spectra indicate that Fe valence remains 3+ with doping, this tendency of change in the nature of the microscopic interaction could be attributed to Ir valence changes, induced by La{sup 3+} electrical doping. Upon comparing both Ca and Sr series, Sr{sub 2−x}La{sub x}FeIrO{sub 6} is more structurally homogenous and presents higher magnetization and transition temperatures. Magnetic susceptibility measurements at high temperatures on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6} indicate a very high ferrimagnetic Curie temperature T{sub C}∼700K. For the Sr{sub 2}FeIrO{sub 6} compound, electrical resistivity experiments under applied pressure suggest that this material might be a Mott insulator. - Graphical abstract: The Weiss constant as a function of La doping for the (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6} series, indicating changes in Fe–Ir magnetic coupling on both families. - Highlights: • The double perovskite series (Ca,Sr){sub 2−x}La{sub x}FeIrO{sub 6} were synthesized. • Changes in the Fe-Ir magnetic coupling due to La doping on both series. • Evidence of high T{sub C} on Sr{sub 1.2}La{sub 0.8}FeIrO{sub 6}. • Indication of Mott insulator behavior on Sr{sub 2}FeIrO{sub 6}.

  6. Two-dimensional electronic femtosecond stimulated Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Ogilvie J.P.

    2013-03-01

    Full Text Available We report two-dimensional electronic spectroscopy with a femtosecond stimulated Raman scattering probe. The method reveals correlations between excitation energy and excited state vibrational structure following photoexcitation. We demonstrate the method in rhodamine 6G.

  7. Electron spectroscopy on high-temperature superconductors and related compounds

    International Nuclear Information System (INIS)

    Knupfer, M.

    1994-01-01

    In the last two classes of materials have been discovered which distinguish themselves due to a transition into the superconducting state at relatively high temperatures. These are the cuprate superconductors and the alkali metal doped fullerenes. In this work the electronic structure of representatives of these materials, undoped and Ca-doped YBa 2 Cu 4 O 8 and A 3 C 60 (A=K, Rb), has been investigated using electron energy-loss spectroscopy and photoemission spectroscopy. (orig.) [de

  8. Spectroscopy of heavy few-electron ions

    International Nuclear Information System (INIS)

    Mokler, P.H.

    1986-07-01

    In this paper we ask first, why is it interesting to investigate heavy-few electron ions. Then the various accelerator-based methods to produce heavy few-electron ions are discussed. In the main part an overview on available heavy few-electron ion data and current experiments is given. The summary will end up with future aspects in this field. (orig.)

  9. Photoelectron spectroscopy via electronic spectroscopy of molecular ions

    International Nuclear Information System (INIS)

    Khan, Z.H.

    1990-01-01

    In this work, a new aspect of the correlation between optical and photoelectron spectra is discussed on the basis of which the first ionization potentials of condensed-ring aromatics can be estimated from certain features in the electronic spectra of their positive ions. Furthermore, it is noticed that the first IP's are very sensitive to molecular size as the latter's inclusion in the regression formulas improves the results considerably. Once the first ionization potential for a molecule is determined, its higher IP's may be computed if the lower-energy electronic bands for its cation are known. This procedure is especially useful for such systems whose uv photoelectron spectra are unknown. (author). 11 refs, 10 figs, 1 tab

  10. Electronic Structures of Reduced and Superreduced Ir2(1,8-diisocyanomenthane)4 n+ Complexes

    Czech Academy of Sciences Publication Activity Database

    Záliš, Stanislav; Hunter, B. M.; Gray, H. B.; Vlček, Antonín

    2017-01-01

    Roč. 56, č. 5 (2017), s. 2874-2883 ISSN 0020-1669 R&D Projects: GA MŠk LD14129 Grant - others:COST(XE) CM1405; COST(XE) CM1202 Institutional support: RVO:61388955 Keywords : electronic structure * electrochemistry * Ir2(1,8-diisocyanomenthane)4 n+ Complexes Subject RIV: CG - Electrochemistry OBOR OECD: Physical chemistry Impact factor: 4.857, year: 2016

  11. Electronic excitation and Auger spectroscopy of hexamethyldissilane

    International Nuclear Information System (INIS)

    Souza, G.G.B. de; Azevedo e Souza, A.C. de; Martins, R.J.; Lucas, C.A.

    1988-01-01

    In this work, it is presented an spectroscopic study of Si 2 (CH 3 ) 6 which presents interesting characteristics in the Si - Si bond. Electron energy loss technique was used in the energy range of 500 - 200 eV for the electron beam. Electronic excitation spectra were obtained for the energy loss range from 5 to 30 eV, and also Auger spectra. (A.C.A.S.) [pt

  12. IrPd nanoalloys: simulations, from surface segregation to local electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Andriamiharintsoa, T. H. [Institut de Physique et Chimie des Matériaux de Strasbourg CNRS-UDS UMR 7504 (France); Rakotomahevitra, A. [Institut pour la Maîtrise de l’Énergie, Faculté des sciences d’Antananarivo (Madagascar); Piccolo, L. [Institut de Recherches sur la Catalyse et l’Environnement de Lyon IRCELYON, UMR 5256 CNRS and Université Lyon 1 (France); Goyhenex, C., E-mail: christine.goyhenex@ipcms.unistra.fr [Institut de Physique et Chimie des Matériaux de Strasbourg CNRS-UDS UMR 7504 (France)

    2015-05-15

    Using semi-empirical modeling, namely tight-binding at different levels of accuracy, the chemical, crystallographic, and electronic structures of bimetallic IrPd nanoparticles are characterized. For the purpose, model cuboctahedral particles containing 561 atoms are considered. Atomistic simulations show that core–shell nanoparticles are highly stable, with a strong surface segregation of Pd, at least for one atomic shell thickness. Within self-consistent tight-binding calculations founded on the density functional theory, an accurate insight is given into the electronic structure of these materials which have a high potential as catalysts.

  13. Evaluation of a setting reaction pathway in the novel composite TiHA-CSD bone cement by FT-Raman and FT-IR spectroscopy

    Science.gov (United States)

    Paluszkiewicz, Czesława; Czechowska, Joanna; Ślósarczyk, Anna; Paszkiewicz, Zofia

    2013-02-01

    The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800 °C, sintered at 1250 °C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

  14. Electronic Structure of the fcc Transition Metals Ir, Rh, Pt, and Pd

    DEFF Research Database (Denmark)

    Andersen, O. Krogh

    1970-01-01

    We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states/atom)/Ry,......We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states....../atom)/Ry, respectively. Spin-orbit coupling is important for all four metals and the coupling parameter varies by 30% over the d bandwidth. Detailed comparisons with de Haas—van Alphen Fermi-surface dimensions have previously been presented and the agreement was very good. Comparison with measured electronic specific...

  15. Investigation of influence of electronic irradiation on photoluminescence spectrum and ir-spectrum of porous silicon

    International Nuclear Information System (INIS)

    Daineko, E.A.; Dihanbayev, K.K.; Akhtar, P.; Hussain, A.

    2007-01-01

    In this article we study the influence of 2-Mev electron irradiation on porous silicon (PS). Photoluminescence (PL) spectrum and IR-spectrum have been done on both newly-prepared PS samples and samples prepared a year ago after the irradiation. We analyzed PL spectrum for both types of PS samples. The experimental results suggest that the peak position in PL spectrum decreases for newly-prepared PS samples. The size of the nanocrystals calculated by the method of singling out of spectrum components was equal to 3.0-3.2 nm. Porosity of the samples was 60-75%. From IR-spectrum of newly-prepared PS samples wide absorption band was observed at 1100 cm/sup -1/ (Si-O-Si bond). Another peak of Si-O-Si group was observed at 850 cm/sub -1/. Also hydrogen absorption bands were appearing from 2000 to 2200 cm/sup -1/, corresponding to vibration modes SiH, SiH/sub 2/, SiH/sub 3/. As a result of electron irradiation the PL intensity of newly-prepared PS samples decreases abruptly by a factor of 30 without peak shifting. As for the samples prepared a year ago we observed a decrease in the PL intensity by 25-30%. From IR-spectrum of PS samples prepared a year ago it was shown that the intensity of bridge bonds corresponding to absorption band 850 cm/sup -1/, decreases gradually. Our experimental data shows that PS samples stored for longer time have better radiation resistant properties than the newly-prepared PS samples due to the replacement of Si-H bonds with more resistant Si-O bonds. Porous silicon, electrochemical anodizing, photoluminescence spectrum, IR-spectrum, electronic irradiation. (author)

  16. Towards a Molecular Movie: Real Time Observation of Hydrogen Bond Breaking by Transient 2D-IR Spectroscopy in a Cyclic Peptide

    Science.gov (United States)

    Kolano, Christoph; Helbing, Jan; Sander, Wolfram; Hamm, Peter

    Transient two-dimensional infrared spectroscopy (T2D-IR) has been used to observe in real time the non-equilibrium structural dynamics of intramolecular hydrogen bond breaking in a small cyclic disulfide-bridged peptide.

  17. An IR and XPS spectroscopy assessment of the physico-chemical surface properties of alumina–YAG nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Spina, Giulia; Bonelli, Barbara, E-mail: barbara.bonelli@polito.it; Palmero, Paola, E-mail: paola.palmero@polito.it; Montanaro, Laura

    2013-12-16

    Well-dispersed nano-crystalline transition alumina suspensions were mixed with yttrium chloride aqueous solutions, with the aim of producing by spray-drying Al{sub 2}O{sub 3}–Y{sub 3}Al{sub 5}O{sub 12} (YAG) composite powders of increasing YAG vol.%. Two samples were prepared, with different Y content, corresponding to 5 and 20 YAG vol.%, respectively. Both samples were then treated at either 600 or 1150 °C. The obtained powders were characterized by X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infra Red (FT-IR) spectroscopy and compared to three reference samples: commercial nano-crystalline transition alumina, YAG and Y{sub 2}O{sub 3}. YAG powders were obtained by co-precipitation route whereas Y{sub 2}O{sub 3} powders were yielded by spray-drying of a yttrium chloride aqueous solution. Modification of physico-chemical properties of the surface of alumina nanoparticles were assessed by combining XPS and FT-IR spectroscopies. On the basis of the results obtained, a possible model is proposed for the structure of the obtained composites, in which Y basically reacts with more acidic hydroxyls of alumina, by forming Y-rich surface grains, the extension of which depends on the thermal treatment. - Highlights: • Al{sub 2}O{sub 3}–Y{sub 3}Al{sub 5}O{sub 12} (YAG) composite nanopowders were prepared by spray drying. • Combined XPS and IR spectroscopy: effective tools to study surface modifications. • Y reacts with more acidic hydroxyls at alumina surface. • Y-rich surface grains form: their extension depends on the thermal treatment.

  18. Electron spectroscopy studies in heavy fermions

    International Nuclear Information System (INIS)

    Arko, A.J.

    1986-02-01

    Photoemission experiments (whereby an electron absorbs a packet of light energy and is able to escape from the host material due to its increased energy) can measure directly the energy distribution of electrons in various materials. Our measurements on a recently-discovered class of metallic materials called ''heavy fermions'' show that the electrons that actually carry the electric current in these metals exist only within an extremely narrow range of energies. This range, which we will call the bandwidth, is narrower than that found in ordinary metals like copper by at least a factor of 10. Indeed it is surprising that they can carry electric current at all since such narrow energy ranges (or band widths) are characteristic of electrons confined to their host atoms, as in a non-metal, rather than of electrons that are free to wander through a metal. 8 refs

  19. Impedance Spectroscopy of Dielectrics and Electronic Conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Pissis, Polycarpos; Macdonald, J. Ross

    2013-01-01

    Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property......, such as admittance or dielectric constant - as a function of frequency and comparing the results with expectations based on physical, chemical, and microstructural models. This article reviews the principles and practical aspects of the technique, the representations of the results, the analysis of data......, and procedures for the correction of measurement errors. The applications of impedance spectroscopy are illustrated with examples from electroceramics and polymer-based dielectric systems. The way in which the technique is applied to the two classes of materials is compared with reference to the different models...

  20. Surface analysis by electron spectroscopy. General concepts and applications

    International Nuclear Information System (INIS)

    Feliu, S.

    1993-01-01

    An introduction is made to the techniques of electron spectroscopy (XPS and AES) used in the study of surface phenomena. Their theoretical principles, the singular information supplied by these techniques and their basic instrumentation (vacuum systems, excitation sources and electron analysers) are described. A revision of their applications to the Materials Science and the Corrosion Sciences is also made. Author. 44 refs

  1. A high dutycycle low cost multichannel analyser for electron spectroscopy

    International Nuclear Information System (INIS)

    Norell, K.E.; Baltzer, P.

    1983-03-01

    A high dutycycle multichannel analyzer has been designed and used in time-of-flight electron spectroscopy. The memory capacity is 64k counts. The number of channels is 8192 with a time resolution of 100 ns. An oscilloscope is used to display the spectra synchronous with the counting. The unit has been built with standard electronic components. (author)

  2. Perforated SiN membrane resonators for nanomechanical IR spectroscopy poster

    DEFF Research Database (Denmark)

    Kurek, Maksymilian; Carnoy, Matthias; Boisen, Anja

    Constant progress in micro- and nanofabrication provides a great opportunity in development of micro- and nanomechanical resonatorsthat can be used for sensing purposes. These sensors usually consist of singly-clamped cantilever beams, doubly-clamped bridges ormembranes that exhibit resonant......, lateral dimension of1×1 mm2 and 2 µm perforation grid pitch were used instead of strings which makes the IR beam alignment significantly simpler whilemaintaining similar sampling efficiency and photothermal IR absorption sensitivity....

  3. Hydrocarbon isotope detection by elastic peak electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kostanovskiy, I.A., E-mail: kostanovskiyia@gmail.com [National Research University MPEI, Krasnokazarmennaya 14, 111250 Moscow (Russian Federation); Afanas’ev, V.P. [National Research University MPEI, Krasnokazarmennaya 14, 111250 Moscow (Russian Federation); Naujoks, D. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Mayer, M. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-07-15

    Highlights: • PCVD hydrocarbon coatings containing protium or deuterium are analyzed via NRA, ERD, XPS and EPES. • EPES analysis with modern electron energy analyzer SPECS Phoibos 225 shows a clear signal from the hydrogen isotopes. • Different primary energies and scattering angles help to quantify isotope content from EPES spectra. - Abstract: Experimental results on the hydrocarbon isotope analysis by elastic peak electron spectroscopy are presented. Amorphous hydrocarbon samples (a-C:H, a-C:D) are prepared by PCVD and analyzed by nuclear reaction analysis (NRA), elastic recoil detection analysis (ERD), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES). Electron energy spectra show a clear signal from the hydrogen isotopes deuterium and protium. Different incident energies and scattering geometries help to resolve plasmon and elastic energy losses.

  4. Hydrocarbon isotope detection by elastic peak electron spectroscopy

    International Nuclear Information System (INIS)

    Kostanovskiy, I.A.; Afanas’ev, V.P.; Naujoks, D.; Mayer, M.

    2015-01-01

    Highlights: • PCVD hydrocarbon coatings containing protium or deuterium are analyzed via NRA, ERD, XPS and EPES. • EPES analysis with modern electron energy analyzer SPECS Phoibos 225 shows a clear signal from the hydrogen isotopes. • Different primary energies and scattering angles help to quantify isotope content from EPES spectra. - Abstract: Experimental results on the hydrocarbon isotope analysis by elastic peak electron spectroscopy are presented. Amorphous hydrocarbon samples (a-C:H, a-C:D) are prepared by PCVD and analyzed by nuclear reaction analysis (NRA), elastic recoil detection analysis (ERD), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES). Electron energy spectra show a clear signal from the hydrogen isotopes deuterium and protium. Different incident energies and scattering geometries help to resolve plasmon and elastic energy losses

  5. Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Sagar Dhakal

    2016-05-01

    Full Text Available Turmeric powder (Curcuma longa L. is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman and Fourier Transform-Infra Red (FT-IR spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0.01% (w/w. FT-Raman and FT-IR spectra were acquired for these mixture samples as well as for pure samples of turmeric powder and metanil yellow. Spectral analysis showed that the FT-IR method in this study could detect the metanil yellow at the 5% concentration, while the FT-Raman method appeared to be more sensitive and could detect the metanil yellow at the 1% concentration. Relationships between metanil yellow spectral peak intensities and metanil yellow concentration were established using representative peaks at FT-Raman 1406 cm−1 and FT-IR 1140 cm−1 with correlation coefficients of 0.93 and 0.95, respectively.

  6. Spectroscopy of electron irradiated polymers in electron microscope

    International Nuclear Information System (INIS)

    Faraj, S.H.; Salih, S.M.

    1981-01-01

    The damage induced by energetic electrons in the course of irradiation of polymers in a transmission electron microscope was investigated spectroscopically. Damage on the molecular level has been detected at very low exposure doses. These effects have been induced by electron doses less than that received by the specimen when it is situated at its usual place of the specimen stage in the electron microscope by a factor of 1,000. (author)

  7. Electron spectroscopy of nanodiamond surface states

    Energy Technology Data Exchange (ETDEWEB)

    Belobrov, P.I.; Bursill, L.A.; Maslakov, K.I.; Dementjev, A.P

    2003-06-15

    Electronic states of nanodiamond (ND) were investigated by PEELS, XPS and CKVV Auger spectra. Parallel electron energy loss spectra (PEELS) show that the electrons inside of ND particles are sp{sup 3} hybridized but there is a surface layer containing distinct hybridized states. The CKVV Auger spectra imply that the HOMO of the ND surface has a shift of 2.5 eV from natural diamond levels of {sigma}{sub p} up to the Fermi level. Hydrogen (H) treatment of natural diamond surface produces a chemical state indistinguishable from that of ND surfaces using CKVV. The ND electronic structure forms {sigma}{sub s}{sup 1}{sigma}{sub p}{sup 2}{pi}{sup 1} surface states without overlapping of {pi}-levels. Surface electronic states, including surface plasmons, as well as phonon-related electronic states of the ND surface are also interesting and may also be important for field emission mechanisms from the nanostructured diamond surface.

  8. Future directions in electron momentum spectroscopy of matter

    International Nuclear Information System (INIS)

    Weigold, E.

    1998-01-01

    The development of coincidence spectrometers with multivariable detection techniques, higher energy kinematics, monochromated and spin-polarised electron sources, will usher in a new generation of electron momentum spectroscopy revealing new electronic phenomena in atoms, molecules and solids. This will be enhanced by developments in target preparation, such as spin polarised, oriented and aligned atoms and molecules, radicals, surfaces and strongly correlated systems in condensed matter. Copyright (1998) CSIRO Australia

  9. Secondary-electron cascade in attosecond photoelectron spectroscopy from metals

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Madsen, Lars Bojer

    2009-01-01

    an analytical model based on an approximate solution to Boltzmann's transport equation to account for the amount and energy distribution of these secondary electrons. Our theory is in good agreement with the electron spectrum found in a recent attosecond streaking experiment. To suppress the background and gain......Attosecond spectroscopy is currently restricted to photon energies around 100 eV. We show that under these conditions, electron-electron scatterings, as the photoelectrons leave the metal, give rise to a tail of secondary electrons with lower energies and hence a significant background. We develop...

  10. Electron impact spectroscopy of methane, silane, and germane

    International Nuclear Information System (INIS)

    Dillon, M.A.; Wang, R.G.; Spence, D.

    1985-01-01

    Electronic spectra of the group IV/sub a/ hydrides, i.e., methane (CH 4 ), silane (SiH 4 ), and germane (GeH 4 ) have been investigated by means of electron energy loss spectroscopy in an energy range that includes all single-electron excitation from the valence shell. Electron impact spectra of the three gases recorded using electrons of 200-eV incidence are presented. The conditions employed were chosen to favor the excitation of states by direct scattering and to exclude those transitions requiring an exchange mechanism

  11. Pressure-modulation dynamic attenuated-total-reflectance (ATR) FT-IR spectroscopy

    Science.gov (United States)

    Marcott, C.; Story, G. M.; Noda, I.; Bibby, A.; Manning, C. J.

    1998-06-01

    A single-reflectance attenuated-total-reflectance (ATR) accessory with a diamond internal-reflection element was modified by the addition of a piezoelectric transducer. Initial dynamic pressure-modulation experiments have been performed in the sample compartment of a step-scanning FT-IR spectrometer. A sinusoidal pressure modulation applied to samples of isotactic polypropylene and linear low density polyethylene resulted in dynamic responses which appear to be similar to those observed in previous dynamic 2D IR experiments. Preliminary pressure-modulation dynamic ATR results are also reported for a styrene-butadiene-styrene triblock copolymer. The new method has the advantages that a much wider variety of sample types and geometries can be studied and less sample preparation is required. Dynamic 2D IR experiments carried out by ATR no longer require thin films of large area and sufficient strength to withstand the dynamic strain applied by a rheometer. The ability to obtain dynamic IR spectroscopic information from a wider variety of sample types and thicknesses would greatly expand the amount of useful information that could be extracted from normally complicated, highly overlapped IR spectra.

  12. Raman and IR-ATR spectroscopy studies of heteroepitaxial structures with a GaN:C top layer

    Science.gov (United States)

    Cerqueira, M. F.; Vieira, L. G.; Alves, A.; Correia, R.; Huber, M.; Andreev, A.; Bonanni, A.; Vasilevskiy, M. I.

    2017-09-01

    This work, motivated by the technologically important task of determination of carbon dopant location in the GaN crystal lattice, employed Raman spectroscopy, with both resonant and non-resonant excitation, and infrared (IR) spectroscopy, in the attenuated total reflection (ATR) configuration, to study lattice vibration modes in a set of carbon-doped GaN (GaN:C) epilayers grown by metalorganic vapour phase epitaxy. We analyse Raman and IR-ATR spectra from the point of view of possible effects of the carbon doping, namely: (i) local vibration mode of C atoms in the nitrogen sublattice (whose frequency we theoretically estimate as 768 cm-1 using an isotope defect model), and (ii) shift in the positions of longitudinal modes owing to the phonon-plasmon coupling. We find only indirect hints of the doping effect on the resonant Raman spectra. However, we show theoretically and confirm experimentally that the IR-ATR spectroscopy can be a much more sensitive tool for this purpose, at least for the considered structures. A weak perturbation of the dielectric function of GaN:C, caused by the substitutional carbon impurity, is shown to produce a measurable dip in the ATR reflectivity spectra at  ≈770 cm-1 for both p- and s-polarizations. Moreover, it influences a specific (guided-wave type) mode observed at  ≈737 cm-1, originating from the GaN layer, which appears in the narrow frequency window where the real parts of the two components of the dielectric tensor of the hexagonal crystal have opposite signs. This interpretation is supported by our modelling of the whole multilayer structure, using a transfer matrix formalism.

  13. Structural, mechanical, and electronic properties of TaB2, TaB, IrB2, and IrB: First-principle calculations

    International Nuclear Information System (INIS)

    Zhao Wenjie; Wang Yuanxu

    2009-01-01

    First-principle calculations were performed to investigate the structural, elastic, and electronic properties of TaB 2 , TaB, IrB 2 , and IrB. The calculated equilibrium structural parameters, shear modulus, and Young's modulus of TaB 2 are well consistent with the available experimental data, and TaB 2 with P6/mmm space group has stronger directional bonding between ions than WB 2 , OsB 2 , IrN 2 , and PtN 2 . For TaB 2 , the hexagonal P6/mmm structure is more stable than the orthorhombic Pmmn one, while for IrB 2 the orthorhombic Pmmn structure is the most stable one. The high shear modulus of P6/mmm phase TaB 2 is mainly due to the strong covalent π-bonding of B-hexagon in the (0001) plane. Such a B-hexagon network can strongly resist against an applied [112-bar0] (0001) shear deformation. Correlation between the hardness and the elastic constants of TaB 2 was discussed. The band structure shows that P6/mmm phase TaB 2 and Pmmn phase IrB 2 are both metallic. The calculations show that both TaB and IrB are elastically stable with the hexagonal P6 3 /mmc structure. - Elastic constant c 44 of TaB 2 is calculated to be 235 GPa. This value is exceptionally high, exceeding those of WB 2 , OsB 2 , WB 4 , OsN 2 , IrN 2 , and PtN 2 .

  14. Conformational study of sarcosine as probed by matrix-isolation FT-IR spectroscopy and molecular orbital calculations

    OpenAIRE

    Gómez-Zavaglia, Andrea; Fausto, R.

    2003-01-01

    Sarcosine (N-methylglycine) has been studied by matrix-isolation FT-IR spectroscopy and molecular orbital calculations undertaken at the DFT/B3LYP and MP2 levels of theory with the 6-311++G(d, p) and 6-31++G(d, p) basis set, respectively. Eleven different conformers were located in the potential energy surface (PES) of sarcosine, with the ASC conformer being the ground conformational state. This form is analogous to the glycine most stable conformer and is characterized by a NH...O= intramole...

  15. Electron spectroscopy of collisional excited atoms

    International Nuclear Information System (INIS)

    Straten, P. van der.

    1987-01-01

    In this thesis measurements are described in which coincidences are detected between scattered projectiles and emitted electrons. This yields information on two-electron excitation processes. In order to show what can be learnt from coincidence experiments a detailed theoretical analysis is given. The transition amplitudes, which contain all the information, are introduced (ch.2). In ch.3 the experimental set-up is shown. The results for the Li + -He system are shown in ch. 7 and are compared with predictions based on the Molecular-Orbitalmodel which however does not account for two-excitation mechanisms. With the transition amplitudes also the wave function of the excited atom has been completely determined. In ch.8 the shape of the electron cloud, induced by the collision, is derived from the amplitudes. The relation between the oscillatory motion of this cloud after the collision and the correlation between the two electrons of the excited atom is discussed. In ch. 6 it is shown that the broad structures in the non-coincident energy spectra of the Li + -He system are erroneously interpretated as a result of electron emission from the (Li-He) + -quasimolecule. A model is presented which explains, based on the results obtained from the coincidence measurements, these broad structures. In ch. 4 the Post-Collision Interaction process is treated. It is shown that for high-energy collisions, in contrast with general assumptions, PCI is important. In ch. 5 the importance of PCI-processes in photoionization of atoms, followed by Auger decay, are studied. From the formulas derived in ch. 4 simple analytical results are obtained. These are applied to recent experiments and good agreement is achieved. 140 refs.; 55 figs.; 9 tabs

  16. Electron coincidence spectroscopy of sodium and potassium

    International Nuclear Information System (INIS)

    Frost, L.; Weigold, E.

    1982-03-01

    The Na 3s and K 4s electron momentum distributions have been obtained using the noncoplanar symmetric (e,2e) reaction at total energies of 800 eV and 1200 eV. They show excellent agreement with the results of plane wave impulse approximation calculations using Roothaan-Hartree-Fock functions, after small corrections are made for the finite angular resolution of the apparatus. The potassium valence s momentum profile is a little narrower than that for sodium, implying a correspondingly slightly larger spatial distribution of the outer valence electrons. The ratio between the (n-1)p and ns cross-sections at their respective maxima in q-space were measured to be 0.009 +- 0.003 and 0.019 +- 0.003 for Na and K respectively. These cross-section ratios are in agreement with the PWIA calculations

  17. Electronic structure of Pu carbides: photoelectron spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Gouder, T.; Havela, L.; Shick, Alexander; Huber, F.

    2008-01-01

    Roč. 403, č. 5-9 (2008), s. 852-853 ISSN 0921-4526 R&D Projects: GA AV ČR(CZ) IAA100100530 Grant - others:EU(XE) RITA -CT-2006-026176 Institutional research plan: CEZ:AV0Z10100520 Keywords : photoemission * electronic structure * plutonium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.822, year: 2008

  18. Electron cyclotron emission spectroscopy on thermonuclear plasmas

    International Nuclear Information System (INIS)

    Tubbing, B.J.D.

    1987-01-01

    Analysis of electron cyclotron emission (ECE) enables one to infer the radial profile of the electron temperature in tokamaks. The Dutch FOM institute for plasma physics has designed, built, installed and operated a grating polychromator for ECE measurements at JET. This thesis deals with a few instrumental aspects of this project and with applications of ECE measurements in tokamak physics studies. Ch. 3 and 4 deal with the wave transport in ECE systems. In Ch. 3 a method is developed to infer the mode conversion, which is a source for transmission losses, in a waveguide component from the antenna pattern of its exit aperture. In Ch. 4 the design and manufacture of the waveguide transition system to the grating polychromator are described. In Ch. 5 a method is reported for calibration of the spectrometers, based on the use of a microwave source which simulates a large area blackbody of very high temperature. The feasibility of the method is tested by applying it to two different ECE systems. In Ch. 6 a study of heat pulse propagation in tokamak plasma's, based on measurement of the electron temperature with the grating polychromator, is presented. 105 refs.; 48 figs.; 8 tabs

  19. Kinetics of the reaction F+NO+M->FNO+M studied by pulse radiolysis combined with time-resolved IR and UV spectroscopy

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Sillesen, A.; Jodkowski, J.T.

    1996-01-01

    The title reaction was initiated by pulse radiolysis of SF6/NO gas mixtures, and the formation of FNO was studied by time-resolved IR and UV spectroscopy. At SF6 pressures of 10-320 mbar at 298 K, the formation of FNO was studied by infrared diode laser spectroscopy at 1857.324 cm(-1). Comparative...

  20. On the merits of conversion electron Mossbauer spectroscopy in geosciences

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Bertelsen, P.; Budtz-Jørgensen, Carl

    2006-01-01

    Described are some applications of conversion electron Mossbauer spectroscopy (CEMS) in geosciences. It is shown how easily this technique can be applied in existing Mossbauer laboratories to investigate natural samples. Some examples demonstrate the kind of information CEMS can give on the weath......Described are some applications of conversion electron Mossbauer spectroscopy (CEMS) in geosciences. It is shown how easily this technique can be applied in existing Mossbauer laboratories to investigate natural samples. Some examples demonstrate the kind of information CEMS can give...

  1. Evidence for resonant bonding in phase-change materials studied by IR spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Shportko

    2017-04-01

    Full Text Available Phase-change materials (PCM attract attention due to their unique properties. This remarkable portfolio also makes them promising for applications in novel data storage devices. In this study, we discuss differences in the optical properties of PCM and non-PCM in the IR caused by presence or absence of resonant bonding.

  2. Organic Spectroscopy Laboratory: Utilizing IR and NMR in the Identification of an Unknown Substance

    Science.gov (United States)

    Glagovich, Neil M.; Shine, Timothy D.

    2005-01-01

    A laboratory experiment that emphasizes the interpretation of both infrared (IR) and nuclear magnetic resonance (NMR) spectra in the elucidation of the structure of an unknown compound was developed. The method helps students determine [to the first power]H- and [to the thirteenth power]C-NMR spectra from the structures of compounds and to…

  3. A Rapid Method of Crude Oil Analysis Using FT-IR Spectroscopy

    African Journals Online (AJOL)

    HP USER

    Nigerian Journal of Basic and Applied Science (June,2016), 24(1): 47-55 ... ABSTRACT: This study determines the viability of the use of Fourier Transform ... IR spectra of Crude oil sample containing a mixture of both degraded (sample 151).

  4. High-pressure behavior of α-boron studied on single crystals by X-ray diffraction, Raman and IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chuvashova, Irina, E-mail: irina.chuvashova@gmail.com [Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Bayerisches Geoinstitut, University of Bayreuth, D-95440 Bayreuth (Germany); Bykova, Elena; Bykov, Maxim [Bayerisches Geoinstitut, University of Bayreuth, D-95440 Bayreuth (Germany); Svitlyk, Volodymyr [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Gasharova, Biliana [Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); IBPT, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Mathis, Yves-Laurent [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); IBPT, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Caracas, Razvan [CNRS, Laboratoire de Géologie de Lyon, ENS de Lyon, UCBL Lyon 1, Université de Lyon (France); Dubrovinsky, Leonid [Bayerisches Geoinstitut, University of Bayreuth, D-95440 Bayreuth (Germany); Dubrovinskaia, Natalia [Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany)

    2017-01-15

    In the present study single crystals of rhombohedral α-B were investigated under pressure to 60 GPa by means of single-crystal X-ray diffraction. The bulk modulus of α-B was found to be K=224(7) GPa (K′=3.0(3)). Measurements of interatomic distances as a function of pressure revealed that the intericosahedral two-center two-electron (2c–2e) bonds are almost as stiff as some of intraicosahedral ones. The three-center two-electron (3c–2e) intericosahedral bonds show much higher compliance compared to other bonds in α-B. The vibrational properties of α-B under pressure were investigated by Raman spectroscopy at pressures up to 160 GPa and IR spectroscopy at pressures up to 53 GPa. - Graphical abstract: The rhombohedral α-B is highly incompressible and extremely stable: it maintains its crystal structure up to 160 GPa and its intericosahedral 2e2c bonds are almost as stiff as some of intraicosahedral ones. - Highlights: • Structural stability of α-B has been investigated up to 160 GPa on single crystals. • Single-crystal x-ray diffraction reveals that α-B is highly incompressible. • Compressibility of B{sub 12} icosahedra is considerably lower than that of the bulk material. • Intericosahedral 2e2c bonds are almost as stiff as some of intraicosahedral ones.

  5. Energy analyzer for Auger electron spectroscopy and low-energy backscattering ion spectroscopy

    International Nuclear Information System (INIS)

    Volkov, S.S.; Gorelik, V.A.; Gutenko, V.T.; Protopopov, O.D.; Trubitsin, A.A.; Shuvalova, Z.A.; Yakushev, G.A.

    1988-01-01

    Energy analyzer for electron Auger spectroscopy and low-energy backscattering ion spectroscopy is described. Analyzer presents one-cascade variant of cylindrical mirror with second-order focusing. Energy relative resolution is continuously adjusted within 0.2-1.2% limits. Signal/noise relation by Cu Auger-line at 1 muA current of exciting beam changes upper limit of range 150-450

  6. Geographic identification of Boletus mushrooms by data fusion of FT-IR and UV spectroscopies combined with multivariate statistical analysis

    Science.gov (United States)

    Yao, Sen; Li, Tao; Li, JieQing; Liu, HongGao; Wang, YuanZhong

    2018-06-01

    Boletus griseus and Boletus edulis are two well-known wild-grown edible mushrooms which have high nutrition, delicious flavor and high economic value distributing in Yunnan Province. In this study, a rapid method using Fourier transform infrared (FT-IR) and ultraviolet (UV) spectroscopies coupled with data fusion was established for the discrimination of Boletus mushrooms from seven different geographical origins with pattern recognition method. Initially, the spectra of 332 mushroom samples obtained from the two spectroscopic techniques were analyzed individually and then the classification performance based on data fusion strategy was investigated. Meanwhile, the latent variables (LVs) of FT-IR and UV spectra were extracted by partial least square discriminant analysis (PLS-DA) and two datasets were concatenated into a new matrix for data fusion. Then, the fusion matrix was further analyzed by support vector machine (SVM). Compared with single spectroscopic technique, data fusion strategy can improve the classification performance effectively. In particular, the accuracy of correct classification of SVM model in training and test sets were 99.10% and 100.00%, respectively. The results demonstrated that data fusion of FT-IR and UV spectra can provide higher synergic effect for the discrimination of different geographical origins of Boletus mushrooms, which may be benefit for further authentication and quality assessment of edible mushrooms.

  7. Classification of edible oils and modeling of their physico-chemical properties by chemometric methods using mid-IR spectroscopy

    Science.gov (United States)

    Luna, Aderval S.; da Silva, Arnaldo P.; Ferré, Joan; Boqué, Ricard

    This research work describes two studies for the classification and characterization of edible oils and its quality parameters through Fourier transform mid infrared spectroscopy (FT-mid-IR) together with chemometric methods. The discrimination of canola, sunflower, corn and soybean oils was investigated using SVM-DA, SIMCA and PLS-DA. Using FT-mid-IR, DPLS was able to classify 100% of the samples from the validation set, but SIMCA and SVM-DA were not. The quality parameters: refraction index and relative density of edible oils were obtained from reference methods. Prediction models for FT-mid-IR spectra were calculated for these quality parameters using partial least squares (PLS) and support vector machines (SVM). Several preprocessing alternatives (first derivative, multiplicative scatter correction, mean centering, and standard normal variate) were investigated. The best result for the refraction index was achieved with SVM as well as for the relative density except when the preprocessing combination of mean centering and first derivative was used. For both of quality parameters, the best results obtained for the figures of merit expressed by the root mean square error of cross validation (RMSECV) and prediction (RMSEP) were equal to 0.0001.

  8. The nature of hydrogen-bonding interactions in nonsteroidal anti-inflammatory drugs revealed by polarized IR spectroscopy

    Science.gov (United States)

    Hachuła, Barbara

    2018-01-01

    The influence of hydrogen-bonding interactions in the solid phase on the IR spectroscopic pattern of the νOsbnd H band of nonsteroidal anti-inflammatory drugs (NSAIDs) was studied experimentally by IR spectroscopy with the use of polarized light at two temperatures (293 K and 77 K) and in isotopic dilution. The neat and deuterated crystals of (S)-naproxen ((S)-NPX), (R)-flurbiprofen ((R)-FBP), (RS)-flurbiprofen ((RS)-FBP) and (RS)-ketoprofen ((RS)-KTP) were obtained by melt crystallization between the two squeezed CaF2 plates. The vibrational spectra of selected α-aryl propionic acid derivatives (2APAs) reflected the characteristics of their hydrogen-bond networks, i.e., 2APAs were characterized by the chain ((S)-NPX, (R)-FBP) and by dimeric ((RS)-FBP, (RS)-KTP) arrangement of hydrogen bonds in the crystal lattice. Spectroscopic results showed that the interchain (through-space) exciton coupling, between two laterally-spaced hydrogen bonds, dominates in the crystals of four NSAIDs. The same exciton coupled hydrogen bonds were also responsible for the H/D isotopic recognition mechanism in the crystalline spectra of deuterated 2APAs. The presented spectral results may help to predict the hydrogen bond motifs in the crystalline NSAIDs, which structures are not yet known, based on their IR spectra of hydrogen bond in the crystals.

  9. Application of fourier-transform infrared (ft-ir) spectroscopy for determination of total phenolics of freeze dried lemon juices

    International Nuclear Information System (INIS)

    Sherazi, S.T.H.; Bhutto, A.A.; Mehesar, S.A.

    2017-01-01

    A cost effective and environmentally safe analytical method for rapid assessment of total phenolic content (TPC) in freeze dried lemon juice samples was developed using transmission Fourier-transform infrared spectroscopy (FT-IR) in conjunction with chemometric techniques. Two types of calibrations i.e. simple Beer's law and partial least square (PLS) were applied to investigate most accurate calibration model based on region from1420 to 1330 cm-1. The better analytical performance was obtained by PLS technique coefficient of determination (R2), root mean square error of calibration (RMSEC) with the value of 0.999 and 0.00864, respectively. The results of TPC in freeze dried lemon juice samples obtained by transmission FT-IR were compared with TPC observed by Folin-Ciocalteu (FC) assay and found to be comparable. Outcomes of the present study indicate that transmission FT-IR spectroscopic approach could be used as an alternative approach in place of Folin-Ciocalteu (FC) assay which is expensive and time-consuming conventional chemical methods for determination of the total phenolic content of lemon fruits. (author)

  10. The characterization of natural gemstones using non-invasive FT-IR spectroscopy: New data on tourmalines.

    Science.gov (United States)

    Mercurio, Mariano; Rossi, Manuela; Izzo, Francesco; Cappelletti, Piergiulio; Germinario, Chiara; Grifa, Celestino; Petrelli, Maurizio; Vergara, Alessandro; Langella, Alessio

    2018-02-01

    Fourteen samples of tourmaline from the Real Museo Mineralogico of Federico II University (Naples) have been characterized through multi-methodological investigations (EMPA-WDS, SEM-EDS, LA-ICP-MS, and FT-IR spectroscopy). The samples show different size, morphology and color, and are often associated with other minerals. Data on major and minor elements allowed to identify and classify tourmalines as follows: elbaites, tsilaisite, schorl, dravites, uvites and rossmanite. Non-invasive, non-destructive FT-IR and in-situ analyses were carried out on the same samples to validate this chemically-based identification and classification. The results of this research show that a complete characterization of this mineral species, usually time-consuming and expensive, can be successfully achieved through non-destructive FT-IR technique, thus representing a reliable tool for a fast classification extremely useful to plan further analytical strategies, as well as to support gemological appraisals. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Biochemical Monitoring of Spinal Cord Injury by FT-IR Spectroscopy--Effects of Therapeutic Alginate Implant in Rat Models.

    Directory of Open Access Journals (Sweden)

    Sandra Tamosaityte

    Full Text Available Spinal cord injury (SCI induces complex biochemical changes, which result in inhibition of nervous tissue regeneration abilities. In this study, Fourier-transform infrared (FT-IR spectroscopy was applied to assess the outcomes of implants made of a novel type of non-functionalized soft calcium alginate hydrogel in a rat model of spinal cord hemisection (n = 28. Using FT-IR spectroscopic imaging, we evaluated the stability of the implants and the effects on morphology and biochemistry of the injured tissue one and six months after injury. A semi-quantitative evaluation of the distribution of lipids and collagen showed that alginate significantly reduced injury-induced demyelination of the contralateral white matter and fibrotic scarring in the chronic state after SCI. The spectral information enabled to detect and localize the alginate hydrogel at the lesion site and proved its long-term persistence in vivo. These findings demonstrate a positive impact of alginate hydrogel on recovery after SCI and prove FT-IR spectroscopic imaging as alternative method to evaluate and optimize future SCI repair strategies.

  12. Examining the structural evolution of bicarbonate–water clusters: insights from photoelectron spectroscopy, basin-hopping structural search, and comparison with available IR spectral studies

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Hui [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Hou, Gao-Lei [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Liu, Yi-Rong [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Wang, Xue-Bin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Huang, Wei [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Univ. of Science and Technology of China, Hefei (China). School of Environmental Science & Optoelectronic Technology

    2016-05-31

    Bicarbonate serves a crucial biochemical role in the physiological pH buffering system and also has important atmospheric implications. In the current study, HCO3$-$(H2O)n (n = 0-13) clusters were successfully produced via electrospray ionization of corresponding bulk salt solution, and were characterized by combining negative ion photoelectron spectroscopy and theoretical calculations. The photoelectron spectra reveal that the electron binding energy monotonically increases with the cluster size up to n = 10 and remains largely the same after n > 10. The photo-detaching feature of the solute HCO3$-$itself, which dominates in the small clusters, diminishes with increase of water coverage. Based on the charge distribution and molecular orbital analyses, the universal high electron binding energy tail that dominates in the larger clusters can be attributed to ionization of water. Thus, the transition of ionization from solute to solvent at the size larger than n=10 has been observed. Extensive theoretical structural search based on the Basin-Hopping unbiased method was carried out, and a plethora of low energy isomers have been obtained for each medium and large size. By comparing the simulated photoelectron spectra and calculated electron binding energies with the experiments, as well as by comparing the simulated infrared spectra with previously reported IR spectra, the probable global minima and the structural evolutionary routes are presented. The nature of bicarbonate-water interactions are mainly electrostatic as implied by the electron localization function (ELF) analysis.

  13. Many-electron effects in photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Martin, R.L.

    1976-06-01

    The deviations from Koopmans' one-electron model of photoionization which lead to satellite structure in the photoelectron spectrum are examined within the formalism of configuration interaction (CI). The mechanisms which contribute to satellite intensity may be classified as continuum state configuration interaction, final ionic state configuration interaction, and initial state configuration interaction. The discussion centers around the last two mechanisms, these being the prime contributors to the satellite intensity well above threshold. Specific examples of theoretical ''spectra'' are presented for the F(1s) region of HF and the 1s region of neon. The agreement between theory and experiment is found to be excellent. In these two instances, initial state configuration interaction contributions increase the satellite intensity and are of nearly equal importance to the final ionic state mixing

  14. Scanning Tunneling Spectroscopy on Electron-Boson Interactions in Superconductors

    OpenAIRE

    Schackert, Michael Peter

    2014-01-01

    This thesis describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  15. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schackert, Michael Peter

    2014-07-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  16. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  17. Spectroelectrochemical study of polyphenylene by in situ external reflection FT-IR spectroscopy. Pt. 2

    International Nuclear Information System (INIS)

    Kvarnstroem, C.; Ivaska, A.

    1994-01-01

    In situ external reflection FT-IR measurements are performed during cyclic voltammetric scans on electrochemically polymerized polyphenylene films. The films are polymerized either in 0.1 or 0.8 M biphenyl in 0.1 M TBABF 4 in acetonitrile. Changes in the IR spectrum of films of different thicknesses are studied when the films are potentially cycled from the neutral to the oxidized states of the polymer. No differences between films made in high or low dimer concentration can be observed in the spectra. The potential-dependent insertion and expulsion of solvent, residual water, anions and cations in and out of the film have different behaviour in films of different thicknesses. Changes in the structure of the segments in the film, from the benzenoid form into the quinoid form, can be followed. Differences between the first and subsequent cyclic potential scans are observed. (orig.)

  18. Identification of the fragment of the 1-methylpyrene cation by mid-IR spectroscopy

    Science.gov (United States)

    Jusko, Pavol; Simon, Aude; Wenzel, Gabi; Brünken, Sandra; Schlemmer, Stephan; Joblin, Christine

    2018-04-01

    The fragment of the 1-methylpyrene cation, 17C 11H+, is expected to exist in two isomeric forms, 1-pyrenemethylium PyrCH2+ and the tropylium containing species PyrC7+. We measured the infrared (IR) action spectrum of cold 17C 11H+ tagged with Ne using a cryogenic ion trap instrument coupled to the FELIX laser. Comparison of the experimental data with density functional theory calculations allows us to identify the PyrCH2+ isomer in our experiments. The IR Multi-Photon Dissociation spectrum was also recorded following the C2H2 loss channel. Its analysis suggests combined effects of anharmonicity and isomerisation while heating the trapped ions, as shown by molecular dynamics simulations.

  19. Gamma-ray and electron spectroscopy in nuclear physics

    International Nuclear Information System (INIS)

    Ejiri, H.

    1989-01-01

    This book is devoted to the role of gamma-ray and conversion-electron (γ-e) spectroscopy in developing our understanding of nuclear structure and nuclear reaction-mechanisms. The book was written because of the spectacular development in the last decade of new γ-e spectroscopic methods, and their application to various kinds of nuclear reactions and the need to present γ-e spectroscopy from the point of view of nuclear structure as well as of reaction mechanism. The importance of γ-e spectroscopy is due to the simplicity and familiarity of the electromagnetic interaction, which gives accurate values for many nuclear quantities and reveals special nuclear properties. γ-e spectroscopy is applied to investigate static as well as dynamic nuclear properties over a wide range of excitation energies from the ground state to states of extreme temperatures and angular momentum, including some new degrees of freedom. (author)

  20. iDEEAA: A novel, versatile apparatus for electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lupulescu, C., E-mail: cosmin.lupulescu@helmholtz-berlin.de [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Arion, T. [Centre for Free-Electron Laser Science (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Hergenhahn, U. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Ovsyannikov, R. [Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Förstel, M. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Gavrila, G. [Technische Universität Chemnitz, Fakultät Elektrotechnik und Informationstechnik, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Eberhardt, W. [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Centre for Free-Electron Laser Science (DESY), Notkestrasse 85, 22607 Hamburg (Germany)

    2013-12-15

    Highlights: •We developed an experimental end station for time- and angle-resolved X-ray electron spectroscopy. •The instrument can operate in combination with synchrotron radiation, VUV Helium discharge source or table-top high-harmonic laser sources. •Band mapping in solids is possible with unprecedented rapidity. •Electron–electron coincidence spectroscopy is performed at higher data collection rate (due to improved transmission) and with improved energy resolution. -- Abstract: We report the development and present status of the iDEEAA (Instrument for Direct Electron Energy and Angular Analysis) experimental end station for time- and angle-resolved X-ray photoelectron spectroscopy. The setup is based on multidimensional detection of photoelectrons by means of both time-of-flight (TOF) and/or electrostatic analyzers. The instrument offers the possibility to record simultaneously and independently photoelectron and Auger electron spectra. Samples can be either gases or solids. The system can operate with multiple photon sources, such as laboratory-based table-top laser extreme ultraviolet (EUV) sources, monochromatic Helium discharge lamp and soft X-ray synchrotron pulses. We demonstrate the performance of the setup by carrying out electron–electron coincidence experiments on CH{sub 4} and by mapping the band structure of Bi{sub 2}Se{sub 3} using photons of the BESSY II electron storage ring.

  1. Rapid authentication and identification of different types of A. roxburghii by Tri-step FT-IR spectroscopy

    Science.gov (United States)

    Chen, Ying; Huang, Jinfang; Yeap, Zhao Qin; Zhang, Xue; Wu, Shuisheng; Ng, Chiew Hoong; Yam, Mun Fei

    2018-06-01

    Anoectochilus roxburghii (Wall.) Lindl. (Orchidaceae) is a precious traditional Chinese medicinal herb and has been perennially used to treat various illness. However, there were unethical sellers who adulterated wild A. roxburghii with tissue cultured and cultivated ones. Therefore, there is an urgent need for an effective authentication method to differentiate between these different types of A. roxburghii. In this research, the infrared spectroscopic tri-step identification approach including Fourier transform infrared spectroscopy (FT-IR), Second derivative infrared spectra (SD-IR) and two-dimensional correlation infrared spectra (2D-IR) was used to develop a simple and rapid method to discriminate between wild, cultivated and tissue cultivated A. roxburghii plant. Through this study, all three types of A. roxburghii plant were successfully identified and discriminated through the infrared spectroscopic tri-step identification method. Besides that, all the samples of wild, cultivated and tissue cultivated A. roxburghii plant were analysed with the Soft Independent Modelling of Class Analogy (SIMCA) pattern recognition technique to test and verify the experimental results. The results showed that the three types of A. roxburghii can be discriminated clearly as the recognition rate was 100% for all three types and the rejection rate was more than 60%. 70% of the validated samples were also identified correctly by the SIMCA model. The SIMCA model was also validated by comparing 70 standard herbs to the model. As a result, it was demonstrated that the macroscopic IR fingerprint method and the classification analysis could discriminate not only between the A. roxburghi samples and the standard herbs, it could also distinguish between the three different types of A. roxburghi plant in a direct, rapid and holistic manner.

  2. The study of the radiation chemical transformation of the hexane on the surface of aluminium by IR-spectroscopy method

    International Nuclear Information System (INIS)

    Rimikhanova, A.N.

    2006-01-01

    Full text: In this work the experimental results of the radiation-chemical transformation of hexane on the aluminum surface obtained by IR spectroscopy method at room temperature have been presented. The metallic aluminum plates which was obtained by stage pressing granules by mark of AD-00 with the reflection coefficient R=0,85 in the middle infrared range of waves length λ=15 ± 2,2 mkm were used. As an adsorbate unsaturated vapors of hexane were used, the absorption of which was being carried out at the room temperature by the method. The radiation of system was carried out with γ-quanta of Co 60 with doze rate of 1,03 Gy/s - 1, and the absorbed doze in the system was (0,5-2)10 4 Gy. IR reflection spectra when beams fall on the sample under angle near the slipping were measured in diapason of 3600-650 cm - 1 by the spectrophotometer S pecord 71IR . The radiation chemical decomposition of hexane in heterosystem was being traced in stretching (3000-2700 cm - 1) and deformation (1500-1300 cm - 1) vibration diapasons of C-H bonds. The analysis of IR reflection spectra of Al-ads.hexane heterosystem showed that the main products of radiation chemical transformation are hydrocarbons C1-C5, olefins: propylene, butene-1, hexene-1, transhexene-3 and hydrocarbons more heavy than hexane. In frequency range of 1700-2000 cm - 1 the absorption bands of Al-H vibration which concern to aluminum hydrides are founded. By increasing of radiation dose the tendency of increasing of hydrogen accumulation as aluminum hydrides has been established

  3. The Influence of Cholesterol on Fast Dynamics Inside of Vesicle and Planar Phospholipid Bilayers Measured with 2D IR Spectroscopy.

    Science.gov (United States)

    Kel, Oksana; Tamimi, Amr; Fayer, Michael D

    2015-07-23

    Phospholipid bilayers are frequently used as models for cell membranes. Here the influence of cholesterol on the structural dynamics in the interior of 1,2-dilauroyl-sn-glycero-3-phosphocholine (dilauroylphosphatidylcholine, DLPC) vesicles and DLPC planar bilayers are investigated as a function of cholesterol concentration. 2D IR vibrational echo spectroscopy was performed on the antisymmetric CO stretch of the vibrational probe molecule tungsten hexacarbonyl, which is located in the interior alkyl regions of the bilayers. The 2D IR experiments measure spectral diffusion, which is caused by the structural fluctuations of the bilayers. The 2D IR measurements show that the bilayer interior alkyl region dynamics occur on time scales ranging from a few picoseconds to many tens of picoseconds. These are the time scales of the bilayers' structural dynamics, which act as the dynamic solvent bath for chemical processes of membrane biomolecules. The results suggest that at least a significant fraction of the dynamics arise from density fluctuations. Samples are studied in which the cholesterol concentration is varied from 0% to 40% in both the vesicles (72 nm diameter) and fully hydrated planar bilayers in the form of aligned multibilayers. At all cholesterol concentrations, the structural dynamics are faster in the curved vesicle bilayers than in the planar bilayers. As the cholesterol concentration is increased, at a certain concentration there is a sudden change in the dynamics, that is, the dynamics abruptly slow down. However, this change occurs at a lower concentration in the vesicles (between 10% and 15% cholesterol) than in the planar bilayers (between 25% and 30% cholesterol). The sudden change in the dynamics, in addition to other IR observables, indicates a structural transition. However, the results show that the cholesterol concentration at which the transition occurs is influenced by the curvature of the bilayers.

  4. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayss, M. K.; Armentrout, P. B.; Oomens, J.; Schaefer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+,K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD spectra

  5. IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

    NARCIS (Netherlands)

    Drayß, M.K.; Armentrout, P.B.; Oomens, J.; Schäfer, M.

    2010-01-01

    Gas-phase structures of alkali metal cationized (Li+, Na+, K+, Rb+, and Cs+) proline (Pro) and N-methyl alanine have been investigated using infrared multiple photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser and computational modeling. Measured IRMPD

  6. Auger electron and X-ray spectroscopy of hollow atoms

    NARCIS (Netherlands)

    Morgenstern, R; Johnson, RL; Schmidtbocking, H; Sonntag, BF

    1997-01-01

    Hollow atoms as formed during collisions of multiply charged ions on metallic, semiconducting and insulating surfaces have in recent years successfully been investigated by various spectroscopic methods: low- and high-resolution X-ray spectroscopy as well as high resolution Auger electron

  7. Introduction to Spin Label Electron Paramagnetic Resonance Spectroscopy of Proteins

    Science.gov (United States)

    Melanson, Michelle; Sood, Abha; Torok, Fanni; Torok, Marianna

    2013-01-01

    An undergraduate laboratory exercise is described to demonstrate the biochemical applications of electron paramagnetic resonance (EPR) spectroscopy. The beta93 cysteine residue of hemoglobin is labeled by the covalent binding of 3-maleimido-proxyl (5-MSL) and 2,2,5,5-tetramethyl-1-oxyl-3-methyl methanethiosulfonate (MTSL), respectively. The excess…

  8. Electronic structure of metallic alloys through Auger and photoemission spectroscopy

    International Nuclear Information System (INIS)

    Kleiman, G.G.; Rogers, J.D.; Sundaram, V.S.

    1981-01-01

    A review is presented of experimental results of electron spectroscopy studies for various series of transition metal alloys as well as a model for their interpretation which leads to the possibility for the first time to determine independently relative variations in the dipole barrier and Fermi energy contributions to the work function. (L.C.) [pt

  9. Electron spectroscopy for atoms, molecules and condensed matter

    International Nuclear Information System (INIS)

    Siegbahn, K.

    1981-12-01

    A review is given of the research performed at the Institute of Physics, Uppsala under the direction of Prof. Siegbahn. in the field of electron spectroscopy applied to solids, liquids and gases. The developemnt of the spectroscopic methods is the central theme of the review. (L.E.)

  10. Application of Fourier-transform infrared (FT-IR) spectroscopy for simple and easy determination of chylomicron-triglyceride and very low density lipoprotein-triglyceride.

    Science.gov (United States)

    Sato, Kenichi; Seimiya, Masanori; Kodera, Yoshio; Kitamura, Akihide; Nomura, Fumio

    2010-02-01

    Fourier-transform infrared (FT-IR) spectroscopy is a simple and reagent-free physicochemical analysis method, and is a potential alternative to more time-consuming and labor-intensive procedures. In this study, we aimed to use FT-IR spectroscopy to determine serum concentrations of chylomicron-triglyceride (TG) and very low density lipoprotein (VLDL)-TG. We analyzed a chylomicron fraction and VLDL fraction, which had been obtained by ultracentrifugation, to search for wavelengths to designate to each fraction. Then, partial least square (PLS) calibrations were developed using a training set of samples, for which TG concentrations had been determined by conventional procedures. Validation was conducted with another set of samples using the PLS model to predict serum TG concentrations on the basis of the samples' IR spectra. We analyzed a total of 150 samples. Serum concentrations of chylomicron-TG and VLDL-TG estimated by FT-IR spectroscopy agreed well with those obtained by the reference method (r=0.97 for both lipoprotein fractions). FT-IR spectrometric analysis required 15mul of serum and was completed within 1min. Serum chylomicron-TG and VLDL-TG concentrations can be determined with FT-IR spectroscopy. This rapid and simple test may have a great impact on the management of patients with dyslipidemia. Copyright 2009. Published by Elsevier B.V.

  11. Relaxation and excitation electronic processes in dielectrics irradiated by ultrafast IR and VUV pulses

    International Nuclear Information System (INIS)

    Gaudin, J.

    2005-11-01

    We studied excitation and relaxation of electrons involved during interaction of visible and VUV femtosecond pulses with dielectrics. The generated population of hot electrons, having energy of few eV to few tens of eV above the bottom of the conduction band, is responsible of phenomena ranging to defect creation to optical breakdown. Owing to two techniques: photoemission and transient photoconductivity we improve the understanding of the The first photoemission experiments deal with dielectrics irradiated by 30 fs IR pulses. The photoemission spectra measured show a large population of electrons which energy rise up to 40 eV. We interpret this result in terms of a new absorption process: direct multi-photons inter-branch transitions. The 2. type of photoemission experiments are time resolved 'pump/probe' investigation. We study the relaxation of electrons excited by a VUV pulses. We used the high order harmonics (HOH) as light sources. We found surprisingly long decay time in the range of ps timescale. Last type of experiments is photoconductivity studies of diamond samples. Using HOH as light source we measure the displacement current induced by excited electrons in the conduction band. Those electrons relax mainly by impact ionisation creating secondary electrons. Hence by probing the number of electrons we were able to measure the efficiency of these relaxation processes. We observe a diminution of this efficiency when the energy of exciting photons is above 20 eV. Owing to Monte-Carlo simulation we interpret this result in terms of band structure effect. (author)

  12. Secondary electron spectroscopy and Auger microscopy at high spatial resolution. Application to scanning electron microscopy

    International Nuclear Information System (INIS)

    Le Gressus, Claude; Massignon, Daniel; Sopizet, Rene

    1979-01-01

    Secondary electron spectroscopy (SES), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS) are combined with ultra high vacuum scanning microscopy (SEM) for surface analysis at high spatial resolution. Reliability tests for the optical column for the vacuum and for the spectrometer are discussed. Furthermore the sensitivity threshold in AES which is compatible with a non destructive surface analysis at high spatial resolution is evaluated. This combination of all spectroscopies is used in the study of the beam damage correlated with the well known secondary electron image (SEI) darkening still observed in ultra high vacuum. The darkening is explained as a bulk decontamination of the sample rather than as a surface contamination from the residual vacuum gas [fr

  13. Spectroscopic techniques in the study of human tissues and their components. Part I: IR spectroscopy.

    Science.gov (United States)

    Olsztyńska-Janus, Sylwia; Szymborska-Małek, Katarzyna; Gąsior-Głogowska, Marlena; Walski, Tomasz; Komorowska, Małgorzata; Witkiewicz, Wojciech; Pezowicz, Celina; Kobielarz, Magdalena; Szotek, Sylwia

    2012-01-01

    Among the currently used methods of monitoring human tissues and their components many types of research are distinguished. These include spectroscopic techniques. The advantage of these techniques is the small amount of sample required, the rapid process of recording the spectra, and most importantly in the case of biological samples - preparation of tissues is not required. In this work, vibrational spectroscopy: ATR-FTIR and Raman spectroscopy will be used. Studies are carried out on tissues: tendons, blood vessels, skin, red blood cells and biological components: amino acids, proteins, DNA, plasma, and deposits.

  14. Electron momentum spectroscopy of the core state of solid carbon

    International Nuclear Information System (INIS)

    Caprari, R.S.; Clark, S.A.C.; McCarthy, I.E.; Storer, P.J.; Vos, M.; Weigold, E.

    1994-08-01

    Electron momentum spectroscopy (binary encounter (e,2e)) experimental results are presented for the core state of an amorphous carbon allotrope. The (e,2e) cross section has two identifiable regions. One is a narrow energy width 'core band peak' that does not disperse with momentum. At higher binding energies there is an energy diffuse 'multiple scattering continuum', which is a consequence of (e,2e) collisions with core electrons that are accompanied by inelastic scattering of one or more of the incoming or outgoing electrons. Comparisons of experimental momentum distributions with the Hartree-Fock atomic carbon ls orbital are presented for both regions. 16 refs., 4 figs

  15. Electron correlation effects in XUV photoabsorption spectroscopy of atoms

    International Nuclear Information System (INIS)

    Codling, K.

    1976-01-01

    Reference is made to sophisticated experiments involving the measurement of the angular distribution of photo-ejected electrons, coincidence electrons and ion spectroscopy, which can only be interpreted in terms of electron correlation effects. After an introductory review of previous work, the lectures fall under the following headings: experimental procedures (light sources, monochromators, absorption cells, limitations on the simple photoasbsorption experiment, and complementary techniques); experimental results (discrete states in the continuum, gross features in the photoionisation continuum (rare gases, alkalis, alkaline earths, rare earths, transition elements)). (U.K.)

  16. Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.

    2013-12-26

    Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.

  17. Monitoring of alcoholic fermentation using near infrared and mid infrared spectroscopies combined with electronic nose and electronic tongue

    International Nuclear Information System (INIS)

    Buratti, S.; Ballabio, D.; Giovanelli, G.; Dominguez, C.M. Zuluanga; Moles, A.; Benedetti, S.; Sinelli, N.

    2011-01-01

    Graphical abstract: Application of non destructive methods for the monitoring of red wine fermentation in correlation with the evolution of chemical parameters. Highlights: → We monitored time-related changes in red wine fermentation process. → NIR and MIR spectroscopies, electronic nose and tongue were applied. → Data were kinetically modelled to identify critical points during fermentation. → NIR, MIR electronic nose and tongue were able to follow the fermentation process. → The models agreed with the evolution of chemical parameters. - Abstract: Effective fermentation monitoring is a growing need due to the rapid pace of change in the wine industry, which calls for fast methods providing real time information in order to assure the quality of the final product. The objective of this work is to investigate the potential of non-destructive techniques associated with chemometric data analysis, to monitor time-related changes that occur during red wine fermentation. Eight micro-fermentation trials conducted in the Valtellina region (Northern Italy) during the 2009 vintage, were monitored by a FT-NIR and a FT-IR spectrometer and by an electronic nose and tongue. The spectroscopic technique was used to investigate molecular changes, while electronic nose and electronic tongue evaluated the evolution of the aroma and taste profile during the must-wine fermentation. Must-wine samples were also analysed by traditional chemical methods in order to determine sugars (glucose and fructose) consumption and alcohol (ethanol and glycerol) production. Principal Component Analysis was applied to spectral, electronic nose and electronic tongue data, as an exploratory tool, to uncover molecular, aroma and taste modifications during the fermentation process. Furthermore, the chemical data and the PC1 scores from spectral, electronic nose and electronic tongue data were modelled as a function of time to identify critical points during fermentation. The results showed that

  18. Monitoring of alcoholic fermentation using near infrared and mid infrared spectroscopies combined with electronic nose and electronic tongue

    Energy Technology Data Exchange (ETDEWEB)

    Buratti, S., E-mail: susanna.buratti@unimi.it [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy); Ballabio, D. [Department of Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Giovanelli, G. [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy); Dominguez, C.M. Zuluanga [Instituto de Ciencia y Tecnologia de Alimentos, Universidad Nacional de Colombia, Ciudad Universitaria, Bogota (Colombia); Moles, A.; Benedetti, S.; Sinelli, N. [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy)

    2011-07-04

    Graphical abstract: Application of non destructive methods for the monitoring of red wine fermentation in correlation with the evolution of chemical parameters. Highlights: > We monitored time-related changes in red wine fermentation process. > NIR and MIR spectroscopies, electronic nose and tongue were applied. > Data were kinetically modelled to identify critical points during fermentation. > NIR, MIR electronic nose and tongue were able to follow the fermentation process. > The models agreed with the evolution of chemical parameters. - Abstract: Effective fermentation monitoring is a growing need due to the rapid pace of change in the wine industry, which calls for fast methods providing real time information in order to assure the quality of the final product. The objective of this work is to investigate the potential of non-destructive techniques associated with chemometric data analysis, to monitor time-related changes that occur during red wine fermentation. Eight micro-fermentation trials conducted in the Valtellina region (Northern Italy) during the 2009 vintage, were monitored by a FT-NIR and a FT-IR spectrometer and by an electronic nose and tongue. The spectroscopic technique was used to investigate molecular changes, while electronic nose and electronic tongue evaluated the evolution of the aroma and taste profile during the must-wine fermentation. Must-wine samples were also analysed by traditional chemical methods in order to determine sugars (glucose and fructose) consumption and alcohol (ethanol and glycerol) production. Principal Component Analysis was applied to spectral, electronic nose and electronic tongue data, as an exploratory tool, to uncover molecular, aroma and taste modifications during the fermentation process. Furthermore, the chemical data and the PC1 scores from spectral, electronic nose and electronic tongue data were modelled as a function of time to identify critical points during fermentation. The results showed that NIR and MIR

  19. IR reflectance spectroscopy of carbon dioxide clathrate hydrates. Implications for Saturn's icy moons.

    Science.gov (United States)

    Oancea, A.; Grasset, O.; Le Menn, E.; Bezacier, L.; Bollengier, O.; Le Mouélic, S.; Tobie, G.

    2012-04-01

    A CO2 spectral band was discovered by VIMS on the Saturn's satellites Dione, Hyperion, Iapetus and Phoebe [1]. The band position on the three first satellites corresponds to CO2 trapped in a complex material, but no indication exists whether this latter is water ice or some mineral or complex organic compound [1]. On Phoebe, the CO2 spectral band is consistent with solid CO2 or CO2 molecules trapped in the small cages of a clathrate hydrate structure [2]. It is thought that clathrate hydrates could play a significant role in the chemistry of the solar nebula [3] and in the physical evolution of astrophysical objects [4]. But so far, no clathrate hydrate structure has been observed in astrophysical environments. Moreover, identification of molecules trapped in a clathrate hydrate structure is extremely difficult because of the strong IR vibration modes of the water ice matrix. In this work, experimental IR reflectance spectra for CO2 clathrate hydrates are studied on grains and films. Clathrates are synthesized in a high pressure autoclave at low temperatures. IR spectral analysis is made with a low pressure and low temperature cryostat. These experimental conditions - 80 spectrum will be presented. A comparison between the absorption bands of CO2 clathrate hydrates obtained in our lab and CO2 absorption bands as detected by VIMS on the icy satellites of Saturn will be shown. This experimental work confirms that VIMS data are not consistent with the presence of structure I CO2 clathrate hydrates on the surface of the icy moons. Possibility of having metastable structure II still remains unsolved and will be discussed. [1] Dalton et al., Space Sci. Rev. 2010, 153 : 113-154. [2] Cruikshank D.P. et al, Icarus, 2010, 206: 561-572. [3] Mousis O. et al , Ap. J. 2009, 691: 1780-1786. [4] Choukroun M. et al, in Solar System Ices, edited by Castillo-Rogez, J. et al., 2011.

  20. Characterization of proton in Y-doped SrZrO3 polycrystal by IR spectroscopy

    International Nuclear Information System (INIS)

    Hibino, T.; Mizutani, K.; Yajima, T.; Iwahara, H.

    1992-01-01

    To characterize proton in Y-doped SrZrO 3 polycrystal, protonic conductivities and infrared spectra were measured. IR spectra exhibited 2 OH bands in 3500-2800 and 2650-2300 cm -1 regions, indicating that proton was bound to lattice oxide ion and that its strength of bonding was rather weak. The decrease in conductivity by replacing H + with D + suggested that the conducting ion was not hydroxide but proton and that it migrated via the dissociation of O-H bond. (author). 15 refs., 5 figs

  1. A Controlled-Environment Chamber for Atmospheric Chemistry Studies Using FT-IR Spectroscopy

    Science.gov (United States)

    1990-06-01

    necessary and identify by block number) FELD GROUP SUB-GROUP i >Chamber, controlled environment; long-path cell ; 07 04 FT-IR; Hydrazine decay...modification doubles the useable path length of the original multipass cell described by White (Reference 8). The pattern of images formed on the nesting...system is shown in Figure 13. 24 z C C02, Ibm, El4 944 C3 ta) caC E-4- 252 14 $4 41) 41) 0. 0 04 04 4 41) ~0 to 0.0 V-4 (A q14 0~ 1% 4-r4 $4 0 u P416 4 4

  2. Identification of herbarium whole-leaf samples of Epilobium species by ATR-IR spectroscopy.

    Science.gov (United States)

    Strgulc Krajsek, Simona; Buh, Primoz; Zega, Anamarija; Kreft, Samo

    2008-02-01

    A simple, high-accuracy FT-IR method based on attenuated total reflection (ATR) was developed for the rapid determination of leaf samples of Epilobium species. The method is superior to other analytical techniques, since there is no need of laborious sample preparation such as grinding or extraction and solvent removal. A total of 70 herbarium specimens, belonging to all 13 Epilobium and to 2 Chamerion species growing in Slovenia, were analyzed. With the 100 most-informative wavenumbers in the range 700-1800 cm(-1), we obtained over 90% accuracy of species identification, with discriminant multivariate statistical analysis on the measurements made on whole dried leaves.

  3. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  4. Electronic structure and magnetic properties of Dy adatom on Ir surface

    Science.gov (United States)

    Shick, A. B.; Lichtenstein, A. I.

    2018-05-01

    The electronic structure and magnetism of individual Dy atom adsorbed on the (1 1 1) surface of Ir is investigated using the combination of the density functional theory with the Hubbard-I approximation to the Anderson impurity model (DFT + HIA). The Dy3+ adatom is found magnetic with the magnetic moment of 9.35μB in the external magnetic field. The spin and orbital magnetic moments, and their ratio are evaluated, and compared with the X-ray magnetic circular dichroism data. The positive magnetic anisotropy energy of ≈ 1.3 meV determines the out-of-plane orientation of the Dy adatom magnetic moment. The role of 5d-4f interorbital exchange polarization in modification of the 4f shell energy spectrum is emphasized. We predict the Dy magnetization to drop by the factor of three with switching off the external magnetic field.

  5. Chemical Sensors Based on IR Spectroscopy and Surface-Modified Waveguides

    Science.gov (United States)

    Lopez, Gabriel P.; Niemczyk, Thomas

    1999-01-01

    Sol-gel processing techniques have been used to apply thin porous films to the surfaces of planar infrared (IR) waveguides to produce widely useful chemical sensors. The thin- film coating serves to diminish the concentration of water and increase the concentration of the analyte in the region probed by the evanescent IR wave. These porous films are composed of silica, and therefore, conventional silica surface modification techniques can be used to give the surface a specific functional character. The sol-gel film was surface-modified to make the film highly hydrophobic. These sensors were shown to be capable of detecting non-polar organic analytes, such as benzonitrile, in aqueous solution with detection limits in the ppb range. Further, these porous sol-gel structures allow the analytes to diffuse into and out of the films rapidly, thus reaching equilibrium in less than ten seconds. These sensors are unique because of the fact that their operation is based on the measurement of an IR absorption spectrum. Thus, these sensors are able to identify the analytes as well as measure concentration with high sensitivity. These developments have been documented in previous reports and publications. Recently, we have also targeted detection of the polar organic molecules acetone and isopropanol in aqueous solution. Polar organics are widely used in industrial and chemical processes, hence it is of interest to monitor their presence in effluents or decontamination process flows. Although large improvements in detection limits were expected with non-polar organic molecules in aqueous solutions using very hydrophobic porous sol-gel films on silicon attenuated total reflectance (Si ATR) waveguides, it was not as clear what the detection enhancements might be for polar organic molecules. This report describes the use of modified sol-gel-coated Si ATR sensors for trace detection and quantitation of small polar organic molecules in aqueous solutions. The detection of both acetone

  6. Study of the processes of carbonization and oxidation of porous silicon by Raman and IR spectroscopy

    International Nuclear Information System (INIS)

    Vasin, A. V.; Okholin, P. N.; Verovsky, I. N.; Nazarov, A. N.; Lysenko, V. S.; Kholostov, K. I.; Bondarenko, V. P.; Ishikawa, Y.

    2011-01-01

    Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 Ω cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550°C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.

  7. The use of XPS and i.r. spectroscopy in zinc mineral flotation studies

    International Nuclear Information System (INIS)

    Garbassi, F.; Morabini, A.; Cozza, C.

    1985-01-01

    In this work, XPS (X-ray photoelectron spectroscopy) is applied to the study of the interaction of dodecylamine acetate with smithsonite ZnCo 3 , in relation with the problem of flotation of the mineral. This study confirms that, in spite of ultra-high conditions during analysis XPS is a technique offering a very valuable contribution to the elucidation of mineral flotation problems

  8. IR and Raman spectroscopy of sodium aluminophosphate vitreous materials for immobilization of high level wastes from nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    Stefanovskij, S.V.; Myasoedov, B.F.; Remizov, M.B.; Belanova, E.A.

    2014-01-01

    The structure of sodium aluminophosphate vitreous materials containing constituents of high level wastes (cesium, magnesium, copper and molybdenum oxides) from uranium-graphite reactor has been studied by IR and Raman spectroscopy techniques coupled with X-ray diffraction. The structural network has been shown to be composed of short phosphorus-oxygen chains with embedded aluminum-oxygen tetrahedra. In the magnesium-bearing samples the cross-linking with Mg 2+ ions is possible. The effect of other oxides (Cs 2 O, MoO 3 , CuO) on the glass structure is negligible for the occuring amounts. The glasses have been devitrified partly at the quenching and much stronger at the annealing. It is reflected in splitting of the vibration bands of the bonds in structural units of the anionic motif of the vitreous materials. (authors)

  9. Impact of Humidity on Quartz-Enhanced Photoacoustic Spectroscopy Based CO Detection Using a Near-IR Telecommunication Diode Laser

    Directory of Open Access Journals (Sweden)

    Xukun Yin

    2016-01-01

    Full Text Available A near-IR CO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS is evaluated using humidified nitrogen samples. Relaxation processes in the CO-N2-H2O system are investigated. A simple kinetic model is used to predict the sensor performance at different gas pressures. The results show that CO has a ~3 and ~5 times slower relaxation time constant than CH4 and HCN, respectively, under dry conditions. However, with the presence of water, its relaxation time constant can be improved by three orders of magnitude. The experimentally determined normalized detection sensitivity for CO in humid gas is 1.556 × 10 − 8   W ⋅ cm − 1 / Hz 1 / 2 .

  10. Investigation of hydrogen adsorption centers on Y2O3 by IR-spectroscopy method in diffusive-scattered light

    International Nuclear Information System (INIS)

    Zubkov, S.A.; Borovkov, V.Yu.

    1985-01-01

    Adsorption of hydrogen and carbon oxide at the yttrium oxide at 80 K (5x30 3 PaH 2 ) and 300 K (6.5x10 2 PaCO) respectively are studied by the method of IR spectroscopy. It is shown, that at the surface of yttrium oxide trained in vacuum at 970 K, at least four types of centres of hydrogen adsorption, able to polarize H-H bond in a molecule, exist. Acid-base couple is the highest polarized centre, in the content of which there is a coordination-unsaturated highly-charged yttrium cation. Low-temperature dissociation of hydrogen on Y 2 O 3 surface occurs on the centres which polarized H-H bond in molecule comparatively slow

  11. Studies of Eu2O3 - Bi2O3 - B2O3 glasses using Raman and IR spectroscopy

    International Nuclear Information System (INIS)

    Pop, Lidia; Culea, Eugen N.; Bratu, I.

    2004-01-01

    The bismuth borate (3Bi 2 O 3 ·B 2 O 3 ) glasses were prepared with different concentrations of Eu 3+ . The structure of these systems were investigated by Raman and IR spectroscopy. The structural study reveals that the glasses contain BiO 3 , BiO 6 , BO 3 , BO 4 and Eu-O structural units. For the samples with a higher content of Eu 2 O 3 , the spectra became very large indicating a more disordered structure. The hygroscopic character of the 3Bi 2 O 3 ·B 2 O 3 glass matrix and the progressive decrease of this behaviour with increasing the Eu 2 O 3 content was observed. Therefore, we conclude that the europium oxide acts as a network modifier in these glasses. (authors)

  12. Beam Transport Devices for the 10 kW IR Free Electron Laser

    International Nuclear Information System (INIS)

    Lawrence Dillon-Townes; Michael Bevins; David Kashy; Stephanie Slachtouski; Ronald Lassiter; George Neil; Michelle Shinn; Joseph Gubeli; Christopher Behre; David Douglas; David W. Waldman; George Biallas; Lawrence Munk; Christopher Gould

    2005-01-01

    Beam transport components for the 10kW IR Free Electron Laser (FEL) at Thomas Jefferson National Accelerator Facility (Jefferson Lab) were designed to manage (1) electron beam transport and (2) photon beam transport. An overview of the components will be presented in this paper. The electron beam transport components were designed to address RF heating, maintain an accelerator transport vacuum of 1 x 10 -8 torr, deliver photons to the optical cavity, and provide 50 kW of beam absorption during the energy recovery process. The components presented include a novel shielded bellows, a novel zero length beam clipper, a one decade differential pumping station with a 7.62 cm (3.0 inch) aperture, and a 50 kW beam dump. The photon beam transport components were designed to address the management of photons delivered by the accelerator transport. The optical cavity manages the photons and optical transport delivers the 10 kW of laser power to experimental labs. The optical cavity component presented is a unique high reflector vessel and the optical transport component presented is a turning mirror cassette

  13. Structure and Absolute Configuration of Ginkgolide B Characterized by IR- and VCD Spectroscopy

    DEFF Research Database (Denmark)

    Andersen, Niels Højmark; Christensen, N.J.; Lassen, Peter Rygaard

    2010-01-01

    Experimental and calculated (B3LYP/6-31G(d)) vibrational Circular dichroism (VCD) and IR spectra are compared, illustrating that the structure and absolute configuration of ginkgolide B (GB) may be characterized directly in solution. A conformational search for GB using MacroModel and subsequent...... DFT optimizations (B3LYP/6-31G(d)) provides a structure for the lowest energy conformer which agrees well with the structure determined by X-ray diffraction. In addition, a conformer at all energy of 7 kJ mol(-1) (B3LYP/6-311+G(2d,2p)) with respect to the lowest energy conformer is predicted...

  14. Solute-solvent complex switching dynamics of chloroform between acetone and dimethylsulfoxide-two-dimensional IR chemical exchange spectroscopy.

    Science.gov (United States)

    Kwak, Kyungwon; Rosenfeld, Daniel E; Chung, Jean K; Fayer, Michael D

    2008-11-06

    Hydrogen bonds formed between C-H and various hydrogen bond acceptors play important roles in the structure of proteins and organic crystals, and the mechanisms of C-H bond cleavage reactions. Chloroform, a C-H hydrogen bond donor, can form weak hydrogen-bonded complexes with acetone and with dimethylsulfoxide (DMSO). When chloroform is dissolved in a mixed solvent consisting of acetone and DMSO, both types of hydrogen-bonded complexes exist. The two complexes, chloroform-acetone and chloroform-DMSO, are in equilibrium, and they rapidly interconvert by chloroform exchanging hydrogen bond acceptors. This fast hydrogen bond acceptor substitution reaction is probed using ultrafast two-dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy. Deuterated chloroform is used in the experiments, and the 2D-IR spectrum of the C-D stretching mode is measured. The chemical exchange of the chloroform hydrogen bonding partners is tracked by observing the time-dependent growth of off-diagonal peaks in the 2D-IR spectra. The measured substitution rate is 1/30 ps for an acetone molecule to replace a DMSO molecule in a chloroform-DMSO complex and 1/45 ps for a DMSO molecule to replace an acetone molecule in a chloroform-acetone complex. Free chloroform exists in the mixed solvent, and it acts as a reactive intermediate in the substitution reaction, analogous to a SN1 type reaction. From the measured rates and the equilibrium concentrations of acetone and DMSO, the dissociation rates for the chloroform-DMSO and chloroform-acetone complexes are found to be 1/24 ps and 1/5.5 ps, respectively. The difference between the measured rate for the complete substitution reaction and the rate for complex dissociation corresponds to the diffusion limited rate. The estimated diffusion limited rate agrees well with the result from a Smoluchowski treatment of diffusive reactions.

  15. Rapid Quantitative Determination of Squalene in Shark Liver Oils by Raman and IR Spectroscopy.

    Science.gov (United States)

    Hall, David W; Marshall, Susan N; Gordon, Keith C; Killeen, Daniel P

    2016-01-01

    Squalene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species-dependent. Presented here is a validated gas chromatography-mass spectrometry analysis method for the quantitation of squalene in shark liver oils, with an accuracy of 99.0 %, precision of 0.23 % (standard deviation), and linearity of >0.999. The method has been used to measure the squalene concentration of 16 commercial shark liver oils. These reference squalene concentrations were related to infrared (IR) and Raman spectra of the same oils using partial least squares regression. The resultant models were suitable for the rapid quantitation of squalene in shark liver oils, with cross-validation r (2) values of >0.98 and root mean square errors of validation of ≤4.3 % w/w. Independent test set validation of these models found mean absolute deviations of the 4.9 and 1.0 % w/w for the IR and Raman models, respectively. Both techniques were more accurate than results obtained by an industrial refractive index analysis method, which is used for rapid, cheap quantitation of squalene in shark liver oils. In particular, the Raman partial least squares regression was suited to quantitative squalene analysis. The intense and highly characteristic Raman bands of squalene made quantitative analysis possible irrespective of the lipid matrix.

  16. Laser desorption single-conformation UV and IR spectroscopy of the sulfonamide drug sulfanilamide, the sulfanilamide-water complex, and the sulfanilamide dimer.

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W

    2017-06-07

    We have studied the conformational preferences of the sulfonamide drug sulfanilamide, its dimer, and its monohydrated complex through laser desorption single-conformation UV and IR spectroscopy in a molecular beam. Based on potential energy curves for the inversion of the anilinic and the sulfonamide NH 2 groups calculated at DFT level, we suggest that the zero-point level wave function of the sulfanilamide monomer is appreciably delocalized over all four conformer wells. The sulfanilamide dimer, and the monohydrated complex each exhibit a single isomer in the molecular beam. The isomeric structures of the sulfanilamide dimer and the monohydrated sulfanilamide complex were assigned based on their conformer-specific IR spectra in the NH and OH stretch region. Quantum Theory of Atoms in Molecules (QTAIM) analysis of the calculated electron density in the water complex suggests that the water molecule is bound side-on in a hydrogen bonding pocket, donating one O-HO[double bond, length as m-dash]S hydrogen bond and accepting two hydrogen bonds, a NHO and a CHO hydrogen bond. QTAIM analysis of the dimer electron density suggests that the C i symmetry dimer structure exhibits two dominating N-HO[double bond, length as m-dash]S hydrogen bonds, and three weaker types of interactions: two CHO bonds, two CHN bonds, and a chalcogen OO interaction. Most interestingly, the molecular beam dimer structure closely resembles the R dimer unit - the dimer unit with the greatest interaction energy - of the α, γ, and δ crystal polymorphs. Interacting Quantum Atoms analysis provides evidence that the total intermolecular interaction in the dimer is dominated by the short-range exchange-correlation contribution.

  17. Infrared Spectroscopy of Gas-Phase M+(CO2)n (M = Co, Rh, Ir) Ion-Molecule Complexes.

    Science.gov (United States)

    Iskra, Andreas; Gentleman, Alexander S; Kartouzian, Aras; Kent, Michael J; Sharp, Alastair P; Mackenzie, Stuart R

    2017-01-12

    The structures of gas-phase M + (CO 2 ) n (M = Co, Rh, Ir; n = 2-15) ion-molecule complexes have been investigated using a combination of infrared resonance-enhanced photodissociation (IR-REPD) spectroscopy and density functional theory. The results provide insight into fundamental metal ion-CO 2 interactions, highlighting the trends with increasing ligand number and with different group 9 ions. Spectra have been recorded in the region of the CO 2 asymmetric stretch around 2350 cm -1 using the inert messenger technique and their interpretation has been aided by comparison with simulated infrared spectra of calculated low-energy isomeric structures. All vibrational bands in the smaller complexes are blue-shifted relative to the asymmetric stretch in free CO 2 , consistent with direct binding to the metal center dominated by charge-quadrupole interactions. For all three metal ions, a core [M + (CO 2 ) 2 ] structure is identified to which subsequent ligands are less strongly bound. No evidence is observed in this size regime for complete activation or insertion reactions.

  18. Sensing the Structural Differences in Cellulose from Apple and Bacterial Cell Wall Materials by Raman and FT-IR Spectroscopy

    Science.gov (United States)

    Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur

    2011-01-01

    Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913

  19. Optical Determination of Lead Chrome Green in Green Tea by Fourier Transform Infrared (FT-IR Transmission Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Xiaoli Li

    Full Text Available The potential of Fourier transform infrared (FT-IR transmission spectroscopy for determination of lead chrome green in green tea was investigated based on chemometric methods. Firstly, the qualitative analysis of lead chrome green in tea was performed based on partial least squares discriminant analysis (PLS-DA, and the correct rate of classification was 100%. And then, a hybrid method of interval partial least squares (iPLS regression and successive projections algorithm (SPA was proposed to select characteristic wavenumbers for the quantitative analysis of lead chrome green in green tea, and 19 wavenumbers were obtained finally. Among these wavenumbers, 1384 (C = C, 1456, 1438, 1419(C = N, and 1506 (CNH cm-1 were the characteristic wavenumbers of lead chrome green. Then, these 19 wavenumbers were used to build determination models. The best model was achieved by least squares support vector machine (LS-SVMalgorithm with high coefficient of determination and low root-mean square error of prediction set (R2p = 0.864 and RMSEP = 0.291. All these results indicated the feasibility of IR spectra for detecting lead chrome green in green tea.

  20. Development of C-lignin with G/S-lignin and lipids in orchid seed coats – an unexpected diversity exposed by ATR-FT-IR spectroscopy

    DEFF Research Database (Denmark)

    Barsberg, Søren Talbro; Lee, Y.-I.; Rasmussen, Hanne Nina

    2018-01-01

    Cite this article: Barsberg ST, Lee Y-I, Rasmussen HN. Development of C-lignin with G/S-lignin and lipids in orchid seed coats – an unexpected diversity exposed by ATR-FT-IR spectroscopy. Seed Science Research https:// doi.org/10.1017/S0960258517000344......Cite this article: Barsberg ST, Lee Y-I, Rasmussen HN. Development of C-lignin with G/S-lignin and lipids in orchid seed coats – an unexpected diversity exposed by ATR-FT-IR spectroscopy. Seed Science Research https:// doi.org/10.1017/S0960258517000344...

  1. Verification of Ganoderma (lingzhi) commercial products by Fourier Transform infrared spectroscopy and two-dimensional IR correlation spectroscopy

    Science.gov (United States)

    Choong, Yew-Keong; Sun, Su-Qin; Zhou, Qun; Lan, Jin; Lee, Han-Lim; Chen, Xiang-Dong

    2014-07-01

    Ganoderma commercial products are typically based on two sources, raw material (powder form and/or spores) and extract (water and/or solvent). This study compared three types of Ganoderma commercial products using 1 Dimensional Fourier Transform infrared and second derivative spectroscopy. The analyzed spectra of Ganoderma raw material products were compared with spectra of cultivated Ganoderma raw material powder from different mushroom farms in Malaysia. The Ganoderma extract product was also compared with three types of cultivated Ganoderma extracts. Other medicinal Ganoderma contents in commercial extract product that included glucan and triterpenoid were analyzed by using FTIR and 2DIR. The results showed that water extract of cultivated Ganoderma possessed comparable spectra with that of Ganoderma product water extract. By comparing the content of Ganoderma commercial products using FTIR and 2DIR, product content profiles could be detected. In addition, the geographical origin of the Ganoderma products could be verified by comparing their spectra with Ganoderma products from known areas. This study demonstrated the possibility of developing verification tool to validate the purity of commercial medicinal herbal and mushroom products.

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

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng, E-mail: dssu@imr.ac.cn [Shenyang National Laboratory of Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016 (China)

    2015-12-07

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

  3. Auger electron spectroscopy for the advanced student laboratory

    International Nuclear Information System (INIS)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa

    2009-01-01

    This paper presents Auger electron spectroscopy with a retarding field analyser designed for an advanced physics experiment carried out in 'Physics Laboratory II' at the Institute of Experimental Physics, University of Wroclaw, Poland. The authors discuss the process of setting up the experiment and the results of the measurement of Auger spectra. The advantages and disadvantages of the apparatus are discussed along with its implementation in the teaching process

  4. Allenylidene Complexes of Ruthenium: Synthesis, Spectroscopy and Electron Transfer Properties

    Czech Academy of Sciences Publication Activity Database

    Winter, R. F.; Záliš, Stanislav

    2004-01-01

    Roč. 248, 15/16 (2004), s. 1565-1583 ISSN 0010-8545 R&D Projects: GA ČR GA203/03/0821; GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : spectroscopy * allenylidine complexes of ruthenium * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.446, year: 2004

  5. Study of solute segregation at interfaces using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    White, C.L.

    1984-01-01

    Interfacial segregation, often confined to within a few atomic distances of the interface, can strongly influence the processing and properties of metals and ceramics. The thinness of such solute-enriched regions can cause them to be particularly suitable for study using surface sensitive microanalytical techniques such as Auger electron spectroscopy (AES). The application of AES to studies of interfacial segregation in metals and ceramics is briefly reviewed, and several examples are presented. 43 references, 14 figures

  6. IR-spectroscopy as an analytical method for identification of horticultural peat

    International Nuclear Information System (INIS)

    Lehtovaara, J.; Herranen, M.; Nyroenen, T.; MacDonald, A.

    1988-01-01

    The process of selecting different peat types for horticultural purposes involves many physical and chemical determinations. Infrared spectroscopy could be used together with the usual methods for the evaluation of peat quality. Due to the fact that different peats contain different amounts of infrared absorbing functional groups, each peat produces a characteristic spectrum. From the spectrum, one may determine the botanical composition, degree of humification, ash content, cation exchange capacity, nitrogen content and carbon content, of the natural peat. The spectrum also shows whether the peat has been fertilized and limed and in some cases the presence of mineral soil or wetting agent mixed in the peat may be detected

  7. Investigation of Sm(3) and Eu(3) coordination compounds with pyrazolones by IR spectroscopy method

    International Nuclear Information System (INIS)

    Panyushkin, V.T.; Grishenko, T.V.; Afanas'ev, Yu.A.; Garnovskij, A.D.; Osipov, O.A.

    1978-01-01

    The synthesis is described of the coordination nitrate compounds of Sm(3) and Eu(3) with pyrazolones: 4-aminoantipyrine (A), 1-ethylpyridyl- 3-phenyl-pyrazolone-5(B); 1-(3'-ethylpyridyl)-3(phenylamine-n)-pyrazolone-5(C). It has been determined by the infrared spectroscopy method that exocyclic oxygen atom is the place of coordination bond localization in the pentioned compounds. The infrared spectra analysis of complexes in the 1700-1800 cm -1 region makes it possible to mention bidentate character of NO 3 -groups in the studied complex compounds

  8. Investigation of thermochemical conversions of coal pitches using high resolution PMR and IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kekin, N.A.; Belkina, T.V.; Stepanenko, M.A.; Gordienko, V.G.

    1982-01-01

    The hydrogen bonds in organic compounds present in coal pitch and fractions were investigated by infrared spectroscopy and proton magnetic resonance. The investigation was extended to include pitch that was thermally treated at 360 degrees C to raise the softening point to 85-90 degrees C. The infrared spectra revealed hydrogen present in OH groups, NH groups, COOH groups, unsaturated carbon double bonds, and multiple carbon double bonds. It was also determined that thermal treating increased the hydrogen present in aromatic compounds and decreased hydrogen present in aliphatic forms. (JMT)

  9. Electron energy loss spectroscopy of gold nanoparticles on graphene

    International Nuclear Information System (INIS)

    DeJarnette, Drew; Roper, D. Keith

    2014-01-01

    Plasmon excitation decay by absorption, scattering, and hot electron transfer has been distinguished from effects induced by incident photons for gold nanoparticles on graphene monolayer using electron energy loss spectroscopy (EELS). Gold nano-ellipses were evaporated onto lithographed graphene, which was transferred onto a silicon nitride transmission electron microscopy grid. Plasmon decay from lithographed nanoparticles measured with EELS was compared in the absence and presence of the graphene monolayer. Measured decay values compared favorably with estimated radiative and non-radiative contributions to decay in the absence of graphene. Graphene significantly enhanced low-energy plasmon decay, increasing mode width 38%, but did not affect higher energy plasmon or dark mode decay. This decay beyond expected radiative and non-radiative mechanisms was attributed to hot electron transfer, and had quantum efficiency of 20%, consistent with previous reports

  10. DNA Electronic Fingerprints by Local Spectroscopy on Graphene

    Science.gov (United States)

    Balatsky, Alexander

    2013-03-01

    Working and scalable alternatives to the conventional chemical methods of DNA sequencing that are based on electronic/ionic signatures would revolutionize the field of sequencing. The approach of a single molecule imaging and spectroscopy with unprecedented resolution, achieved by Scanning Tunneling Spectroscopy (STS) and nanopore electronics could enable this revolution. We use the data from our group and others in applying this local scanning tunneling microscopy and illustrate possibilities of electronic sequencing of freeze dried deposits on graphene. We will present two types of calculated fingerprints: first in Local Density of States (LDOS) of DNA nucleotide bases (A,C,G,T) deposited on graphene. Significant base-dependent features in the LDOS in an energy range within few eV of the Fermi level were found in our calculations. These features can serve as electronic fingerprints for the identification of individual bases in STS. In the second approach we present calculated base dependent electronic transverse conductance as DNA translocates through the graphene nanopore. Thus we argue that the fingerprints of DNA-graphene hybrid structures may provide an alternative route to DNA sequencing using STS. Work supported by US DOE, NORDITA.

  11. The applicability of Fourier transform infrared (FT-IR) spectroscopy in waste management

    International Nuclear Information System (INIS)

    Smidt, Ena; Meissl, Katharina

    2007-01-01

    State and stability or reactivity of waste materials are important properties that must be determined to obtain information about the future behavior and the emission potential of the materials. Different chemical and biological parameters are used to describe the stage of organic matter in waste materials. Fourier transform infrared spectroscopy provides information about the chemistry of waste materials in a general way. Several indicator bands that are referred to functional groups represent components or metabolic products. Their presence and intensity or their absence shed light on the phase of degradation or stabilization. The rapid assessment of the stage of organic matter decomposition is a very important field of application. Therefore, infrared spectroscopy is an appropriate tool for process and quality control, for the assessment of abandoned landfills and for checking of the successful landfill remediation. A wide range of applications are presented in this study for different waste materials. Progressing stages of a typical yard/kitchen waste composting process are shown. The fate of anaerobically 'stabilized' leftovers in a subsequent liquid aerobic process is revealed by spectroscopic characteristics. A compost that underwent the biological stabilization process is distinguished from a 'substrate' that comprises immature biogenic waste mixed with mineral compounds. Infrared spectra of freeze-dried leachate from untreated and aerated landfill material prove the effect of the aerobic treatment during 10 weeks in laboratory-scale experiments

  12. Characterization of silicon-oxide interfaces and organic monolayers by IR-UV ellipsometry and FTIR spectroscopy

    Science.gov (United States)

    Hess, P.; Patzner, P.; Osipov, A. V.; Hu, Z. G.; Lingenfelser, D.; Prunici, P.; Schmohl, A.

    2006-08-01

    VUV-laser-induced oxidation of Si(111)-(1×1):H, Si(100):H, and a-Si:H at 157 nm (F II laser) in pure O II and pure H IIO atmospheres was studied between 30°C and 250°C. The oxidation process was monitored in real time by spectroscopic ellipsometry (NIR-UV) and FTIR spectroscopy. The ellipsometric measurements could be simulated with a three-layer model, providing detailed information on the variation of the suboxide interface with the nature of the silicon substrate surface. Besides the silicon-dioxide and suboxide layer, a dense, disordered, roughly monolayer thick silicon layer was included, as found previously by molecular dynamics calculations. The deviations from the classical Deal-Grove mechanism and the self-limited growth of the ultrathin dioxide layers (TMS) groups and n-alkylthiol monolayers on gold-coated silicon. The C-H stretching vibrations of the methylene and methyl groups could be identified by FTIR spectroscopy and IR ellipsometry.

  13. HIGH-RESOLUTION IR ABSORPTION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS: THE REALM OF ANHARMONICITY

    Energy Technology Data Exchange (ETDEWEB)

    Maltseva, Elena; Buma, Wybren Jan [University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Tielens, Alexander G. G. M. [Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Huang, Xinchuan; Lee, Timothy J. [SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Oomens, Jos, E-mail: w.j.buma@uva.nl, E-mail: petrignani@strw.leidenuniv.nl [Radboud University, Toernooiveld 7, 6525 ED Nijmegen (Netherlands)

    2015-11-20

    We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3-μm CH stretching region of polycyclic aromatic hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold (∼4 K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main bands that fall within 0.5% of the experimental frequencies. The implications for the aromatic infrared bands, specifically the 3-μm band, are discussed.

  14. Spectroelectrochemical study of polyphenylene by in situ external reflection FT-IR spectroscopy. Pt. 1

    International Nuclear Information System (INIS)

    Kvarnstroem, C.; Ivaska, A.

    1994-01-01

    In situ spectroelectrochemical measurements with external reflection FT-IR are performed at different stages of polymerization of 0.05, 0.1 and 0.8 M biphenyl in 0.1 M TBABF 4 in acetonitrile. The biphenyl concentration is not found to have any effect on the structure of the polymer formed. Formation of oligomers and the ratio of ortho/para-substituted polymer chains during film growth are studied. The first coupling of dimers to oligomers is found to take place in the vicinity of the electrode surface and at a later stage of polymerization the oligomers start to form polymer film on the electrode. A mixed para and ortho coupling resulting in crosslinking between chains is observed already at the early stage of polymerization. However, when a lower current density is used a more ordered polymer structure is obtained. A breakdown of the polymer film due to overoxidation can be seen when the potential is increased to 2.0 V. (orig.)

  15. High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons: The Realm of Anharmonicity

    Science.gov (United States)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2016-01-01

    We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3 micrometers CH stretching region of Polycyclic Aromatic Hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold ((is) approximately 4K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions enhanced with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main modes that fall within 0.5% of the experimental frequencies. The implications for the Aromatic Infrared Bands, specifically the 3-m band are discussed.

  16. DFT and time-resolved IR investigation of electron transfer between photogenerated 17- and 19-electron organometallic radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cahoon, James B.; Kling, Matthias F.; Sawyer, Karma R.; Andersen, Lars K.; Harris, Charles B.

    2008-04-30

    The photochemical disproportionation mechanism of [CpW(CO){sub 3}]{sub 2} in the presence of Lewis bases PR{sub 3} was investigated on the nano- and microsecond time-scales with Step-Scan FTIR time-resolved infrared spectroscopy. 532 nm laser excitation was used to homolytically cleave the W-W bond, forming the 17-electron radicals CpW(CO){sub 3} and initiating the reaction. With the Lewis base PPh{sub 3}, disproportionation to form the ionic products CpW(CO){sub 3}PPh{sub 3}{sup +} and CpW(CO){sub 3}{sup -} was directly monitored on the microsecond time-scale. Detailed examination of the kinetics and concentration dependence of this reaction indicates that disproportionation proceeds by electron transfer from the 19-electron species CpW(CO){sub 3}PPh{sub 3} to the 17-electron species CpW(CO){sub 3}. This result is contrary to the currently accepted disproportionation mechanism which predicts electron transfer from the 19-electron species to the dimer [CpW(CO){sub 3}]{sub 2}. With the Lewis base P(OMe){sub 3} on the other hand, ligand substitution to form the product [CpW(CO){sub 2}P(OMe){sub 3}]{sub 2} is the primary reaction on the microsecond time-scale. Density Functional Theory (DFT) calculations support the experimental results and suggest that the differences in the reactivity between P(OMe){sub 3} and PPh{sub 3} are due to steric effects. The results indicate that radical-to-radical electron transfer is a previously unknown but important process for the formation of ionic products with the organometallic dimer [CpW(CO){sub 3}]{sub 2} and may also be applicable to the entire class of organometallic dimers containing a single metal-metal bond.

  17. Study of electron beam effects on surfaces using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS)

    International Nuclear Information System (INIS)

    Gettings, M.; Coad, J.P.

    1976-02-01

    Discrepancies in the surface analyses of oxidised or heavily contaminated materials have been observed between X-ray Photoelectron Spectroscopy (XPS) and techniques using electron beams (primarily Auger Electron Spectroscopy (AES)). These discrepancies can be ascribed to the influence of the primary electron beam and to illustrate the various types of electron effects different materials were analysed using XPS and Secondary Ion Mass Spectroscopy (SIMS) before and after large area electron bombardment. The materials used included chrome and stainless steels, nickel, platinum, glass and brass. (author)

  18. The influence of optical parameters on impurity determinations by IR spectroscopy

    International Nuclear Information System (INIS)

    Lombard, O.J.

    1985-01-01

    The important role of impurities in semiconductor materials is the subject of continuous research. The concentration of interstitial oxygen impurities in silicon are determined with the aid of infrared spectroscopy. The maximum absorption coefficient of the oxygen absorption peak, centered at 9,06 μm, is determined and the impurity concentration is then calculated using a calibration factor. This procedure was evaluated, paying particular attention to those optical parameters which may influence these impurity determinations. A thorough discussion of the theoretical and experimental aspects of infrared spectroscopy in general is followed by an overview of previous experimental work. This lead to some theoretical analysis regarding the influence of the index of refraction, the index of absorption and multiple reflections in the silicon wafer on impurity determinations. This lead to specific experimental investigations. The influence of the surface morphology of samples on impurity determinations was studied by determining the reflectance of silicon surfaces. It was established that the surface reflectance plays a role and that it must be taken into consideration for accurate impurity concentration determinations. The most accurate values for the absorption coefficient due to oxygen in silicon are calculated. This requires that the surface of the silicon wafers must be highly polished for the formula to be valid. Acceptable values for the absorption coefficient of damaged surfaces are obtained if the uncorrected formula is used. Experimental results may deviate as much as 32% from the real impurity concentration if the wrong formula is used to calculate the absorption coefficient of oxygen in silicon at 9,06 μm

  19. Characterization of a new Tc (V) - glucosazine complex by UV - VIS and IR spectroscopy

    International Nuclear Information System (INIS)

    Ganzerli Valentini, M.T.; Stella, R.; Maggi, L.

    1989-01-01

    A new radiopharmaceutical is proposed for brain and heart functional and radiodiagnostic studies. A Tc complex containing the glucose molecule and chelating groups that do not alter the basic chemical features of the molecule has been prepared. The ligand is formed by the combination of one hydrazine molecule with two sugar molecules and is the first product of the D-glucose-hydrazine reaction that in aqueous basic medium may proceed up to hydrazone and in acid medium up to osazone. These transformations are observed at pH>5 through the UV absorption peaks at 274 and 224 nm, and at pH 1 . UV absorption spectra of the complex, dissolved in water as well as in acetonitrile, have been recorded: the characteristic single peak at 274 nm and at 276 nm respectively for the two solvents is unaffected by the presence of free ligand, due to the quasi null absorption in this spectral region. Molar extinction coefficient is found equal to 20850 L.mol 1 .cm 1 in solutions whose Tc concentration was in the range 2x10 5 -5x10 4 M and the ligand 10 2 - 10 1 M. The IR absorption spectrum has a C=N stretching band at 1620 cm 1 which means that the acyclic form of the azine is predominant; other large and strong bands refer to OH stretching at 3300 cm 1 , to C-O stretching at 1020 cm 1 and to C-N stretching (typical of the cyclic form) at 1080 cm 1 . (author)

  20. Characterization of soil organic matter by FT-IR spectroscopy and its relationship with chlorpyrifos sorption.

    Science.gov (United States)

    Parolo, María Eugenia; Savini, Mónica Claudia; Loewy, Ruth Miriam

    2017-07-01

    Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (K OC ) assuming that the main factor that influences the amount sorbed is the organic carbon content (OC) of the soil. However, K OC can vary across a range of soils. The influence of certain soil characteristics on the chlorpyrifos K OC values variation for 12 representative soils of the Northpatagonian Argentinian region with different physicochemical properties was investigated for this study. The chlorpyrifos sorption coefficients normalized by the OC content were experimentally obtained using the batch equilibrium method; the K OC values ranged between 9000-20,000 L kg -1 . The soil characteristics assessed were pH, clay content and spectral data indicative of soil organic matter (SOM) quality measured by FT-IR on the whole soil. The bands considered in the spectroscopic analyses were those corresponding to the aliphatic components, 2947-2858 cm -1 (band A) and the hydrophilic components, 1647-1633 cm -1 (band B). A significant relationship was found (R 2  = 0.66) between chlorpyrifos sorption (K OC ) and the variables pH and A/B height band ratio. The correlation between the values predicted by the derived model and the experimental data was significant (r = 0.89 p chlorpyrifos sorption coefficient through the use of a simple, rapid, and environmentally-friendly measurement. K OC analysis in relation to soil properties represents a valuable contribution to the understanding of the attenuation phenomena of the organic contaminants off-site migration in the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Low-dose electron energy-loss spectroscopy using electron counting direct detectors.

    Science.gov (United States)

    Maigné, Alan; Wolf, Matthias

    2018-03-01

    Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS. With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector. Here we report the use of an electron-counting direct-detection camera for EEL spectroscopy. We studied the oxygen K edge of amorphous ice and obtained a signal noise ratio up to 10 times higher than with a conventional CCD.We report the application of electron counting to record time-resolved EEL spectra of a biological protein embedded in amorphous ice, revealing chemical changes observed in situ while exposed by the electron beam. A change in the fine structure of nitrogen K and the carbon K edges were recorded during irradiation. A concentration of 3 at% nitrogen was detected with a total electron dose of only 1.7 e-/Å2, extending the boundaries of EELS signal detection at low electron doses.

  2. Quantum dynamics and electronic spectroscopy within the framework of wavelets

    International Nuclear Information System (INIS)

    Toutounji, Mohamad

    2013-01-01

    This paper serves as a first-time report on formulating important aspects of electronic spectroscopy and quantum dynamics in condensed harmonic systems using the framework of wavelets, and a stepping stone to our future work on developing anharmonic wavelets. The Morlet wavelet is taken to be the mother wavelet for the initial state of the system of interest. This work reports daughter wavelets that may be used to study spectroscopy and dynamics of harmonic systems. These wavelets are shown to arise naturally upon optical electronic transition of the system of interest. Natural birth of basis (daughter) wavelets emerging on exciting an electronic two-level system coupled, both linearly and quadratically, to harmonic phonons is discussed. It is shown that this takes place through using the unitary dilation and translation operators, which happen to be part of the time evolution operator of the final electronic state. The corresponding optical autocorrelation function and linear absorption spectra are calculated to test the applicability and correctness of the herein results. The link between basis wavelets and the Liouville space generating function is established. An anharmonic mother wavelet is also proposed in the case of anharmonic electron–phonon coupling. A brief description of deriving anharmonic wavelets and the corresponding anharmonic Liouville space generating function is explored. In conclusion, a mother wavelet (be it harmonic or anharmonic) which accounts for Duschinsky mixing is suggested. (paper)

  3. Highly Stable, All-fiber, High Power ZBLAN Supercontinuum Source Reaching 4.75 µm used for Nanosecond mid-IR Spectroscopy

    DEFF Research Database (Denmark)

    Moselund, Peter M.; Petersen, Christian; Leick, Lasse

    2013-01-01

    We demonstrate compact all-fiber mid-IR supercontinuum generation up to 4.75 μm with 1.2 W output power during hundreds of hours. This source is applied to upconversion spectroscopy using the energy corresponding to a single pulse....

  4. Classification and structural analysis of live and dead salmonella cells using fourier transform infrared (FT-IR) spectroscopy and principle component analysis (PCA)

    Science.gov (United States)

    Fourier Transform Infrared Spectroscopy (FT-IR) was used to detect Salmonella typhimurium and Salmonella enteritidis foodborne bacteria and distinguish between live and dead cells of both serotypes. Bacteria were loaded individually on the ZnSe Attenuated Total Reflection (ATR) crystal surface and s...

  5. Resonance tunneling electron-vibrational spectroscopy of polyoxometalates.

    Science.gov (United States)

    Dalidchik, F I; Kovalevskii, S A; Balashov, E M

    2017-05-21

    The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier-Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters-energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level.

  6. Investigation into rare earth n-aminobenzoates by thermography and IR spectroscopy

    International Nuclear Information System (INIS)

    Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

    1977-01-01

    N-aminobenzoates of r.e.e. of the composition of M(C 6 H 4 NH 2 COO) 3 x nH 2 O have been studied by thermography and infrared spectroscopy (M=La,Ce,Pr,Nd,Sm,Eu,Cd,TdHo,Er, Tm,Yb,Lu; n=1,2). It has been established that thermal decomposition of crystallohydrates of r.e.e. n-aminobenzoates is accompanied by the formation as intermediates of non-aqueous r.e.e. n-aminobenzoates stable within a rather wide temperature range (200-300 deg). The final products of thermolysis are oxides of the corresponding r.e.e. The assignment is given of the main absorption bands in infrared spectra of n-aminobenzoates of r.e.e. The assumptions have been made about their nature: crystallization water in crystallohydrates is outward of the sphere and connected with the ligand aminogroup; the metal is, evidently, not coordinated with the nitrogen of the aminogroup. n-aminobenzoate ion is a bidentate ligand

  7. Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

    Energy Technology Data Exchange (ETDEWEB)

    McKee, Kristopher; Meyer, Matthew; Smith, Emily

    2012-04-13

    Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (D{sub RS}). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3–4.6 for aqueous pyridine or 2.2–3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89–95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm–1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

  8. Conformer-Specific IR Spectroscopy of Laser-Desorbed Sulfonamide Drugs: Tautomeric and Conformational Preferences of Sulfanilamide and its Derivatives

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W.

    2017-06-01

    Molecules containing the sulfonamide group R^{1}-SO_2-NHR^{2} have a longstanding history as antimicrobial agents. Even though nowadays they are not commonly used in treating humans anymore, they continue to be studied as effective inhibitors of metalloenzyme carbonic anhydrases. These enzymes are important targets for a variety of diseases, such as, for instance, breast cancer, glaucoma, and obesity. Here we present the results of our laser desorption single-conformation UV and IR study of sulfanilamide (NH_2Ph-SO_2-NHR, R=H), a variety of singly substituted derivatives, and their monohydrated complexes. Depending on the substituent, the sulfonamide group can either adopt an amino or an imino tautomeric form. The form prevalent in the crystal is not necessarily also the tautomeric form we identified in the molecular beam after laser desorbing the sample. Furthermore, we explored the effect of complexation with a single water molecule on the tautomeric and conformational preferences of the sulfonamides. Our conformer-specific IR spectra in the NH and OH stretch region (3200-3750 \\wn) suggest that the intra- and intermolecular interactions governing the structures of the monomers and water complexes are surprisingly diverse. We have undertaken both Quantum Theory of Atoms in Molecules (QTAIM) and Interacting Quantum Atoms (IQA) analyses of calculated electron densities to quantitatively characterize the nature and strengths of the intra- and intermolecular interactions prevalent in the monomer and water complex structures.

  9. Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xiaowei; Fagiani, Matias R. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, D-04103 Leipzig (Germany); Gewinner, Sandy; Schöllkopf, Wieland [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Asmis, Knut R., E-mail: knut.asmis@uni-leipzig.de, E-mail: js@chemie.hu-berlin.de [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, D-04103 Leipzig (Germany); Bischoff, Florian A.; Berger, Fabian; Sauer, Joachim, E-mail: knut.asmis@uni-leipzig.de, E-mail: js@chemie.hu-berlin.de [Institut für Chemie, Humboldt-Universität zu Berlin, Unter den Linden 6, D-10099 Berlin (Germany)

    2016-06-28

    We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono- and dialuminum oxide anions. The infrared photodissociation spectra of D{sub 2}-tagged AlO{sub 1-4}{sup −} and Al{sub 2}O{sub 3-6}{sup −} are measured in the region from 400 to 1200 cm{sup −1}. Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al{sub 2}O{sub 3-6}{sup −} anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO{sub 3}{sup −}. Terminal Al–O stretching modes are found between 1140 and 960 cm{sup −1}. Superoxo and peroxo stretching modes are found at higher (1120-1010 cm{sup −1}) and lower energies (850-570 cm{sup −1}), respectively. Four modes in-between 910 and 530 cm{sup −1} represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al–(O){sub 2}–Al ring.

  10. 2012 ELECTRONIC SPECTROSCOPY & DYNAMICS GORDON RESEARCH CONFERENCE, JULY 22-27, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Kohler, Bern

    2012-07-27

    Topics covered in this GRC include high-resolution spectroscopy, coherent electronic energy transport in biology, excited state theory and dynamics, excitonics, electronic spectroscopy of cold and ultracold molecules, and the spectroscopy of nanostructures. Several sessions will highlight innovative techniques such as time-resolved x-ray spectroscopy, frequency combs, and liquid microjet photoelectron spectroscopy that have forged stimulating new connections between gas-phase and condensed-phase work.

  11. Hubble space telescope near-ir transmission spectroscopy of the super-Earth HD 97658B

    Energy Technology Data Exchange (ETDEWEB)

    Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Dragomir, Diana [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Kreidberg, Laura; Bean, Jacob L. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Kempton, Eliza M.-R. [Department of Physics, Grinnell College, Grinnell, IA 50112 (United States); McCullough, P. R. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Gillon, Michael [Institut d' Astrophysique et de Géophysique, Universiteé de Liége, Liége 1 (Belgium); Homeier, Derek [Centre de Recherche Astrophysique de Lyon, F-69364 Lyon (France); Howard, Andrew W., E-mail: hknutson@caltech.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2014-10-20

    Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's (WFC3) scanning mode to measure the wavelength-dependent transit depth in 30 individual bandpasses. Our averaged differential transmission spectrum has a median 1σ uncertainty of 23 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 10σ level. They are consistent at the 0.4σ level with a flat line model, as well as effectively flat models corresponding to a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of 10 mbar or higher.

  12. Rapid screening and identification of illicit drugs by IR absorption spectroscopy and gas chromatography

    Science.gov (United States)

    Mengali, Sandro; Liberatore, Nicola; Luciani, Domenico; Viola, Roberto; Cardinali, Gian Carlo; Elmi, Ivan; Poggi, Antonella; Zampolli, Stefano; Biavardi, Elisa; Dalcanale, Enrico; Bonadio, Federica; Delemont, Olivier; Esseiva, Pierre; Romolo, Francesco S.

    2013-01-01

    Analytical instruments based on InfraRed Absorption Spectroscopy (IRAS) and Gas Chromatography (GC) are today available only as bench-top instrumentation for forensic labs and bulk analysis. Within the 'DIRAC' project funded by the European Commission, we are developing an advanced portable sensor, that combines miniaturized GC as its key chemical separation tool, and IRAS in a Hollow Fiber (HF) as its key analytical tool, to detect and recognize illicit drugs and key precursors, as bulk and as traces. The HF-IRAS module essentially consists of a broadly tunable External Cavity (EC) Quantum Cascade Laser (QCL), thermo-electrically cooled MCT detectors, and an infrared hollow fiber at controlled temperature. The hollow fiber works as a miniaturized gas cell, that can be connected to the output of the GC column with minimal dead volumes. Indeed, the module has been coupled to GC columns of different internal diameter and stationary phase, and with a Vapour Phase Pre-concentrator (VPC) that selectively traps target chemicals from the air. The presentation will report the results of tests made with amphetamines and precursors, as pure substances, mixtures, and solutions. It will show that the sensor is capable of analyzing all the chemicals of interest, with limits of detection ranging from a few nanograms to about 100-200 ng. Furthermore, it is suitable to deal with vapours directly trapped from the headspace of a vessel, and with salts treated in a basic solution. When coupled to FAST GC columns, the module can analyze multi-components mixes in less than 5 minutes.

  13. THz Electron Paramagnetic Resonance / THz Spectroscopy at BESSY II

    Directory of Open Access Journals (Sweden)

    Karsten Holldack

    2016-02-01

    Full Text Available The THz beamline at BESSY II employs high power broadband femto- to picosecond long THz pulses for magneto-optical THz and FIR studies. A newly designed set-up exploits the unique properties of ultrashort THz pulses generated by laser-energy modulation of electron bunches in the storage ring or alternatively from compressed electron bunches. Experiments from 0.15 to 5 THz (~ 5 – 150 cm-1 may be conducted at a user station equipped with a fully evacuated high resolution FTIR spectrometer (0.0063 cm-1, lHe cooled bolometer detectors, a THz TDS set-up and different sample environments, including a superconducting high field magnet (+11 T - 11T with variable temperature insert (1.5 K – 300 K, a sample cryostat and a THz attenuated total reflection chamber.  Main applications are Frequency Domain Fourier transform THz-Electron Paramagnetic Resonance (FD-FT THz-EPR, THz-FTIR spectroscopy and optical pump - THz probe time domain spectroscopy (TDS, with sub-ps time resolution.

  14. Impact of animal density on cattle nutrition in dry Mediterranean rangelands: a faecal near-IR spectroscopy-aided study.

    Science.gov (United States)

    Landau, S Y; Dvash, L; Yehuda, Y; Muklada, H; Peleg, G; Henkin, Z; Voet, H; Ungar, E D

    2018-02-01

    In the context of determining the sustainable carrying capacity of dry-Mediterranean herbaceous rangelands, we examined the effect of animal density on cattle nutrition, which is fundamental to animal performance and welfare. The effects on dietary components of low (0.56 cows/ha; L) and high (1.11 cows/ha; H) animal densities were monitored for three consecutive years in grazing beef cows. In the dry season (summer and early autumn), cows had free access to N-rich poultry litter (PL) given as a dietary supplement. In each season, near-IR spectroscopy (NIRS) was used to predict the chemical composition of herbage samples (ash, NDF, CP, in vitro dry matter digestibility (IVDMD) and metabolizable energy (ME) content from IVDMD). Near-IR spectroscopy was applied also to faecal samples to determine the chemical composition of the diet selected by the animal, as well as the contents of ash, NDF and CP in the faeces themselves. A faecal-NIRS equation was applied to estimate the dietary proportion of PL. Seasonal categories were green, dry without PL supplementation and dry with it. We found no effects of animal density on nutrition during the green season but effects were apparent when cows consumed dry pasture. Ash content predicted by faecal NIRS was higher in the diet than in plant samples clipped from pasture, which infers that cows ingested soil. Dietary and faecal ash contents were higher (Panimals. During the dry period, dietary contents of ME were higher in L than in H (Panimal health, the above results cast doubts on the long-term sustainability of the higher of the animal densities tested. Although it may be sustainable vis-à-vis the vegetation, treatment H may have exceeded the boundaries of what is acceptable for cow health. Chemical information revealed with NIRS can be used to evaluate whether animal densities are compatible with animal health and welfare standards and can play a role in determining the carrying capacity of Mediterranean rangelands.

  15. Electron spectroscopy for surface analysis - the ES300 electron spectrometer and its applications

    International Nuclear Information System (INIS)

    Walker, J.A.J.; Price, W.B.

    1980-07-01

    The features of the ES300 electron spectrometer are described together with factors which affect the energy spectrum, experimental variables and interpretation of the spectral information. A discussion of five applications illustrates the use of X-ray photo-electron spectroscopy (XPS) in the diverse work of the Risley Nuclear Power Development Laboratories (RNL). The analytical results are given for each of the examples and their interpretation discussed in the chemical context of the original problem. (author)

  16. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    tunneling microscope (STM). Especially at low temperatures the Kondo resonance is used to probe magnetic interaction with ferromagnetic islands and between two atoms. The latter showing a crossover between Kondo screened atoms and antiferromagnetically coupled atoms close to the quantum critical point....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...

  17. Design of nuclear spectroscopy electronics based on the EUROsystem standard

    International Nuclear Information System (INIS)

    Pahor, J.

    1987-11-01

    The development of modular nuclear instruments in the EUROcard system has been continued by the design of a staircase generator; such an instrument is needed for accurate testing of spectroscopy amplifiers. The generator provides very precisely defined steps with the period between them varying from 8 to 50 microseconds, the output voltage continuously variable from 2 to 5 V, and attenuated ion steps between 1 and 100. Great care was taken that individual steps exhibit no overshot, thus providing a very clean signal to the input of a tested amplifier. The circuitry is kept simple, and it can be easily constructed in any electronics laboratory. Figs

  18. Diode laser spectroscopy of oxygen electronic band at 760 nm

    International Nuclear Information System (INIS)

    Lucchesini, A.; De Rosa, M.; Gozzini, S.

    1998-01-01

    Collisional broadening and shift coefficients have been obtained by analyzing the line shapes of oxygen absorptions in the 760 nm electronic band. By using a diode laser spectrometer with commercially available etherostructure Al x Ga 1-x As diode lasers operating in 'free-running mode', line shape parameters have been collected at room temperature by varying the gas pressure. A systematic study has been carried on seven absorption lines by scanning the diode laser emission wavelength around the gas resonances. The weak absorption lines have been detected by using the wavelength modulation (WM) spectroscopy technique with second-harmonic detection

  19. 8th international conference on electronic spectroscopy and structure

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Art

    2000-10-16

    Gathering from 33 countries around the world, 408 registrants and a number of local drop-in participants descended on the Clark Kerr Campus of the University of California, Berkeley, from Monday, August 7 through Saturday, August 12, 2000 for the Eighth International Conference on Electronic Structure and Spectroscopy (ICESS8). At the conference, participants benefited from an extensive scientific program comprising more than 100 oral presentations (plenary lectures and invited and contributed talks) and 330 poster presentations, as well as ample time for socializing and a tour of the Advanced Light Source (ALS) at the nearby Lawrence Berkeley National Laboratory.

  20. Inelastic electron tunneling spectroscopy of a single nuclear spin.

    Science.gov (United States)

    Delgado, F; Fernández-Rossier, J

    2011-08-12

    Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance.

  1. Probing Plasmonic Nanostructures with Electron Energy - Loss Spectroscopy

    DEFF Research Database (Denmark)

    Raza, Søren

    for nonlocal response. The experimental work comprises the use of electron energy-loss spectroscopy (EELS) to excite and study both localized and propagating surface plasmons in metal structures. Following a short introduction, we present the theoretical foundation to describe nonlocal response in Maxwell......, dimer with nanometer-sized gaps, core-shell nanowire with ultrathin metal shell, and a thin metal film. In all cases we compare the nonlocal models with the local-response approximation. Below the plasma frequency, we find that the distance between the induced positive and negative surface charges...

  2. A new Density Functional Theory (DFT) based method for supporting the assignment of vibrational signatures of mannan and cellulose—Analysis of palm kernel cake hydrolysis by ATR-FT-IR spectroscopy as a case study

    DEFF Research Database (Denmark)

    Barsberg, Søren Talbro; Sanadi, Anand Ramesh; Jørgensen, Henning

    2011-01-01

    Attenuated Total Reflectance (ATR) FT-IR spectroscopy gives in situ information on molecular concentration, organization and interactions in plant cell walls. We demonstrate its potential for further developments by a case study which combines ATR-FT-IR spectroscopy with a recently published DFT...... a decreasing degree of polymerization to be a plausible cause, although others may interfere. Keywords: Cellulose; Mannan; FT-IR; DFT; Molecular modelling; Palm kernel...

  3. Electron energy-loss spectroscopy on fullerenes and fullerene compounds

    International Nuclear Information System (INIS)

    Armbruster, J.

    1996-03-01

    A few years ago, a new form of pure carbon, the fullerenes, has been discovered, which shows many fascinating properties. Within this work the spatial and electronic structure of some selected fullerene compounds have been investigated by electron-energy-loss spectroscopy in transmission. Phase pure samples of alkali intercalated fullerides A x C 60 (A=Na, K, Cs) have been prepared using vacuum distillation. Measruements of K 3 C 60 show a dispersion of the charge carrier plasmon close to zero. This can be explained by calculations, which take into account both band structure and local-field (inhomogeneity) effects. The importance of the molecular structure can also be seen from the A 4 C 60 compounds, where the non-metallic properties are explained by a splitting of the t 1u and t 1g derived bands that is caused by electron-correlation and Jahn-Teller effects. First measurements of the electronic structure of Na x C 60 (x>6) are presented and reveal a complete transfer from the sodium atoms but an incomplete transfer onto the C 60 molecules. This behaviour can be explained by taking into account additional electronic states that are situated between the sodium atoms in the octahedral sites and are predicted by calculations using local density approximation. The crystal structure of the higher fullerenes C 76 and C 84 is found to be face-centered cubic

  4. ESIPT and photodissociation of 3-hydroxychromone in solution: photoinduced processes studied by static and time-resolved UV/Vis, fluorescence, and IR spectroscopy.

    Science.gov (United States)

    Chevalier, Katharina; Grün, Anneken; Stamm, Anke; Schmitt, Yvonne; Gerhards, Markus; Diller, Rolf

    2013-11-07

    The spectral properties of fluorescence sensors such as 3-hydroxychromone (3-HC) and its derivatives are sensitive to interaction with the surrounding medium as well as to substitution. 3-HC is a prototype system for other derivatives because it is the basic unit of all flavonoides undergoing ESIPT and is not perturbed by a substituent. In this study, the elementary processes and intermediate states in the photocycle of 3-HC as well as its anion were identified and characterized by the use of static and femtosecond time-resolved spectroscopy in different solvents (methylcyclohexane, acetonitrile, ethanol, and water at different pH). Electronic absorption and fluorescence spectra and lifetimes of the intermediate states were obtained for the normal, tautomer and anionic excited state, while mid-IR vibrational spectra yielded structural information on ground and excited states of 3-HC. A high sensitivity on hydrogen-bonding perturbations was observed, leading to photoinduced anion formation in water, while in organic solvents, different processes are suggested, including slow picosecond ESIPT and contribution of the trans-structure excited state or a different stable solvation state with different direction of OH. The formation of the latter could be favored by the lack of a substituent increasing contact points for specific solute-solvent interactions at the hydroxyl group compared to substituted derivatives. The effect of substituents has to be considered for the design of future fluorescence sensors based on 3-HC.

  5. FT-IR spectroscopy and multivariate analysis as an auxiliary tool for diagnosis of mental disorders: Bipolar and schizophrenia cases

    Science.gov (United States)

    Ogruc Ildiz, G.; Arslan, M.; Unsalan, O.; Araujo-Andrade, C.; Kurt, E.; Karatepe, H. T.; Yilmaz, A.; Yalcinkaya, O. B.; Herken, H.

    2016-01-01

    In this study, a methodology based on Fourier-transform infrared spectroscopy and principal component analysis and partial least square methods is proposed for the analysis of blood plasma samples in order to identify spectral changes correlated with some biomarkers associated with schizophrenia and bipolarity. Our main goal was to use the spectral information for the calibration of statistical models to discriminate and classify blood plasma samples belonging to bipolar and schizophrenic patients. IR spectra of 30 samples of blood plasma obtained from each, bipolar and schizophrenic patients and healthy control group were collected. The results obtained from principal component analysis (PCA) show a clear discrimination between the bipolar (BP), schizophrenic (SZ) and control group' (CG) blood samples that also give possibility to identify three main regions that show the major differences correlated with both mental disorders (biomarkers). Furthermore, a model for the classification of the blood samples was calibrated using partial least square discriminant analysis (PLS-DA), allowing the correct classification of BP, SZ and CG samples. The results obtained applying this methodology suggest that it can be used as a complimentary diagnostic tool for the detection and discrimination of these mental diseases.

  6. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    Science.gov (United States)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  7. Quantification of water and silanol species on various silicas by coupling IR spectroscopy and in-situ thermogravimetry.

    Science.gov (United States)

    Gallas, Jean-Paul; Goupil, Jean-Michel; Vimont, Alexandre; Lavalley, Jean-Claude; Gil, Barbara; Gilson, Jean-Pierre; Miserque, Olivier

    2009-05-19

    Five silica samples (four precipitated silicas provided by commercial suppliers and one with the MCM-41 structure) have been studied by infrared spectroscopy and by a homemade thermogravimetry-infrared spectrum (TG-IR) setup. The silanol amount, accessibility to water, and different alcohols, and the affinity to water of these various silicas were compared and quantified. TG-IR measurements allowed the precise determination of the integrated molar absorption coefficient of the (nu+delta)OH band, epsilon(nu+delta)OH=(0.16+/-0.01) cm micromol(-1). It is independent of the sample origin and the concentration of silanol groups on silicas. For the precipitated dried samples evacuated at room temperature, the silanol concentration COH varies between 3.6 and 7.0 mmol g(-1). It is 5.3 mmol g(-1) in the case of the MCM-41 sample. Exchange experiments with D2O, followed by back-exchanges with different alcohols (methanol, propan-2-ol, 2-methyl-propan-2-ol, and 3-ethyl-pentan-3-ol) have been followed by infrared spectroscopy. All of the silanols of the MCM-41 sample are accessible to water and alcohol molecules. By contrast, about 20% of the silanols in precipitated samples are not exchanged by D2O (internal silanols). Accessibility decreases with alcohol size; the main effect is relative to methanol. Taking into account the sample specific surface areas and the silanol accessibility to D2O, the surface silanol density of precipitated silicas is close to 8 OH per nm2, at maximum coverage. At variance, the silanol surface density of the MCM silica is much lower, 4 OH per nm2. The TG-IR setup has also been used to determine the amount of water adsorbed on silicas through the intensity of the deltaH2O band. It varies linearly with the concentration of adsorbed water, whatever the silica sample. The integrated molar absorption coefficient of two bands, epsilondeltaH2O=(1.53+/-0.03) cm micromol(-1) and epsilon(nu+delta)H2O=(0.22+/-0.01) cm micromol(-1), have been determined. The

  8. Characterization of functional LB films using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Kuroda, Shin-ichi

    1995-01-01

    The role of ESR spectroscopy in the characterization of functional LB films is discussed. Unpaired electrons in LB films are associated with isolated radical molecules produced by charge transfer, paramagnetic metallic ions such as Cu 2+ , strongly interacting spins in the mixed valence states in charge-transfer salts, and so on. These spins often manifest the functions of materials. They can also act as microscopic probes in the ESR analysis devoted for the elucidation of characteristic properties of LB films. In structural studies, ESR is of particular importance in the analysis of molecular orientation of LB films. ESR can unambiguously determine the orientation of molecules through g-value anisotropy: different g value, different resonance field. Two types of new control methods of molecular orientation in LB films originated from the ESR analysis: study of in-plane orientation in dye LB films which led to the discovery of flow-orientation effect, and observation of drastic change of orientation of Cu-porphyrin in LB films using the trigger molecule, n-hexatriacontane. In the studies of electronic properties, hyperfine interactions between electron and nuclear spins provide information about molecular orbitals and local structures. Stable isotopes have been successfully applied to the stable radicals in merocyanine LB films to identify hyperfine couplings. In conducting LB films composed of charge-transfer salts, quasi-one-dimensional antiferromagnetism in semiconducting films and spin resonance of conduction electrons in metallic films are observed. Results provide microscopic evidence for the development of columnar structures of constituent molecules. Development of new functional LB films may provide more cases where ESR spectroscopy will clarify the nature of such films. (author)

  9. Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-05-07

    Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

  10. Atomic column resolved electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Duscher, G.; Pennycook, S.J.; Browning, N.D.

    1998-01-01

    Spatially resolved electron energy-loss spectroscopy (EELS) is rapidly developing into a unique and powerful tool to characterize internal interfaces. Because atomic column resolved Z-contrast imaging can be performed simultaneously with EELS in the scanning transmission electron microscope, this combination allows the atomic structure to be correlated with the electronic structure, and thus the local properties of interfaces or defects can be determined directly. However, the ability to characterize interfaces and defects at that level requires not only high spatial resolution but also the exact knowledge of the beam location, from where the spectrum is obtained. Here we discuss several examples progressing from cases where the limitation in spatial resolution is given by the microscopes or the nature of the sample, to one example of impurity atoms at a grain boundary, which show intensity and fine structure changes from atomic column to atomic column. Such data can be interpreted as changes in valence of the impurity, depending on its exact site in the boundary plane. Analysis ofthis nature is a valuable first step in understanding the microscopic structural, optical and electronic properties of materials. (orig.)

  11. FT-IR spectroscopy: A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grape must.

    Science.gov (United States)

    Grangeteau, Cédric; Gerhards, Daniel; Terrat, Sebastien; Dequiedt, Samuel; Alexandre, Hervé; Guilloux-Benatier, Michèle; von Wallbrunn, Christian; Rousseaux, Sandrine

    2016-02-01

    The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FT-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the species identified, some of them present organoleptic potentials in winemaking, particularly Starmerella bacillaris (synonym Candidazemplinina). So in a second time, we evaluated the capacity of the FT-IR technique to discriminate the isolates of this species because few techniques were able to study intraspecific NS yeast biodiversity. The results obtained were validated by using a classic method as ITS sequencing. Biodiversity at strain level was high: 19 different strains were identified from 58 isolates. So, FT-IR spectroscopy seems to be an accurate and reliable method for identifying major genera present in the musts. The two biggest advantages of the FT-IR are the capacity to characterize intraspecific biodiversity of non-Saccharomyces yeasts and the possibility to discriminate a lot of strains. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Impulsive IR-multiphoton dissociation of acrolein: observation of non-statistical product vibrational excitation in CO ( v=1-12) by time resolved IR fluorescence spectroscopy

    Science.gov (United States)

    Chowdhury, P. K.

    2000-10-01

    On IR-multiphoton excitation, vibrationally highly excited acrolein molecules undergo concerted dissociation generating CO and ethylene. The vibrationally excited products, CO and ethylene, are detected immediately following the CO 2 laser pulse by observing IR fluorescence at 4.7 and 3.2 μm, respectively. The nascent CO is formed with significant vibrational excitation, with a Boltzmann population distribution for v=1-12 levels corresponding to T v=12 950±50 K. The average vibrational energy in the product CO is found to be 26 kcal mol -1, in contrast to its statistical share of 5 kcal mol -1, available from the product energy distribution. The nascent vibrationally excited ethylene either dissociates by absorbing further infrared laser photons from the tail of the CO 2 laser pulse or relaxes by collisional deactivation. Ethylene IR-fluorescence excitation spectrum showed a structure in the quasi-continuum, with a facile resonance at 10.53 μm corresponding to the 10P(14) CO 2 laser line, which explains the higher acetylene yield observed at a higher pressure. A hydrogen atom transfer mechanism followed by C-C impulsive break in the acrolein transition state may be responsible for such non-statistical product energy distribution.

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

    Energy Technology Data Exchange (ETDEWEB)

    Colliex, Christian, E-mail: christian.colliex@u-psud.fr; Kociak, Mathieu; Stéphan, Odile

    2016-03-15

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

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

    Science.gov (United States)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

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

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

    International Nuclear Information System (INIS)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-01-01

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

  16. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  17. Angular distribution of scattered electron and medium energy electron spectroscopy for metals

    International Nuclear Information System (INIS)

    Oguri, Takeo; Ishioka, Hisamichi; Fukuda, Hisashi; Irako, Mitsuhiro

    1986-01-01

    The angular distribution (AD) of scattered electrons produced by medium energy incident electrons (E P = 50 ∼ 300 eV) from polycrystalline Ti, Fe, Ni, Cu and Au were obtained by the angle-resolved medium energy electron spectrometer. The AD of the energy loss peaks are similar figures to AD of the elastically reflected electron peaks. Therefore, the exchanged electrons produced by the knock-on collision between the incident electrons and those of metals without momentum transfer are observed as the energy loss spectra (ELS). This interpretation differs from the inconsequent interpretation by the dielectric theory or the interband transition. The information depth and penetration length are obtained from AD of the Auger electron peaks. The contribution of the surface to spectra is 3 % at the maximum for E P = 50 eV. The true secondary peaks representing the secondary electron emission spectroscopy (SES) are caused by the emissions of the energetic electrons (kT e ≥ 4 eV), and SES is the inversion of ELS. The established fundamental view is that the medium energy electron spectra represent the total bulk density of states. (author)

  18. Study of wide band-gap crystal LiCaAlF6 by IR-reflection spectroscopy and ab initio calculations

    International Nuclear Information System (INIS)

    Novikova, N.N.; Klimin, S.A.; Mavrin, B.N.

    2017-01-01

    Polarized IR-reflection spectra and results of ab initio calculations of vibrational and electronic properties of LiCaAlF6 single crystal are presented. It is shown that the crystal band gap is direct. Experimental and theoretical parameters are obtained for dipole-active and all phonons, respectively, including silent modes. Experimental IR-reflection and Raman spectra are well described in the frame of results obtained by ab initio calculations. The peculiarities are discussed concerning the structure of electronic bands, the interatomic interactions, the character of lattice vibrations, and the phonon dispersion.

  19. Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

    Science.gov (United States)

    Yang, Ke R; Matula, Adam J; Kwon, Gihan; Hong, Jiyun; Sheehan, Stafford W; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H; Tiede, David M; Chen, Lin X; Batista, Victor S

    2016-05-04

    The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-μ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

  20. On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy

    Science.gov (United States)

    Hora, Nicholas J.; Wahl, Benjamin M.; Soares, Camilla; Lara, Skylee A.; Lanska, John R.; Phillips, James A.

    2018-04-01

    The nature of the interactions between silicon tetrafluoride and series of nitrogen bases, including nitriles (RCN, with R > CH3), pyridine, and various fluoro-substituted pyridines, has been investigated via quantum-chemical computations, low-temperature IR spectroscopy, and bulk reactivity experiments. Using (primarily) M06 with the 6-311+G(2df,2pd) basis set, we obtained equilibrium structures, binding energies, harmonic frequencies, and N-Si potentials in the gas-phase and in bulk dielectric media for an extensive series of 1:1 molecular complexes, including: C6H5CH2CN-SiF4, CH3CH2CN-SiF4, (CH3)3CCN-SiF4, C5H5N-SiF4, 4-FC5H4N-SiF4, 3,5-C5F2H3N-SiF4, 2,6-C5F2H3N-SiF4 and 3,4,5-C5F3H2N-SiF4. In addition, for the analogous 2:1 complexes of pyridine and 3,5-difluororpyridine, we obtained equilibrium structures, binding energies, and harmonic frequencies. The N-Si distances in the 1:1 nitrile complexes are fairly long, ranging from 2.84 Å to 2.88 Å, and the binding energies range from 4.0 to 4.2 kcal/mol (16.7-17.6 kJ/mol). Also, computations predict extremely anharmonic N-Si potentials, for which the inner portions of the curve are preferentially stabilized in dielectric media, which predict an enhancement of these interactions in condensed-phases. However, we see no evidence of bulk reactivity between C6H5CH2CN, CH3CH2CN, or (CH3)3CCN and SiF4, nor any significant interaction between (CH3)3CCN and SiF4 in low temperature IR spectra of solid, (CH3)3CCN/SiF4 thin films. Conversely, the interactions in four of the five 1:1, pyridine-SiF4 complexes are generally stronger; binding energies range from 5.7 to 9.6 kcal/mol (23.8-40.2 kJ/mol), and correspondingly the N-Si distances are relatively short (2.12-2.25 Å). The exception is 2,6-C5F2H3N-SiF4, for which the binding energy is only 3.6 kcal/mol (15.1 kJ/mol), and the N-Si distance is quite long (3.12 Å). In addition, both pyridine and 3,5-difluororpyridine were found to form stable reaction products with SiF4

  1. IR spectroscopy together with multivariate data analysis as a process analytical tool for in-line monitoring of crystallization process and solid-state analysis of crystalline product

    DEFF Research Database (Denmark)

    Pöllänen, Kati; Häkkinen, Antti; Reinikainen, Satu-Pia

    2005-01-01

    -ray powder diffraction (XRPD) as a reference technique. In order to fully utilize DRIFT, the application of multivariate techniques are needed, e.g., multivariate statistical process control (MSPC), principal component analysis (PCA) and partial least squares (PLS). The results demonstrate that multivariate...... Fourier transform infra red (ATR-FTIR) spectroscopy provides valuable information on process, which can be utilized for more controlled crystallization processes. Diffuse reflectance Fourier transform infra red (DRIFT-IR) is applied for polymorphic characterization of crystalline product using X......Crystalline product should exist in optimal polymorphic form. Robust and reliable method for polymorph characterization is of great importance. In this work, infra red (IR) spectroscopy is applied for monitoring of crystallization process in situ. The results show that attenuated total reflection...

  2. Role of Bi promotion and solvent in platinum-catalyzed alcohol oxidation probed by in situ X-ray absorption and ATR-IR spectroscopy

    DEFF Research Database (Denmark)

    Mondelli, C.; Grunwaldt, Jan-Dierk; Ferri, D.

    2010-01-01

    the catalysts under working conditions using in situ X-ray absorption spectroscopy (XAS) and attenuated total reflection infrared spectroscopy (ATR-IR), aiming at uncovering the roles of the metal promoter and the reaction medium. XAS confirms that Bi is oxidized more easily than Pt, maintaining the catalytic...... surfaces than on step or kink sites. Side products, CO and benzoate species, appearing during the reaction reveal that the geometric suppression of undesired reactions does not occur to the same extent on Pt-based catalysts as on Pd, suggesting that decarbonylation of the produced aldehyde on Pt may occur...

  3. The structure of salt bridges between Arg(+) and Glu(-) in peptides investigated with 2D-IR spectroscopy: Evidence for two distinct hydrogen-bond geometries.

    Science.gov (United States)

    Huerta-Viga, Adriana; Amirjalayer, Saeed; Domingos, Sérgio R; Meuzelaar, Heleen; Rupenyan, Alisa; Woutersen, Sander

    2015-06-07

    Salt bridges play an important role in protein folding and in supramolecular chemistry, but they are difficult to detect and characterize in solution. Here, we investigate salt bridges between glutamate (Glu(-)) and arginine (Arg(+)) using two-dimensional infrared (2D-IR) spectroscopy. The 2D-IR spectrum of a salt-bridged dimer shows cross peaks between the vibrational modes of Glu(-) and Arg(+), which provide a sensitive structural probe of Glu(-)⋯Arg(+) salt bridges. We use this probe to investigate a β-turn locked by a salt bridge, an α-helical peptide whose structure is stabilized by salt bridges, and a coiled coil that is stabilized by intra- and intermolecular salt bridges. We detect a bidentate salt bridge in the β-turn, a monodentate one in the α-helical peptide, and both salt-bridge geometries in the coiled coil. To our knowledge, this is the first time 2D-IR has been used to probe tertiary side chain interactions in peptides, and our results show that 2D-IR spectroscopy is a powerful method for investigating salt bridges in solution.

  4. Fourier Transform Infrared Spectroscopy (FT-IR) and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Developmental Cotton Fibers.

    Science.gov (United States)

    Liu, Yongliang; Kim, Hee-Jin

    2017-06-22

    With cotton fiber growth or maturation, cellulose content in cotton fibers markedly increases. Traditional chemical methods have been developed to determine cellulose content, but it is time-consuming and labor-intensive, mostly owing to the slow hydrolysis process of fiber cellulose components. As one approach, the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy technique has also been utilized to monitor cotton cellulose formation, by implementing various spectral interpretation strategies of both multivariate principal component analysis (PCA) and 1-, 2- or 3-band/-variable intensity or intensity ratios. The main objective of this study was to compare the correlations between cellulose content determined by chemical analysis and ATR FT-IR spectral indices acquired by the reported procedures, among developmental Texas Marker-1 (TM-1) and immature fiber ( im ) mutant cotton fibers. It was observed that the R value, CI IR , and the integrated intensity of the 895 cm -1 band exhibited strong and linear relationships with cellulose content. The results have demonstrated the suitability and utility of ATR FT-IR spectroscopy, combined with a simple algorithm analysis, in assessing cotton fiber cellulose content, maturity, and crystallinity in a manner which is rapid, routine, and non-destructive.

  5. Rapid discrimination of sea buckthorn berries from different H. rhamnoides subspecies by multi-step IR spectroscopy coupled with multivariate data analysis

    Science.gov (United States)

    Liu, Yue; Zhang, Ying; Zhang, Jing; Fan, Gang; Tu, Ya; Sun, Suqin; Shen, Xudong; Li, Qingzhu; Zhang, Yi

    2018-03-01

    As an important ethnic medicine, sea buckthorn was widely used to prevent and treat various diseases due to its nutritional and medicinal properties. According to the Chinese Pharmacopoeia, sea buckthorn was originated from H. rhamnoides, which includes five subspecies distributed in China. Confusion and misidentification usually occurred due to their similar morphology, especially in dried and powdered forms. Additionally, these five subspecies have vital differences in quality and physiological efficacy. This paper focused on the quick classification and identification method of sea buckthorn berry powders from five H. rhamnoides subspecies using multi-step IR spectroscopy coupled with multivariate data analysis. The holistic chemical compositions revealed by the FT-IR spectra demonstrated that flavonoids, fatty acids and sugars were the main chemical components. Further, the differences in FT-IR spectra regarding their peaks, positions and intensities were used to identify H. rhamnoides subspecies samples. The discrimination was achieved using principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). The results showed that the combination of multi-step IR spectroscopy and chemometric analysis offered a simple, fast and reliable method for the classification and identification of the sea buckthorn berry powders from different H. rhamnoides subspecies.

  6. Discrimination of edible oils and fats by combination of multivariate pattern recognition and FT-IR spectroscopy: A comparative study between different modeling methods

    Science.gov (United States)

    Javidnia, Katayoun; Parish, Maryam; Karimi, Sadegh; Hemmateenejad, Bahram

    2013-03-01

    By using FT-IR spectroscopy, many researchers from different disciplines enrich the experimental complexity of their research for obtaining more precise information. Moreover chemometrics techniques have boosted the use of IR instruments. In the present study we aimed to emphasize on the power of FT-IR spectroscopy for discrimination between different oil samples (especially fat from vegetable oils). Also our data were used to compare the performance of different classification methods. FT-IR transmittance spectra of oil samples (Corn, Colona, Sunflower, Soya, Olive, and Butter) were measured in the wave-number interval of 450-4000 cm-1. Classification analysis was performed utilizing PLS-DA, interval PLS-DA, extended canonical variate analysis (ECVA) and interval ECVA methods. The effect of data preprocessing by extended multiplicative signal correction was investigated. Whilst all employed method could distinguish butter from vegetable oils, iECVA resulted in the best performances for calibration and external test set with 100% sensitivity and specificity.

  7. Combining FT-IR spectroscopy and multivariate analysis for qualitative and quantitative analysis of the cell wall composition changes during apples development.

    Science.gov (United States)

    Szymanska-Chargot, M; Chylinska, M; Kruk, B; Zdunek, A

    2015-01-22

    The aim of this work was to quantitatively and qualitatively determine the composition of the cell wall material from apples during development by means of Fourier transform infrared (FT-IR) spectroscopy. The FT-IR region of 1500-800 cm(-1), containing characteristic bands for galacturonic acid, hemicellulose and cellulose, was examined using principal component analysis (PCA), k-means clustering and partial least squares (PLS). The samples were differentiated by development stage and cultivar using PCA and k-means clustering. PLS calibration models for galacturonic acid, hemicellulose and cellulose content from FT-IR spectra were developed and validated with the reference data. PLS models were tested using the root-mean-square errors of cross-validation for contents of galacturonic acid, hemicellulose and cellulose which was 8.30 mg/g, 4.08% and 1.74%, respectively. It was proven that FT-IR spectroscopy combined with chemometric methods has potential for fast and reliable determination of the main constituents of fruit cell walls. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Two-dimensional IR spectroscopy of the anti-HIV agent KP1212 reveals protonated and neutral tautomers that influence pH-dependent mutagenicity

    OpenAIRE

    Peng, Chunte Sam; Fedeles, Bogdan I.; Singh, Vipender; Li, Deyu; Amariuta, Tiffany; Essigmann, John M.; Tokmakoff, Andrei

    2015-01-01

    The anti-HIV drug KP1212 was designed to intentionally increase the mutation rate of HIV, thereby causing viral population collapse. Its mutagenicity and thus antiviral activity was proposed to be the result of tautomerization. We used 2D IR spectroscopy to identify rapidly interconverting tautomers under physiological conditions. The traditionally rare enol–imino tautomer for nucleobases was found to be the major species for KP1212, providing a structural support for the tautomer hypothesis....

  9. Gas flow counter conversion electron Moessbauer spectroscopy (GFC-CEMS)

    International Nuclear Information System (INIS)

    Williamson, A.; Vijay, Y.K.; Jain, I.P.

    1999-01-01

    Conversion Electron Moessbauer Spectroscopy (CEMS) is well established technique to study surface properties of materials. However non availability of commercial experimental set up and complexity of operational parameters have been restricting the working experimental groups with in the country and abroad. In this paper we have presented the development work for the design of Gas Flow Counter (GFC), e.g. convenient sample mount, grounding, steady flow rate adjustment and minimum He-losses so that the detector operation and installation becomes convenient and dependable. The basic design is modified e.g. large volume to maintain steady gas flow, sample mount close to central wire and O-ring fitted flange. The CEMS spectra are recorded using conventional Moessbauer drive and 57 Co source. The calibrated spectrum shows a detection efficiency of about 20% for natural iron and steel foil. The CEMS spectrum for FeTi bulk and transmission Moessbauer Spectroscopy (TMS) spectrum of FeTi thin film deposited by vacuum evaporation on thin glass substrate were recorded to test the performance of GFC-CEMS. (author)

  10. Electronic structure of atoms: atomic spectroscopy information system

    International Nuclear Information System (INIS)

    Kazakov, V V; Kazakov, V G; Kovalev, V S; Meshkov, O I; Yatsenko, A S

    2017-01-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists. (paper)

  11. Identification of irradiated chicken meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Chawla, S.P.; Thomas, Paul

    2004-01-01

    Studies were carried out on detection of irradiation treatment in chicken using electron spin resonance (ESR) spectroscopy. The effect of gamma- irradiation treatment on radiation induced signal in different types of chicken namely, broiler, deshi and layers was studied. Irradiation treatment induced a characteristic ESR signal that was not detected in non-irradiated samples. The shape of the signal was not affected by type of the bone. The intensity of radiation induced ESR signal was affected by factors such as absorbed radiation dose, bone type irradiation temperature, post-irradiation storage, post-irradiation cooking and age of the bird. Deep-frying resulted in the formation of a symmetric signal that had a different shape and was weaker than the radiation induced signal. This technique can be effectively used to detect irradiation treatment in bone-in chicken meat even if stored and/or subjected to various traditional cooking procedures. (author)

  12. Ballistic electron emission spectroscopy on Ag/Si devices

    Energy Technology Data Exchange (ETDEWEB)

    Bannani, A; Bobisch, C A; Matena, M; Moeller, R [Department of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg (Germany)], E-mail: amin.bannani@uni-due.de

    2008-09-17

    In this work we report on ballistic electron emission spectroscopy (BEES) studies on epitaxial layers of silver grown on silicon surfaces, with either a Si(111)-(7 x 7) or Si(100)-(2 x 1) surface reconstruction. The experiments were done at low temperature and in ultra-high vacuum (UHV). In addition, BEES measurements on polycrystalline Ag films grown on hydrogen-terminated H:Si(111)-(1 x 1) and H:Si(100)-(2 x 1) surfaces were performed. The Schottky barrier heights were evaluated by BEES. The results are compared to the values for the barrier height reported for macroscopic Schottky diodes. We show that the barrier heights for the epitaxial films substantially differ from the values measured on polycrystalline Ag films, suggesting a strong effect of the interface on the barrier height.

  13. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

    Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

    2017-10-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

  14. Determination of the electron-electron collisional frequency by means of plasma electron spectroscopy

    International Nuclear Information System (INIS)

    Kolokolov, N.B.; Kudryavtsev, A.A.; Romanenko, V.A.

    1989-01-01

    Methods of controlling fast part of electron distribution function (DF) in nonlocal regime of current-free plasma are suggested and realized. Artificially created step in DF fast part has a simple link with frequencies of electron-electron and elastic electron-atom collisions that may be defined in the corresponding experiments

  15. Use of analytical electron microscopy and auger electron spectroscopy for evaluating materials

    International Nuclear Information System (INIS)

    Jones, R.H.; Bruemmer, S.M.; Thomas, M.T.; Baer, D.R.

    1982-11-01

    Analytical electron microscopy (AEM) can be used to characterize the microstructure and microchemistry of materials over dimensions less than 10 nm while Auger electron spectroscopy (AES) can be used to characterize the chemical composition of surfaces and interfaces to a depth of less than 1 nm. Frequently, the information gained from both instruments can be coupled to give new insight into the behavior of materials. Examples of the use of AEM and AES to characterize segregation, sensitization and radiation damage are presented. A short description of the AEM and AES techniques are given

  16. Structural, Electronic and Elastic Properties of Heavy Fermion YbTM2 (TM= Ir and Pt) Laves Phase Compounds

    Science.gov (United States)

    Pawar, H.; Shugani, M.; Aynyas, M.; Sanyal, S. P.

    2018-02-01

    The structural, electronic and elastic properties of YbTM2 (TM = Ir and Pt) Laves phase intermetallic compounds which crystallize in cubic (MgCu2-type) structure, have been investigated using ab-initio full potential linearized augmented plane wave (FP-LAPW) method with LDA and LDA+U approximation. The calculated ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B‧) are in good agreement with available experimental and theoretical data. The electronic properties are analyzed from band structures and density of states. Elastic constants are predicted first time for these compounds which obey the stability criteria for cubic system.

  17. Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

    International Nuclear Information System (INIS)

    Khalid, R.

    2013-01-01

    Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

  18. Pore closure in zeolitic imidazolate frameworks under mechanical pressure† †Electronic supplementary information (ESI) available: Experimental details; synthetic procedures; supplementary data analyses; additional PXRD, thermal and elemental analyses as well as IR and 1H NMR spectroscopy data. See DOI: 10.1039/c7sc04952h

    Science.gov (United States)

    Wharmby, Michael T.; Kieslich, Gregor; Hante, Inke; Schneemann, Andreas; Wu, Yue; Daisenberger, Dominik; Cheetham, Anthony K.

    2018-01-01

    We investigate the pressure-dependent mechanical behaviour of the zeolitic imidazolate framework ZIF-4 (M(im)2; M2+ = Co2+ or Zn2+, im– = imidazolate) with high pressure, synchrotron powder X-ray diffraction and mercury intrusion measurements. A displacive phase transition from a highly compressible open pore (op) phase with continuous porosity (space group Pbca, bulk modulus ∼1.4 GPa) to a closed pore (cp) phase with inaccessible porosity (space group P21/c, bulk modulus ∼3.3–4.9 GPa) is triggered by the application of mechanical pressure. Over the course of the transitions, both ZIF-4 materials contract by about 20% in volume. However, the threshold pressure, the reversibility and the immediate repeatability of the phase transition depend on the metal cation. ZIF-4(Zn) undergoes the op–cp phase transition at a hydrostatic mechanical pressure of only 28 MPa, while ZIF-4(Co) requires about 50 MPa to initiate the transition. Interestingly, ZIF-4(Co) fully returns to the op phase after decompression, whereas ZIF-4(Zn) remains in the cp phase after pressure release and requires subsequent heating to switch back to the op phase. These variations in high pressure behaviour can be rationalised on the basis of the different electron configurations of the respective M2+ ions (3d10 for Zn2+ and 3d7 for Co2+). Our results present the first examples of op–cp phase transitions (i.e. breathing transitions) of ZIFs driven by mechanical pressure and suggest potential applications of these functional materials as shock absorbers, nanodampers, or in mechanocalorics. PMID:29675212

  19. An X-ray photoelectron spectroscopy study of the products of the interaction of gaseous IrF6 with fine UO2F2

    Directory of Open Access Journals (Sweden)

    Prusakov Vladimir N.

    2007-01-01

    Full Text Available Nuclear fuel reprocessing by fluorination, a dry method of regeneration of spent nuclear fuel, uses UO2F2 for the separation of plutonium from gaseous mixtures. Since plutonium requires special treatment, IrF6 was used as a thermodynamic model of PuF6. The model reaction of the interaction of gaseous IrF6 with fine UO2F2 in the sorption column revealed a change of color of the sorption column contents from pale-yellow to gray and black, indicating the formation of products of such an interaction. The X-ray photoelectron spectroscopy study showed that the interaction of gaseous IrF6 with fine UO2F2 at 125 °C results in the formation of stable iridium compounds where the iridium oxidation state is close to Ir3+. The dependence of the elemental compositions of the layers in the sorption column on the penetration depth of IrF6 was established.

  20. Vibrational and electronic spectroscopy of ion-implantation-induced defects in fused silica and crystalline quartz

    International Nuclear Information System (INIS)

    Arnold, G.W.

    1978-01-01

    Defects produced by implantation of various atomic species in fused and crystalline SiO 2 were studied using infrared reflection spectroscopy (IRS) with UV-visible spectroscopy. We observe a new vibrational band at 830 cm -1 which is tentatively associated with the creation of two nonbridging O atoms in SiO 4 units. Numerous chemical effects were also observed, including evidence for chemical incorporation of Li and anomalously large O-vacancy production for Al + , B + and Si + implantation

  1. Analysis of quantum semiconductor heterostructures by ballistic electron emission spectroscopy

    Science.gov (United States)

    Guthrie, Daniel K.

    1998-09-01

    The microelectronics industry is diligently working to achieve the goal of gigascale integration (GSI) by early in the 21st century. For the past twenty-five years, progress toward this goal has been made by continually scaling down device technology. Unfortunately, this trend cannot continue to the point of producing arbitrarily small device sizes. One possible solution to this problem that is currently under intensive study is the relatively new area of quantum devices. Quantum devices represent a new class of microelectronic devices that operate by utilizing the wave-like nature (reflection, refraction, and confinement) of electrons together with the laws of quantum mechanics to construct useful devices. One difficulty associated with these structures is the absence of measurement techniques that can fully characterize carrier transport in such devices. This thesis addresses this need by focusing on the study of carrier transport in quantum semiconductor heterostructures using a relatively new and versatile measurement technique known as ballistic electron emission spectroscopy (BEES). To achieve this goal, a systematic approach that encompasses a set of progressively more complex structures is utilized. First, the simplest BEES structure possible, the metal/semiconductor interface, is thoroughly investigated in order to provide a foundation for measurements on more the complex structures. By modifying the semiclassical model commonly used to describe the experimental BEES spectrum, a very complete and accurate description of the basic structure has been achieved. Next, a very simple semiconductor heterostructure, a Ga1-xAlxAs single-barrier structure, was measured and analyzed. Low-temperature measurements on this structure were used to investigate the band structure and electron-wave interference effects in the Ga1-xAlxAs single barrier structure. These measurements are extended to a simple quantum device by designing, measuring, and analyzing a set of

  2. Attosecond photoelectron spectroscopy of electron transport in solids

    International Nuclear Information System (INIS)

    Magerl, Elisabeth

    2011-01-01

    Time-resolved photoelectron spectroscopy of condensed matter systems in the attosecond regime promises new insights into excitation mechanisms and transient dynamics of electrons in solids. This timescale became accessible directly only recently with the development of the attosecond streak camera and of laser systems providing few-cycle, phase-controlled laser pulses in the near-infrared, which are used to generate isolated, sub-femtosecond extreme-ultraviolet pulses with a well-defined timing with respect to the near-infrared pulse. Employing these pulses, the attosecond streak camera offers time resolutions as short as a few 10 attoseconds. In the framework of this thesis, a new, versatile experimental apparatus combining attosecond pulse generation in gases with state of the art surface science techniques is designed, constructed, and commissioned. Employing this novel infrastructure and the technique of the attosecond transient recorder, we investigate transport phenomena occurring after photoexcitation of electrons in tungsten and rhenium single crystals and show that attosecond streaking is a unique method for resolving extremely fast electronic phenomena in solids. It is demonstrated that electrons originating from different energy levels, i.e. from the conduction band and the 4f core level, are emitted from the crystal surface at different times. The origin of this time delay, which is below 150 attoseconds for all studied systems, is investigated by a systematic variation of several experimental parameters, in particular the photon energy of the employed attosecond pulses. These experimental studies are complemented by theoretical studies of the group velocity of highly-excited electrons based on ab initio calculations. While the streaking technique applied on single crystals can provide only information about the relative time delay between two types of photoelectrons, the absolute transport time remains inaccessible. We introduce a scheme of a reference

  3. Attosecond photoelectron spectroscopy of electron transport in solids

    Energy Technology Data Exchange (ETDEWEB)

    Magerl, Elisabeth

    2011-03-31

    Time-resolved photoelectron spectroscopy of condensed matter systems in the attosecond regime promises new insights into excitation mechanisms and transient dynamics of electrons in solids. This timescale became accessible directly only recently with the development of the attosecond streak camera and of laser systems providing few-cycle, phase-controlled laser pulses in the near-infrared, which are used to generate isolated, sub-femtosecond extreme-ultraviolet pulses with a well-defined timing with respect to the near-infrared pulse. Employing these pulses, the attosecond streak camera offers time resolutions as short as a few 10 attoseconds. In the framework of this thesis, a new, versatile experimental apparatus combining attosecond pulse generation in gases with state of the art surface science techniques is designed, constructed, and commissioned. Employing this novel infrastructure and the technique of the attosecond transient recorder, we investigate transport phenomena occurring after photoexcitation of electrons in tungsten and rhenium single crystals and show that attosecond streaking is a unique method for resolving extremely fast electronic phenomena in solids. It is demonstrated that electrons originating from different energy levels, i.e. from the conduction band and the 4f core level, are emitted from the crystal surface at different times. The origin of this time delay, which is below 150 attoseconds for all studied systems, is investigated by a systematic variation of several experimental parameters, in particular the photon energy of the employed attosecond pulses. These experimental studies are complemented by theoretical studies of the group velocity of highly-excited electrons based on ab initio calculations. While the streaking technique applied on single crystals can provide only information about the relative time delay between two types of photoelectrons, the absolute transport time remains inaccessible. We introduce a scheme of a reference

  4. Ultra-Broadband Two-Dimensional Electronic Spectroscopy and Pump-Probe Microscopy of Molecular Systems

    Science.gov (United States)

    Spokoyny, Boris M.

    Ultrafast spectroscopy offers an unprecedented view on the dynamic nature of chemical reactions. From charge transfer in semiconductors to folding and isomerization of proteins, these all important processes can now be monitored and in some instances even controlled on real, physical timescales. One of the biggest challenges of ultrafast science is the incredible energetic complexity of most systems. It is not uncommon to encounter macromolecules or materials with absorption spectra spanning significant portions of the visible spectrum. Monitoring a multitude of electronic and vibrational transitions, all dynamically interacting with each other on femtosecond timescales poses a truly daunting experimental task. The first part of this thesis deals with the development of a novel Two-Dimensional Electronic Spectroscopy (2DES) and its associated, advanced detection methodologies. Owing to its ultra-broadband implementation, this technique enables us to monitor femtosecond chemical dynamics that span the energetic landscape of the entire visible spectrum. In order to demonstrate the utility of our method, we apply it to two laser dye molecules, IR-144 and Cresyl Violet. Variation of photophysical properties on a microscopic scale in either man-made or naturally occurring systems can have profound implications on how we understand their macroscopic properties. Recently, inorganic hybrid perovskites have been tapped as the next generation solar energy harvesting materials. Their remarkable properties include low exciton binding energy, low exciton recombination rates and long carrier diffusion lengths. Nevertheless, considerable variability in device properties made with nearly identical preparation methods has puzzled the community. In the second part of this thesis we use non-linear pump probe microscopy to study the heterogeneous nature of femtosecond carrier dynamics in thin film perovskites. We show that the local morphology of the perovskite thin films has a

  5. Transfer of spectral weight in spectroscopies of correlated electron systems

    International Nuclear Information System (INIS)

    Rozenberg, M.J.; Kotliar, G.; Kajueter, H.

    1996-01-01

    We study the transfer of spectral weight in the photoemission and optical spectra of strongly correlated electron systems. Within the local impurity self-consistent approximation, that becomes exact in the limit of large lattice coordination, we consider and compare two models of correlated electrons, the Hubbard model and the periodic Anderson model. The results are discussed in regard to recent experiments. In the Hubbard model, we predict an anomalous enhancement optical spectral weight as a function of temperature in the correlated metallic state which is in qualitative agreement with optical measurements in V 2 O 3 . We argue that anomalies observed in the spectroscopy of the metal are connected to the proximity to a crossover region in the phase diagram of the model. In the insulating phase, we obtain excellent agreement with the experimental data, and present a detailed discussion on the role of magnetic frustration by studying the k-resolved single-particle spectra. The results for the periodic Anderson model are discussed in connection to recent experimental data of the Kondo insulators Ce 3 Bi 4 Pt 3 and FeSi. The model can successfully explain the thermal filling of the optical gap and the corresponding changes in the photoemission density of states. The temperature dependence of the optical sum rule is obtained, and its relevance to the interpretation of the experimental data discussed. Finally, we argue that the large scattering rate measured in Kondo insulators cannot be described by the periodic Anderson model. copyright 1996 The American Physical Society

  6. FT-IR, FT-Raman, UV-visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol.

    Science.gov (United States)

    Chain, Fernando E; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandán, Silvia A

    2015-03-05

    In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G(∗) basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated (1)H NMR and (13)C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Application of Fourier transform infrared (FT-IR) spectroscopy to the study of the modification of epoxidized sunflower oil by acrylation.

    Science.gov (United States)

    Irinislimane, Ratiba; Belhaneche-Bensemra, Naima

    2012-12-01

    Commercial sunflower oil was epoxidized at the laboratory-scale. The epoxidized sunflower oil (ESFO) was modified following the acrylation reaction. Modification was carried out simultaneously using acrylic acid (AA) and triethylamine (TEA). To optimize the reaction conditions, the effects of four temperatures (40, 60, 80, and 100 °C), the ESFO:AA (100:100) ratio, and 0.2% TEA were investigated. The rate of conversion was analyzed with both FT-IR and titration of the oxirane ring. After that, the temperature with the highest conversion was selected and used throughout for all modification reactions. Then, four ratios (100:100, 100:90, 100:80, and 100:75) of ESFO:AA were analyzed at four different concentrations of TEA (0.2, 0.3, 0.4, and 0.5%) to determine the best estimate for both the ESFO:AA ratio and the catalyst concentration. Conversion rate was analyzed using FT-IR spectroscopy by measuring the concentrations of ester, carbonyl, and alcohol groups. Moreover, oxirane-ring concentration was estimated using the titration method (with gentian violet as indicator) and FT-IR spectroscopy (epoxy ring absorptions at 1270 cm(-1) and 877 cm(-1)). Based on conversion yield, the optimum ESFO:AA ratio corresponds to 100:80; the best temperature reaction was at 60 °C, and the best TEA concentration was 0.2%. The critical amounts of reactants needed to reach maximum conversion were established. The final acid value of the acrylated ESFO after washing (pH = 7) was 2.1 mg potassium hydroxide (KOH)·g(-1). All results show that FT-IR spectroscopy is a simple, low-cost, rapid method for investigating the kinetics of a reaction.

  8. Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

    Science.gov (United States)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2017-02-01

    The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (ke) and photon scattering correction factor (ksc) are needed. ke factor corrects the charge loss from the collecting volume and ksc factor corrects the scattering of photons into collecting volume. In this work ke and ksc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the ke and ksc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

  9. Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

    International Nuclear Information System (INIS)

    Mohammadi, S.M.; Tavakoli-Anbaran, H.; Zeinali, H.Z.

    2017-01-01

    The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (k e ) and photon scattering correction factor (k sc ) are needed. k e factor corrects the charge loss from the collecting volume and k sc factor corrects the scattering of photons into collecting volume. In this work k e and k sc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the k e and k sc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

  10. Correlated electronic properties of different SrIrO{sub 3}/SrTiO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Kraberger, Gernot J.; Aichhorn, Markus [Institute of Theoretical and Computational Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria)

    2016-07-01

    Strontium iridates are materials that combine strong electronic correlations with pronounced spin-orbit coupling, giving rise to fascinating physical properties. Strategies to purposefully influence and design these materials are a crucial step to further advance this field. A highly promising candidate for achieving this goal is the formation of heterostructures with other materials. Motivated by this quest, we perform calculations within the DFT+DMFT framework to investigate how the geometry of heterostructures of perovskite SrIrO{sub 3} with SrTiO{sub 3} influences their correlated electronic structure. We explore the differences between (001)- and (111)-stacked heterostructures, where the latter are particularly interesting because they form buckled honeycomb lattices that have non-trivial topological properties. For the (001)-heterostructures the effect of varying the thickness of the SrIrO{sub 3} layers, and thus their effective dimensionality, are studied. As an important ingredient we have to consider the effect of lattice distortions - in the form of a rotation of the oxygen cages - on the electronic correlations. We argue how the interplay of all these factors together allows a targeted modification of the electronic properties of the material.

  11. Faecal near-IR spectroscopy to determine the nutritional value of diets consumed by beef cattle in east Mediterranean rangelands.

    Science.gov (United States)

    Landau, S Y; Dvash, L; Roudman, M; Muklada, H; Barkai, D; Yehuda, Y; Ungar, E D

    2016-02-01

    Rapid assessment of the nutritional quality of diets ingested by grazing animals is pivotal for successful cow-calf management in east Mediterranean rangelands, which receive unpredictable rainfall and are subject to hot-spells. Clipped vegetation samples are seldom representative of diets consumed, as cows locate and graze selectively. In contrast, faeces are easily sampled and their near-IR spectra contain information about nutrients and their utilization. However, a pre-requisite for successful faecal near-infrared reflectance spectroscopy (FNIRS) is that the calibration database encompass the spectral variability of samples to be analyzed. Using confined beef cows in Northern and Southern Israel, we calibrated prediction equations based on individual pairs of known dietary attributes and the NIR spectra of associated faeces (n=125). Diets were composed of fresh-cut green fodder of monocots (wheat and barley), dicots (safflower and garden pea) and natural pasture collected at various phenological states over 2 consecutive years, and, optionally, supplements of barley grain and dried poultry litter. A total of 48 additional pairs of faeces and diets sourced from cows fed six complete mixed rations covering a wide range of energy and CP concentrations. Precision (linearity of calibration, R2cal, and of cross-validation, R2cv) and accuracy (standard error of cross-validation, SEcv) were criteria for calibration quality. The calibrations for dietary ash, CP, NDF and in vitro dry matter digestibility yielded R2cal values >0.87, R2cv of 0.81 to 0.89 and SEcv values of 16, 13, 39 and 31 g/kg dry matter, respectively. Equations for nutrient intake were of low quality, with the exception of CP. Evaluation of FNIRS predictions was carried out with grazing animals supplemented or not with poultry litter, and implementation of the method in one herd over 2 years is presented. The potential usefulness of equations was also established by calculating the Mahalanobis (H

  12. Correlation Effects and Hidden Spin-Orbit Entangled Electronic Order in Parent and Electron-Doped Iridates Sr_{2}IrO_{4}

    Directory of Open Access Journals (Sweden)

    Sen Zhou

    2017-10-01

    Full Text Available Analogs of the high-T_{c} cuprates have been long sought after in transition metal oxides. Because of the strong spin-orbit coupling, the 5d perovskite iridates Sr_{2}IrO_{4} exhibit a low-energy electronic structure remarkably similar to the cuprates. Whether a superconducting state exists as in the cuprates requires understanding the correlated spin-orbit entangled electronic states. Recent experiments discovered hidden order in the parent and electron-doped iridates, some with striking analogies to the cuprates, including Fermi surface pockets, Fermi arcs, and pseudogap. Here, we study the correlation and disorder effects in a five-orbital model derived from the band theory. We find that the experimental observations are consistent with a d-wave spin-orbit density wave order that breaks the symmetry of a joint twofold spin-orbital rotation followed by a lattice translation. There is a Berry phase and a plaquette spin flux due to spin procession as electrons hop between Ir atoms, akin to the intersite spin-orbit coupling in quantum spin Hall insulators. The associated staggered circulating J_{eff}=1/2 spin current can be probed by advanced techniques of spin-current detection in spintronics. This electronic order can emerge spontaneously from the intersite Coulomb interactions between the spatially extended iridium 5d orbitals, turning the metallic state into an electron-doped quasi-2D Dirac semimetal with important implications on the possible superconducting state suggested by recent experiments.

  13. Electron beam interactions with CO on W[100] studied by Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Housley, M.; King, D.A.

    1977-01-01

    The interaction of 2500 eV electrons with carbon monoxide chemisorbed on tungsten [100] was investigated by rapid-scan Auger electron spectroscopy. When no α state was present the O and C signals from the β state of CO were invariant during electron bombardment, giving an upper limit estimate for the electron stimulated desorption cross section, Qsub(β), of 2 x 10 -21 cm 2 . With the crystal at room temperature and saturated with CO, however, electron-beam induced accumulation of carbon was observed and characterised, the rate of the process being independent of CO pressure at pressures above 2 x 10 -8 Torr. At 450 K the rate was found to be pressure dependent up to at least 6 x 10 -7 Torr. A model is proposed for the accumulation process, which is based on electron beam dissociation of α 2 -CO to form adsorbed carbon and gaseous O and the creation of new sites for further α 2 -CO adsorption; it is in quantitative agreement with the results and yields a cross section for ESD of α 2 -CO (Qsub(α 2 )=1.55 X 10 -18 cm 2 ) in clo 2 e agreement with direct measurements. (Auth.)

  14. Differentiation between probiotic and wild-type Bacillus cereus isolates by antibiotic susceptibility test and Fourier transform infrared spectroscopy (FT-IR).

    Science.gov (United States)

    Mietke, Henriette; Beer, W; Schleif, Julia; Schabert, G; Reissbrodt, R

    2010-05-30

    Animal feed often contains probiotic Bacillus strains used as feed additives. Spores of the non-pathogenic B. cereus var. toyoi (product name Toyocerin) are used. Distinguishing between toxic wild-type Bacillus cereus strains and this probiotic strain is essential for evaluating the quality and risk of feed. Bacillus cereus CIP 5832 (product name Paciflor was used as probiotic strain until 2001. The properties of the two probiotic strains are quite similar. Differentiating between probiotic strains and wild-type B. cereus strains is not easy. ss-lactam antibiotics such as penicillin and cefamandole exhibit an inhibition zone in the agar diffusion test of probiotic B. cereus strains which are not seen for wild-type strains. Therefore, performing the agar diffusion test first may make sense before FT-IR testing. When randomly checking these strains by Fourier transform infrared spectroscopy (FT-IR), the probiotic B. cereus strains were separated from wild-type B. cereus/B. thuringiensis/B. mycoides/B. weihenstephanensis strains by means of hierarchical cluster analysis. The discriminatory information was contained in the spectral windows 3000-2800 cm(-1) ("fatty acid region"), 1200-900 cm(-1) ("carbohydrate region") and 900-700 cm(-1) ("fingerprint region"). It is concluded that FT-IR spectroscopy can be used for the rapid quality control and risk analysis of animal feed containing probiotic B. cereus strains. (c) 2010 Elsevier B.V. All rights reserved.

  15. A Q-switched Ho:YAG laser assisted nanosecond time-resolved T-jump transient mid-IR absorbance spectroscopy with high sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Deyong; Li, Yunliang; Li, Hao; Weng, Yuxiang, E-mail: yxweng@iphy.ac.cn [Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Xianyou [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, Qingxu [School of Physics and Optoelectronic Technology, Dalian University of Technology, No. 2, Linggong Road, Dalian 116023 (China)

    2015-05-15

    Knowledge of dynamical structure of protein is an important clue to understand its biological function in vivo. Temperature-jump (T-jump) time-resolved transient mid-IR absorbance spectroscopy is a powerful tool in elucidating the protein dynamical structures and the folding/unfolding kinetics of proteins in solution. A home-built setup of T-jump time-resolved transient mid-IR absorbance spectroscopy with high sensitivity is developed, which is composed of a Q-switched Cr, Tm, Ho:YAG laser with an output wavelength at 2.09 μm as the T-jump heating source, and a continuous working CO laser tunable from 1580 to 1980 cm{sup −1} as the IR probe. The results demonstrate that this system has a sensitivity of 1 × 10{sup −4} ΔOD for a single wavelength detection, and 2 × 10{sup −4} ΔOD for spectral detection in amide I′ region, as well as a temporal resolution of 20 ns. Moreover, the data quality coming from the CO laser is comparable to the one using the commercial quantum cascade laser.

  16. Studies of ultrathin magnetic films and particle-surface interactions with spin-sensitive electron spectroscopies

    International Nuclear Information System (INIS)

    Walters, G.K.; Dunning, F.B.

    1991-06-01

    Research during the current grant year has focused on: Investigation of probing depth in electron scattering from epitaxially grown paramagnetic films by means of Spin-Polarized Electron Energy Loss Spectroscopy; and studies of the dynamics of metastable He(2 3 S) deexcitation at surfaces utilizing Spin-Polarized Metastable Deexcitation Spectroscopy . This report discussed this research

  17. The Use and Evaluation of Scaffolding, Student Centered-Learning, Behaviorism, and Constructivism to Teach Nuclear Magnetic Resonance and IR Spectroscopy in a Two-Semester Organic Chemistry Course

    Science.gov (United States)

    Livengood, Kimberly; Lewallen, Denver W.; Leatherman, Jennifer; Maxwell, Janet L.

    2012-01-01

    Since 2002, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry have been introduced at the beginning of the first-semester organic chemistry lab course at this university. Starting in 2008, each individual student was given 20 unique homework problems that consisted of multiple-choice [superscript 1]H NMR and IR problems…

  18. Electronic structure of germanium selenide investigated using ultra-violet photo-electron spectroscopy

    Science.gov (United States)

    Mishra, P.; Lohani, H.; Kundu, A. K.; Patel, R.; Solanki, G. K.; Menon, Krishnakumar S. R.; Sekhar, B. R.

    2015-07-01

    The valence band electronic structure of GeSe single crystals has been investigated using angle resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy. The experimentally observed bands from ARPES, match qualitatively with our LDA-based band structure calculations along the Γ-Z, Γ-Y and Γ-T symmetry directions. The valence band maximum occurs nearly midway along the Γ-Z direction, at a binding energy of -0.5 eV, substantiating the indirect band gap of GeSe. Non-dispersive features associated with surface states and indirect transitions have been observed. The difference in hybridization of Se and Ge 4p orbitals leads to the variation of dispersion along the three symmetry directions. The predominance of the Se 4pz orbitals, evidenced from theoretical calculations, may be the cause for highly dispersive bands along the Γ-T direction. Detailed electronic structure analysis reveals the significance of the cation-anion 4p orbitals hybridization in the valence band dispersion of IV-VI semiconductors. This is the first comprehensive report of the electronic structure of a GeSe single crystal using ARPES in conjugation with theoretical band structure analysis.

  19. Electronic structure of germanium selenide investigated using ultra-violet photo-electron spectroscopy

    International Nuclear Information System (INIS)

    Mishra, P; Lohani, H; Sekhar, B R; Kundu, A K; Menon, Krishnakumar S R; Patel, R; Solanki, G K

    2015-01-01

    The valence band electronic structure of GeSe single crystals has been investigated using angle resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy. The experimentally observed bands from ARPES, match qualitatively with our LDA-based band structure calculations along the Γ–Z, Γ–Y and Γ–T symmetry directions. The valence band maximum occurs nearly midway along the Γ–Z direction, at a binding energy of −0.5 eV, substantiating the indirect band gap of GeSe. Non-dispersive features associated with surface states and indirect transitions have been observed. The difference in hybridization of Se and Ge 4p orbitals leads to the variation of dispersion along the three symmetry directions. The predominance of the Se 4p z orbitals, evidenced from theoretical calculations, may be the cause for highly dispersive bands along the Γ–T direction. Detailed electronic structure analysis reveals the significance of the cation–anion 4p orbitals hybridization in the valence band dispersion of IV–VI semiconductors. This is the first comprehensive report of the electronic structure of a GeSe single crystal using ARPES in conjugation with theoretical band structure analysis. (paper)

  20. IR-spectroscopy of environmental relevant ice-aerosols: Analysis of phase transitions; IR-Spektrometrie umweltrelevanter Eisaerosole: Untersuchung von Phasenuebergaengen

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, T. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Kuestenforschung

    2002-07-01

    Fourier transform infrared spectroscopy was used to investigate the transition area of water from the monomer to nanoparticles. To achieve the ambient temperature range from 130 K to 300 K in a collisional cooling cell a cooled gas plant was established. With the given parameters a transition temperature of 167 K was found. This temperature appeared to be a bifurcation point: small fluctuations of the temperature - due to the fuzzy control of the cell heating - caused distinct changes of the spectra. Slight increments of the temperature extend the transition period monomer/nanoparticle and let significant deviations to the typical particle spectrum occur (appearance and width of the band, respectively). The H{sub 2}O (D{sub 2}O)/He sample gas mixtures were generated by a reliable dew-point technique and were injected into the collisional cooling cell at the corresponding temperature. (orig.)

  1. Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hui; Huang, Chao; Yang, Fan [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Du, Li [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China)

    2015-12-01

    Graphical abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction caused by the addition of Ir. - Highlights: • Mesoporous nanoparticles were synthesized and used as support for metal catalyst. • PdIr bimetallic catalyst exhibited significantly improved hydrogenation activity. • The strong promotion of Ir was recognized firstly and investigated intensively. • PdIr exhibits 18 times higher activity than Pd to the hydrogenation of nitrobenzene. - Abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction

  2. Many-electron effect in the resonant Auger electron spectroscopy spectra of adsorbates

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    It is shown by a many-body theory that a resonantly excited core hole state in a chemisorbed molecule such as CO/Ni, CO/Pd, and CO/Pt relaxes to a fully relaxed one, i.e., the ionized core hole state of the smallest binding energy observed by photoelectron spectroscopy, before the core hole decays so that the resonant Auger electron spectroscopy (RAES) spectrum shows the normal Auger decay spectrum. It is shown by a many-body theory that the Auger peaks on the higher kinetic energy (K.E.) side in the RAES or AES spectrum, i.e., so called back-bonding peaks, are the two-hole states consisting of a valence hole and a hole in the adsorbate-substrate hybrid states below the substrate Fermi level. The latter hole is the change in the density of the hybrid states occupied by the screening electron from the core hole state to the valence-hole state. The difference between the back-bonding peak energy and the single valence-hole energy provides an important information about the change in the density of the hybrid states occupied by the screening electron from the core hole state to the valence-hole state. The difference between the RAES spectrum measured at the resonance energy and the AES spectrum measured at far above the ionization limit shows the competition between relaxation and decay of shakeup satellites such as the charge transfer (CT) shakeup. The relaxation rate of the CT shakeup state can be determined by Auger-photoelectron coincidence spectroscopy (APECS)

  3. Electronic structure of EuN: Growth, spectroscopy, and theory

    DEFF Research Database (Denmark)

    Richter, J. H.; Ruck, B.J.; Simpson, M.

    2011-01-01

    and the lowest-lying 8S multiplet. The Hubbard-I model is also in good agreement with purely atomic multiplet calculations for the Eu M-edge XAS. LSDA+U and DMFT calculations find a metallic ground state, while QSGW results predict a direct band gap at X for EuN of about 0.9 eV that matches closely an absorption...... and QSGW models capture the density of conduction band states better than does LSDA+U. Only the Hubbard-I model contains a correct description of the Eu 4f atomic multiplets and locates their energies relative to the band states, and we see some evidence in XAS for hybridization between the conduction band...... edge seen in optical transmittance at 0.9 eV, and a smaller indirect gap. Overall, the combination of theoretical methods and spectroscopies provides insights into the complex nature of the electronic structure of this material. The results imply that EuN is a narrow-band-gap semiconductor that lies...

  4. Analysis of contaminants on electronic components by reflectance FTIR spectroscopy

    International Nuclear Information System (INIS)

    Griffith, G.W.

    1982-09-01

    The analysis of electronic component contaminants by infrared spectroscopy is often a difficult process. Most of the contaminants are very small, which necessitates the use of microsampling techniques. Beam condensers will provide the required sensitivity but most require that the sample be removed from the substrate before analysis. Since it can be difficult and time consuming, it is usually an undesirable approach. Micro ATR work can also be exasperating, due to the difficulty of positioning the sample at the correct place under the ATR plate in order to record a spectrum. This paper describes a modified reflection beam condensor which has been adapted to a Nicolet 7199 FTIR. The sample beam is directed onto the sample surface and reflected from the substrate back to the detector. A micropositioning XYZ stage and a close-focusing telescope are used to position the contaminant directly under the infrared beam. It is possible to analyze contaminants on 1 mm wide leads surrounded by an epoxy matrix using this device. Typical spectra of contaminants found on small circuit boards are included

  5. Probing the spin-orbit Mott state in Sr3Ir2O7 by electron doping

    Science.gov (United States)

    Hogan, Thomas C.

    Iridium-based members of the Ruddlesden-Popper family of oxide compounds are characterized by a unique combination of energetically comparable effects: crystal-field splitting, spin-orbit coupling, and electron-electron interactions are all present, and the combine to produce a Jeff = 1/2 ground state. In the bilayer member of this series, Sr3Ir2O7, this state manifests as electrically insulating, with unpaired Ir4+ spins aligned along the long axis of the unit cell to produce a G-type antiferromagnet with an ordered moment of 0.36 uB. In this work, this Mott state is destabilized by electron doping via La3+ substitution on the Sr-site to produce (Sr1-x Lax)3Ir2O7. The introduction of carriers initially causes nano-scale phase-separated regions to develop before driving a global insulator-to-metal transition at x=0.04. Coinciding with this transition is the disappearance of evidence of magnetic order in the system in either bulk magnetization or magnetic scattering experiments. The doping also enhances a structural order parameter observed in the parent compound at forbidden reciprocal lattice vectors. A more complete structural solution is proposed to account for this previously unresolved distortion, and also offers an explanation as to the anomalous net ferromagnetism seen prior in bulk measurements. Finally, spin dynamics are probed via a resonant x-ray technique to reveal evidence of spin-dimer-like behavior dominated by inter-plane interactions. This result supports a bond-operator treatment of the interaction Hamiltonian, and also explains the doping dependence of high temperature magnetic susceptibility.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yedra, Ll.; Estradé, S., E-mail: sestrade@ub.edu [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); TEM-MAT, CCiT, Universitat de Barcelona, Solé i Sabarís 1, 08028 Barcelona (Spain); Torruella, P.; Eljarrat, A.; Peiró, F. [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Darbal, A. D. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); Weiss, J. K. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); NanoMEGAS SPRL, Blvd. Edmond Machtens 79, B-1080 Brussels (Belgium)

    2014-08-04

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

  7. The effect of defects and disorder on the electronic properties of ZnIr2O4

    International Nuclear Information System (INIS)

    Ramo, David Muñoz; Bristowe, Paul D.

    2014-01-01

    We analyze by means of ab initio calculations the role of imperfections on the electronic structure of ZnIr 2 O 4 , ranging from point defects in the spinel phase to the fully amorphous phase. We find that interstitial defects and anion vacancies in the spinel have large formation energies, in agreement with the trends observed in other spinels. In contrast, cation vacancies and antisites have lower formation energies. Among them, the zinc antisite and the zinc vacancy are the defects with the lowest formation energy. They are found to act as acceptors, and may be responsible for the spontaneous hole doping in the material. They may also induce optical transitions that would reduce the transparency of the material. Amorphization of ZnIr 2 O 4 leads a large decrease of the band gap and appearance of localized states at the edges of the band gap region, which may act as charge traps and prevent amorphous ZnIr 2 O 4 from being a good hole conductor

  8. The effect of defects and disorder on the electronic properties of ZnIr{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Ramo, David Muñoz, E-mail: dm586@cam.ac.uk; Bristowe, Paul D., E-mail: pdb1000@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-08-28

    We analyze by means of ab initio calculations the role of imperfections on the electronic structure of ZnIr{sub 2}O{sub 4}, ranging from point defects in the spinel phase to the fully amorphous phase. We find that interstitial defects and anion vacancies in the spinel have large formation energies, in agreement with the trends observed in other spinels. In contrast, cation vacancies and antisites have lower formation energies. Among them, the zinc antisite and the zinc vacancy are the defects with the lowest formation energy. They are found to act as acceptors, and may be responsible for the spontaneous hole doping in the material. They may also induce optical transitions that would reduce the transparency of the material. Amorphization of ZnIr{sub 2}O{sub 4} leads a large decrease of the band gap and appearance of localized states at the edges of the band gap region, which may act as charge traps and prevent amorphous ZnIr{sub 2}O{sub 4} from being a good hole conductor.

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

    Science.gov (United States)

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

    2015-06-28

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

  10. Identification of Serine Conformers by Matrix-Isolation IR Spectroscopy Aided by Near-Infrared Laser Induced Conformational Change, 2D Correlation Analysis, and Quantum Mechanical Anharmonic Computations

    Science.gov (United States)

    Najbauer, Eszter E.; Bazsó, Gábor; Apóstolo, Rui; Fausto, Rui; Biczysko, Malgorzata; Barone, Vincenzo; Tarczay, György

    2018-01-01

    The conformers of α-serine were investigated by matrix-isolation IR spectroscopy combined with NIR laser irradiation. This method, aided by 2D correlation analysis, enabled unambiguously grouping the spectral lines to individual conformers. On the basis of comparison of at least nine experimentally observed vibrational transitions of each conformer with empirically scaled (SQM) and anharmonic (GVPT2) computed IR spectra, 6 conformers were identified. In addition, the presence of at least one more conformer in Ar matrix was proved, and a short-lived conformer with a half-live of (3.7±0.5)·103 s in N2 matrix was generated by NIR irradiation. The analysis of the NIR laser induced conversions revealed that the excitation of the stretching overtone of both the side-chain and the carboxylic OH groups can effectively promote conformational changes, but remarkably different paths were observed for the two kinds of excitations. PMID:26201050

  11. IR + VUV double resonance spectroscopy and extended density functional theory studies of ketone solvation by alcohol: 2-butanone·(methanol)n, n = 1-4 clusters.

    Science.gov (United States)

    Shin, Joong-Won; Bernstein, Elliot R

    2017-09-28

    Infrared plus vacuum ultraviolet (IR + VUV) photoionization vibrational spectroscopy of 2-butanone/methanol clusters [MEK·(MeOH) n , n = 1-4] is performed to explore structures associated with hydrogen bonding of MeOH molecules to the carbonyl functional group of the ketone. IR spectra and X3LYP/6-31++G(d,p) calculations show that multiple isomers of MEK·(MeOH) n are generated in the molecular beam as a result of several hydrogen bonding sites available to the clusters throughout the size range investigated. Isomer interconversion involving solvating MeOH rearrangement should probably occur for n = 1 and 2. The mode energy for a hydrogen bonded OH stretching transition gradually redshifts as the cluster size increases. Calculations suggest that the n = 3 cluster isomers adopt structures in which the MEK molecule is inserted into the cyclic MeOH hydrogen bond network. In larger structures, the cyclic network may be preserved.

  12. Detection of Soluble and Fixed NH4+ in Clay Minerals by DTA and IR Reflectance Spectroscopy : A Potential Tool for Planetary Surface Exploration

    Science.gov (United States)

    Janice, Bishop; Banin, A.; Mancinelli, R. L.; Klovstad, M. R.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Nitrogen is an essential element for life. It is the only element among the six major biogenic elements, C, O, S, O, P, H, whose presence in the Martian soil has not been positively and directly established. We describe here a study assessing the ability to detect NH4 in soils by two methods: differential thermal analysis (DTA) and infrared (IR) reflectance spectroscopy. Four standard clay minerals (kaolinite, montmorillonite, illite and attapulgite) and an altered tephra sample from Mauna Kea were treated with NH4 in this study. Samples of the NH4-treated and leached clays were analyzed by DTA and infrared (IR) reflectance spectroscopy to quantify the delectability of soluble and sorbed/fixed NH4. An exotherm at 270-280 C was clearly detected in the DTA curves of NH4-treated (non-leached) samples. This feature is assigned to the thermal decomposition reaction of NH4. Spectral bands observed at 1.56, 2.05, 2.12, 3.06, 3.3, 3.5, 5.7 and 7.0 microns in the reflectance spectra of NH4-treated and leached samples are assigned to the sorbed/fixed ammonium in the clays. The montmorillonite has shown the most intense absorbance due to fixed ammonium among the leached samples in this study, as a result of its high cation sorption capacity. It is concluded that the presence of sorbed or fixed NH4 in clays may be detected by infrared (IR) reflectance or emission spectroscopy. Distinction between soluble and sorbed NH4 may be achieved through the presence or absence of several spectral features assigned to the sorbed NH4 moietyi and, specifically, by use of the 4.2 micrometer feature assigned to solution NH4. Thermal analyses furnish supporting evidence of ammonia in our study through detection of N released at temperatures of 270-330 C. Based on these results it is estimated that IR spectra measured from a rover should be able to detect ammonia if present above 20 mg NH4/g sample in the surface layers. Orbital IR spectra and thermal analyses measured on a rover may be able to

  13. Electron energy loss spectroscopy microanalysis and imaging in the transmission electron microscope: example of biological applications

    International Nuclear Information System (INIS)

    Diociaiuti, Marco

    2005-01-01

    This paper reports original results obtained in our laboratory over the past few years in the application of both electron energy loss spectroscopy (EELS) and electron spectroscopy imaging (ESI) to biological samples, performed in two transmission electron microscopes (TEM) equipped with high-resolution electron filters and spectrometers: a Gatan model 607 single magnetic sector double focusing EEL serial spectrometer attached to a Philips 430 TEM and a Zeiss EM902 Energy Filtering TEM. The primary interest was on the possibility offered by the combined application of these spectroscopic techniques with those offered by the TEM. In particular, the electron beam focusing available in a TEM allowed us to perform EELS and ESI on very small sample volumes, where high-resolution imaging and electron diffraction techniques can provide important structural information. I show that ESI was able to improve TEM performance, due to the reduced chromatic aberration and the possibility of avoiding the sample staining procedure. Finally, the analysis of the oscillating extended energy loss fine structure (EXELFS) beyond the ionization edges characterizing the EELS spectra allowed me, in a manner very similar to the extended X-ray absorption fine structure (EXAFS) analysis of the X-ray absorption spectra, to obtain short-range structural information for such light elements of biological interest as O or Fe. The Philips EM430 (250-300 keV) TEM was used to perform EELS microanalysis on Ca, P, O, Fe, Al and Si. The assessment of the detection limits of this method was obtained working with well-characterized samples containing Ca and P, and mimicking the actual cellular matrix. I applied EELS microanalysis to Ca detection in bone tissue during the mineralization process and to P detection in the cellular membrane of erythrocytes treated with an anti-tumoral drug, demonstrating that the cellular membrane is a drug target. I applied EELS microanalysis and selected area electron

  14. Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

    Energy Technology Data Exchange (ETDEWEB)

    Dicken, D. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Tadhunter, C. [University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Morganti, R. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Axon, D.; Robinson, A.; Magagnoli, M. [Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Kharb, P. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Ramos Almeida, C. [Instituto de Astrofisica de Canarias (IAC), C/V ia Lactea, s/n, E-38205 La Laguna, Tenerife (Spain); Mingo, B. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Hardcastle, M. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nesvadba, N. P. H.; Singh, V. [Institut d' Astrophysique Spatiale, CNRS, Université Paris Sud, F-91405 Orsay (France); Kouwenhoven, M. B. N. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871 (China); Rose, M.; Spoon, H. [224 Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Inskip, K. J. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Holt, J., E-mail: daniel.dicken@cea.fr [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2014-06-20

    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

  15. Study of transition metal cations state on the catalyst surface by IR-spectroscopy of adsorbed test-molecules (CO, NO)

    International Nuclear Information System (INIS)

    Davydov, A.A.

    1993-01-01

    Using the methods of IR spectroscopy and ESR spectral manifestations of CO and NO in complexes with cations of vanadium in different oxidation degrees and coordination states have been studied. V 5+ cations do not coordinate NO and CO, but coordinate ammonia. Regular decrease of νCO values in V n+ -CO complexes with vanadium oxidation degree decrease has been shown. Spectral manifestation of NO complexes with V 4+ and V 3+ have been followed. The formation of V 4+ -NO, V 3+ -NO and V 3+ (NO) complexes has been established

  16. DETERMINATION OF CRYSTALLINITY INDEX OF CARBOHYDRATE COMPONENTS IN HEMP (CANNABIS SATIVA L. WOODY CORE BY MEANS OF FT-IR SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    Esat Gümüşkaya

    2005-04-01

    Full Text Available In this study; it was investigated chemical compositions of hemp woody core and changes in crystallinity index of its carbohydrate components by using FT-IR spectroscopy was investigated. It was determined that carbohyrate components ratio in hemp woody core were similar to that in hard wood, but lignin content in hemp woody core was higher than in hard wood. Crystallinity index of carbohydrate components in hemp woody core increased by removing amorphous components. It was designated that monoclinic structure in hemp woody core and its carbohydrate components was dominant, but triclinic ratio increased by treated chemical isolation of carbohydrate from hemp woody core.

  17. Mass spectroscopy of recoiled ions, secondary ion mass spectroscopy, and Auger electron spectroscopy investigation of Y2O3-stabilized ZrO2(100) and (110)

    International Nuclear Information System (INIS)

    Herman, G.S.; Henderson, M.A.; Starkweather, K.A.; McDaniel, E.P.

    1999-01-01

    We have studied the (100) and (110) surfaces of yttria-stabilized cubic ZrO 2 using Auger electron spectroscopy, low energy electron diffraction (LEED), direct recoil spectroscopy, mass spectroscopy of recoiled ions (MSRI), and secondary ion mass spectroscopy (SIMS). The concentration of yttrium at the surface was weakly influenced by the surface structure under the experimental conditions investigated. Both MSRI and SIMS indicated a more enhanced yttrium signal than zirconium signal at the surface compared to the respective bulk concentrations. The surfaces were not very well ordered as indicated by LEED. The yttria-stabilized cubic ZrO 2 single crystal surfaces may not be a suitable model material for pure phase ZrO 2 surfaces due to significant yttria concentrations at the surface. copyright 1999 American Vacuum Society

  18. Using IR spectroscopy and multivariate curve resolution to elucidate mechanism of heat-induced decomposition of an organic complex

    DEFF Research Database (Denmark)

    Karpushkin, Evgeny; Gvozdik, Nataliya; Kucheryavskiy, Sergey V.

    the opportunity to carry out simultaneous thermogravimetry/differential scanning calorimetry analysis and IR/Raman/mass spectrometry investigation of the evolving gaseous products. However, elucidation of the mechanism of the reactions occurring upon heat- ing is not completely straightforward, due to a number...

  19. Modelling high-resolution electron microscopy based on core-loss spectroscopy

    International Nuclear Information System (INIS)

    Allen, L.J.; Findlay, S.D.; Oxley, M.P.; Witte, C.; Zaluzec, N.J.

    2006-01-01

    There are a number of factors affecting the formation of images based on core-loss spectroscopy in high-resolution electron microscopy. We demonstrate unambiguously the need to use a full nonlocal description of the effective core-loss interaction for experimental results obtained from high angular resolution electron channelling electron spectroscopy. The implications of this model are investigated for atomic resolution scanning transmission electron microscopy. Simulations are used to demonstrate that core-loss spectroscopy images formed using fine probes proposed for future microscopes can result in images that do not correspond visually with the structure that has led to their formation. In this context, we also examine the effect of varying detector geometries. The importance of the contribution to core-loss spectroscopy images by dechannelled or diffusely scattered electrons is reiterated here

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

    Science.gov (United States)

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

    2015-10-01

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

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

    International Nuclear Information System (INIS)

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira da Silva, F.; Lange, E. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Institut de Chimie-Bât. B6C, Université de Liège, B-4000 Liège 1 (Belgium); Brunger, M. J., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); and others

    2015-10-14

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

  3. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Laurent, G.; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A.

    2003-01-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O 6+ + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O 4+ (1s 2 nln ' l ' ) populated after double electron-capture events

  4. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nenov, Artur, E-mail: Artur.Nenov@unibo.it; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K. [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Rivalta, Ivan [Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, IFN-CNR, Piazza Leonardo Da Vinci 32, IT-20133 Milano (Italy); Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States); Garavelli, Marco, E-mail: marco.garavelli@unibo.it, E-mail: marco.garavelli@ens-lyon.fr [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France)

    2015-06-07

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

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

    International Nuclear Information System (INIS)

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-01-01

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

  6. Honey bee odorant-binding protein 14: effects on thermal stability upon odorant binding revealed by FT-IR spectroscopy and CD measurements.

    Science.gov (United States)

    Schwaighofer, Andreas; Kotlowski, Caroline; Araman, Can; Chu, Nam; Mastrogiacomo, Rosa; Becker, Christian; Pelosi, Paolo; Knoll, Wolfgang; Larisika, Melanie; Nowak, Christoph

    2014-03-01

    In the present work, we study the effect of odorant binding on the thermal stability of honey bee (Apis mellifera L.) odorant-binding protein 14. Thermal denaturation of the protein in the absence and presence of different odorant molecules was monitored by Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). FT-IR spectra show characteristic bands for intermolecular aggregation through the formation of intermolecular β-sheets during the heating process. Transition temperatures in the FT-IR spectra were evaluated using moving-window 2D correlation maps and confirmed by CD measurements. The obtained results reveal an increase of the denaturation temperature of the protein when bound to an odorant molecule. We could also discriminate between high- and low-affinity odorants by determining transition temperatures, as demonstrated independently by the two applied methodologies. The increased thermal stability in the presence of ligands is attributed to a stabilizing effect of non-covalent interactions between odorant-binding protein 14 and the odorant molecule.

  7. Comparative investigation of Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) in the determination of cotton fiber crystallinity.

    Science.gov (United States)

    Liu, Yongliang; Thibodeaux, Devron; Gamble, Gary; Bauer, Philip; VanDerveer, Don

    2012-08-01

    Despite considerable efforts in developing curve-fitting protocols to evaluate the crystallinity index (CI) from X-ray diffraction (XRD) measurements, in its present state XRD can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous fraction in a sample. The greatest barrier to establishing quantitative XRD is the lack of appropriate cellulose standards, which are needed to calibrate the XRD measurements. In practice, samples with known CI are very difficult to prepare or determine. In a previous study, we reported the development of a simple algorithm for determining fiber crystallinity information from Fourier transform infrared (FT-IR) spectroscopy. Hence, in this study we not only compared the fiber crystallinity information between FT-IR and XRD measurements, by developing a simple XRD algorithm in place of a time-consuming and subjective curve-fitting process, but we also suggested a direct way of determining cotton cellulose CI by calibrating XRD with the use of CI(IR) as references.

  8. 2D IR spectroscopy reveals the role of water in the binding of channel-blocking drugs to the influenza M2 channel

    International Nuclear Information System (INIS)

    Ghosh, Ayanjeet; Gai, Feng; Hochstrasser, Robin M.; Wang, Jun; DeGrado, William F.; Moroz, Yurii S.; Korendovych, Ivan V.; Zanni, Martin

    2014-01-01

    Water is an integral part of the homotetrameric M2 proton channel of the influenza A virus, which not only assists proton conduction but could also play an important role in stabilizing channel-blocking drugs. Herein, we employ two dimensional infrared (2D IR) spectroscopy and site-specific IR probes, i.e., the amide I bands arising from isotopically labeled Ala30 and Gly34 residues, to probe how binding of either rimantadine or 7,7-spiran amine affects the water dynamics inside the M2 channel. Our results show, at neutral pH where the channel is non-conducting, that drug binding leads to a significant increase in the mobility of the channel water. A similar trend is also observed at pH 5.0 although the difference becomes smaller. Taken together, these results indicate that the channel water facilitates drug binding by increasing its entropy. Furthermore, the 2D IR spectral signatures obtained for both probes under different conditions collectively support a binding mechanism whereby amantadine-like drugs dock in the channel with their ammonium moiety pointing toward the histidine residues and interacting with a nearby water cluster, as predicted by molecular dynamics simulations. We believe these findings have important implications for designing new anti-influenza drugs

  9. Simple methods via Mid-IR or {sup 1}H NMR spectroscopy for the determination of the iodine value of vegetable oils

    Energy Technology Data Exchange (ETDEWEB)

    Shimamoto, Gustavo G.; Favaro, Martha M.A.; Tubino, Matthieu, E-mail: tubino@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Química

    2015-07-01

    Two methods for determining the iodine value in vegetable oils are described. One employs mid-infrared (mid-IR) spectroscopy and the other uses hydrogen nuclear magnetic resonance ({sup 1}H NMR). The determination of the iodine value is based on either the transmittance intensity of mid-IR signals or on the {sup 1}H NMR signal integration and multivariate calibration. Both of the methods showed adequate coefficients of determination (r{sup 2} = 0.9974 and 0.9978, respectively) when compared to Wijs method, which is recommended by the norm EN 14111. A statistical comparison between the results from the proposed methods and from Wijs method shows that both instrumental methods offer equivalent results and greater precision compared to Wijs method. The regressions obtained from the constructed models were considered statistically significant and useful for making predictions. The proposed methods present several advantages compared to Wijs method because they significantly reduce analysis time, reagent consumption and waste generation. Furthermore, an analyst can choose between the mid-IR or {sup 1}H NMR to determine the iodine value. (author)

  10. 2D IR spectroscopy reveals the role of water in the binding of channel-blocking drugs to the influenza M2 channel

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Ayanjeet, E-mail: ayanjeet@sas.upenn.edu, E-mail: gai@sas.upenn.edu; Gai, Feng, E-mail: ayanjeet@sas.upenn.edu, E-mail: gai@sas.upenn.edu; Hochstrasser, Robin M. [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Wang, Jun; DeGrado, William F. [Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143 (United States); Moroz, Yurii S.; Korendovych, Ivan V. [Department of Chemistry, Syracuse University, Syracuse, New York 13244 (United States); Zanni, Martin [Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2014-06-21

    Water is an integral part of the homotetrameric M2 proton channel of the influenza A virus, which not only assists proton conduction but could also play an important role in stabilizing channel-blocking drugs. Herein, we employ two dimensional infrared (2D IR) spectroscopy and site-specific IR probes, i.e., the amide I bands arising from isotopically labeled Ala30 and Gly34 residues, to probe how binding of either rimantadine or 7,7-spiran amine affects the water dynamics inside the M2 channel. Our results show, at neutral pH where the channel is non-conducting, that drug binding leads to a significant increase in the mobility of the channel water. A similar trend is also observed at pH 5.0 although the difference becomes smaller. Taken together, these results indicate that the channel water facilitates drug binding by increasing its entropy. Furthermore, the 2D IR spectral signatures obtained for both probes under different conditions collectively support a binding mechanism whereby amantadine-like drugs dock in the channel with their ammonium moiety pointing toward the histidine residues and interacting with a nearby water cluster, as predicted by molecular dynamics simulations. We believe these findings have important implications for designing new anti-influenza drugs.

  11. Temperature-dependent surface structure, composition, and electronic properties of the clean SrTiO3(111) crystal face: Low-energy-electron diffraction, Auger-electron spectroscopy, electron energy loss, and ultraviolet-photoelectron spectroscopy studies

    International Nuclear Information System (INIS)

    Lo, W.J.; Somorjai, G.A.

    1978-01-01

    Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO 2 surface, there are always significant concentrations of Ti 3+ in an annealed ordered SrTiO 3 (111) surface. This stable active Ti 3+ monolayer on top of a substrate with large surface dipole potential makes SrTiO 3 superior to TiO 2 when used as a photoanode in the photoelectrochemical cell

  12. Electron spectroscopy studies of argon K-shell excitation and vacancy cascades

    International Nuclear Information System (INIS)

    Southworth, S.H.; MacDonald, M.A.; LeBrun, T.; Azuma, Y.; Cooper, J.W.

    1995-01-01

    Electron spectroscopy combined with tunable synchrotron radiation has been used for studies of Ar K-shell excitation and vacancy decay processes. In addition, electrons and fluorescent X-rays have been recorded in coincidence to select subsets of the ejected electron spectra. Examples are presented for Ar 1s photoelectrons and KLL and LMM Auger spectra

  13. Crystal structure, IR and Mössbauer spectroscopy and magnetic properties of KZnFe(PO{sub 4}){sub 2} related to the zeolite-ABW-like compounds

    Energy Technology Data Exchange (ETDEWEB)

    Badri, Abdessalem [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia); Hidouri, Mourad, E-mail: mourad_hidouri@yahoo.fr [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia); Wattiaux, Alain [Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux I, 87 Avenue du Dr. A. Schweitzer, Pessac-Cedex 33608 (France); López, María Luisa; Veiga, María Luisa [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid 28040 (Spain); Amara, Mongi Ben [UR Matériaux Inorganiques, Faculté des Sciences, Université de Monastir, Monastir 5019 (Tunisia)

    2014-07-01

    Highlights: • The reported structure of KZnFe(PO{sub 4}){sub 2} is closely related to the zeolite ABW-type. • The structure is described in detail. • The IR and Mössbauer spectroscopy results are reported. • The magnetic properties are developed. - Abstract: The new iron phosphate KZnFe(PO{sub 4}){sub 2} has been synthesized by flux method and solid state reaction, and characterized by X-ray diffraction, IR, Mössbauer spectroscopy and magnetic susceptibility. This compound crystallizes in the monoclinic space group C2/c with the cell parameters: a = 13.514(4) Å, b = 13.273(6) Å, c = 8.742(3) Å and β = 100.07(2)°. It displays strong similarities with the phosphates KCoAl(PO{sub 4}){sub 2} and NaCoPO{sub 4} and features some analogies with the zeolite-ABW structural type. 3D framework is built up by a corner-sharing between MO{sub 4} (M = 0.5 Zn + 0.5 Fe) and PO{sub 4} tetrahedra. The K{sup +} ions are found within crossing tunnels perpendicular to the (1 0 0), (0 1 0) and (0 0 1) planes, delimited by this framework. A Mössbauer study confirmed the presence of Fe{sup 3+} ions in a tetrahedral environment. Magnetic measurements revealed an antiferromagnetic behavior with T{sub N} = 8.5 K.

  14. Identification of Quercus agrifolia (coast live oak resistant to the invasive pathogen Phytophthora ramorum in native stands using Fourier-transform infrared (FT-IR spectroscopy

    Directory of Open Access Journals (Sweden)

    Anna Olivia Conrad

    2014-10-01

    Full Text Available Over the last two decades coast live oak (CLO dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; > 99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern.

  15. Study of Chemical Intermediates by Means of ATR-IR Spectroscopy and Hybrid Hard- and Soft-Modelling Multivariate Curve Resolution-Alternating Least Squares

    Directory of Open Access Journals (Sweden)

    Junxiu Ma

    2017-01-01

    Full Text Available 3,5-Diamino-1,2,4-triazole (DAT became a significant energetic materials intermediate, and the study of its reaction mechanism has fundamental significance in chemistry. The aim of this study is to investigate the ability of online attenuated total reflection infrared (ATR-IR spectroscopy combined with the novel approach of hybrid hard- and soft-modelling multivariate curve resolution-alternating least squares (HS-MCR analysis to monitor and detect changes in structural properties of compound during 3,5-diamino-1,2,4-triazole (DAT synthesis processes. The subspace comparison method (SCM was used to obtain the principal components number, and then the pure IR spectra of each substance were obtained by independent component analysis (ICA and HS-MCR. The extent of rotation ambiguity was estimated from the band boundaries of feasible solutions calculated using the MCR-BANDS procedure. There were five principal components including two intermediates in the process in the results. The reaction rate constants of DAT formation reaction were also obtained by HS-MCR. HS-MCR was used to analyze spectroscopy data in chemical synthesis process, which not only increase the information domain but also reduce the ambiguities of the obtained results. This study provides the theoretical basis for the optimization of synthesis process and technology of energetic materials and provides a strong technical support of research and development of energy material with extraordinary damage effects.

  16. Study of Chemical Intermediates by Means of ATR-IR Spectroscopy and Hybrid Hard- and Soft-Modelling Multivariate Curve Resolution-Alternating Least Squares.

    Science.gov (United States)

    Ma, Junxiu; Qi, Juan; Gao, Xinyu; Yan, Chunhua; Zhang, Tianlong; Tang, Hongsheng; Li, Hua

    2017-01-01

    3,5-Diamino-1,2,4-triazole (DAT) became a significant energetic materials intermediate, and the study of its reaction mechanism has fundamental significance in chemistry. The aim of this study is to investigate the ability of online attenuated total reflection infrared (ATR-IR) spectroscopy combined with the novel approach of hybrid hard- and soft-modelling multivariate curve resolution-alternating least squares (HS-MCR) analysis to monitor and detect changes in structural properties of compound during 3,5-diamino-1,2,4-triazole (DAT) synthesis processes. The subspace comparison method (SCM) was used to obtain the principal components number, and then the pure IR spectra of each substance were obtained by independent component analysis (ICA) and HS-MCR. The extent of rotation ambiguity was estimated from the band boundaries of feasible solutions calculated using the MCR-BANDS procedure. There were five principal components including two intermediates in the process in the results. The reaction rate constants of DAT formation reaction were also obtained by HS-MCR. HS-MCR was used to analyze spectroscopy data in chemical synthesis process, which not only increase the information domain but also reduce the ambiguities of the obtained results. This study provides the theoretical basis for the optimization of synthesis process and technology of energetic materials and provides a strong technical support of research and development of energy material with extraordinary damage effects.

  17. Application of FT-IR Absorption Spectroscopy to Characterize Waste and Bio-Fuels for Pyrolysis and Gasification

    Czech Academy of Sciences Publication Activity Database

    Kalisz, S.; Svoboda, Karel; Robak, Z.; Baxter, D.; Andersen, L. K.

    2008-01-01

    Roč. 8, - (2008), s. 51-52 ISSN 1733-4381 Institutional research plan: CEZ:AV0Z40720504 Keywords : ft-Iir spectroscopy * bio-fuels * gasification Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  18. Imaging of lipids in atherosclerotic lesion in aorta from ApoE/LDLR-/- mice by FT-IR spectroscopy and Hierarchical Cluster Analysis.

    Science.gov (United States)

    P Wrobel, Tomasz; Mateuszuk, Lukasz; Chlopicki, Stefan; Malek, Kamilla; Baranska, Malgorzata

    2011-12-21

    Spectroscopy-based approaches can provide an insight into the biochemical composition of a tissue sample. In the present work Fourier transform infrared (FT-IR) spectroscopy was used to develop a reliable methodology to study the content of free fatty acids, triglycerides, cholesteryl esters as well as cholesterol in aorta from mice with atherosclerosis (ApoE/LDLR(-/-) mice). In particular, distribution and concentration of palmitic, oleic and linoleic acid derivatives were analyzed. Spectral analysis of pure compounds allowed for clear discrimination between free fatty acids and other similar moieties based on the carbonyl band position (1699-1710 cm(-1) range). In order to distinguish cholesteryl esters from triglycerides a ratio of carbonyl band to signal at 1010 cm(-1) was used. Imaging of lipids in atherosclerotic aortic lesions in ApoE/LDLR(-/-) mice was followed by Hierarchical Cluster Analysis (HCA). The aorta from C57Bl/6J control mice (fed with chow diet) was used for comparison. The measurements were completed with an FT-IR spectrometer equipped with a 128 × 128 FPA detector. In cross-section of aorta from ApoE/LDLR(-/-) mice a region of atherosclerotic plaque was clearly identified by HCA, which was later divided into 2 sub-regions, one characterized by the higher content of cholesterol, while the other by higher contents of cholesteryl esters. HCA of tissues deposited on normal microscopic glass, hence limited to the 2200-3800 cm(-1) spectral range, also identified a region of atherosclerotic plaque. Importantly, this region correlates with the area stained by standard histological staining for atherosclerotic plaque (Oil Red O). In conclusion, the use of FT-IR and HCA may provide a novel tool for qualitative and quantitative analysis of contents and distribution of lipids in atherosclerotic plaque.

  19. Constraining the Volatile Composition and Coma Photochemistry in Jupiter Family Comet 41P/Tuttle-Giacobini-Kresak with High Resolution IR and Optical Spectroscopy

    Science.gov (United States)

    McKay, Adam; DiSanti, Michael; Cochran, Anita; Dello Russo, Neil; Bonev, Boncho; Vervack, Ronald; Gibb, Erika; Roth, Nathan; Kawakita, Hideyo

    2018-01-01

    Over the past 20 years optical and IR spectroscopy of cometary comae has expanded our understanding both of cometary volatile composition and coma photochemistry. However, these observations tend to be biased towards Nearly Isotropic Comets (NIC'S) from the Oort Cloud, rather than the generally fainter and less active Jupiter Family Comets (JFC's) that are thought to originate from the Scattered Disk. However, early 2017 provided a rare opportunity to study several JFC's. We present preliminary results from IR and optical spectroscopy of JFC 41P/Tuttle-Giacobini-Kresak obtained during its 2017 apparition. IR spectra were obtained with the NIRSPEC instrument on Keck II and the new iSHELL spectrograph on NASA IRTF. High spectral resolution optical spectra were obtained with the Tull Coude spectrograph on the 2.7-meter Harlan J. Smith Telescope at McDonald Observatory. We will discuss mixing ratios of HCN, NH3, C2H6, C2H2, H2CO, and CH3OH compared to H2O and compare these to previous observations of comets. Preliminary results from the NIRSPEC observations indicate that 41P has typical C2H2 and HCN abundances compared to other JFC's, while the C2H6 abundance is similar to that of NIC's, but is enriched compared to other JFC's. H2CO appears to be heavily depleted in 41P. Analysis of the iSHELL spectra is underway and we will include results from these observations, which complement those from NIRSPEC and extend the scope or our compositional study by measuring additional molecules. We will also present abundances for CN, C2, NH2, C3, and CH obtained from the optical spectra and discuss the implications for the coma photochemistry.This work is supported by the NASA Postdoctoral Program, administered by the Universities Space Research Association, with additional funding from the NSF and NASA PAST.

  20. Time dependent thermal treatment of oxidized MWCNTs studied by the electron and mass spectroscopy methods

    Czech Academy of Sciences Publication Activity Database

    Stobinski, L.; Lesiak, B.; Zemek, Josef; Jiříček, Petr

    2012-01-01

    Roč. 258, č. 20 (2012), s. 7912-7917 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z10100521 Keywords : MWCNTs * ox-MWCNTs * functional materials * electron spectroscopy * mass spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.112, year: 2012

  1. Coordination-resolved local bond relaxation, electron binding-energy shift, and Debye temperature of Ir solid skins

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Maolin [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); Wang, Yan [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); School of Information and Electronic Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); Yang, Xuexian [Department of Physics, Jishou University, Jishou, Hunan 416000 (China); Yang, Yezi [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); Li, Can [Center for Coordination Bond Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 330018 (China); Sun, Chang Q., E-mail: ecqsun@ntu.edu.sg [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2014-11-30

    Highlights: • Cohesive energy of the representative bond determines the core-level shift. • XPS derives the energy level of an isolated atom and its bulk shift. • XPS derives the local bond length, bond energy, binding energy density. • Thermal XPS resolves the Debye temperature and atomic cohesive energy. - Abstract: Numerical reproduction of the measured 4f{sub 7/2} energy shift of Ir(1 0 0), (1 1 1), and (2 1 0) solid skins turns out the following: (i) the 4f{sub 7/2} level of an isolated Ir atom shifts from 56.367 eV to 60.332 eV by 3.965 eV upon bulk formation; (ii) the local energy density increases by up to 130% and the atomic cohesive energy decreases by 70% in the skin region compared with the bulk values. Numerical match to observation of the temperature dependent energy shift derives the Debye temperature that varies from 285.2 K (Surface) to 315.2 K (Bulk). We clarified that the shorter and stronger bonds between under-coordinated atoms cause local densification and quantum entrapment of electron binding energy, which perturbs the Hamiltonian and the core shifts in the skin region.

  2. Studies on low energy ion-atom collisions by means of electron-spectroscopy

    International Nuclear Information System (INIS)

    Hirosi Suzuki

    1991-01-01

    The typical results of studies on autoionization processes produced by low energy ion-atom collisions are given by means of the ejected electron spectroscopy, which have been performed by Atomic Physics Group of Sophia University

  3. Electronic properties of Mn-phthalocyanine–C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Roth, Friedrich; Herzig, Melanie; Knupfer, Martin; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

    2015-01-01

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C 60 (MnPc:C 60 ) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C 60 . Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C 60 bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C 60 to MnPc thin films

  4. Electron emission relevant to inner-shell photoionization of condensed water studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hikosaka, Y., E-mail: hikosaka@las.u-toyama.ac.jp [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan); Mashiko, R.; Konosu, Y.; Soejima, K. [Department of Environmental Science, Niigata University, Niigata 950-2181 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); SOKENDAI, Okazaki 444-8585 (Japan)

    2016-11-15

    Highlights: • Multi-electron coincidence spectroscopy is applied to the study of electron emissions from condensed H2O molecules. • Coincidence Auger spectra are obtained for different photoelectron energies. • The energy distribution of the slow electrons ejected in the Auger decay is deduced from three-fold coincidences. - Abstract: Multi-electron coincidence spectroscopy using a magnetic-bottle electron spectrometer has been applied to the study of the Auger decay following O1s photoionization of condensed H{sub 2}O molecules. Coincidence Auger spectra are obtained for three different photoelectron energy ranges. In addition, the energy distribution of the slow electrons ejected in the Auger decay of the O1s core hole is deduced from three-fold coincidences.

  5. Electron spectroscopy using a multi-detector array

    International Nuclear Information System (INIS)

    Butler, P.A.; Cann, K.J.; Trzaska, W.H.

    1996-01-01

    A description is given of the novel electron spectrometer SACRED, which uses a multi-element Si array to detect cascades of conversion electrons. Its application to the study of deformed structures in 222 Th is described. (orig.)

  6. Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.J.

    2010-04-30

    In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not

  7. Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

    International Nuclear Information System (INIS)

    Zhou, X.J.

    2010-01-01

    In addition to the record high superconducting transition temperature (T c ), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T c , and anomalous normal state properties above T c . In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T c . As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T c superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not thought possible

  8. Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling

    Science.gov (United States)

    Liu, Yan; Yu, Li; Jia, Xiaowen; Zhao, Jianzhou; Weng, Hongming; Peng, Yingying; Chen, Chaoyu; Xie, Zhuojin; Mou, Daixiang; He, Junfeng; Liu, Xu; Feng, Ya; Yi, Hemian; Zhao, Lin; Liu, Guodong; He, Shaolong; Dong, Xiaoli; Zhang, Jun; Xu, Zuyan; Chen, Chuangtian; Cao, Gang; Dai, Xi; Fang, Zhong; Zhou, X. J.

    2015-08-01

    The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations.

  9. Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling.

    Science.gov (United States)

    Liu, Yan; Yu, Li; Jia, Xiaowen; Zhao, Jianzhou; Weng, Hongming; Peng, Yingying; Chen, Chaoyu; Xie, Zhuojin; Mou, Daixiang; He, Junfeng; Liu, Xu; Feng, Ya; Yi, Hemian; Zhao, Lin; Liu, Guodong; He, Shaolong; Dong, Xiaoli; Zhang, Jun; Xu, Zuyan; Chen, Chuangtian; Cao, Gang; Dai, Xi; Fang, Zhong; Zhou, X J

    2015-08-12

    The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations.

  10. Investigation of the Cross-Section Stratifications of Icons Using Micro-Raman and Micro-Fourier Transform Infrared (FT-IR) Spectroscopy.

    Science.gov (United States)

    Lazidou, Dimitra; Lampakis, Dimitrios; Karapanagiotis, Ioannis; Panayiotou, Costas

    2018-01-01

    The cross-section stratifications of samples, which were removed from six icons, are studied using optical microscopy, micro-Raman spectroscopy, and micro-Fourier transform infrared (FT-IR) spectroscopy. The icons, dated from the 14th to 19th centuries, are prominent examples of Byzantine painting art and are attributed to different artistic workshops of ​​northern Greece. The following materials are identified in the cross-sections of the icon samples using micro-Raman spectroscopy: anhydrite; calcite; carbon black; chrome yellow; cinnabar; gypsum; lead white; minium; orpiment; Prussian blue; red ochre; yellow ochre; and a paint of organic origin which can be either indigo ( Indigofera tinctoria L. and others) or woad ( Isatis tinctoria L.). The same samples are investigated using micro-FT-IR which leads to the following identifications: calcite; calcium oxalates; chrome yellow; gypsum; kaolinite; lead carboxylates; lead sulfate (or quartz); lead white; oil; protein; Prussian blue; saponified oil; shellac; silica; and tree resin. The study of the cross-sections of the icon samples reveals the combinations of the aforementioned inorganic and organic materials. Although the icons span over a long period of six centuries, the same stratification comprising gypsum ground layer, paint layers prepared by modified "egg tempera" techniques (proteinaceous materials mixed with oil and resins), and varnish layer is revealed in the investigated samples. Moreover, the presence of three layers of varnishes, one at the top and other two as intermediate layers, in the cross-section analysis of a sample from Virgin and Child provide evidence of later interventions.

  11. In-beam conversion electron spectroscopy using the SACRED array

    International Nuclear Information System (INIS)

    Jones, P.M.; Cann, K.J.; Cocks, J.F.C.; Jones, G.D.; Julin, R.; Schulze, B.; Smith, J.F.; Wilson, A.N.

    1997-01-01

    Conversion electron studies of medium-heavy to heavy nuclear mass systems are important where the internal conversion process begins to dominate over gamma-ray emission. The use of a segmented detector array sensitive to conversion electrons has been used to study multiple conversion electron cascades from nuclear transitions. The application of the silicon array for conversion electron detection (SACRED) for in-beam measurements has successfully been implemented. (orig.). With 2 figs

  12. Growth and trends in Auger-electron spectroscopy and x-ray photoelectron spectroscopy for surface analysis

    International Nuclear Information System (INIS)

    Powell, C.J.

    2003-01-01

    A perspective is given of the development and use of surface analysis, primarily by Auger-electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS), for solving scientific and technological problems. Information is presented on growth and trends in instrumental capabilities, instrumental measurements with reduced uncertainties, knowledge of surface sensitivity, and knowledge and effects of sample morphology. Available analytical resources are described for AES, XPS, and secondary-ion mass spectrometry. Finally, the role of the American Vacuum Society in stimulating improved surface analyses is discussed

  13. Auger electron spectroscopy analysis of high metal content micro-structures grown by electron beam induced deposition

    International Nuclear Information System (INIS)

    Cicoira, F.; Hoffmann, P.; Olsson, C.O.A.; Xanthopoulos, N.; Mathieu, H.J.; Doppelt, P.

    2005-01-01

    An auger electron spectroscopy study was carried out on Rh-containing micro-structures grown by electron beam induced deposition (EBID) of the iso-structural and iso-electronic precursors [RhCl(PF 3 ) 2 ] 2 and [RhCl(CO) 2 ] 2 . A material containing between 55 and 60 at.% Rh was obtained from both precursors. The chemical composition of structures grown from the two different precursors indicates a similar decomposition mechanism. Deposits grown from [RhCl(PF 3 ) 2 ] 2 showed a chemical composition independent of electron energy and electron dose in the investigated range of conditions

  14. Electronic structure investigation of oxidized aluminium films with electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Guo, X.; Canney, S.; Kheifets, A.S.; Vos, M.; Fang, Z.; Utteridge, S.; McCarthy, I.E.; Weigold, E.

    1996-09-01

    Electron momentum spectroscopy (EMS) of (e, 2e) measurements with oxidized aluminium thin films have been performed. Due to the surface sensitive mature of the EMS spectrometer employed the measured (e, 2e) events come from the front oxidized layer as viewed by the electron detectors. The measurements show clearly two major features in the spectral momentum density distribution and they are related to the upper valence band and the lower valence band of aluminum oxide. The first is a 'dual parabola' energy-momentum dispersion pattern spanning about 8 eV in the upper valence band. This 'dual parabola' pattern has been qualitatively reproduced by a linear muffin-tin orbital (LMTO) calculation on spherically averaged α-A1 2 O 3 with nearly the same energy span. In the lower valence band, the LMTO calculation indicates a dispersion spanning about 5 eV, and the measured spectral momentum density plot shows a similar 'bowl' shape but with less dispersion. The possible causes which blur the dispersion in the lower valence band are discussed. Other features in the spectral momentum density distribution are also discussed and compared with the LMTO calculation. 45 refs., 1 tab., 10 figs

  15. First quantitative measurements by IR spectroscopy of dioxins and furans by means of broadly tunable quantum cascade lasers

    International Nuclear Information System (INIS)

    Siciliani de Cumis, M; D’Amato, F; Viciani, S; Patrizi, B; Foggi, P; Galea, C L

    2013-01-01

    We demonstrate the possibility of a quantitative analysis of the concentration of several dioxins and furans, among the most toxic ones, by only using infrared absorption laser spectroscopy. Two broadly tunable quantum cascade lasers, emitting in the mid-infrared, have been used to measure the absorption spectra of dioxins and furans, dissolved in CCl 4 , in direct absorption mode. The minimum detectable concentrations are inferred by analyzing diluted samples. A comparison between this technique and standard Fourier transform spectroscopy has been carried out and an analysis of future perspectives is reported. (paper)

  16. Experimental results from a DC photocathode electron gun for an IR FEL

    International Nuclear Information System (INIS)

    Kehne, D.; Engwall, D.; Legg, R.; Shinn, M.

    1997-01-01

    A 350 keV DC photocathode gun capable of delivering the high-brightness CW electron beam necessary for Jefferson Lab's infrared free-electron laser is described. The gun is to be used with a superconducting radiofrequency linac operating at 1.497 GHz and is mode-locked to the 40th subharmonic of the fundamental using a Nd:YLF drive laser. The gun provides 20--25 ps bunches at up to 135 pC/bunch. Experimental measurements of transverse and longitudinal beam properties are presented. Transverse emittance is measured using a slit-wire scanner emittance meter, and energy spread is measured using the slit and a spectrometer magnet. Longitudinal emittance is measured using a combination of sampling aperture, kicker cavity, slit and spectrometer. Measurements for bunch charges of 135 pC are described and compared with simulations

  17. The New High Magnetic Field Laboratory at Dresden: a Pulsed-Field Laboratory at an IR Free-Electron-Laser

    International Nuclear Information System (INIS)

    Pobell, F.; Bianchi, A. D.; Herrmannsdoerfer, T.; Krug, H.; Zherlitsyn, S.; Zvyagin, S.; Wosnitza, J.

    2006-01-01

    We report on the construction of a new high magnetic field user laboratory which will offer pulsed-field coils in the range (60 T, 500 ms, 40 mm) to (100 T, 10 ms, 20 mm) for maximum field, pulse time, and bore diameter of the coils. These coils will be energized by a modular 50 MJ/24 kV capacitor bank. Besides many other experimental techniques, as unique possibilities NMR in pulsed fields as well as infrared spectroscopy at 5 to 150 μm will be available by connecting the pulsed field laboratory to a nearby free-electron-laser facility

  18. Polar phonons in β-Ga2O3 studied by IR reflectance spectroscopy and first-principle calculations

    Science.gov (United States)

    Azuhata, Takashi; Shimada, Kazuhiro

    2017-08-01

    IR reflectance spectra of β-Ga2O3 are measured in the range from 400 to 1100 cm-1 using the (\\bar{2}01) and (010) planes for pure transverse Au- and Bu-mode phonons, respectively. The spectra measured using the (010) plane depend remarkably on the polarization direction of the incident light because of the monoclinic symmetry. Reflectance spectra simulated using parameters obtained from first-principle calculations are in good agreement with the experimental spectra. By adjusting the calculated phonon parameters so as to reproduce the experimental spectra, the polar phonon parameters were determined for six modes above 400 cm-1.

  19. Synthesis, structural, X-ray photoelectron spectroscopy (XPS) studies and IR induced anisotropy of Tl{sub 4}HgI{sub 6} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine); Khyzhun, O.Y. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Piasecki, M. [Institute of Physics, J. Dlugosz University Częstochowa, Armii Krajowej 13/15, Częstochowa (Poland); Kityk, I.V., E-mail: iwank74@gmail.com [Electrical Engineering Department, Czestochowa University Technology, Armii Krajowej 17, PL-42-217, Czestochowa (Poland); Lakshminarayana, G. [Wireless and Photonic Networks Research Centre, Faculty of Engineering, Universiti Putra Malaysia, 43400, Serdang, Selangor (Malaysia); Luzhnyi, I. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky St., 03142, Kyiv (Ukraine); Fochuk, P.M. [Yuriy Fed’kovych Chernivtsi National University, 2 Kotziubynskoho Str., 58012, Chernivtsi (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, Pekarska Street 50, 79010, Lviv (Ukraine); Levkovets, S.I.; Yurchenko, O.M.; Piskach, L.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, Voli Ave. 13, Lutsk, 43025 (Ukraine)

    2017-02-01

    In the present work, we report on the synthesis and structural properties including X-ray protoelectron spectroscopy (XPS) analysis of Tl{sub 4}HgI{sub 6} crystals that were grown by Bridgman-Stockbarger method up to 80 mm in length and 18 mm in diameter. The existence of the ternary compound Tl{sub 4}HgI{sub 6} that melts incongruently at 641 K was confirmed. Phase equilibria and structural properties for the TlI–HgI{sub 2} system were investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD) methods. X-ray photoelectron spectra were measured for both pristine and Ar{sup +} ion-bombarded Tl{sub 4}HgI{sub 6} single crystal surfaces. The data reveal that the Tl{sub 4}HgI{sub 6} single crystal is sensitive with respect to Ar{sup +} ion-bombardment as 3.0 keV Ar{sup +} irradiation over 5 min at an ion current density 14 μA/cm{sup 2} induces changes to the elemental stoichiometry of the Tl{sub 4}HgI{sub 6} surface, leading to a decrease of the mercury content in the topmost surface layers. X-ray photoelectron spectroscopy (XPS) measurements indicate very low hygroscopic nature of the Tl{sub 4}HgI{sub 6} single crystal surface. The IR coherent bicolor laser treatment at wavelengths 10.6/5.3 μm has shown an occurrence of anisotropy at wavelengths 1540 nm of Er:glass laser. This may open the applications of Tl{sub 4}HgI{sub 6} as a material for IR laser triggering. - Highlights: • Phase diagram of the HgI{sub 2}–TlI system was built. • Tl{sub 4}HgI{sub 6} single crystals were grown by Bridgman Stockbarger method. • XRD, XPS analysis was done. • Ir induced anisotropy was established. • The compounds may be proposed as Ir laser operated polarizers.

  20. Determination of alkaloids in capsules, milk and ethanolic extracts of poppy (Papaver somniferum L.) by ATR-FT-IR and FT-Raman spectroscopy.

    Science.gov (United States)

    Schulz, Hartwig; Baranska, Malgorzata; Quilitzsch, Rolf; Schütze, Wolfgang

    2004-10-01

    Fourier transform (FT) infrared spectroscopy using a diamond composite ATR crystal and NIR-FT-Raman spectroscopy techniques were applied for the simultaneous identification and quantification of the most important alkaloids in poppy capsules. Most of the characteristic Raman signals of the alkaloids can be identified in poppy milk isolated from unripe capsules. But also poppy extracts present specific bands relating clearly to the alkaloid fraction. Raman spectra obtained by excitation with a Nd:YAG laser at 1064 nm show no disturbing fluorescence effects; therefore the plant tissue can be recorded without any special preparation. The used diamond ATR technique allows to measure very small sample amounts (5-10 microL or 2-5 mg) without the necessity to perform time-consuming pre-treatments. When applying cluster analysis a reliable discrimination of "low-alkaloid" and "high-alkaloid" poppy single-plants can be easily achieved. The examples presented in this study provide clear evidence of the benefits of Raman and ATR-IR spectroscopy in efficient quality control, forensic analysis and high-throughput evaluation of poppy breeding material.

  1. Melting of a beta-Hairpin Peptide Using Isotope-Edited 2D IR Spectroscopy and Simulations

    NARCIS (Netherlands)

    Smith, Adam W.; Lessing, Joshua; Ganim, Ziad; Peng, Chunte Sam; Tokmakoff, Andrei; Roy, Santanu; Jansen, Thomas L. C.; Knoester, Jasper

    2010-01-01

    Isotope-edited two-dimensional infrared spectroscopy has been used! to characterize the conformational heterogeneity of the beta-hairpin peptide TrpZip2 (17.2) across its thermal unfolding transition Four isotopologues were synthesized to probe hydrogen bonding and solvent exposure of the beta-turn

  2. Melting of a beta-hairpin peptide using isotope-edited 2D IR spectroscopy and simulations.

    NARCIS (Netherlands)

    Smith, A.W.; Lessing, J.; Ganim, Z.; Peng, C.S.; Tokmakoff, A.; Roy, S.; Jansen, T.L.Th.A.; Knoester, J.

    2010-01-01

    Isotope-edited two-dimensional infrared spectroscopy has been used to characterize the conformational heterogeneity of the beta-hairpin peptide TrpZip2 (TZ2) across its thermal unfolding transition. Four isotopologues were synthesized to probe hydrogen bonding and solvent exposure of the beta-turn

  3. Status of the development of electron volt inelastic neutron spectroscopy

    International Nuclear Information System (INIS)

    Newport, R.J.; Taylor, A.D.; Williams, W.G.

    1984-05-01

    High energy inelastic neutron scattering spectroscopy is reviewed in the light of material presented at the 'High Energy Excitations in Condensed Matter' (HEECM) Workshop, held at Los Alamos National Laboratory 13-15 February 1984. Particular attention is paid to the development of instrumentation based on nuclear resonance analysers. (author)

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

    Science.gov (United States)

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

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

  5. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopics of a mixed actinide sample has been proposed by measuring the coincidence of the alpha particle during radioactive decay with the conversion electron (or Auger) emitted during the relaxation of the daughter isotope. This presents a unique signature to allow the deconvolution of isotopes that possess overlapping alpha particle energy. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector. A passivated ion implanted planar silicon detector provided measurements of alpha spectroscopy. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information to aid in the coincident measurement approach.

  6. Efficient spin transitions in inelastic electron tunneling spectroscopy.

    Science.gov (United States)

    Lorente, Nicolás; Gauyacq, Jean-Pierre

    2009-10-23

    The excitation of the spin degrees of freedom of an adsorbed atom by tunneling electrons is computed using strong coupling theory. Recent measurements [Heinrich, Science 306, 466 (2004)] reveal that electron currents in a magnetic system efficiently excite its magnetic moments. Our theory shows that the incoming electron spin strongly couples with that of the adsorbate so that memory of the initial spin state is lost, leading to large excitation efficiencies. First-principles transmissions are evaluated in quantitative agreement with the experiment.

  7. Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

    Science.gov (United States)

    Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

    2017-09-13

    Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

  8. Sulfato/thiosulfato reducing bacteria characterization by FT-IR spectroscopy: a new approach to biocorrosion control.

    Science.gov (United States)

    Rubio, Celine; Ott, Christelle; Amiel, Caroline; Dupont-Moral, Isabelle; Travert, Josette; Mariey, Laurence

    2006-03-01

    Sulfato and Thiosulfato Reducing Bacteria (SRB, TRB) can induce corrosion process on steel immersed in seawater. This phenomenon, called biocorrosion, costs approximatively 5 billion euros in France each year. We provide the first evidence that Fourier Transformed InfraRed (FTIR) spectroscopy is a competitive technique to evaluate the sulfurogen flora involved in biocorrosion in comparison with time consuming classical identification methods or PCR analyses. A great discrimination was obtained between SRB, TRB and some contamination bacteria known to be present in seawater and seem to be able to reduce sulfate under particular conditions. Moreover, this preliminary study demonstrates that FTIR spectroscopic and genotypic results present a good correlation (these results are confirmed by other data obtained before or later, data not shown here). The advantages gained by FTIR spectroscopy are to give information on strain phenotype and bacterial metabolism which are of great importance in corrosion processes.

  9. Enhancing the sensitivity of mid-IR quantum cascade laser-based cavity-enhanced absorption spectroscopy using RF current perturbation.

    Science.gov (United States)

    Manfred, Katherine M; Kirkbride, James M R; Ciaffoni, Luca; Peverall, Robert; Ritchie, Grant A D

    2014-12-15

    The sensitivity of mid-IR quantum cascade laser (QCL) off-axis cavity-enhanced absorption spectroscopy (CEAS), often limited by cavity mode structure and diffraction losses, was enhanced by applying a broadband RF noise to the laser current. A pump-probe measurement demonstrated that the addition of bandwidth-limited white noise effectively increased the laser linewidth, thereby reducing mode structure associated with CEAS. The broadband noise source offers a more sensitive, more robust alternative to applying single-frequency noise to the laser. Analysis of CEAS measurements of a CO(2) absorption feature at 1890  cm(-1) averaged over 100 ms yielded a minimum detectable absorption of 5.5×10(-3)  Hz(-1/2) in the presence of broadband RF perturbation, nearly a tenfold improvement over the unperturbed regime. The short acquisition time makes this technique suitable for breath applications requiring breath-by-breath gas concentration information.

  10. Development of an Electron-Positron Source for Positron Annihilation Lifetime Spectroscopy

    Science.gov (United States)

    2009-12-19

    REPORT Development of an electron- positron source for positron annihilation lifetime spectroscopy : FINAL REPORT 14. ABSTRACT 16. SECURITY...to generate radiation, to accelerate particles, and to produce electrons and positrons from vacuum. From applications using existing high-repetition...theoretical directions. This report reviews work directed toward the application of positron generation from laser interaction with matter 1. REPORT DATE

  11. X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)

    International Nuclear Information System (INIS)

    Marrs, R.E.; Bennett, C.; Chen, M.H.

    1988-01-01

    An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab

  12. Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

    NARCIS (Netherlands)

    Schmitz, O.; Beigman, I. L.; Vainshtein, L. A.; Schweer, B.; Kantor, M.; Pospieszczyk, A.; Xu, Y.; Krychowiak, M.; Lehnen, M.; Samm, U.; Unterberg, B.

    2008-01-01

    Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T-e(r, t) and electron density ne(r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed

  13. A new apparatus for electron-ion multiple coincidence momentum imaging spectroscopy

    International Nuclear Information System (INIS)

    Morishita, Y.; Kato, M.; Pruemper, G.; Liu, X.-J.; Lischke, T.; Ueda, K.; Tamenori, Y.; Oura, M.; Yamaoka, H.; Suzuki, I.H.; Saito, N.

    2006-01-01

    We have developed a new experimental apparatus for the electron-ion multiple coincidence momentum imaging spectroscopy in order to obtain the angular distributions of vibration-resolved photoelectrons from molecules fixed in space. The apparatus consists of a four-stage molecular supersonic jet and a spectrometer analyzing three-dimensional momenta of fragment ions and electrons in coincidence

  14. Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB2 and IrB2

    Science.gov (United States)

    Zhang, R. F.; Legut, D.; Wen, X. D.; Veprek, S.; Rajan, K.; Lookman, T.; Mao, H. K.; Zhao, Y. S.

    2014-09-01

    The energetically most stable orthorhombic structure of OsB2 and IrB2 is dynamically stable for OsB2 but unstable for IrB2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB2 and by an in-plane bond splitting instability in IrB2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB2. In contrast, an in-plane electronic instability in IrB2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB2 nor OsB2 can be intrinsically superhard.

  15. Visible/IR light and x-rays in femtosecond synchronism from an x-ray free-electron laser

    International Nuclear Information System (INIS)

    Adams, B. A.; Experimental Facilities Division

    2005-01-01

    A way is proposed to obtain pulses of visible/infrared light in femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL), using the recently proposed emittance-slicing technique. In an XFEL undulator, only the short section of an electron bunch whose emittance is left unchanged by the slicing will emit intense coherent x-rays in the XFEL undulator. At the same time, the bunch emits highly collimated transition undulator radiation (TUR) into a cone whose opening angle is the reciprocal relativisticity parameter gamma. Due to the variation of the transverse momentum induced by the emittance slicing, the effective number of charges contributing to the TUR varies along the bunch, and is higher in the sliced-out part that emits the coherent x-rays. As with coherent synchrotron radiation (CSR), the TUR is thus coherently enhanced (CTUR) at near-infrared wavelengths. Coming from the same part of the bunch the CTUR and the coherent x-rays are perfectly synchronized to each other. Because both types of radiation are generated in the long straight XFEL undulator, there are no dispersion effects that might induce a timing jitter. With typical XFEL parameters, the energy content of the single optical cycle of near-IR CTUR light is about 100 Nano-Joule, which is quite sufficient for most pump-probe experiments

  16. Hydrogen Bonding in Proteins and Water Studied by Far-IR and Low-Wavenumber Raman Spectroscopy

    International Nuclear Information System (INIS)

    Greve, Tanja Maria; Birklund Andersen, Kristine; Engdahl, Anders; Nelander, Bengt; Faurskov Nielsen, Ole

    2008-01-01

    Far-IR spectra with a synchrotron radiation source were for the first time recorded through a microscope coupled to an FTIR-spectrometer. A comparison with spectra recorded with an ordinary globar source revealed that no artifacts occurred with synchrotron radiation. A comparison of ATR (Si-prism) and transmission spectra of a tetrapeptide showed that the ATR-microscope technique could be applied. ATR- and transmission spectra were recorded of polyglycine and compared to the low wavenumber Raman spectrum in the R(v)-representation. A protein band at 115-125 cm -1 was assigned to hydrogen bond modes. Collectively these modes might drive conformational changes in proteins. Based mainly on previously published results the determination of water with a structure like that in bulk liquid water was performed for human and animal skin samples. Changes in water content were reported for freezing and thawing of human skin biopsies and for human skin with benign or malignant skin diseases.

  17. Dynamics of liquids, molecules, and proteins measured with ultrafast 2D IR vibrational echo chemical exchange spectroscopy.

    Science.gov (United States)

    Fayer, M D

    2009-01-01

    A wide variety of molecular systems undergo fast structural changes under thermal equilibrium conditions. Such transformations are involved in a vast array of chemical problems. Experimentally measuring equilibrium dynamics is a challenging problem that is at the forefront of chemical research. This review describes ultrafast 2D IR vibrational echo chemical exchange experiments and applies them to several types of molecular systems. The formation and dissociation of organic solute-solvent complexes are directly observed. The dissociation times of 13 complexes, ranging from 4 ps to 140 ps, are shown to obey a relationship that depends on the complex's formation enthalpy. The rate of rotational gauche-trans isomerization around a carbon-carbon single bond is determined for a substituted ethane at room temperature in a low viscosity solvent. The results are used to obtain an approximate isomerization rate for ethane. Finally, the time dependence of a well-defined single structural transformation of a protein is measured.

  18. Influence of composition and roughness on the pigment mapping of paintings using mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) and multivariate calibration.

    Science.gov (United States)

    Sessa, Clarimma; Bagán, Héctor; García, Jose Francisco

    2014-10-01

    Mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) is a very interesting technique for artwork characterization purposes. However, the fact that the spectra obtained are a mixture of surface (specular) and volume (diffuse) reflection is a significant drawback. The physical and chemical features of the artwork surface may produce distortions in the spectra that hinder comparison with reference databases acquired in transmission mode. Several studies attempted to understand the influence of the different variables and propose procedures to improve the interpretation of the spectra. This article is focused on the application of mid-IR FORS and multivariate calibration to the analysis of easel paintings. The objectives are the evaluation of the influence of the surface roughness on the spectra, the influence of the matrix composition for the classification of unknown spectra, and the capability of obtaining pigment composition mappings. A first evaluation of a fast procedure for spectra management and pigment discrimination is discussed. The results demonstrate the capability of multivariate methods, principal component analysis (PCA), and partial least squares discrimination analysis (PLS-DA), to model the distortions of the reflectance spectra and to delimitate and discriminate areas of uniform composition. The roughness of the painting surface is found to be an important factor affecting the shape and relative intensity of the spectra. A mapping of the major pigments of a painting is possible using mid-IR FORS and PLS-DA when the calibration set is a palette that includes the potential pigments present in the artwork mixed with the appropriate binder and that shows the different paint textures.

  19. Generation and reactivity of the phenyl cation in cryogenic argon matrices: monitoring the reactions with nitrogen and carbon monoxide directly by IR spectroscopy.

    Science.gov (United States)

    Winkler, Michael; Sander, Wolfram

    2006-08-18

    The phenyl cation 1 has been prepared by co-deposition of iodobenzene 6 or bromobenzene 7 with a microwave-induced argon plasma and characterized by IR spectroscopy in cryogenic argon matrices. The cation can clearly be identified by its strongest absorption at 3110 cm(-1) that is rapidly bleached upon visible light irradiation. This characteristic band is observed neither in the conventional photochemistry of 6 or 7 nor in discharge experiments with alkyl halides or chlorobenzene. The latter finding is in line with energetic considerations. According to density functional theory (DFT) computations, the strongest absorption of 1 is caused by a C-H stretching vibration that involves almost entirely the ortho-hydrogens. This is confirmed by isotopic labeling experiments. Co-deposition of halobenzene/N2 mixtures leads to a decrease of the 3110 cm(-1) absorption, whereas several new signals are detected in the 2200-2400 cm(-1) range of the IR spectrum. Annealing of a matrix that contains 1 and 1% N2 leads to an increase of a broad band at 2260 cm(-1) that is assigned to the benzenediazonium ion 2. A sharp signal at 2327 cm(-1) that had previously been assigned to the N-N stretching vibration of 2 is due to molecular nitrogen. The mechanism that triggers the IR activity of N2 is not yet understood. Annealing of a matrix that contains 1 and 0.5% CO leads to an increase of a broad band at 2217 cm(-1) that is considerably stronger than the 2260 cm(-1) absorption of 2. This signal is assigned to the C-O stretching vibration of the benzoyl cation 12, in excellent agreement with previous investigations of 12 in superacidic media. Some consequences of the measured frequencies with regard to bonding in 2 and 12 are discussed.

  20. A conformational study of protonated noradrenaline by UV-UV and IR dip double resonance laser spectroscopy combined with an electrospray and a cold ion trap method.

    Science.gov (United States)

    Wako, Hiromichi; Ishiuchi, Shun-Ichi; Kato, Daichi; Féraud, Géraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe; Fujii, Masaaki

    2017-05-03

    The conformer-selected ultraviolet (UV) and infrared (IR) spectra of protonated noradrenaline were measured using an electrospray/cryogenic ion trap technique combined with photo-dissociation spectroscopy. By comparing the UV photo dissociation (UVPD) spectra with the UV-UV hole burning (HB) spectra, it was found that five conformers coexist under ultra-cold conditions. Based on the spectral features of the IR dip spectra of each conformer, two different conformations on the amine side chain were identified. Three conformers (group I) were assigned to folded and others (group II) to extended structures by comparing the observed IR spectra with the calculated ones. Observation of the significantly less-stable extended conformers strongly suggests that the extended structures are dominant in solution and are detected in the gas phase by kinetic trapping. The conformers in each group are assignable to rotamers of OH orientations in the catechol ring. By comparing the UV-UV HB spectra and the calculated Franck-Condon spectra obtained by harmonic vibrational analysis of the S 1 state, with the aid of relative stabilization energies of each conformer in the S 0 state, the absolute orientations of catechol OHs of the observed five conformers were successfully determined. It was found that the 0-0 transition of one folded conformer is red-shifted by about 1000 cm -1 from the others. The significant red-shift was explained by a large contribution of the πσ* state to S 1 in the conformer in which an oxygen atom of the meta-OH group is close to the ammonium group.

  1. IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Yicun; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2015-07-07

    Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm{sup −1} and a positive band centered at 1670 cm{sup −1}. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

  2. IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

    Science.gov (United States)

    Ni, Yicun; Skinner, J. L.

    2015-07-01

    Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm-1 and a positive band centered at 1670 cm-1. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

  3. On the Use of Fourier Transform Infrared (FT-IR) Spectroscopy and Synthetic Calibration Spectra to Quantify Gas Concentrations in a Fischer-Tropsch Catalyst System

    Science.gov (United States)

    Ferguson, Frank T.; Johnson, Natasha M.; Nuth, Joseph A., III

    2015-01-01

    One possible origin of prebiotic organic material is that these compounds were formed via Fischer-Tropsch-type (FTT) reactions of carbon monoxide and hydrogen on silicate and oxide grains in the warm, inner-solar nebula. To investigate this possibility, an experimental system has been built in which the catalytic efficiency of different grain-analog materials can be tested. During such runs, the gas phase above these grain analogs is sampled using Fourier transform infrared (FT-IR) spectroscopy. To provide quantitative estimates of the concentration of these gases, a technique in which high-resolution spectra of the gases are calculated using the high-resolution transmission molecular absorption (HITRAN) database is used. Next, these spectra are processed via a method that mimics the processes giving rise to the instrumental line shape of the FT-IR spectrometer, including apodization, self-apodization, and broadening due to the finite resolution. The result is a very close match between the measured and computed spectra. This technique was tested using four major gases found in the FTT reactions: carbon monoxide, methane, carbon dioxide, and water. For the ranges typical of the FTT reactions, the carbon monoxide results were found to be accurate to within 5% and the remaining gases accurate to within 10%. These spectra can then be used to generate synthetic calibration data, allowing the rapid computation of the gas concentrations in the FTT experiments.

  4. Tuning the hybridization and magnetic ground state of electron and hole doped CeOs2Al10 : An x-ray spectroscopy study

    Science.gov (United States)

    Chen, Kai; Sundermann, Martin; Strigari, Fabio; Kawabata, Jo; Takabatake, Toshiro; Tanaka, Arata; Bencok, Peter; Choueikani, Fadi; Severing, Andrea

    2018-04-01

    Here we present linear and circular polarized soft x-ray absorption spectroscopy (XAS) data at the Ce M4 ,5 edges of the electron (Ir) and hole-doped (Re) Kondo semiconductor CeOs2Al10 . Both substitutions have a strong impact on the unusual high Néel temperature TN=28.5 K, and also the direction of the ordered moment in case of Ir. The substitution dependence of the linear dichroism is weak thus validating the crystal-field description of CeOs2Al10 being representative for the Re and Ir substituted compounds. The impact of electron and hole doping on the hybridization between conduction and 4 f electrons is related to the amount of f0 in the ground state and reduction of x-ray magnetic circular dichroism. A relationship of c f -hybridization strength and enhanced TN is discussed. The direction and doping dependence of the circular dichroism strongly supports the idea of strong Kondo screening along the crystallographic a direction.

  5. Catalysis of GTP hydrolysis by small GTPases at atomic detail by integration of X-ray crystallography, experimental, and theoretical IR spectroscopy.

    Science.gov (United States)

    Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R; Gerwert, Klaus; Kötting, Carsten

    2015-10-02

    Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg(2+) coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg(2+) in GTPases. The Mg(2+) coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Catalysis of GTP Hydrolysis by Small GTPases at Atomic Detail by Integration of X-ray Crystallography, Experimental, and Theoretical IR Spectroscopy*

    Science.gov (United States)

    Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R.; Gerwert, Klaus; Kötting, Carsten

    2015-01-01

    Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg2+ coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg2+ in GTPases. The Mg2+ coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. PMID:26272610

  7. Vibrational spectroscopy and analytical electron microscopy studies of Fe-V-O and In-V-O thin films

    CERN Document Server

    Vuk, A S; Drazic, G; Colomban, P

    2002-01-01

    Orthovanadate (M sup 3 sup + VO sub 4; M= Fe, In) and vanadate (Fe sub 2 V sub 4 O sub 1 sub 3) thin films were prepared using sol-gel synthesis and dip coating deposition. Using analytical electron microscopy (AEM), the chemical composition and the degree of crystallization of the phases present in the thin Fe-V-O films were investigated. TEM samples were prepared in both orientations: parallel (plan view) and perpendicular (cross section) to the substrate. In the first stages of crystallization, when the particle sizes were in the nanometer range, the classical identification of phases using electron diffraction was not possible. Instead of measuring d values, experimentally selected area electron diffraction (SAED) patterns were compared to calculated (simulated) patterns in order to determine the phase composition. The problems of evaluating the ratio of amorphous and crystalline phases in thin films are reported. Results of TEM and XRD as well as IR and Raman spectroscopy showed that the films made at lo...

  8. The Electron-Phonon Interaction as Studied by Photoelectron Spectroscopy

    International Nuclear Information System (INIS)

    Lynch, D.W.

    2004-01-01

    With recent advances in energy and angle resolution, the effects of electron-phonon interactions are manifest in many valence-band photoelectron spectra (PES) for states near the Fermi level in metals

  9. Vacuum ultraviolet spectroscopy of some hydrocarbons by electron impact technique

    International Nuclear Information System (INIS)

    Azevedo e Souza, A.C. de.

    1985-07-01

    A detailed description of the construction and operation of the electron impact spectrometer of the Electron Impact Laboratory at the Chemistry Institute of Federal University of Rio de Janeiro are presented. The main characteristics of this spectrometer are: incident energy from 0.5 to 3.0 KeV; angular range from -60 0 to + 60 0 ; energy loss from 0 to 500 eV; energy resolution from 0.5 to 2.5 eV and; electron velocity analyser equal to electrostatic (Mollenstedt type. The data acquisition system is based on a microcomputer Motorola; recently an APPLE II system has been incorporated to the spectrometer. Electron energy loss spectra for the nitrogen molecule as well as for some hydrocarbons (C 2 H 6 , C 2 H 4 , C 2 H 2 ) have been obtained. The data were converted into double differential cross sections and generalized oscillator strenghts. (author) [pt

  10. Microanalysis by spectroscopy of transmitted electron energy losses

    International Nuclear Information System (INIS)

    Colliex, C.; Trebbia, P.

    1978-01-01

    Among the various signals which, in a transmission electron microscope, result from the interactions between the primary beam of well defined energy E 0 and the sample, the spectrum of the energy distribution of the electrons transmitted contains useful informations on the chemical and physical properties of the sample. Consequently the adaptation of an energy dispersive system on an electron microscope enables new fields of research to be investigated, particularly a localised chemical analysis technique with a space resolution scale equal to that of the electron microscope. It is this second aspect that we suggest describing in particular here. Already, this technique appears to be indispensable in the problems arising from the analysis of very small quantities of matter: detection limits in the order of 10 -19 to 10 -20 g (around 100 to 1000 atoms) would seem to be resonably possible [fr

  11. IR spectroscopy and quantum-chemical studies on the binding and activation of CO on metal catalysts. IR-spektroskopische und quantenmechanische Untersuchungen zur Bindung und Aktivierung von Kohlenmonoxid an Metallkatalysatoren

    Energy Technology Data Exchange (ETDEWEB)

    Miessner, H.

    1988-05-04

    The present study is concerned with the investigation of the interaction and activation of CO with metal carrier catalysts. In connection with the catalytic investigations on the generation of oxygenous products from synthesis gas or methanol, attention was directed mainly to rhodium carrier catalysts. The aim of the investigations was to characterise the rhodium catalysts, which, during CO hydrogenation, occupy an exceptional position among the metals of the 8th auxiliary group, and which show a special selectivity with respect to oxygenous C{sub 2}{sup +} products. Since the influence of the carrier is of a decisive importance in this connection, a whole lot of carriers were incorporated in the study: Al{sub 2}O{sub 3}, SiO{sub 2}, TiO{sub 2}, ZnO, MgO, X and Y zeolites with different Si:Al ratios of 1.1-100. To solve the problems mentioned, IR spectroscopy, particularly with the help of CO as a probe molecule, and quantum-chemical model calculations were applied. For interpretation purposes, the results of catalytic CO hydrogenation and of methanol carbonylation as well as of further physico-chemical investigation methods such as temperature-programmed reduction, the chemisorption of hydrogen and CO and the temperature-programmed desorption of CO were consulted. (orig./EF).

  12. Atomic and molecular photoelectron and Auger-electron-spectroscopy studies using synchrotron radiation

    International Nuclear Information System (INIS)

    Southworth, S.H.

    1982-01-01

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were also measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra of the ejected electrons. The double-angle-TOF method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collection efficiency and the elimination of certain systematic errors. An electron spectroscopy study of inner-shell photoexcitation and ionization of Xe, photoelectron angular distributions from H 2 and D 2 , and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

  13. High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Knut, Ronny; Lindblad, Rebecka [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Gorgoi, Mihaela [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Karis, Olof, E-mail: olof.karis@physics.uu.se [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden)

    2013-10-15

    Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems.

  14. High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

    International Nuclear Information System (INIS)

    Knut, Ronny; Lindblad, Rebecka; Gorgoi, Mihaela; Rensmo, Håkan; Karis, Olof

    2013-01-01

    Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems

  15. Electron momentum density measurements by means of positron annihilation and Compton spectroscopy

    International Nuclear Information System (INIS)

    Gerber, W.; Dlubek, G.; Marx, U.; Bruemmer, O.; Prautzsch, J.

    1982-01-01

    The electron momentum density is measured applying positron annihilation and Compton spectroscopy in order to get information about electron wave functions. Compton spectroscopic measurements of Pd-Ag and Cu-Zn alloy systems are carried out taking into account crystal structure, mixability, and order state. Three-dimensional momentum densities of silicon are determined in order to get better information about its electronic structure. The momentum density and the spin density of ferromagnetic nickel are investigated using angular correlation curves

  16. Determination of free radical scavenger agent efficiency in Syrian consumed sunflower oil using FT-IR spectroscopy

    International Nuclear Information System (INIS)

    Allaf, A. W.; Al-Zier, A.

    2013-06-01

    Edible oils can be oxidized spontaneously by thermal process in the presence of atmospheric oxygen causing an oxidation to these oils and forming the hydroperoxides; this oxidative process is a major cause of cooking oils deterioration. Many synthetic or natural antioxidants additives have been used as free radical scavenger agent. In this work, Eugenol methylether has been used as free radical scavenger agent at three different concentrations to heated sunflower oil at 160°C for ten hours using Fourier transform infrared (FTIR) spectroscopy for analysis and evaluations. Before any additives, three characteristic absorption bands were observed at 3544, 3473 and 3290 cm-1 in heated oil. The recorded bands were assigned to 7Tthe unbounded7T, 7Tbounded 7Thydroperoxide or free alcohols 7Tgroups7T and to the O-H stretching alcohol associated group, respectively. After the addition of Eugenol methylether at 0.8 mL/L concentration, the bands intensity of hydroperoxide formation content is reduced. It has been shown that the free radical scavenger agent plays an acceptable role in reducing the hydroperoxide formation content as the result of thermal oxidation. It is proved that FTIR spectroscopy is an effective analytical tool for such investigatio (author).

  17. Electronic structure, superconductivity, and spin fluctuations in the A15 compounds A3B: A = V, Nb; B = Ir,Pt,Au

    International Nuclear Information System (INIS)

    Jarlborg, T.; Junod, A.; Peter, M.

    1983-01-01

    The electronic structure of six A15 compounds V 3 Ir, V 3 Pt, V 3 Au, Nb 3 Ir, Nb 3 Pt, and Nb 3 Au has been determined by means of self-consistent semirelativistic linear muffin-tin orbital band calculations. Parameters related to superconductivity such as electron-phonon coupling, transition temperature, electronic specific heat, and magnetic exchange enhancement are derived from the electronic-structure results. Generally the results obtained agree well with experimental values, with the exception of Nb 3 Pt and V 3 Au. In the former compound the density of states (DOS) has a sharp increase at E/sub F/ making the exact DOS value uncertain. In V 3 Au the high calculated T/sub c/ and the Stoner factor indicate that spin fluctuations may be limiting the T/sub c/. .AE

  18. Resolving molecular vibronic structure using high-sensitivity two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bizimana, Laurie A.; Brazard, Johanna; Carbery, William P.; Gellen, Tobias; Turner, Daniel B., E-mail: dturner@nyu.edu [Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003 (United States)

    2015-10-28

    Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.

  19. Sensing cocaine in saliva with attenuated total reflection infrared (ATR-IR) spectroscopy combined with a one-step extraction method

    Science.gov (United States)

    Hans, Kerstin M.-C.; Gianella, Michele; Sigrist, Markus W.

    2012-03-01

    On-site drug tests have gained importance, e.g., for protecting the society from impaired drivers. Since today's drug tests are majorly only positive/negative, there is a great need for a reliable, portable and preferentially quantitative drug test. In the project IrSens we aim to bridge this gap with the development of an optical sensor platform based on infrared spectroscopy and focus on cocaine detection in saliva. We combine a one-step extraction method, a sample drying technique and infrared attenuated total reflection (ATR) spectroscopy. As a first step we have developed an extraction technique that allows us to extract cocaine from saliva to an almost infrared-transparent solvent and to record ATR spectra with a commercially available Fourier Transform-infrared spectrometer. To the best of our knowledge this is the first time that such a simple and easy-to-use one-step extraction method is used to transfer cocaine from saliva into an organic solvent and detect it quantitatively. With this new method we are able to reach a current limit of detection around 10 μg/ml. This new extraction method could also be applied to waste water monitoring and controlling caffeine content in beverages.

  20. Hydrogel-Embedded Model Photocatalytic System Investigated by Raman and IR Spectroscopy Assisted by Density Functional Theory Calculations and Two-Dimensional Correlation Analysis.

    Science.gov (United States)

    Geitner, Robert; Götz, Stefan; Stach, Robert; Siegmann, Michael; Krebs, Patrick; Zechel, Stefan; Schreyer, Kristin; Winter, Andreas; Hager, Martin D; Schubert, Ulrich S; Gräfe, Stefanie; Dietzek, Benjamin; Mizaikoff, Boris; Schmitt, Michael; Popp, Jürgen

    2018-03-15

    The presented study reports the synthesis and the vibrational spectroscopic characterization of different matrix-embedded model photocatalysts. The goal of the study is to investigate the interaction of a polymer matrix with photosensitizing dyes and metal complexes for potential future photocatalytic applications. The synthesis focuses on a new rhodamine B derivate and a Pt(II) terpyridine complex, which both contain a polymerizable methacrylate moiety and an acid labile acylhydrazone group. The methacrylate moieties are afterward utilized to synthesize functional model hydrogels mainly consisting of poly(ethylene glycol) methacrylate units. The pH-dependent and temperature-dependent behavior of the hydrogels is investigated by means of Raman and IR spectroscopy assisted by density functional theory calculations and two-dimensional correlation spectroscopy. The spectroscopic results reveal that the Pt(II) terpyridine complex can be released from the polymer matrix by cleaving the C═N bond in an acid environment. The same behavior could not be observed in the case of the rhodamine B dye although it features a comparable C═N bond. The temperature-dependent study shows that the water evaporation has a significant influence neither on the molecular structure of the hydrogel nor on the model photocatalytic moieties.

  1. Oxidation of substituted alkyl radicals by IrCl62-, Fe(CN)63-, and MnO4- in aqueous solution. Electron transfer versus chlorine transfer from IrCl62-

    International Nuclear Information System (INIS)

    Steenken, S.; Neta, P.

    1982-01-01

    Alkyl radicals substituted at C/sub α/ by alkyl, carboxyl, hydroxyl, alkoxyl, and chlorine react in aqueous solutions with Ir/sup IV/Cl 6 2- to yield Ir(III) species. In the case of substitution by hydroxyl and alkoxyl, the rate constants are in the diffusion-controlled range ((4-6) x 10 9 M -1 s -1 ) and the reaction proceeds by electron transfer. In the case of ethyl, methyl, carboxymethyl, and chloromethyl radicals the rate constants range from 3.1 x 10 9 for ethyl to 2.8 x 10 7 M -1 s -1 for trichloromethyl and the reaction proceeds by chlorine transfer from IrCl 6 2- to the alkyl radical. With isopropyl and tert-butyll radicals the reaction proceeds by both electron and chlorine transfer. Alkyl radicals also react with Fe(CN) 6 3- . The rate constants increase strongly with increasing alkylation at C/sub α/ from 5 x 10 6 for methyl to 3.6 x 10 9 M -1 s -1 for tert-butyl, indicating that the transition state for the reaction is highly polar. Rate constants for reaction of MnO 4 - with alkyl radicals are of the order 10 9 M -1 s -1 . 4 figures, 1 table

  2. Living Matter Observations with a Novel Hyperspectral Supercontinuum Confocal Microscope for VIS to Near-IR Reflectance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Francesca R. Bertani

    2013-10-01

    Full Text Available A broad range hyper-spectroscopic microscope fed by a supercontinuum laser source and equipped with an almost achromatic optical layout is illustrated with detailed explanations of the design, implementation and data. The real novelty of this instrument, a confocal spectroscopic microscope capable of recording high resolution reflectance data in the VIS-IR spectral range from about 500 nm to 2.5 μm wavelengths, is the possibility of acquiring spectral data at every physical point as defined by lateral coordinates, X and Y, as well as at a depth coordinate, Z, as obtained by the confocal optical sectioning advantage. With this apparatus we collect each single scanning point as a whole spectrum by combining two linear spectral detector arrays, one CCD for the visible range, and one InGaAs infrared array, simultaneously available at the sensor output channel of the home made instrument. This microscope has been developed for biomedical analysis of human skin and other similar applications. Results are shown illustrating the technical performances of the instrument and the capability in extracting information about the composition and the structure of different parts or compartments in biological samples as well as in solid statematter. A complete spectroscopic fingerprinting of samples at microscopic level is shown possible by using statistical analysis on raw data or analytical reflectance models based on Abelés matrix transfer methods.

  3. HIGH-RESOLUTION IR ABSORPTION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS IN THE 3 μ m REGION: ROLE OF PERIPHERY

    Energy Technology Data Exchange (ETDEWEB)

    Maltseva, Elena; Petrignani, Annemieke; Buma, Wybren Jan [University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Candian, Alessandra; Mackie, Cameron J.; Tielens, Alexander G. G. M. [Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Huang, Xinchuan [SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Lee, Timothy J. [NASA Ames Research Center, Moffett Field, California 94035-1000 (United States); Oomens, Jos, E-mail: w.j.buma@uva.nl [Radboud University, Toernooiveld 7, 6525 ED Nijmegen (Netherlands)

    2016-11-01

    In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μ m absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950–3150 cm{sup −1} range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μ m region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μ m band, and on features such as the two-component emission character of this band and the 3 μ m emission plateau.

  4. Intra-operative on-line discrimination of kidney cancer from normal tissue by IR ATR spectroscopy of extracellular fluid

    Science.gov (United States)

    Urboniene, V.; Velicka, M.; Ceponkus, J.; Pucetaite, M.; Jankevicius, F.; Sablinskas, V.; Steiner, G.

    2016-03-01

    Determination of cancerous and normal kidney tissues during partial, simple or radical nephrectomy surgery was performed by using differences in the IR absorption spectra of extracellular fluid taken from the corresponding tissue areas. The samples were prepared by stamping of the kidney tissue on ATR diamond crystal. The spectral measurements were performed directly in the OR during surgery for 58 patients. It was found that intensities of characteristic spectral bands of glycogen (880-1200 cm-1) in extracellular fluid are sensitive to the type of the tissue and can be used as spectral markers of tumours. Characteristic spectral band of lactic acid (1730 cm-1) - product of the anaerobic glycolysis, taking place in the cancer cells is not suitable for use as a spectral marker of cancerous tissue, since it overlaps with the band of carbonyl stretch in phospholipids and fatty acids. Results of hierarchical cluster analysis of the spectra show that the spectra of healthy and tumour tissue films can be reliably separated into two groups. On the other hand, possibility to differentiate between tumours of different types and grades remains in question. While the fluid from highly malignant G3 tumour tissue contains highly pronounced glycogen spectral bands and can be well separated from benign and G1 tumours by principal component analysis, the variations between spectra from sample to sample prevent from obtaining conclusive results about the grouping between different tumour types and grades. The proposed method is instant and can be used in situ and even in vivo.

  5. Ultra-Sensitive Transition-Edge Sensors (TESs) for Far-IR/Submm Space-Borne Spectroscopy

    Science.gov (United States)

    Kenyon, M.; Day, P. K.; Bradford, C. M.; Bock, J .J.; Leduc, H. G.

    2011-01-01

    We have built surface micromachined thin-film metallized Si(x)N(y) optical absorbers for transition-edge sensors (TESs) suitable for the Background - Limited far-IR/Submm Spectrograph (BLISS). BLISS is a broadband (38 micrometers - 433 micrometers), grating spectrometer consisting of five wavebands each with a modest resolution of R (is) approx. 1000. Because BLISS requires the effective noise equivalent power (NEP) of the TES to be below 10 (exp 19) W/Hz(exp 1/2), our TESs consist of four long (1000 micrometers), narrow (0.4 micrometers ), and thin (0.25 micrometers ) Si(x) N(y) support beams that reduce the thermal conductance G between the substrate and the optical absorber. To reduce the heat capacity of the absorber and make the response time tau fast enough for BLISS, our absorbers are patterned into a mesh geometry with a fill factor of less than 10%. We use a bilayer of Ti/Au to make the effective impedance of the absorber match the impedance of the incoming radiation for each band. Measurements of the response time of the metallized absorbers to heat pulses show that their heat capacity exceeds the predictions of the Debye model. Our results are suggestive that the surface of the low pressure chemical vapor deposition (LPCVD) Si(x)N(y) used in the absorbers' construction is the source of microstates that dominate the heat capacity.

  6. High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3-micrometers Region: Role of Periphery

    Science.gov (United States)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2017-01-01

    In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3-micrometers absorption band. To this purpose we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 per cm range. The experimental spectra are compared with standard harmonic calculations, and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3-micrometers region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive dataset of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly-condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3-micrometers band, and on features such as the two-component emission character of this band and the 3-micrometers emission plateau.

  7. ATR-IR spectroscopy for the detection of induced-phase transition in Langmuir-Blodgett monolayer film

    International Nuclear Information System (INIS)

    Widayati, Suci

    1996-01-01

    The rate at which a solid substrate is transferred through the Air/Water interface in the Langmuir-Blodgett process of preparing monomolecular films influences the final structure of the transferred film. This phenomenon has been observed from the attenuated total reflectance infra-red (ATR-IR) spectra of fatty acid monolayer transferred onto germanium substrate. This transfer-induced effect is most evidence when the monolayer is transferred from an expanded region of the surface-pressure-molecular area isotherm, but has limited influence on the hydrocarbon chain conformation of film molecules transferred in the condensed phases at high surface pressure. Such a conformational ordering may due to a kinetically limited phase transition taking place in the meniscus formed between the solid substrate and aqueous sub phase. In addition, these results suggest that the structure of the amphiphilic molecules may modulate the extent and nature of the dipping-speed-induced structural changes taking place in the monomolecular L-B film. In order to use monomolecular L-B films to accurately characterize the structure, orientation and phase properties of monolayers at the Air/Water interface, the L-B transfer must be performed at transfer speeds that minimize this structural phase transition

  8. Electron temperature measurements in lowdensity plasmas by helium spectroscopy

    International Nuclear Information System (INIS)

    Brenning, N.

    1977-09-01

    This method to use relative intensities of singlet and triplet lines of neutral helium to measure electron temperature in low-density plasmas is examined. Calculations from measured and theoretical data about transitions in neutral helium are carried out and compared to experimental results. It is found that relative intensities of singlet and triplet lines from neutral helium only can be used for TE determination in low-density, short-duration plasmas. The most important limiting processes are excitation from the metastable 2 3 S level and excitation transfer in collisions between electrons and excited helium atoms. An evaluation method is suggested, which minimizes the effect of these processes. (author)

  9. Intramolecular dynamics due to electron transitions: from photoelectron spectroscopy to Femtochemistry

    International Nuclear Information System (INIS)

    Gadzuk, J.W.

    1999-01-01

    Select spectroscopic and chemical physics problems associated with atomic motion triggered by electronic transitions are the topics of this paper. The story starts with the initial stimulation provided by Dick Brundle's photoelectron spectroscopy studies of adsorbed molecules and continues to contemporary examples in photoelectron spectroscopy and Femtochemistry, all of which are theoretically modelled within a unified framework of time-dependent, driven oscillators and decaying states. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Stochastic stimulated electronic x-ray Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Victor Kimberg

    2016-05-01

    → π * transition. Our theoretical model describes the evolution of the spectral and temporal characteristics of the transmitted x-ray radiation, by solving the equation of motion for the electronic and vibrational degrees of freedom of the system self consistently with the propagation by Maxwell equations.

  11. Electronic structure of palladium and its relation to uv spectroscopy

    DEFF Research Database (Denmark)

    Christensen, N.E.

    1976-01-01

    The electronic-energy-band structure of palladium has been calculated by means of the relativistic augmented-plane-wave method covering energies up to 30 eV above the Fermi level. The optical interband transitions producing structure in the dielectric function up to photon energies of 25 eV have ...

  12. A study of electron scattering through noise spectroscopy

    NARCIS (Netherlands)

    Kumar, Manohar

    2012-01-01

    Charge counting statistics (C.S.) of traversing electron in quantum devices like atomic-molecular junctions is sensitive to the local perturbation in the charge field at the contact and in the quantum channels. The first cumulant of C.S. i.e. current-voltage characteristic of such devices has been

  13. High Energy Electron Dosimetry by Alanine/ESR Spectroscopy

    International Nuclear Information System (INIS)

    Chu, Sung Sil

    1989-01-01

    Dosimetry based on electron spin resonance(ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to l Gy. In a water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies (6-21 MeV) and therapeutic dose levels(1-60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by 2-5% than those calculated by nominal energy CE factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator

  14. Electron beam imaging and spectroscopy of plasmonic nanoantenna resonances

    NARCIS (Netherlands)

    Vesseur, P.C.

    2011-01-01

    Nanoantennas are metal structures that provide strong optical coupling between a nanoscale volume and the far field. This coupling is mediated by surface plasmons, oscillations of the free electrons in the metal. Increasing the control over the resonant plasmonic field distribution opens up a wide

  15. The Utilization of Spin Polarized Photoelectron Spectroscopy as a Probe of Electron Correlation with an Ultimate Goal of Pu

    International Nuclear Information System (INIS)

    Tobin, James; Yu, Sung; Chung, Brandon; Morton, Simon; Komesu, Takashi; Waddill, George

    2008-01-01

    We are developing the technique of spin-polarized photoelectron spectroscopy as a probe of electron correlation with the ultimate goal of resolving the Pu electronic structure controversy. Over the last several years, we have demonstrated the utility of spin polarized photoelectron spectroscopy for determining the fine details of the electronic structure in complex systems such as those shown in the paper.

  16. Minerals from Macedonia. XII. The dependence of quartz and opal color on trace element composition - AAS, FT IR and micro-Raman spectroscopy study

    International Nuclear Information System (INIS)

    Makreski, Petre; Jovanovski, Gligor; Stafilov, Trajce; Boev, Blazho

    2004-01-01

    The dependence of the color of quartz and opal natural minerals, collected from different localities in the Republic of Macedonia (Alinci, Belutche, Budinarci, Mariovo, Sasa, Sazhdevo, Chanishte, Cheshinovo, Zletovo) on their element composition is studied using Fourier transform infrared spectroscopy (FT IR), micro-Raman spectroscopy and atomic absorption spectrometry (AAS). In order to determine the content of different trace elements (Al, Cd, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn), 15 quartz and 2 opal mineral samples, using flame atomic absorption spectrometry (FAAS) and Zeeman electrothermal atomic absorption spectrometry (ETAAS) are studied. To avoid matrix interferences, the method for elimination of silicium is proposed. Optimal instrumental parameters for ETAAS determination (temperature and time for drying, pyrolysis and atomizing) are established by extensive testing for each investigated element. It is found that the milky white color of quartz minerals is due to the presence of traces of Ca, the appearance of black color is the result of the existence of Pb, Mn and Al impurities, and the occurrence of Fe and Cr introduce appearance of red and green color, respectively. Preliminary identification of the minerals is based on the comparison of our results, obtained by using the infrared and Raman vibrational spectroscopy, with the corresponding literature data for the analogous mineral species originating all over the world. An overview of the basic morphological and physico-chemical characteristics of the quartz and opal minerals and the geology of the localities is given. The colored pictures of the studied quartz and opal minerals are presented as well. (Author)

  17. Infrared spectroscopy of gas-phase clusters using a free-electron laser

    International Nuclear Information System (INIS)

    Heijnsbergen, D. van; Helden, G. von; Meijer, G.

    2002-01-01

    Most clusters produced in the gas phase, especially those containing metals, remain largely uncharaterized, among these are transition metal - carbide, -oxide and -nitride clusters. A method for recording IR spectra of strongly bound gas-phase clusters is presented. It is based on a free-electron laser called Felix, characterized by wide wavelength tuning range, covering almost the full 'molecular finger print' region, high power and fluence which make it suited to excite gas-phase species i.e. gas -phase clusters. Neutral clusters were generated by laser vaporization technique, ions that were created after the interaction with the free-electron laser were analyzed in a flight mass spectrometer. Experiments were run with titanium carbide clusters and their IR spectra given. It was shown that this method is suited to strongly bound clusters with low ionization energies, a condition met for many pure metal clusters and metal compound clusters. (nevyjel)

  18. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

    2003-05-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

  19. Two dimensional molecular electronics spectroscopy for molecular fingerprinting, DNA sequencing, and cancerous DNA recognition.

    Science.gov (United States)

    Rajan, Arunkumar Chitteth; Rezapour, Mohammad Reza; Yun, Jeonghun; Cho, Yeonchoo; Cho, Woo Jong; Min, Seung Kyu; Lee, Geunsik; Kim, Kwang S

    2014-02-25

    Laser-driven molecular spectroscopy of low spatial resolution is widely used, while electronic current-driven molecular spectroscopy of atomic scale resolution has been limited because currents provide only minimal information. However, electron transmission of a graphene nanoribbon on which a molecule is adsorbed shows molecular fingerprints of Fano resonances, i.e., characteristic features of frontier orbitals and conformations of physisorbed molecules. Utilizing these resonance profiles, here we demonstrate two-dimensional molecular electronics spectroscopy (2D MES). The differential conductance with respect to bias and gate voltages not only distinguishes different types of nucleobases for DNA sequencing but also recognizes methylated nucleobases which could be related to cancerous cell growth. This 2D MES could open an exciting field to recognize single molecule signatures at atomic resolution. The advantages of the 2D MES over the one-dimensional (1D) current analysis can be comparable to those of 2D NMR over 1D NMR analysis.

  20. Structural defects in multiferroic BiMnO3 studied by transmission electron microscopy and electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Yang, H.; Chi, Z. H.; Yao, L. D.; Zhang, W.; Li, F. Y.; Jin, C. Q.; Yu, R. C.

    2006-01-01

    The multiferroic material BiMnO 3 synthesized under high pressure has been systematically studied by transmission electron microscopy and electron energy-loss spectroscopy, and some important structural defects are revealed in this multiferroic material. The frequently observed defects are characterized to be Σ3(111) twin boundaries, Ruddlesden-Popper [Acta Crystallogr. 11, 54 (1958)] antiphase boundaries, and a p p superdislocations connected with a small segment of Ruddlesden-Popper defect. These defects are present initially in the as-synthesized sample. In addition, we find that ordered voids (oxygen vacancies) are easily introduced into the multiferroic BiMnO 3 by electron-beam irradiation

  1. High-dose dosimetry using electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Kojima, Takuji; Tanaka, Ryuichi

    1992-01-01

    An electron spin resonance (ESR) dosimeter capable of measuring large doses of radiation in radiotherapy and radiation processing is outlined. In particular, an alanine/ESR dosimeter is discussed, focusing on the development of elements, the development of the ESR dosimetric system, the application of alanine/ESR dosimeter, and basic researches. Rod elements for gamma radiation and x radiation and film elements for electron beams are described in detail. The following recent applications of the alanine/ESR dosimeter are introduced: using as a transfer dosimeter, applying to various types of radiation, diagnosing the deterioration of radiological materials and equipments, and applying to ESR imaging. The future subjects to be solved in the alanine/ESR dosimetric system are referred to as follows: (1) improvement of highly accurate elements suitable for the measurement of various types of radiation, (2) establishment of sensitive calibration method of the ESR equipment itself, and (3) calibration and standardization of radiation doses. (K.N.) 65 refs

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

    DEFF Research Database (Denmark)

    Raza, Søren; Esfandyarpour, Majid; Koh, Ai Leen

    2016-01-01

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

  3. Study of the electronic structure of pure aluminium, aluminium oxide and nitride by spectroscopy of electrons excited under electronic and photonic bombardment (X and UV)

    International Nuclear Information System (INIS)

    Gautier-Soyer, Martine

    1985-01-01

    This research thesis reports the use of electron spectroscopy with electrons excited under electronic or photonic (X or UV) bombardment for the study of electronic state density of aluminium, aluminium oxide (Al 2 O 3 ) and aluminium nitride (AlN). The objective is to get an insight into phenomena related to technological problems of adherence, wear, lubrication, corrosion or breakdown met in metals, insulators and semiconductors. The author highlighted the presence of occupied surface states on Al(111) and Al(100), and electronic levels localised in the forbidden band of Al 2 O 3 and AlN, induced by structural defects which promote surface reactivity [fr

  4. Auger electron spectroscopy study on interaction between aluminum thin layers and uranium substrate

    International Nuclear Information System (INIS)

    Zhou Wei; Liu Kezhao; Yang Jiangrong; Xiao Hong; Jiang Chunli; Lu Lei

    2005-01-01

    Aluminum thin layers on uranium were prepared by sputter deposition at room temperature in ultra high vacuum analysis chamber. Interaction between U and Al, and growth mode were investigated by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). It is shown that Al thin film growth follows the volmer-weber (VW) mode. At room temperature, Al and U interact with each other, resulting in interdiffusion action and formation of U-Al alloys at U/Al interface. Annealing promotes interaction and interdiffusion between U and Al, and UAl x maybe formed at interface. (authors)

  5. Morphology, surface roughness, electron inelastic and quasi-elastic scattering in elastic peak electron spectroscopy of polymers

    International Nuclear Information System (INIS)

    Lesiak, B.; Kosinski, A.; Nowakowski, R.; Koever, L.; Toth, J.; Varga, D.; Cserny, I.; Sulyok, A.; Gergely, G.

    2006-01-01

    Complete text of publication follows. Elastic peak electron spectroscopy (EPES) deals with the interaction of electrons with atoms of a solid surface, studying the distribution of electrons backscattered elastically. The nearest vicinity of the elastic peak, (low kinetic energy region) reflects both, electron inelastic and quasi-elastic processes. The incident electrons produce surface excitations, inducing surface plasmons with the corresponding loss peaks separated by 1 - 20 eV energy from the elastic peak. Quasi-elastic losses result from the recoil of scattering atoms of different atomic number, Z. The respective energy shift and Doppler broadening of the elastic peak depend on Z, the primary electron energy, E, and the measurement geometry. Quantitative surface analytical application of EPES, such as determination of parameters describing electron transport, requires a comparison of experimental data with corresponding data derived from Monte Carlo (MC) simulation. Several problems occur in EPES studies of polymers. The intensity of elastic peak, considered in quantitative surface analysis, is influenced by both, the inelastic and quasi-elastic scattering processes (especially for hydrogen scattering atoms and primary electron energy above 1000 eV). An additional factor affecting the elastic peak intensity is the surface morphology and roughness. The present work compares the effect of these factors on the elastic peak intensity for selected polymers (polyethylene, polyaniline and polythiophenes). X-ray photoelectron spectroscopy (XPS) and helium pycnometry are applied for deriving the surface atomic composition and the bulk density, while scanning electron microscopy (SEM) and atomic force microscopy (AFM) for determining surface morphology and roughness. According to presented results, the influence of surface morphology and roughness is larger than those of surface excitations or recoil of hydrogen atoms. The component due to recoil of hydrogen atoms can be

  6. In Situ SIMS and IR Spectroscopy of Well-Defined Surfaces Prepared by Soft Landing of Mass-Selected Ions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Gunaratne, Kalupathirannehelage Don D.; Laskin, Julia

    2014-06-16

    Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+, onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

  7. Investigation on LPCVD SiON films by means of Rutherford backscattering, FT-IR and UV-VIS Spectroscopy

    International Nuclear Information System (INIS)

    Dudu, D.; Ivanov, E.; Bercu, B.N.; Bercu, M.; Modreanu, M.

    2003-01-01

    The SiON layers deposited by LPCVD (Low Vapour Chemical Deposition ) on Si (111) substrate has been investigated by complementary techniques as Rutherford backscattering and optical spectroscopy. We have determined the evolution of chemical content in respect with oxygen relative to nitrogen. The change in oxygen content versus time was produced by exposing the sample in wet oxygen at 1000 deg. C for different periods. The change in oxygen amount was determined by monitoring the Si-O-Si integral intensity of the absorption band at 1071cm -1 . Also the behavior of the refractive index versus time in an oxidative atmosphere gave a complementary information about the oxygen content. Alpha scattering spectra obtained by means of cyclotron facilities was used as another technique for oxygen to nitrogen ratio determination. Both visible spectra and RBS data were fitted by using the corresponding simulating approaches based on light propagation in non-homogeneous media and respectively on multiple scattering theory. The time evolution of O content indicated a diffused controlled process through the gas/solid interface. (authors)

  8. Synthesis and electronic properties of LnRhAsO and LnIrAsO compositions

    International Nuclear Information System (INIS)

    Muir, Sean; Sleight, A.W.; Subramanian, M.A.

    2011-01-01

    The synthesis and characterization of the new compositions LnRhAsO (Ln=Ce, Nd) and LnIrAsO (Ln=La, Ce, Nd) are reported. These compounds crystallize in the ZrCuSiAs type structure, isostructural to iron pnictide LnFeAsO materials. Upon substitution of Rh for Fe, both a and c lattice parameters increase relative to 3d transition metal compounds; however, when Ir is substituted for Rh the a-parameter decreases slightly while the c-parameter expands. The decrease in a lattice parameter corresponds to a short metal-metal distance in Ir compounds. CeRhAsO and CeIrAsO compositions show abrupt decreases in resistivity at 7 and 10 K, respectively, coinciding with a small shift in magnetization at the transition temperature. - Graphical abstract: LnIrAsO (Ln=La, Ce, Nd) and LnRhAsO (Ln=Ce, Rh) have been synthesized. These new transition metal oxypnictide compositions are isostructural to LaFeAsO. The 5d Ir compositions demonstrate a shorter metal-metal interaction than the 4d Rh compositions. Highlights: → LnIrAsO (Ln=La, Ce, Nd) and LnRhAsO (Ln=Ce, Nd) have been synthesized. → Ir compositions show a decreased a-parameter and increased c-parameter relative to Rh compositions. → All LnIrAsO and LnRhAsO compositions are metallic while CeIrAsO and CeRhAsO show a sudden drop in resistivity at 10 and 7 K, respectively.

  9. X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hamad, Kimberly Sue [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

  10. Monte Carlo wave-packet approach to trace nuclear dynamics in molecular excited states by XUV-pump-IR-probe spectroscopy

    Science.gov (United States)

    Jing, Qingli; Bello, Roger Y.; Martín, Fernando; Palacios, Alicia; Madsen, Lars Bojer

    2018-04-01

    Recent research interests have been raised in uncovering and controlling ultrafast dynamics in excited neutral molecules. In this work we generalize the Monte Carlo wave packet (MCWP) approach to XUV-pump-IR-probe schemes to simulate the process of dissociative double ionization of H2 where singly excited states in H2 are involved. The XUV pulse is chosen to resonantly excite the initial ground state of H2 to the lowest excited electronic state of 1Σu + symmetry in H2 within the Franck-Condon region. The delayed intense IR pulse couples the excited states of 1Σu + symmetry with the nearby excited states of 1Σg + symmetry. It also induces the first ionization from H2 to H2 + and the second ionization from H2 + to H++H+. To reduce the computational costs in the MCWP approach, a sampling method is proposed to determine in time the dominant ionization events from H2 to H2+. By conducting a trajectory analysis, which is a unique possibility within the MCWP approach, the origins of the characteristic features in the nuclear kinetic energy release spectra are identified for delays ranging from 0 to 140 fs and the nuclear dynamics in the singly excited states in H2 is mapped out.

  11. Thermal behavior of J-aggregates in a Langmuir-Blodgett film of pure merocyanine dye investigated by UV-visible and IR absorption spectroscopy.

    Science.gov (United States)

    Hirano, Yoshiaki; Tateno, Shinsuke; Maio, Ari; Ozaki, Yukihiro

    2009-03-05

    We have characterized the structure of J-aggregate in a Langmuir-Blodgett film of pure merocyanine dye (MS18) fabricated under an aqueous subphase containing a cadmium ion (Cd2+) and have investigated its thermal behavior by UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR absorption spectra indicate that temperature-dependent changes in the MS18 aggregation state in the pure MS18 system are closely and mildly linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of MS18 hydrocarbon chain, respectively. The J-aggregate in the pure MS18 system dissociates from 25 to 150 degrees C, and the dissociation temperature at 150 degrees C is higher by 50 degrees C than that in the previous MS18- arachidic acid (C20) binary system. The lower dissociation temperature in the binary system originates from the fact that temperature-dependent structural disorder of cadmium arachidate (CdC20), being phase-separated from MS18, has an influence on the dissociation of J-aggregate. From 160 to 180 degrees C, thermally induced blue-shifted bands, caused by the oligomeric MS18 aggregation, appear at around 520 nm in the pure MS18 system by contraries, regardless of the lack of driving force by the melting phenomenon of CdC20. The temperature at which the 520 nm bands occur is in good agreement with the melting point (160 degrees C) of hydrocarbon chain in MS18 with Cd2+, whereas its chromophore part is clearly observed to melt near 205 degrees C by UV-visible spectra. Therefore, it is suggested that the driving force that induces the 520 nm band in the pure MS18 system arises from the partial melting of hydrocarbon chain in MS18 with Cd2+.

  12. Real time observation of proteolysis with Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy: Watching a protease eat a protein

    Science.gov (United States)

    Güler, Günnur; Džafić, Enela; Vorob'ev, Mikhail M.; Vogel, Vitali; Mäntele, Werner

    2011-06-01

    Fourier transform infrared (FT-IR)- and UV-circular dichroism (UV-CD) spectroscopy have been used to study real-time proteolytic digestion of β-lactoglobulin (β-LG) and β-casein (β-CN) by trypsin at various substrate/enzyme ratios in D 2O-buffer at 37 °C. Both techniques confirm that protein substrate looses its secondary structure upon conversion to the peptide fragments. This perturbation alters the backbone of the protein chain resulting in conformational changes and degrading of the intact protein. Precisely, the most significant spectral changes which arise from digestion take place in the amide I and amide II regions. The FT-IR spectra for the degraded β-LG show a decrease around 1634 cm -1, suggesting a decrease of β-sheet structure in the course of hydrolysis. Similarly, the intensity around the 1654 cm -1 band decreases for β-CN digested by trypsin, indicating a reduction in the α-helical part. On the other hand, the intensity around ˜1594 cm -1 and ˜1406 cm -1 increases upon enzymatic breakdown of both substrates, suggesting an increase in the antisymmetric and symmetric stretching modes of free carboxylates, respectively, as released digestion products. Observation of further H/D exchange in the course of digestion manifests the structural opening of the buried groups and accessibility to the core of the substrate. On the basis of the UV-CD spectra recorded for β-LG and β-CN digested by trypsin, the unordered structure increases concomitant with a decrease in the remaining structure, thus, revealing breakdown of the intact protein into smaller fragments. This model study in a closed reaction system may serve as a basis for the much more complex digestion processes in an open reaction system such as the stomach.

  13. Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

    International Nuclear Information System (INIS)

    Bodi, Andras; Johnson, Melanie; Gerber, Thomas; Gengeliczki, Zsolt; Sztaray, Balint; Baer, Tomas

    2009-01-01

    An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm -1 field, which enables the direct measurement of rate constants in the 10 3 -10 7 s -1 range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

  14. Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy

    Science.gov (United States)

    Fletcher, Leigh N.; Irwin, P. G. J; Achterberg, R. K.; Orton, G. S.; Flasar, F. M.

    2015-01-01

    Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause

  15. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

    Science.gov (United States)

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  16. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meng; Xu, Chunkai, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn; Zhang, Panke; Li, Zhean; Chen, Xiangjun, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn [Hefei National Laboratory for Physical Science at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026 (China)

    2016-08-15

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  17. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

    International Nuclear Information System (INIS)

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-01-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  18. Parallel β-sheet vibrational couplings revealed by 2D IR spectroscopy of an isotopically labeled macrocycle: quantitative benchmark for the interpretation of amyloid and protein infrared spectra.

    Science.gov (United States)

    Woys, Ann Marie; Almeida, Aaron M; Wang, Lu; Chiu, Chi-Cheng; McGovern, Michael; de Pablo, Juan J; Skinner, James L; Gellman, Samuel H; Zanni, Martin T

    2012-11-21

    Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel β-sheets. Using a synthetic macrocycle that enforces a two stranded parallel β-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C═(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of β-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel β-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent

  19. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  20. Characterization of the isolated [Co3Ni (EtOH )] + cluster by IR spectroscopy and spin-dynamics calculations

    Science.gov (United States)

    Dutta, D.; Becherer, M.; Bellaire, D.; Dietrich, F.; Gerhards, M.; Lefkidis, G.; Hübner, W.

    2018-06-01

    We experimentally and theoretically study the geometry, as well as the electronic and vibrational properties, of the heterotetranuclear magnetic cluster [Co3Ni (EtOH )] +, which is prepared in the gas phase with molecular beam expansion. We characterize the cluster and identify possible isomers through the comparison of experimentally observed infrared spectra with state-of-the-art quantum chemistry calculations, more specifically by focusing on the OH stretching frequency. Furthermore, we suggest ultrafast, laser-induced, local spin-flip scenarios on every Co atom, and report a cooperative effect, in which the spin density is localized on one Co atom, gets transiently transferred to another, and then bounces back pointing in the opposite direction. Finally, we predict a tolerance of the suggested scenarios with respect to the laser detuning of about 20 meV, which lies within an experimentally applicable range. Our joint investigation is an additional step toward the implementation of laser-controlled nanospintronic devices.