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Journal articles on the topic 'Atomic/Molecular Structure and Spectra'

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Published: 4 June 2021
Last updated: 29 January 2023

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1

Bruley, John, David B. Williams, and Ming-Wei Tseng. "Point-defect distributions in ceramics by spectrum-line profiling." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 312–13. http://dx.doi.org/10.1017/s0424820100137938.

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Electron energy-loss spectroscopy is well suited to the study of interfaces because the ionization edges can be used to identify the atomic species present and the near edge fine structures on the edges reveal information on the electronic structure surrounding these atoms. This information can be extracted from regions of sample approaching atomic dimensions. A challenge is to be able to map and interpret spectral features with a level of confidence that will allow explanations of physical properties of interest.The term Spectrum-Line is used here to refer to a linear array of spectra, recorded sequentially along a line traced out by the electron probe and is the 1 dimensional analog of the Spectrum-Image. Processing Spectrum-Lines to generate quantitative profiles can provide a vivid picture of changes in composition, a valence state, or site occupancy across an interface. To aid interpretation and guide further spectrum analysis the near-edge fine structures can be compared to spectra from compounds whose atomic coordinations are well known or modeled using the results of band-structure or molecular orbital calculations of electronic structures.
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2

Crépin, C., and A. Tramer. "Vibrational structure in atomic emission spectra: Hg atoms in molecular matrices." Journal of Chemical Physics 107, no. 7 (August 15, 1997): 2205–14. http://dx.doi.org/10.1063/1.474600.

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3

Vijaya Chamundeeswari, S. P., E. James Jebaseelan Samuel, and N. Sundaraganesan. "Molecular structure, vibrational spectra, NMR and UV spectral analysis of sulfamethoxazole." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 118 (January 2014): 1–10. http://dx.doi.org/10.1016/j.saa.2013.07.063.

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4

Li, Zhe, Hsin-Yi Tiffany Chen, Koen Schouteden, Thomas Picot, Ting-Wei Liao, Aleksandr Seliverstov, Chris Van Haesendonck, Gianfranco Pacchioni, Ewald Janssens, and Peter Lievens. "Unraveling the atomic structure, ripening behavior, and electronic structure of supported Au20 clusters." Science Advances 6, no. 1 (January 2020): eaay4289. http://dx.doi.org/10.1126/sciadv.aay4289.

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The free-standing Au20 cluster has a unique tetrahedral shape and a large HOMO-LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap of around 1.8 electron volts. The “magic” Au20 has been intensively used as a model system for understanding the catalytic and optical properties of gold nanoclusters. However, direct real-space ground-state characterization at the atomic scale is still lacking, and obtaining fundamental information about the corresponding structural, electronic, and dynamical properties, is challenging. Here, using cluster-beam deposition and low-temperature scanning tunneling microscopy, atom-resolved topographic images and electronic spectra of supported Au20 clusters are obtained. We demonstrate that individual size-selected Au20 on ultrathin NaCl films maintains its pyramidal structure and large HOMO-LUMO gap. At higher cluster coverages, we find sintering of the clusters via Smoluchowski ripening to Au20n agglomerates. The evolution of the electron density of states deduced from the spectra reveals gap reduction with increasing agglomerate size.
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5

Samsonowicz, Mariola. "Molecular structure of calcium, magnesium, strontium and barium m-nitrobenzoates." Spectroscopy 24, no. 3-4 (2010): 433–37. http://dx.doi.org/10.1155/2010/501245.

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The effect of calcium, magnesium, strontium and barium ions on the electronic structure of m-nitrobenzoates was studied. The FT-IR spectra of m-nitrobenzoic acid and its salts were registered, assigned and analyzed. Characteristic shifts and changes in intensities of bands along the metal series were observed. The structures of m-nitrobenzoic acid and its calcium, magnesium, strontium and barium salts were optimized at the B3LYP/LANL2DZ level. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated.
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6

Flambaum, V. V., and V. A. Dzuba. "Search for variation of the fundamental constants in atomic, molecular, and nuclear spectra." Canadian Journal of Physics 87, no. 1 (January 1, 2009): 25–33. http://dx.doi.org/10.1139/p08-072.

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The search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ = me/mp) is reviewed. Strong emphasis is given to establishing the relationships between the change in the measured frequencies of atomic, molecular, or nuclear transitions and the corresponding change of the fundamental constants. Transitions in which the sensitivity of the frequency change to the variation of the fine-structure constant is strongly enhanced are discussed and most recent experimental results are presented. Most attention is given to the use of atomic, molecular, and nuclear transitions in the study of quasar absorption spectra and in atomic clock experiments.PACS Nos.: 31.25.Eb, 31.25.Jf
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7

Benson, Chris S., N. Hładczuk, L. D. Spencer, A. Robb, J. Scott, I. Valtchanov, R. Hopwood, and D. A. Naylor. "The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder – III. Line identification and off-axis spectra." Monthly Notices of the Royal Astronomical Society 496, no. 4 (June 13, 2020): 4906–22. http://dx.doi.org/10.1093/mnras/staa1613.

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ABSTRACT The European Space Agency Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the atomic/molecular transitions that correspond to the spectral features extracted by the FF. We use a template of 307 atomic fine structure and molecular lines that are commonly found in SPIRE FTS spectra for the cross-match. The routine makes use of information provided by the line identification to search for low signal-to-noise ratio features that have been excluded or missed by the iterative FF. In total, the atomic/molecular transitions of 178 942 lines are identified (corresponding to 83 per cent of the entire FF catalogue), and an additional 33 840 spectral lines associated with missing features from SPIRE FTS observations are added to the FF catalogue.
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8

Drew, Elliot D., and Robert W. Janes. "PDBMD2CD: providing predicted protein circular dichroism spectra from multiple molecular dynamics-generated protein structures." Nucleic Acids Research 48, W1 (April 28, 2020): W17—W24. http://dx.doi.org/10.1093/nar/gkaa296.

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Abstract PDBMD2CD is a new web server capable of predicting circular dichroism (CD) spectra for multiple protein structures derived from molecular dynamics (MD) simulations, enabling predictions from thousands of protein atomic coordinate files (e.g. MD trajectories) and generating spectra for each of these structures provided by the user. Using MD enables exploration of systems that cannot be monitored by direct experimentation. Validation of MD-derived data from these types of trajectories can be difficult via conventional structure-determining techniques such as crystallography or nuclear magnetic resonance spectroscopy. CD is an experimental technique that can provide protein structure information from such conditions. The website utilizes a much faster (minimum ∼1000×) and more accurate approach for calculating CD spectra than its predecessor, PDB2CD (1). As well as improving on the speed and accuracy of current methods, new analysis tools are provided to cluster predictions or compare them against experimental CD spectra. By identifying a subset of the closest predicted CD spectra derived from PDBMD2CD to an experimental spectrum, the associated cluster of structures could be representative of those found under the conditions in which the MD studies were undertaken, thereby offering an analytical insight into the results. PDBMD2CD is freely available at: https://pdbmd2cd.cryst.bbk.ac.uk.
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9

Zhou, Dapeng, Cuiping Zhai, and Xiaopeng Xuan. "Molecular structure and vibrational spectra of N4-acetylcytosine." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 112 (August 2013): 139–45. http://dx.doi.org/10.1016/j.saa.2013.04.051.

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10

Parkinson, W. H. "Commission 14 : Atomic and Molecular Data (Donnees Atomiques et Moleculaires)." Transactions of the International Astronomical Union 21, no. 1 (1991): 105–36. http://dx.doi.org/10.1017/s0251107x00009949.

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Since its creation, the Commission has been keen on activating the cross-discipline interaction between astrophysics and atomic and molecular physics. The need for a variety of atomic and molecular data has become more and more important for the recent past years. This need will certainly increase still more in the next years, due to the creation of new ground based instruments and to the launch of new space missions : they will produce large amounts of high resolution spectra from the X-rays to the infrared and millimeter wavelengths involving many atoms, ions and molecules. At the 1988 Baltimore meeting there was a general consensus that the aim of the Commission is to watch over the atomic and molecular spectral and structure data, together with the energy exchange processes in atomic and molecular physics relevant for astrophysics. In particular, the Commission is concerned by the interactions between photons and atoms (or ions or molecules), including wavelengths and line transition probabilities data, and by the interactions between particles, including atomic, molecular, ionic and electronic collision cross-sections, and by related phenomena, such as line broadening, collisional redistribution of radiation and line polarization. All these informations are essential for the interpretation of astronomical observations, such as spectroscopic diagnosis and theoretical modelling of astrophysical media.
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11

Charnock, G. T. P., M. Krzystyniak, and Ilya Kuprov. "Molecular structure refinement by direct fitting of atomic coordinates to experimental ESR spectra." Journal of Magnetic Resonance 216 (March 2012): 62–68. http://dx.doi.org/10.1016/j.jmr.2012.01.003.

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12

Ozeki, H., and S. Saito. "Microwave spectra of HPO and DPO: molecular structure." Journal of Molecular Spectroscopy 219, no. 2 (June 2003): 305–12. http://dx.doi.org/10.1016/s0022-2852(03)00052-3.

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13

Azhgalieva, A. S., N. V. Klassen, A. M. Likhter, A. P. Pokidov, T. N. Fursova, and I. S. Tsebruk. "Diagnostics of atomic- molecular interactions in nano-compositions organics-inorganics by means of infrared spectroscopy." Journal of Physics: Conference Series 2056, no. 1 (October 1, 2021): 012035. http://dx.doi.org/10.1088/1742-6596/2056/1/012035.

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Abstract This paper prolongs our studies of the formation and properties of the organic-inorganic scintillating compositions from activated polystyrene and inorganic nanoparticles from cesium iodid and sulfate. The compositions from the solution of polystyrene in benzene and nano- or micro-particles of cesium iodide were solidified in the form of thin films. Then some of the films were subjected to rolling. The variations of the infrared transmission spectra of the compositions were measured either during their solidification or after the solidification and rolling. The new absorption band was revealed in the process of the solidification and disappeared after it. The fractal-like structures of parallel rows were formed in the films. Quasi-periodical oscillations of the transmission spectra were found in several infrared regions ascribed to the interaction of the infrared radiation with the fractal super-structure of the films. The modifications of the absorption spectra found in our experiments are attributed to the interactions of polystyrene molecules with benzene molecules and nanoparticles of cesium iodide.
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14

Langhoff, P. W., J. A. Boatz, R. J. Hinde, and J. A. Sheehy. "Atomic spectral methods for molecular electronic structure calculations." Journal of Chemical Physics 121, no. 19 (November 15, 2004): 9323–42. http://dx.doi.org/10.1063/1.1794634.

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15

Heyer, Mark, Paul F. Goldsmith, Robert Simon, Rebeca Aladro, and Oliver Ricken. "Searching for Converging Flows of Atomic Gas onto a Molecular Cloud." Astrophysical Journal 941, no. 1 (December 1, 2022): 62. http://dx.doi.org/10.3847/1538-4357/aca097.

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Abstract We present new observations of [C ii] 2 P 3/2 → 2 P 1/2 fine structure line emission from an isolated molecular cloud using the upGREAT instrument on board SOFIA. These data are analyzed together with archival CO J=1–0 and H i 21 cm emission spectra to investigate the role of converging atomic gas flows in the formation of molecular clouds. Bright [C ii] emission is detected throughout the mapped area that likely originates from photodissociation regions excited by UV radiation fields produced by newborn stars within the cloud. Upon spatial averaging of the [C ii] spectra, we identify weak [C ii] emission within velocity intervals where the H i 21 cm line is brightest; these are blueshifted relative to velocities of the CO and bright [C ii] emission by 4 km s−1. The brightness temperatures, velocity dispersions, and alignment with H i 21 cm velocities connect this [C ii] emission component to the cold, neutral atomic gas of the interstellar medium, known as the cold, neutral medium (CNM). We propose that this CNM feature is an accretion flow onto the farside of the existing molecular cloud. The mass infall rate is 3.2 × 10−4 M ⊙ yr−1. There is no direct evidence of a comparable redshifted component in the [C ii] or H i 21 cm spectral lines that would indicate the presence of a converging flow.
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16

Tiwari, Rai, Kumar, Parigger, and Rai. "Atomic and Molecular Laser-Induced Breakdown Spectroscopy of Selected Pharmaceuticals." Atoms 7, no. 3 (July 19, 2019): 71. http://dx.doi.org/10.3390/atoms7030071.

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Laser-induced breakdown spectroscopy (LIBS) of pharmaceutical drugs that contain paracetamol was investigated in air and argon atmospheres. The characteristic neutral and ionic spectral lines of various elements and molecular signatures of CN violet and C2 Swan band systems were observed. The relative hardness of all drug samples was measured as well. Principal component analysis, a multivariate method, was applied in the data analysis for demarcation purposes of the drug samples. The CN violet and C2 Swan spectral radiances were investigated for evaluation of a possible correlation of the chemical and molecular structures of the pharmaceuticals. Complementary Raman and Fourier-transform-infrared spectroscopies were used to record the molecular spectra of the drug samples. The application of the above techniques for drug screening are important for the identification and mitigation of drugs that contain additives that may cause adverse side-effects.
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17

Augustyniak, Aleksander, Mariusz Zdanowicz, and Tomasz Osuch. "Self-Similarity Properties of Complex Quasi-Periodic Fibonacci and Cantor Photonic Crystals." Photonics 8, no. 12 (December 7, 2021): 558. http://dx.doi.org/10.3390/photonics8120558.

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In this paper, the influence of structural modifications on basic quasi-periodic (QP) photonic crystals (PhC’s) on self-similarity feature in their spectral responses is examined. Investigated crystals are chosen based on a present knowledge on the QP crystals, and are classified according to their structure. One of the QP crystals considered for the calculations is a concatenation, Fibonacci structure. It characterizes with a self-similar spectra for its different orders, which means, that the spectral shape repeats itself and can be partially identical for a different orders of the Fibonacci QP crystal. The calculations were also performed for the fractal structure, based on a Cantor QP crystal. Just as for the case of the Fibonacci structure, it characterizes with a self-similar spectra for different orders of the structure. Considered photonic devices are next put through simple modification operations by multiplication, conjugation or mirror reflection. Resulting, modified structures are used for the calculations of their spectral response. Results show, that the self-similarity of the spectra is not affected by performed modifications, and thus spectral response of QP PhC can be designed without losing this feature. Moreover the regular expansion of the repeated central part of the spectrum that appears in higher-order Fibonacci QP PhC spectra (due to the self-similarity) with the increase Fibonacci crystal order is presented here for the first time.
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18

Григорьев, Л. В., И. С. Морозов, Н. В. Журавлев, А. А. Семенов, and А. А. Никитин. "Фотолюминесцентные и фотоэлектрические свойства тонкопленочной структуры ZnO-LiNbO-=SUB=-3-=/SUB=- в ультрафиолетовом и видимом диапазонах спектра." Физика и техника полупроводников 54, no. 3 (2020): 232. http://dx.doi.org/10.21883/ftp.2020.03.49024.9294.

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In article are presebted the results of study the structural, optical, photoluminescent and photoelectric properties structure of the layer thin-film ZnO on the monocrystal LiNbO3 substrate. Presents the results of X-ray structural analysis of a zinc oxide thin film synthesized on a single-crystal lithium niobate substrate and on a KU-1 quartz substrate are presented. Are presented the results investigations of transmission spectra, reflection spectra and absorption spectra in the ultraviolet and visible spectral range. Are presented investigations spectral dependence of photoluminescence and the spectral dependence of the photoconductivity currents in the thin film structure of ZnO-LiNbO3 and the structure of ZnO-SiO2 in the ultraviolet and visible spectral range.
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19

Jagdale, Bapu Sonu, Vishnu Ashok Adole, Thansing Bhavsing Pawar, and Bhatu Shivaji Desale. "Molecular Structure, Frontier Molecular Orbitals, MESP and UV–Visible Spectroscopy Studies of Ethyl 4-(3,4-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate: A Theoretical and Experimental Appraisal." Material Science Research India 17, SpecialIssue1 (August 1, 2020): 13–26. http://dx.doi.org/10.13005/msri.17.special-issue1.04.

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n the current investigation, we wish to report a combined study on the theoretical and experimental investigation of structural, molecular, and spectral properties of ethyl 4-(3,4-dimethoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (EDMT). The EDMT molecule is synthesized and characterized by UV-Visible, FT-IR, 1H NMR, 13C NMR, DEPT, and mass spectral techniques. The density functional theory (DFT) investigation was performed by using the B3LYP level of theory at 6-311++G (d,p) basis set. Frontier molecular orbital (FMO) analysis is likewise examined. An TD-DFT method was used for the UV-Visible spectral analysis by using the B3LYP level and 6-311++G (d,p) basis set in the DMSO solvent. Experimental and theoretical UV-Visible spectra were compared in the present study. Various reactivity descriptors are discussed. Besides, Mulliken atomic charges, molecular electrostatic surface potential (MESP), and some valuable thermodynamic functions are studied.
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20

Nicholls, R. W., S. Sahal, A. H. Gabriel, T. Kato, F. J. Lovas, S. L. Mandel’shtam, H. Nussbaumer, W. H. Parkinson, Z. R. Rudzigas, and W. L. Wiese. "Commision 14: Atomic and Molecular Data (Donnees Atomiques Et Moleculaires)." Transactions of the International Astronomical Union 20, no. 1 (1988): 111–17. http://dx.doi.org/10.1017/s0251107x00007057.

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The Commission has, since its inception, been devoted to the continually increasing needs of astronomy and astrophysics for reliable atomic and molecular data a) for diagnostic interpretation of astronomical observations, and b) for support of theoretical modelling of astrophysical situations. At the 1985 Delhi General Assembly, the Commission reviewed the scope of its subject matter, and considered whether it should be extended to include higher energy physical processes than are commonly treated by atomic and molecular data. It was concluded that there was no strong demand for this change, which, if implemented, would make the work of the Commission too diffuse. The appropriateness of the past working group structure was also carefully reviewed in the light of contemporary needs. The following working groups, which have evolved from those of past years, together with their chairmen was approved: 1:Atomic Spectra and Wavelength Standards (excluding primary standards): W.C. Martin2:Atomic Transition Probabilities: W.L Wiese3:Collision Processes: A. Dalgarno4:Line Broadening: N. Feautrier5:Molecular Structure and Transition Data: W.H. Parkinson
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21

Allegretti, Patricia E., M. de las Mercedes Schiavoni, Celia Guzmán, Agustín Ponzinibbio, and Jorge J. P. Furlong. "Mass Spectral Study of the Occurrence of Tautomeric Forms of Thiohydantoins." European Journal of Mass Spectrometry 13, no. 4 (August 2007): 291–306. http://dx.doi.org/10.1255/ejms.885.

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Mass spectrometry is used to evaluate the occurrence of thio-enol structures among the several possible tautomers of thiohydantoins and dithiohydantoins. Mass spectra of differently-substituted thiohydantoins are examined looking for common mass spectral behaviors to be predicted. Ion fragmentations from specific tautomers allow the most stable thio-enol structure for both type of compounds. The mass spectrum of the alkylation product of 5,5-dimethyldithiohydantoin and the nuclear magnetic resonance spectra of the alkylation products of both 2-thiohydantoin and dithiohydantoin support the fact that the most likely thio-enol structure is determined by the presence of one or two thio-carbonyl groups in the hydantoin molecule.
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22

Григорьев, Л. В., А. А. Семенов, and А. В. Михайлов. "Оптические и фотолюминесцентные свойства тонкой пленки оксида цинка на подложке из тантала лития." Оптика и спектроскопия 130, no. 2 (2022): 242. http://dx.doi.org/10.21883/os.2022.02.51990.2581-21.

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Presents the results of the study of the structural, optical and photo luminescent properties of the thin films ZnO on LiNbO3 substrate. The results of X-ray structural analysis of a zinc oxide film synthesized on a single-crystal LiTaO3 substrate and on a KU-1 quartz substrate are presented. Present the transmission spectra, reflection spectra and the spectral dependence of zinc oxide thin films on substrate LiTaO3 and the structure of ZnO-SiO2 in the ultraviolet and visible spectral ranges.
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23

Ryabchikova, Tatiana, Yury Pakhomov, and Nikolai Piskunov. "VALD: The Meeting Point of Data Producers and Data Users." Galaxies 6, no. 3 (September 3, 2018): 93. http://dx.doi.org/10.3390/galaxies6030093.

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Vienna Atomic Line Database (VALD) contains data on atomic and molecular energy levels and parameters of spectral lines required for stellar spectra analysis. Hundreds of millions of lines for fine spectral synthesis and for opacity calculations are collected in the present version of VALD (VALD3). Critical evaluation of the data and the diversity of extraction tools support the high popularity of VALD among users. The data model of VALD3 incorporates obligatory links to the bibliography making our database more attractive as a publishing platform for data producers. The VALD data quality and completeness are constantly improving allowing better reproduction of stellar spectra. To illustrate continuous evolution of the data content we present a comparative analysis of the recent experimental and theoretical atomic data for Fe-group elements, which will be included in the next VALD release. This release will also include a possibility for extracting the line data with full isotopic and hyperfine structures.
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24

Sinha, Rajeev K. "Probing the Structure of Moxifloxacin and Norfloxacin by Density Functional Theory and Raman Spectroscopy-=SUP=-*-=/SUP=-." Оптика и спектроскопия 130, no. 6 (2022): 811. http://dx.doi.org/10.21883/os.2022.06.52618.40-22.

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In the present work, structures of two fluoroquinolone molecules namely Moxifloxacin and Norfloxacin are investigated using density functional theory and the Raman spectroscopy. The density functional theory calculation with B3LYP-6-31+G(d,p) level of theory reveals several structures of two molecules. The low energy stable structures of Moxifloxacin show multiple intramolecular H-bonds which could be responsible for the stabilization of these structures, however, the orientation of the (4aS, 7aS)-hexahydro-1H-pyrrolo[3,4-b]pyridin (hpb) ring determines the most stable structure. In Norfloxacin, the orientation of the ethyl group in the plane perpendicular to the ring frame determines the most stable structure whereas, the orientation of piperazine ring is critical for the determination of stable structure of the Norfloxacin zwitterion. Complexes of most stable structures of Moxifloxacin and Norfloxacin with one and two water molecules were also calculated. The Raman spectra were calculated for low energy structures of Moxifloxacin and Norfloxacin and also for their complexes with one and two water molecules. The experimental Raman spectra were obtained on powder sample of two molecules utilizing our lab-built Raman spectroscopy setup. The experimental Raman spectra were analyzed in light of the calculated Raman spectra of neutral molecules and their complexes with water. It was found that, in the powder form, the Raman spectra of two molecules can be better explained if intermolecular H-bonding with water molecules is considered. The study, therefore, confirms the hygroscopic nature of two molecules under ambient environment. Keywords: Moxifloxacin, Norfloxacin, density functional theory, Raman spectroscopy.
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25

Pain, Jean-Christophe, Franck Gilleron, and Thomas Blenski. "Detailed computation of hot-plasma atomic spectra." Laser and Particle Beams 33, no. 2 (March 20, 2015): 201–10. http://dx.doi.org/10.1017/s0263034615000257.

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AbstractWe present recent evolutions of the detailed opacity code SCO-RCG which combines statistical modelings of levels and lines with fine-structure calculations. The code now includes the Partially Resolved Transition Array model, which allows one to replace a complex transition array by a small-scale detailed calculation preserving energy and variance of the genuine transition array and yielding improved higher-order moments. An approximate method for studying the impact of strong magnetic field on opacity and emissivity was also recently implemented. The Zeeman line profile is modeled by fourth-order Gram-Charlier expansion series, which is a Gaussian multiplied by a linear combination of Hermite polynomials. Electron collisional line broadening is often modeled by a Lorentzian function and one has to calculate the convolution of a Lorentzian with Gram-Charlier distribution for a huge number of spectral lines. Since the numerical cost of the direct convolution would be prohibitive, we propose, to obtain the resulting profile, a fast and precise algorithm, relying on a representation of the Gaussian by cubic splines.
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26

Mathammal, R., N. Jayamani, and N. Geetha. "Molecular Structure, NMR, HOMO, LUMO, and Vibrational Analysis of O-Anisic Acid and Anisic Acid Based on DFT Calculations." Journal of Spectroscopy 2013 (2013): 1–18. http://dx.doi.org/10.1155/2013/171735.

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This work deals with the vibrational spectroscopy of O-Anisic acid (OAA) and Anisic acid (AA). The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) with standard B3LYP/6-31G** method and basis set combinations. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The infrared and Raman spectra were also predicted from the calculated intensities. The effects of carbonyl and methyl substitutions on the structure and vibrational frequencies have been investigated. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. The13C and1H NMR chemical shifts of the DFA and CA molecules were calculated using the gauge-invariant-atomic orbital (GIAO) method in DMSO solution using IEF-PCM model and compared with experimental data.
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27

YOSHIMURA, DAISUKE, KAZUHIKO SEKI, TAKAYUKI MIYAMAE, HISAO ISHII, SHINJI HASEGAWA, KOJI KAMIYA OKUDAIRA, and NOBUO UENO. "INTRAMOLECULAR ENERGY BAND DISPERSION IN ORIENTED THIN FILM OF n-CF3(CF2)22CF3 STUDIED BY ANGLE-RESOLVED UPS AND THEORETICAL SIMULATION." Surface Review and Letters 09, no. 01 (February 2002): 407–12. http://dx.doi.org/10.1142/s0218625x02002397.

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Electronic structure of perfluorotetracosane [n- CF 3 ( CF 2)22 CF 3; PFT], which is an oligomer of poly(tetrafluoroethylene) (PTFE), was investigated by angle-resolved photoemission spectroscopy (ARUPS) with synchrotron radiation. Theoretical simulations of ARUPS spectra were also performed by the independent atomic center (IAC) approximation combined with ab initio molecular orbital (MO) calculations. Measured normal-emission spectra for end-on oriented (the long-chain axis of PFT is perpendicular to the surface) films showed an incident photon energy dependence due to the intramolecular energy band dispersion. The energy band structure along the long-chain direction of PFT obtained from measured and calculated spectra is also discussed.
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Welty, Daniel E. "High-Resolution Optical Observations of Interstellar Absorption Lines." Highlights of Astronomy 13 (2005): 808–10. http://dx.doi.org/10.1017/s1539299600017196.

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AbstractWe briefly note several current topics concerning the properties of interstellar clouds for which high-resolution optical spectra play a significant role: (1) the recognition and characterization of small-scale (sub-pc) structure in both atomic and molecular gas; (2) the discovery of variations in the 7Li/6Li isotopic ratio in the nearby Galactic ISM; (3) the determination of atomic and molecular abundances and physical conditions for heavily reddened (“translucent”) Galactic sightlines; and (4) studies of interstellar clouds in the LMC and SMC.
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29

Barik, Bijay Kumar, Madhukar Mallya H., Rajeev K. Sinha, and Santhosh Chidangi. "Structure and Spectroscopic Studies of Aloe-emodin and Chrysophanol using Density Functional Theory and Experimental Methods-=SUP=-*-=/SUP=-." Оптика и спектроскопия 130, no. 6 (2022): 825. http://dx.doi.org/10.21883/os.2022.06.52621.39-22.

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The experimental and theoretical spectra studies of Aloe-emodin and Chrysophanol are reported in this work. Experimentally the Fourier transform infrared, Raman, and UV-Visible spectra were recorded for Aloe-emodin and Chrysophanol. With the help of density functional theory and B3LYP, the functional triple zeta basis set def-TZVP was used to optimize structures and calculate the vibrational frequencies. It was found out that the conformations of Aloe-emodin and Chrysophanol with the double intramolecular hydrogen bonds between the OH and C=O groups were the most stable conformations among the different conformations obtained. The intramolecular hydrogen bonds increase the bond lengths of the respective O-H and C=O bonds which are involved to form the intra molecular hydrogen bonds. The calculated infrared frequencies of the most stable geometry of Aloe-emodin and Chrysophanol correlate well with their respective Fourier transform infrared spectra. The vibrational frequency analysis for both the molecules was done in detail for all the vibrational modes assigning the individual ring vibrations besides the different types of individual vibrations of specific bonds. The Fourier transform infrared and the Raman spectral bands attained from the experiments correlate well with the theoretical data. Keywords:
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30

Förner, Wolfgang, and Hassan M. Badawi. "A DFT Analysis of the Molecular Structures and Vibrational Spectra of Diphenylsulfone and 4,4'-Sulfonyldianiline (Dapsone)." Zeitschrift für Naturforschung B 66, no. 1 (January 1, 2011): 69–76. http://dx.doi.org/10.1515/znb-2011-0112.

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We have performed density functional calculations with the B3LYP functional and a 6-311G** basis set to obtain the vibrational spectra in harmonic approximation of the anti-leprosy drug Dapsone and the parent compound diphenylsulfone. Although the chemical difference between the two molecules is not that pronounced (Dapsone has amino groups in the para positions in the phenyl rings), Dapsone is an active drug, while to our knowledge diphenylsulfone shows no medical activity. We compared the theoretical results to experimental vibrational spectra found in the literature. With the help of the program GAUSSVIEW we were able to assign the experimentally found spectral lines to specific atomic motions. The remarkable difference between the two molecules, regarding their structural behavior, is that the drug Dapsone has a more flexible structure of the phenyl ring than the parent molecule has. This might contribute to a greater ability of the drug to fit into receptor sites in a cell membrane although one has to be well aware that this plays most propably only a minor role in the drug activity of Dapsone
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31

Celik, Sefa, A. Demet Demirag, Aysen E. Ozel, and Sevim Akyuz. "Molecular Structure, Vibrational Spectra, Molecular Docking, and ADMET Study of Cellulose Triacetate II." Optics and Spectroscopy 128, no. 8 (August 2020): 1138–50. http://dx.doi.org/10.1134/s0030400x20080329.

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32

Weidlich, Olaf, Christoph Rödig, and Friedrich Siebert. "Time-Resolved Step-Scan Ftir Investigations on the M1→M2 Transition in the Light-Driven Proton Pump Bacteriorhodopsin." Laser Chemistry 19, no. 1-4 (January 1, 1999): 179–85. http://dx.doi.org/10.1155/1999/54345.

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Using time-resolved step-scan FTIR spectroscopy, it has become possible to identify two different M states in the 5 to 300 μs time range, which clearly differ from the MN state. The identification has become possible by measuring a pure BR→KL difference spectrum at 100 ns, which can be used to correct for the contributions of this intermediate in the later difference spectra. The subtraction of the later corrected difference spectra thus represent L→M1, M2 difference spectra with varying relative amount of the two M states. The comparison of these spectra clearly reveals differences in the amide-II spectral range, and possibly also in the amide-I range. From these observations it can be concluded that the two M states do not differ in the chromophore structure but in the protein structure.
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33

Nandiyanto, Asep Bayu Dani, Risti Ragadhita, and Meli Fiandini. "Interpretation of Fourier Transform Infrared Spectra (FTIR): A Practical Approach in the Polymer/Plastic Thermal Decomposition." Indonesian Journal of Science and Technology 8, no. 1 (September 20, 2022): 113–26. http://dx.doi.org/10.17509/ijost.v8i1.53297.

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Fourier transform infrared (FTIR) is one of the tools to represent molecular structure based on atomic vibration. It can denote a specific property of the chemical bond and molecular structure in the material, especially when analyzing specimens relating to plastics, polymers, and organic components. The FTIR peaks and spectrum act as a fingerprint of a specific molecular structure and chemical bonding, which need a sufficient reference database to distinguish them. This paper is to address issues of the need for a reference database of FTIR. This paper exhibits step-by-step information on how to read and interpret the FTIR spectra and identify a molecule's backbone with its functional groups. Practical examples from the analysis of several plastics/polymers and the thermally decomposing plastics/polymers were included to help and guide the reader to comprehend the basic concept of FTIR spectra.
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34

Mariñoso Guiu, Joan, Antoni Macià, and Stefan T. Bromley. "How to accurately model IR spectra of nanosized silicate grains." Proceedings of the International Astronomical Union 15, S350 (April 2019): 431–33. http://dx.doi.org/10.1017/s174392132000006x.

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AbstractWe assess the accuracy of various computational methods for obtaining infrared (IR) spectra of nanosized silicate dust grains directly from their atomistic structure and atomic motions. First, IR spectra for a selection of small nanosilicate clusters with a range of sizes and chemical compositions are obtained within the harmonic oscillator approximation employing density functional theory (DFT) based quantum chemical calculations. To check if anharmonic effects play a significant role in the IR spectra of these nanoclusters, we further obtain their IR spectra from finite temperature DFT-based ab initio molecular dynamics (AIMD). Finally, we also study the effect of temperature on the broadening of the obtained IR spectra peaks in larger nanosilicate grains with a range of crystallinities. In this case, less computationally costly classical molecular dynamics simulations are necessary due to the large number of atoms involved. Generally, we find that although DFT-based methods are more accurate, surprisingly good IR spectra can also be obtained from classical molecular dynamics calculations.
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35

Dereli, Ö., Y. Erdogdu, M. T. Gulluoglu, N. Sundaraganesan, E. Türkkan, Ü. Sayin, and A. Özmen. "Molecular Structure and Vibrational Spectra of Alpha-benzoinoxime by Density Functional Method." Оптика и спектроскопия 116, no. 2 (2014): 205–13. http://dx.doi.org/10.7868/s0030403414020056.

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36

Palafox, M. Alcolea. "Vibrational Spectra and Structure of Diphenylacetilenes." Spectroscopy Letters 29, no. 2 (March 1996): 241–66. http://dx.doi.org/10.1080/00387019608001600.

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37

Skonieczny, R., P. Popielarski, W. Bała, K. Fabisiak, K. Paprocki, M. Jancelewicz, M. Kowalska, and M. Szybowicz. "Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate." Materials Science-Poland 34, no. 3 (September 1, 2016): 676–83. http://dx.doi.org/10.1515/msp-2016-0086.

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AbstractThe cobalt phthalocyanine (CoPc) thin films (300 nm thick) deposited on n-type silicon substrate have been studied using micro-Raman spectroscopy, atomic force spectroscopy (AFM) and I-V measurement. The CoPc thin layers have been deposited at room temperature by the quasi-molecular beam evaporation technique. The micro-Raman spectra of CoPc thin films have been recorded in the spectral range of 1000 cm-1 to 1900 cm-1 using 488 nm excitation wavelength. Moreover, using surface Raman mapping it was possible to obtain information about polymorphic forms distribution (before and after annealing) of metallophthalocyanine (α and β form) from polarized Raman spectra. The I-V characteristics of the Au/CoPc/n-Si/Al Schottky barrier were also investigated. The obtained results showed that influence of the annealing process plays a crucial role in the ordering and electrical conductivity of the molecular structure of CoPc thin films deposited on n-type silicon substrate.
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38

Teterin, Yury, Konstantin Maslakov, Mikhail Ryzhkov, Anton Teterin, Kirill Ivanov, Stepan Kalmykov, Vladimir Petrov, and Dmitry Suglobov. "Valence XPS structure and chemical bond in Cs2UO2Cl4." Nuclear Technology and Radiation Protection 31, no. 1 (2016): 37–50. http://dx.doi.org/10.2298/ntrp1601037t.

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Quantitative analysis was done of the valence electrons X-ray photoelectron spectra structure in the binding energy (BE) range of 0 eV to ~35 eV for crystalline dicaesium tetrachloro-dioxouranium (VI) (Cs2UO2Cl4). This compound contains the uranyl group UO2. The BE and structure of the core electronic shells (~35 eV-1250 eV), as well as the relativistic discrete variation calculation results for the UO2Cl4(D4h) cluster reflecting U close environment in Cs2UO2Cl4 were taken into account. The experimental data show that many-body effects due to the presence of cesium and chlorine contribute to the outer valence (0-~15 eV BE) spectral structure much less than to the inner valence (~15 eV-~35 eV BE) one. The filled U5f electronic states were theoretically calculated and experimentally confirmed to be present in the valence band of Cs2UO2Cl4. It corroborates the suggestion on the direct participation of the U5f electrons in the chemical bond. Electrons of the U6p atomic orbitals participate in formation of both the inner (IVMO) and the outer (OVMO) valence molecular orbitals (bands). The filled U6p and the O2s, Cl3s electronic shells were found to make the largest contributions to the IVMO formation. The molecular orbitals composition and the sequence order in the binding energy range 0 eV-~35 eV in the UO2Cl4 cluster were established. The experimental and theoretical data allowed a quantitative molecular orbitals scheme for the UO2Cl4 cluster in the BE range 0-~35 eV, which is fundamental for both understanding the chemical bond nature in Cs2UO2Cl4 and the interpretation of other X-ray spectra of Cs2UO2Cl4. The contributions to the chemical binding for the UO2Cl4 cluster were evaluated to be: the OVMO contribution - 76%, and the IVMO contribution - 24 %.
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39

Ben-Nun, M., J. D. Mills, R. J. Hinde, C. L. Winstead, J. A. Boatz, G. A. Gallup, and P. W. Langhoff. "Atomic Spectral-Product Representations of Molecular Electronic Structure: Metric Matrices and Atomic-Product Composition of Molecular Eigenfunctions†." Journal of Physical Chemistry A 113, no. 26 (July 2, 2009): 7687–97. http://dx.doi.org/10.1021/jp901427x.

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40

Świsłocka, Renata, Ewa Regulska, Joanna Karpińska, Grzegorz Świderski, and Włodzimierz Lewandowski. "Molecular Structure and Antioxidant Properties of Alkali Metal Salts of Rosmarinic Acid. Experimental and DFT Studies." Molecules 24, no. 14 (July 21, 2019): 2645. http://dx.doi.org/10.3390/molecules24142645.

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The molecular structure of alkali metal rosmarinates was studied in comparison to rosmarinic acid using FT-IR, FT-Raman, 1H and 13C NMR spectroscopy, as well as density functional theory (DFT) calculations. The B3LYP/6-311+G(d,p) method was used to calculate optimized geometrical structures of studied compounds, atomic charges, dipole moments, energies, as well as the wavenumbers and intensities of the bands in vibrational and NMR spectra. Theoretical parameters were compared to experimental data. Antioxidant activity was determined using two spectrophotometric methods: (i) Assessing the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable radical and (ii) assay of antioxidant power of ferric ions reducing (FRAP). The linear correlations were found between HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) energy gap and the reducing power expressed as FRAP (R = 0.77) as well as between IC50 values (the ability of quenching DPPH radicals) and Δνas-s(COO) in IR spectra (differences between asymmetric and symmetric stretching vibrations bands) (R = 0.99). Photochemical properties of studied compounds were also evaluated. The influence of alkali metal on the electronic system of the rosmarinic acid molecule was discussed.
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41

Beuther, H., Y. Wang, J. Soler, H. Linz, J. Henshaw, E. Vazquez-Semadeni, G. Gomez, et al. "Dynamical cloud formation traced by atomic and molecular gas." Astronomy & Astrophysics 638 (June 2020): A44. http://dx.doi.org/10.1051/0004-6361/202037950.

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Context. Atomic and molecular cloud formation is a dynamical process. However, kinematic signatures of these processes are still observationally poorly constrained. Aims. We identify and characterize the cloud formation signatures in atomic and molecular gas. Methods. Targeting the cloud-scale environment of the prototypical infrared dark cloud G28.3, we employed spectral line imaging observations of the two atomic lines HI and [CI] as well as molecular lines observations in 13CO in the 1–0 and 3–2 transitions. The analysis comprises investigations of the kinematic properties of the different tracers, estimates of the mass flow rates, velocity structure functions, a histogram of oriented gradients (HOG) study, and comparisons to simulations. Results. The central infrared dark cloud (IRDC) is embedded in a more diffuse envelope of cold neutral medium traced by HI self-absorption and molecular gas. The spectral line data as well as the HOG and structure function analysis indicate a possible kinematic decoupling of the HI from the other gas compounds. Spectral analysis and position–velocity diagrams reveal two velocity components that converge at the position of the IRDC. Estimated mass flow rates appear rather constant from the cloud edge toward the center. The velocity structure function analysis is consistent with gas flows being dominated by the formation of hierarchical structures. Conclusions. The observations and analysis are consistent with a picture where the IRDC G28.3 is formed at the center of two converging gas flows. While the approximately constant mass flow rates are consistent with a self-similar, gravitationally driven collapse of the cloud, external compression (e.g., via spiral arm shocks or supernova explosions) cannot be excluded yet. Future investigations should aim at differentiating the origin of such converging gas flows.
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42

Xuan, Xiaopeng, Xinsheng Wang, and Na Wang. "Theoretical study of molecular structure and vibrational spectra of 1,4-dihydroxyanthraquinone." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 79, no. 5 (September 2011): 1091–98. http://dx.doi.org/10.1016/j.saa.2011.04.024.

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43

Atalay, Y., and D. Avcı. "Theoretical studies of molecular structure and vibrational spectra of melaminium citrate." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 67, no. 2 (June 2007): 327–33. http://dx.doi.org/10.1016/j.saa.2006.07.022.

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44

Teterin, Yury, Anton Teterin, Nikolay Yakovlev, Igor Utkin, Kirill Ivanov, Leonid Shustov, Labud Vukcevic, and George Bek-Uzarov. "X-Ray photoelectron study of actinide (Th, U, Pu, Am) nitrates." Nuclear Technology and Radiation Protection 18, no. 2 (2003): 31–35. http://dx.doi.org/10.2298/ntrp0302031t.

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In this work an X-ray photoelectron spectroscopy study of nitrates Th(NO3)4.4H2O UO2(NO3)2-nH2O, Pu(NO3)4-nH2O, and Am(NO3)2.nH2O was done in the binding energy range from 0 to 1000 eV in order to draw a correlation of the fine spectral structure parameters with the actinide ions oxidation states close environment structure, and chemical bond nature. The linearity of the dependence of the An5fn line intensity on the number n5f of the An5f electrons was proven to remain up to the Am3+ ion with the electron configu5fra-tion{Rn 5f6. The spectral structure in the binding energy range from 0 to ~ 15 eV was associated with the formation of the outer valence molecular orbitals due to the interaction of the An6d-, 7s, 5f - O2p electrons, and the fine spectral structure in the binding energy range from ~ 15 to ~50 eV - with the formation of the inner valence molecular orbitals due to the interaction of the An6p - O2s electrons from the filled neighboring atomic orbitals of actinide and oxygen in the studied compounds. The fine structure of the core level electron spectra in the binding energy range from ~50 to 1000 eV was shown to correlate with the actinide ion oxidation state.
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45

Globus, Tatiana, Igor Sizov, and Boris Gelmont. "Sub-THz specific relaxation times of hydrogen bond oscillations in E.coli thioredoxin. Molecular dynamics and statistical analysis." Faraday Discuss. 171 (2014): 179–93. http://dx.doi.org/10.1039/c4fd00029c.

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Hydrogen bonds (H-bonds) in biological macromolecules are important for the molecular structure and functions. Since interactions via hydrogen bonds are weaker than covalent bonds, it can be expected that atomic movements involving H-bonds have low frequency vibrational modes. Sub-Terahertz (sub-THz) vibrational spectroscopy that combines measurements with molecular dynamics (MD) computational prediction has been demonstrated as a promising approach for biological molecule characterization. Multiple resonance absorption lines have been reported. The knowledge of relaxation times of atomic oscillations is critical for the successful application of THz spectroscopy for hydrogen bond characterization. The purpose of this work is to use atomic oscillations in the 0.35–0.7 THz range, found from molecular dynamic (MD) simulations of E.coli thioredoxin (2TRX), to study relaxation dynamics of two intra-molecular H-bonds, O⋯H–N and O⋯H–C. Two different complimentary techniques are used in this study, one is the analysis of the statistical distribution of relaxation time and dissipation factor values relevant to low frequency oscillations, and the second is the analysis of the autocorrelation function of low frequency quasi-periodic movements. By studying hydrogen bond atomic displacements, it was found that the atoms are involved in a number of collective oscillations, which are characterized by different relaxation time scales ranging from 2–3 ps to more than 150 ps. The existence of long lasting relaxation processes opens the possibility to directly observe and study H-bond vibrational modes in sub-THz absorption spectra of bio-molecules if measured with an appropriate spectral resolution. The results of measurements using a recently developed frequency domain spectroscopic sensor with a spectral resolution of 1 GHz confirm the MD analysis.
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46

Jalilian, M. R. "Spectra and structure of binary azeotropes." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 66, no. 1 (January 2007): 91–93. http://dx.doi.org/10.1016/j.saa.2006.02.028.

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47

Jalilian, M. R. "Spectra and structure of binary azeotropes." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 66, no. 4-5 (April 2007): 976–78. http://dx.doi.org/10.1016/j.saa.2006.05.009.

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48

Jalilian, M. R. "Spectra and structure of binary azeotropes." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 69, no. 3 (March 2008): 812–15. http://dx.doi.org/10.1016/j.saa.2007.05.032.

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49

Fishman, A. I., A. I. Noskov, A. B. Remizov, and D. V. Chachkov. "Vibrational spectra and structure of isopropylbenzene." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 71, no. 3 (December 2008): 1128–33. http://dx.doi.org/10.1016/j.saa.2008.03.008.

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Кривобок, В. С., Д. А. Литвинов, С. Н. Николаев, Е. Е. Онищенко, Д. А. Пашкеев, М. А. Чернопицский, and Л. Н. Григорьева. "Экситонные эффекты и примесно-дефектное излучение в GaAs/AlGaAs-структурах, применяемых для изготовления детекторов среднего ИК-диапазона." Физика и техника полупроводников 53, no. 12 (2019): 1632. http://dx.doi.org/10.21883/ftp.2019.12.48617.9214.

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AbstractA series of undoped GaAs/Al_ x Ga_1 –_ x As multiple quantum well heterostructures, whose doped analogs are used for the production of photodetectors operating in the spectral range 8–12 μm, is fabricated by molecular-beam epitaxy. For the heterostructures, the spectral position of absorption lines corresponding to the allowed transitions between quantum-confined electron and hole levels in GaAs layers is established. The influence of impurity–defect states on the luminescence and absorption spectra of quantum wells is studied. The excitonic corrections for the allowed transitions are determined in relation to the quantum-well width and the aluminum content in the barrier layers. The role of excitonic effects in restoring the structure of single-electron states from interband-absorption spectra (luminescence-excitation spectra) and the relationship between these states and the working region of IR photodetectors based on GaAs/Al_ x Ga_1 –_ x As quantum wells are discussed.
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