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851.
Tatiana M. Petrova Alexander M. Solodov Alexander A. Solodov Vladimir M. Deichuli Vitalii I. Starikov 《Molecular physics》2018,116(23-24):3631-3641
ABSTRACTThe water vapour line broadening (γ) and shifting (δ) coefficients for 149 lines of 10 vibrational bands 2ν1, 2ν3, ν1?+?ν3, 2ν2?+?ν3, ν1?+?2ν2, ν2?+?2ν3, 2ν1?+?ν2, 3ν2?+?ν3, ν1?+?3ν2 and 6ν2 induced by hydrogen pressure were measured with a Bruker IFS 125 HR spectrometer. The measurements were performed at room temperature with a spectral resolution of 0.01 cm–1 and in a wide pressure range of H2. The calculations of the broadening coefficients γ and δ were performed in the framework of the semi-classical method using an effective vibrationally dependent interaction potential. The optimal sets of potential parameters that give the best agreement with the measured broadening coefficients for each vibrational band separately were found. Then combined experimental data of 16 vibrational bands of H2O perturbed by H2 were used to determine the analytical dependence of some potential parameters on vibrational quantum numbers. The analytical expressions that reproduce the broadening coefficients γ for different vibrational bands are proposed. 相似文献
852.
Yasuhiro Miwa Tomoki Nagahama Harumi Sato Atsushi Tani Kei Takeya 《Molecules (Basel, Switzerland)》2022,27(15)
Semi-clathrate hydrates are attractive heat storage materials because the equilibrium temperatures, located above 0 °C in most cases, can be changed by selecting guest cations and anions. The equilibrium temperatures are influenced by the size and hydrophilicity of guest ions, hydration number, crystal structure, and so on. This indicates that intermolecular and/or interionic interaction in the semi-clathrate hydrates may be related to the variation of the equilibrium temperatures. Therefore, intermolecular and/or interionic interaction in semi-clathrate hydrates with quaternary onium salts was directly observed using low-frequency Raman spectroscopy, a type of terahertz spectroscopy. The results show that Raman peak positions were mostly correlated with the equilibrium temperatures: in the semi-clathrate hydrates with higher equilibrium temperatures, Raman peaks around 65 cm−1 appeared at a higher wavenumber and the other Raman peaks at around 200 cm−1 appeared at a lower wavenumber. Low-frequency Raman observation is a valuable tool with which to study the equilibrium temperatures in semi-clathrate hydrates. 相似文献
853.
S. Senthilkumar M. Briget Mary V. Ramakrishnan 《Journal of Raman spectroscopy : JRS》2007,38(3):288-294
The vibrational assignments of the observed wavenumbers have been made by analyzing the infrared and Raman spectra of L ‐valinium picrate in the crystalline state at room temperature. L ‐Valinium acts as the cation of the crystal and the carbonyl CO group exists in the protonated form in it. Asymmetric deformation and symmetric deformation modes of the isopropyl group have been identified, indicating that the two CH3 groups are in different environments. The stretching and bending modes of the various functional groups have been shifted owing to the extensive intermolecular hydrogen bonding in the crystal. The symmetry of the picrate anion has not been modified in the crystal by the hydrogen bonding with the cation. Fermi resonance is also observed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
854.
Tanner George Samantha W. McWilliams Jason D. Masuda Melbourne J. Schriver 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(4):125-132
The known 1,3,4-oxathiazol-2-ones with crystal structures reported in the Cambridge Structural Database are limited (13 to date) and this article expands the library to 15. In addition, convenient starting materials for the future exploration of 1,3,4-oxathiazol-2-ones are detailed. An unexpected halogenated propanamide has also been identified as a by-product of one reaction, presumably reacting with HCl generated in situ. The space group of 5-[(E)-2-chloroethenyl]-1,3,4-oxathiazol-2-one, C4H2ClNO2S, ( 1 ), is P21, with a high Z′ value of 6; the space group of rac-2,3-dibromo-3-chloropropanamide, C3H4Br2ClNO, ( 2 ), is P21, with Z′ = 4; and the structure of rac-5-(1,2-dibromo-2-phenylethyl)-1,3,4-oxathiazol-2-one, C10H7Br2NO2S, ( 3 ), crystallizes in the space group Pca21, with Z′ = 1. Both of the structures of compounds 2 and 3 are modeled with two-component disorder and each molecular site hosts both of the enantiomers of the racemic pairs (S,S)/(R,R) and (R,S)/(S,R), respectively. 相似文献
855.
The removal of impurity gases (N2, CO2) in natural gas is critical to the efficient use of natural gas. In this work, the selective adsorption for N2 and CO2 over CH4 on MIL-100 (M) (M=4Cr, 10Cr, 6Fe, 1In, 1Sc, 3V) is studied by density functional theory (DFT) calculations. The calculated adsorption energy of the large-size cluster model (LC) of MIL-100 (M) shows that the 4MIL-100 (4Cr) is the best at the refinement of natural gas due to the lower adsorption energy of CH4 (−2.58 kJ/mol) in comparison with that of N2 (−21.49 kJ/mol) and CO2 (−23.82 kJ/mol). 1MIL-100 (1Sc) and 1MIL-100 (6Fe) can also achieve selective adsorption and follows the order 4MIL-100 (4Cr)>1MIL-100 (1Sc)>1MIL-100 (6Fe). In the research of the selective adsorption mechanism of MIL-100 (M) (M=4Cr, 1Sc, 6Fe), the independent gradient model (IGM) indicates that these outstanding adsorbents interact with CO2 and N2 mainly through the electrostatic attractive interaction, while the van der Walls interaction dominates in the interaction with CH4. The atomic Projected Density of State (PDOS) further confirms that CH4 contributes least to the intermolecular interaction than that of CO2 and N2. Through the scrutiny of molecular orbitals, it is found that electrons transfer from the gas molecule to the metal site in the adsorption of CO2 and N2. Not only does the type of the metallic orbitals, but also the delocalization of the involved orbitals determines the selective adsorption performance of MIL-100. Both Cr and Sc share their orbitals with the gases, making 1MIL-100 (1Sc) another potential effective separator for CH4. Additionally, the comparison of adsorption energy and PDOS shows that the introduction of ligands such as benzene impedes the electron donation from gas molecules (CO2, N2) to the metal site, indicating electron-withdrawing ligands will further favor the adsorption. 相似文献
856.
Prof. José Bretón Prof. Javier Hernández-Rojas Dr. Marta I. Hernández Dr. José Campos-Martínez Dr. Tomás González-Lezana 《Chemphyschem》2023,24(22):e202300425
We present a new analytical potential energy surface (PES) for the interaction between the trihydrogen cation and a He atom, , in its electronic ground state. The proposed PES has been built as a sum of two contributions: a polarization energy term due to the electric field generated by the molecular cation at the position of the polarizable He atom, and an exchange-repulsion and dispersion interactions represented by a sum of “atom-bond” potentials between the three bonds of and the He atom. All parameters of this new PES have been chosen and fitted from data obtained from high-level ab-initio calculations. Using this new PES plus the Aziz-Slaman potential for the interaction between Helium atoms and assuming pair-wise interactions, we carry out classical Basin-Hopping (BH) global optimization, semiclassical BH with Zero Point Energy corrections, and quantum Diffusion Monte Carlo simulations. We have found the minimum energy configurations of small He clusters doped with , , with N=1–16. The study of the energies of these clusters allows us to find a pronounced anomaly for N=12, in perfect agreement with previous experimental findings, which we relate to a greater relative stability of this aggregate. 相似文献
857.
Natalya Permyakova Tatyana Zheltonozhskaya Nikolay Strilchyk Nina Zagdanskaya Lesya Momot Vladimir Syromyatnikov 《Macromolecular Symposia》2003,203(1):247-258
Complex formation in the model three-component system, including polymer-polymer complex of poly(styrene-alt-maleic acid) (PSMA) and poly(ethylene oxide) (PEO), and also silica sol (SiO2) in aqueous solution as a function of molecular weight of PEO and the order of component mixing, were investigated. The degree of binding of PSMA links with PEO and SiO2 as well as the Gibbs energy of formation of the polymer-polymer complex and polymer-colloid complexes were defined. It was shown that the main factor of stabilization of the structure is hydrogen bonds. The conditions of three-component polymer-colloid system are practically independent of the order of component mixing. The spontaneous formation of polymer-colloid complexes between chemically complementary polymers and small dispersed particles is considered as the main reason for the abnormally high binding ability of colloid particles to the polymer-polymer complex. 相似文献
858.
Single molecule force spectroscopy (SMFS) is a new kind of technique based on atomic force microscope, which allows detecting force as low as pico-newtons directly. Herein based on our recent work, we want to demonstrate the investigation of supramolecular structures and interactions in polymer systems by SMFS, such as desorption force between polymer and substrate, identifiability of polymer micelle and its interaction with surfactant, splitting force of ion-induced helical structure in polysaccharide. It shows well that SMFS is a powerful tool in the study of supramolecular science. 相似文献
859.
《Mendeleev Communications》2023,33(3):413-415
Molecular interactions in the quaternary fluid system acetic acid–n-propanol–n-propyl acetate–water were analyzed by classical and ab initio molecular dynamics methods. It was shown that ab initio molecular dynamics simulation can reproduce the molecular mobility tendency and structural features of a multicomponent system without empirical parameters. 相似文献
860.
In the present work, we analyze the influence of the polarization effects taking place during the course of a 2DIR spectroscopy experiment performed on a molecular system undergoing an intermolecular vibrational energy transfer process. When both donor and acceptor molecules participating in the vibrational energy transfer are embedded in a host solvent, they face rotational diffusion that strongly distorts the resulting 2DIR spectra. It could be expected that the difference between rotational diffusion constants will be of particular interest. For this purpose, the polarization effects are discussed according to the different orderings of the laser-molecule interactions. Next, we study the distortions of the spectra as a function of the rotational diffusion constants of the individual molecules. The knowledge of these polarization effects is relevant to the interpretation of the spectra. Finally, the conclusions reached in this work for a vibrational energy transfer are valid for any other type of third-order optical process performed on the same molecular system. 相似文献