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61.
Electronic states in solids with disorder give rise to an elastic (Rayleigh) contribution to the scattering spectrum which becomes resonantly enhanced for excitation in the electronic transition. It is shown theoretically that from this resonant Rayleigh process, if temporally resolved, the coherence time of the electronic states may be deduced. Experimentally this is demonstrated for the first time by studying the n = 1 heavy-hole exciton in GaAs/AlGaAs quantum well structures. Employing picosecond time-resolved spectroscopy and analyzing the data within the developed theory, coherence times are found between 5 and 30 ps in agreement with earlier results obtained by non-linear optical techniques. 相似文献
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In 2020, the world tried to combat the corona virus (COVID-19) pandemic. A proven treatment method specific to Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is still not found. In this study, seven new antiviral compounds were designed for COVID-19 treatment. The ability of these compounds to inhibit COVID-19’s RNA processing was calculated by the molecular docking study. It has been observed that the compounds can have high binding affinities especially against NSP12 (between -9.06 and -8.00 kcal/mol). The molecular dynamics simulation of NSP12-ZG 7 complex proved the stability of interaction. The synthesis of two most active molecules was performed by one-pot reaction and characterized by FT-IR, 1H-NMR, 13C-NMR, and mass spectroscopy. The compounds presented with their synthesis are inhibitory core structures against SARS-CoV-2 infection. 相似文献
64.
Infrared and Raman spectra of crystalline, melted and solvated ortho-terphenyl and its perdeuterated isotopomer, D14-ortho-tephenyl, have been recorded. Optimized geometries and vibrational frequencies were calculated by the semiempirical RHF/AM1 method and by DFT using the B3LYP functional and 6–31G(d) basis set. In both cases the lowest energy conformation is of C2 symmetry. With the scaled AM1 and B3LYP/6-31G(d) force fields the average error in reproducing the experimental molecular vibrational frequencies is 13cm?1 and 5cm?1, respectively. The AM1 potential energy surface for phenyl torsions was mapped on a 15° grid. The barrier to concerted internal rotation is estimated to lie between 3 kJ mol?1 and 6kJ mol?1. The calculations of the lattice dynamics at k = 0 in the low temperature fully ordered crystal phase of parent and deuterated ortho-terphenyl were performed with inclusion of six low lying intramolecular vibrations. The conformational change of the ortho-terphenyl molecule induced by crystal packing forces was taken into account by re-defining the unperturbed molecular vibrational state. Although an accurate assignment of lattice vibrations was not possible, the calculated spectra give quite a reasonable picture of the low frequency dynamics in crystalline ortho-terphenyl. The relevance of the results obtained to the glass forming property of ortho-terphenyl is discussed. 相似文献
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Bengt EK 《Letters in Mathematical Physics》1981,5(2):149-154
A method to construct Euclidean covariant fields corresponding to a relativistic quantum field theory with arbitrary spins is presented. The constructed fields act on a state space with an indefinite inner product, they commute (or anticommute) totally and (except for hermitian Fermion fields) adjoint relativistic fields correspond to adjoint Euclidean fields. The cases where this method can be applied include all Gårding-Wightman theories invariant under space inversion. 相似文献
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J. Schwarze W. Krämer G. Fandel G. Zäpfel A. Kalliauer J. Reese P. Mertens 《Mathematical Methods of Operations Research》1981,25(8):B274-B278
Ohne Zusammenfassung 相似文献
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Nico Schwarze Dr. Simon Steinhauer Beate Neumann Dr. Hans‐Georg Stammler Prof. Dr. Berthold Hoge 《Angewandte Chemie (International ed. in English)》2016,55(50):15528-15530
Pure anhydrous hexafluorosilicic acid (H2[SiF6]) is a still elusive species, although its existence in aqueous solutions is well documented. Desiccation inevitably leads to decomposition to form tetrafluorosilane and hydrogen fluoride. An oxonium hexafluorosilicate turned out to not be stable at room temperature. Partial substitution of the fluorine atoms with strong electron‐withdrawing perfluoroalkyl groups results in substantial stabilization of the corresponding fluorosilicic acids. Mono‐ and bis(pentafluoroethyl)‐substituted fluorosilicic acids were prepared through conversion of the respective halosilanes (Si(C2F5)nX4?n, with X=Cl, Br) with aqueous HF, and were obtained as colorless solids. They can be stored at room temperature for several months without decomposition, and thus are the first examples of stable fluorosilicic acids. 相似文献