Atomic structure and phonons of a Pb ultrathin film on the Al(100) surface

The effect of high dynamic pressures on the electrical conductivity of the amorphous conducting carbon phase (glassy carbon) has been studied. The electrical conductivity of glassy carbon samples has been measured under the condition of shock compression and subsequent release wave. The history of the shock loading of glassy carbon has been calculated with the developed semiempirical equations of state. It has been shown the electrical conductivity of glassy carbon samples in the compression phase at a pressure of 45(5) GPa decreases abruptly by two orders of magnitude. In the relief phase, partially reversible change in the electrical conductivity of an amorphous carbon sample occurs. The recorded effect has been treated as a result of a partially reversible physicochemical transformation of shock-compressed amorphous carbon.     

Unusual Formation of the Paramagnetic Complex (η4-C4Me4)CoI2(PhTeI) and Specific Features of Its Electronic,Molecular, and Crystal Structures

Russian Journal of Coordination Chemistry - The 18-electron (η4-C4Me4)Co(CO)2TeI2Ph compound noticeably decomposes upon prolonged storage and also unusually transforms into the 17-electron...     

Structure and analysis of atomic vibrations in clusters of Cu n (n ≤ 20)

The binding energy, equilibrium geometry, and vibration frequencies of free clusters Cu _n (2 ≤ n ≤ 20) are calculated using the potentials of interatomic interactions found using the tight-binding approximation. The nonmonotonic dependence of the clusters’ minimum vibration frequency on their sizes and the extreme values for the number of atoms in a cluster n = 4, 6, 13, and 19 is demonstrated. It is noted that this result agrees with the theoretical and experimental data on stable structures of small and medium metallic clusters.     

Structure and Dynamic Stability of a Multilayer Na Film on the Cu(001) Surface

Mechanisms of atomic layer-by-layer formation of the equilibrium structure of multilayer Na film on the Cu(001) surface have been studied taking into account relaxation and dynamic (phonon) processes. It has been shown that the atomic rearrangement of the substrate-commensurate с(2 × 2) superstructure of the first Na monolayer to a bcc (110)-oriented structure begins with the second monolayer. The dynamic contribution to the formation of the structure of the growing Na film has been estimated. It has been shown that phonon modes select exponentially observed structures from statically favorable structures. All calculations have been performed with interatomic potentials constructed with the embedded atom method. The comparison of the calculated vibrational frequencies with the existing experimental data has demonstrated their good agreement.

     

Vibrations of linear cobalt clusters on a stepped copper surface

The results of calculations of vibrational properties of cobalt dimers and trimers on the Cu(110) surface are reported. The local phonon density of states and their polarizations are analyzed. The calculations are performed using interatomic interaction potentials constructed in a tight-binding approximation. It was shown that the vibrational modes of the free standing dimer and trimer remain in the supported clusters but the revealed anisotropy of the local surface relaxation leads to deformation of the interatomic bonds and, as a result, to splitting and shifting of the phonon frequencies. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 67–73, January, 2009.     

Electron-phonon interaction in the quantum well state of the 1 ML Na/Cu(111) system

The electron-phonon interaction in the quantum well state formed by a Na monolayer coating on Cu(111) is investigated theoretically. The calculations show that the electron-phonon coupling constant γ in this state decreases insignificantly (≈1%) compared to the value of γ for a clean copper surface. The corresponding electron-phonon contribution to the lifetime τ of the quantum well state increases by a factor of 1.5 compared to τ for the clean Cu(111) surface.     

Vibrational properties of the Pt(111)-<Emphasis Type="Italic">p</Emphasis>(2 × 2)-K surface superstructure

The vibrational spectra of the Pt(111)-p(2 × 2)-K ordered surface superstructure formed on the platinum surface upon adsorption of 0.25 potassium monolayer are calculated using the interatomic interaction potentials obtained within the tight-binding approximation. The surface relaxation, the dispersion of surface phonons, the local density of surface vibrational states, and the polarization of vibrational modes of adatoms and substrate atoms are discussed. The theoretical results are in good agreement with the recently obtained experimental data.     

Liquid phase hydrogenolysis of dibenzyl ether over metals of the VIIIth group

It has been shown that depending on the catalyst and the solvent used, during the conversion of dibenzyl ether to toluene hydrogenolysis of C-O ether bonds, dehydrogenation and hydrogenolysis of benzyl alcohol formed, hydrogenation and decarbonylation of benzaldehyde, and the recombination of benzyl radicals and the benzylation of toluene can take place. The activity of catalysts in hydrogenolysis reactions of dibenzyl ether and benzyl alcohol to produce toluene decreases as follows: Pd/C>Pd>Raney Ni>Rh, whereas the selectivity drops down in the order: Raney Ni>Pd>Pd/C>Rh. The reaction rates depend on the solvent and diminish in the order: ethanol>2-propanol>benzene.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1257–1261, July, 1993.     

Synthesis and fungicidal activity of new 4-hydroxy-6-trifluoromethyl-2-phenylindoles

Starting from 1,3-dinitro-5-trifluoromethylbenzene, a pioneering synthesis and dimethylaminomethylation of new 2-aryl- 4-hydroxy-6-trifluoromethylindoles have been performed. The study of fungicidal activity has revealed the effect of dimethylaminomethyl group position on fungitoxic properties.