Numerical investigation of atomic dynamics in strong ultrashort laser pulses

The algorithms for the numerical solution of the stationary and nonstationary Schrödinger equations that allow the analysis of the dynamics of single-electron atoms in the presence of an external strong linearly polarized electromagnetic field in the dipole approximation are presented. Several examples of the simulation of atomic dynamics in the presence of high-intensity laser fields are considered to illustrate the possibilities of the proposed algorithms.     

Generation of XUV attosecond pulses in the process of atomic ionization by few-cycle laser radiation

Ionization of a model two-electron atom in the presence of a strong field of ultrashort laser pulses is investigated using the numerical integration of the nonstationary Schrödinger equation, which describes the dynamics of a quantum system in the presence of an electromagnetic wave. The features of two-electron ionization in the presence of one-and two-cycle pulses are analyzed. The suppression of double ionization in the presence of ultrashort laser pulses related to a finite-time interelectron energy exchange upon the laser action is demonstrated. The features of the generation of high-order harmonics and single XUV attosecond pulses are studied for the atomic ionization by few-cycle laser pulses. The parameters of the laser pulse are optimized for the effective generation of a single XUV attosecond pulse.     

Quantum Entanglement and Phase Control of Nonclassical Electromagnetic Fields Interacting with Atomic Systems

JETP Letters - The interaction of a three-level atom with two quantum field modes has been studied analytically. Strong quantum entanglement between individual parts of the considered multipartite...     

Study of the chemical reactions' influence on semiconductor films structure formation by the Monte-Carlo method

The investigation by the Monte-Carlo method of the growth of the silicon epitaxial film at a chloride CVD system has allowed to find out the composition of adsorption layer, the micromechanism of the reactions of Si atoms building-in into the growing crystalline layer and the growth conditions influence on the growth rate and film surface roughness. The change of adsorptive layer composition in the system SiCl₄—HCl—H₂ (fraction of adaatoms, silicon atoms built-in a crystal and molecules SiCl₂) depending on temperature has been determined. The change of silicon film growth rate depending on temperature and concentration change of SiH₂Cl₂ has been established and the contribution of growth mechanism (with participation of adatom, silicon atoms and molecules SiCl₂) into the total rate of film growth has been shown.     

Peculiarities of the ionization of many-electron systems and generation of attosecond pulses in ultrashort laser fields

The ionization of a model two-electron atom in the field of a strong ultrashort laser pulse is studied by numerical integration of the nonstationary Schrödinger equation describing the dynamics of a quantum system in the field of an electromagnetic wave. Pecularities of the two-electron ionization are analyzed for pulses whose duration amounts to one to two periods of oscillation of the electric field of the wave at different frequencies of the incident radiation. For extremely short pulses, the double ionization is found to be suppressed. This effect is caused by the finiteness of the interelectron energy exchange time during the laser action. Peculiarities of the generation of high-order harmonics and single XUV attosecond pulses upon ionization of atoms by laser pulses, whose duration is within one to two optical cycles, are investigated.     

Influence of Conditions of Zinc Selenide Oxidation with Atmospheric Oxygen on the Composition of Volatile Products

The qualitative and quantitative composition of volatile products of zinc selenide oxidation with atmospheric oxygen was determined. The influence of the process conditions on quantitative composition of the volatile products was studied.     

Crown compounds for anions. Sandwich complex of cyclic trimeric perfluoro-o-phenylenemercury with [B12H11SCN]2– anion

The reaction of cyclic trimeric perfluoro-o-phenylenemercury (o-C₆F₄Hg)₃ (1) with the polyhedral [B₁₂H₁₁SCN]^2– anion in THF at 20 °C affords the {[(o-C₆F₄Hg)₃](B₁₂H₁₁SCN)}^2– (4) and {[(o-C₆F₄Hg)₃]₂(B₁₂H₁₁SCN)}^2– (5) complexes. Complex 5 was isolated as the tetrabutylammonium salt. X-ray diffraction analysis showed that this complex has a bent-sandwich structure in which the [B₁₂H₁₁SCN]^2– anion is located between the planes of two molecules 1 and is coordinated to both these molecules through B—H—Hg bridges and S—Hg bonds. The stability constants of complexes 4 and 5 in THF (20 °C), which were determined from the IR spectroscopic data, are 16 L mol^–1 and 992 L² mol^–2, respectively.     

Metal Complexes with the N-Heterocyclic Ligand: Synthesis,Structures, and Thermal Decomposition

Russian Journal of Coordination Chemistry - The heterometallic nickel and iron chalcogenide complexes, (η5-C5H5)Ni(MeIm)S(µ2-SnPr)Mn(CO)2(η5-C5H5) (I) and...     

Binding of ferrocene by cyclic trimeric perfluoro-<Emphasis Type="Italic">o</Emphasis>-phenylenemercury. Synthesis and structure of the first double-decker sandwich complex of a sandwich

The first double-decker sandwich complex of a sandwich was synthesized and fully characterized. The complex was prepared by the reaction of cyclic trimeric perfluoro-o-phenylene-mercury (o-C₆F₄Hg)₃ (1) with ferrocene in an ethereal solution at 20 °C and has the composition {[(o-C₆F₄Hg)₃]₂(Cp₂Fe)} (2). The ferrocene sandwich in 2 is located between the planes of two mercury-containing macrocycles and is coordinated to each of them through donation of the -electrons of the ⁵-Cp ligands to vacant orbitals of the mercury atoms of the adjacent molecule 1. It was concluded that all carbon atoms of the ⁵-Cp rings in complex 2 are involved in the bonding to the macrocycles. Complexation with 1 leads to considerable shifts of the (C-H) and (C-H) bands of ferrocene in the IR spectrum to high frequencies. The structure of complex 2 was determined by X-ray diffraction.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2754–2756, December, 2004.     

Crown compounds for anions. The nature of chemical bonds in the complexes of halide anions with cyclic trimeric perfluoro-o-phenylenemercury and some of its analogs

Geometries and electronic structures of the complexes of halide anions with cyclic trimerico-phenylenemercury, (o-C₆H₄Hg)₃, perfluoro-o-phenylenemercury, (o-C₆F₄Hg)₃, vinylenemercury, (C₂H₂Hg)₃, and perfluorovinylenemercury, (C₂F₂Hg)₃, were modelled by the MNDO method. Calculations were performed for [L-X]^– semisandwich complexes, [X-L-X]^2– bipyramidal complexes, and [L-X-L]^– sandwich complexes (where X=Hal,L is a mercury-containing macrocycle). Based on the results of calculations, we concluded that it was advantageous to describe the chemical bonding between halide anions and mercury-containing macrocycles in terms of generalized chemical bonds, which were successfully used for -complexes of transition metals. In the [L-X]^– semisandwich complexes, the halide anion and the metallacycle are involved in the formation of three generalized chemical bonds: one headlight-shaped -bond and two two-lobe -bonds. In the [X-L-X]^2– bipyramidal complexes, each halide anion forms three generalized chemical bonds with the macrocycle. It is possible because the macrocycleL has unoccupied molecular orbitals suitable for the formation of such bonds; these MOs consist mainly of the orbitals of mercury atoms directed toward both the upper and lower halogen atoms. In the [L-X-L]^– sandwich complexes, the halide anion cannot be bonded to each ringvia three bonds, and, hence, an unsymmetrical structure is formed, in which the rings are located at different distances from the central atom: the [L-X]^– semisandwich complex solvated by macrocycleL.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1035–1042, June, 1995.The authors are grateful to V. I. Faustov for valuable remarks.This work was supported by the Russian Foundation for Basic Research (Project No. 93-03-18342).