Dmitry L. Dorofeev

Dynamic polarizabilities of atoms in their low-excited states : He, Be, Mg and Ca

The quantum defect Green function formalism is applied to calculate the dynamic scalar and tensor polarizabilities of some atoms in their excited states (21S, 23S, 21P and 23P for He, 21P and 23P for Be, 33P for Mg and 43P for Ca). Experimental and calculated oscillator strength values were used to provide an account for low-excited states (reduce–adding correction of the Green function) while the high-excited and continuum states are accounted semi-analytically. The calculated polarizability values are in good (within several per cent) agreement with the available experimental data and the ab initio numerical data.

General quantum resonances of the kicked particle

The quantum resonances (QRs) of the kicked particle are studied in a most general framework by also considering arbitrary periodic kicking potentials. It is shown that QR can arise, in general, for any rational value of the Bloch quasimomentum. This is illustrated in the case of the main QRs for arbitrary potentials. In this case, which is shown to be precisely described by the linear kicked rotor, exact formulas are derived for the diffusion coefficients determining the asymptotic evolution of the average kinetic energy of either an incoherent mixture of plane waves or a general wave packet. The momentum probability distribution is exactly calculated and studied for a two-harmonic potential. It clearly exhibits additional resonant values of the quasimomentum and it is robust under small deviations from QR.

Fluctuations and transients in quantum-resonant evolution

The quantum-resonant evolution of the mean kinetic energy (MKE) of the kicked particle is studied in detail on different time scales for general periodic kicking potentials. It is shown that the asymptotic time behavior of a wave-packet MKE is typically a linear growth with bounded fluctuations having a simple number-theoretical origin. For a large class of wave packets, the MKE is shown to be exactly the superposition of its asymptotic behavior and transient logarithmic corrections. Both fluctuations and transients can be significant for not too large times but they may vanish identically under some conditions. In the case of incoherent mixtures of plane waves, it is shown that the MKE never exhibits asymptotic fluctuations but transients usually occur.

Diabatic Rydberg states in polar molecules with a complex core

Based on a new solution of the Schrodinger equation for an electron in Coulomb + rotating dipole potential, diabatic (inverse Born-Oppenheimer) Rydberg states are treated in polar molecules. The obtained exact solution contains explicit dependence on the molecular core coupling scheme which is considered to be intermediate between Hunds (a), (c) and (b) cases. Analytical expressions are derived for the diabatic quantum defects of the Rydberg states in polar molecules with such a complex core.

Method of the quantum defect Green's function for calculation of dynamic atomic polarizabilities

The quantum defect Green’s function enabling one to take into account exactly the contribution of highly excited and continuum states to the polarizability is found. The contribution of the ground and low-lying excited states is taken into account by using experimental values of the corresponding oscillator strengths. The good accuracy of the method proposed is demonstrated by calculation of the scalar dipole dynamic polarizabilities of noble gas atoms with consideration of the fine structure of the terms.

Charge distribution of the Kr ions resulting from the X-ray irradiation at 1.3 keV

The model of effective atomic potential and the Monte Carlo method are used to calculate the charge distribution of the Kr ions that are formed due to irradiation of neutral atoms by X-ray photons at an energy of 1.3 keV. The calculated results are in good agreement with the recent experimental data and can be used for development and maintenance of gas detectors that monitor the intensity of X-ray free-electron lasers.

Oscillator strengths for the Rydberg states of NaHe

The oscillator strengths for Rydberg states of a NaHe molecule are calculated using a semianalytic procedure with the l-coupling effect taken into account (due to the dipole potential of a core). This effect gives rise to nonzero oscillator strengths for transitions forbidden in the atomic model of molecular Rydberg states. The difference between calculations in terms of the atomic model and calculations with consideration of the dipole moment of a core is shown for allowed transitions.

Magnetohydrodynamic generator of pseudosound

The theory of a periodic flow of a conducting magnetized liquid in the presence of an ac current passing through it is described. It is shown that the flow arising under these conditions is of pseudosound character rather than sonic, as stated in some publications. Experimental data demonstrating the transformation of pseudosound flow into sound waves are presented.