A. I. Parkhomenko

Spectral anomalies of light-induced drift of rubidium and lithium under monochromatic excitation

The anomalous light-induced drift (LID) of atoms caused by a velocity dependence of collision frequencies has been investigated in the frame of the theory without adjustable parameters. Our results open the possibility of experimental probing of models of interatomic potentials. The extension of the strong-collision model to the case of velocity-dependent collision rates, is the basis of our approach. The obtained model describes the anomalous LID both in the case of arbitrary mass ratio of absorbing- and buffer-gas particles and in the case of arbitrary ratio of the homogeneous and Doppler widths. In particular, we applied our model to describe the anomalous LID in alkali - noble-gas mixtures (Rb - Kr and Li - Ne systems). Qualitatively another anomaly of the LID velocity was also found in the low-pressure region. As pointed out, the optical pumping effect and the hyperfine structure of the ground electronic state, but not the velocity dependence of the collision rates, are the sources of this new anomaly.

Spectral anomalies in light-induced drift in alkali-noble gas mixtures

The spectral shape of a light-induced drift (LID) signal in alkali-noble gas mixtures has been investigated. Realistic calculations of the velocity dependence of the transport cross sections in different quantum states have been made with the help of the semiempirical potentials of Pascale and Vandeplanque (1974). The anomalous LID spectral profile for the Li-Ne system has been obtained theoretically.

Light-induced drift in a heavy buffer gas

Abstract A strong velocity dependence of the relative change of the transport cross-sections σi(ν) of particles under optical excitation (up to a change of the sign [ σ m (ν)−σ n (ν)] σ n (ν) ) has been found. In the model of the Lorentz gas it is shown that this fact changes qualitatively the character of the dependence of the drift velocity on the radiation frequency.

Effect of phase memory under collisions on field work and light-induced drift of gas particles

The influence of phase memory under collisions on the field work and the light induced drift (LID) effect of two-level gas particles is studied. It is shown that the phase memory effects may lead to the case where about half of the particles interacting with radiation amplify the incident radiation. The integral absorption coefficient for this remains positive due to growing radiation absorption by another half of the particles. It has been found that the phase memory strongly affects the LID under v k (v is the collision frequency, k is the Doppler line width): calculation of LID without regard for the phase memory can lead to underestimation of the LID effect value by a factor of (v/k)2 1. Interaction of the particles in the hard sphere model is used to illustrate that the phase memory begins to affect the LID when the relative difference of the transport cross-sections of the particles is ground and excited states is small: Δσ/σ /R, where is the de Broglie wavelength at thermal velocities, R is the sphere radius.