Structure and Dynamics of the He_2~*(a~3Σ_u~+) Molecular Complex in Condensed Phases of Helium

摘要

An investigation is made of the absorption spectra of triplet metastable helium molecules in the a~3Σ_u~+ state in liquid ~4He and ~3He at various pressures and in dense ~3He gas. An analysis of the spectrum corresponding to the a~3Σ_u~+ → c~3Σ_g~+ transition confirms the conclusion that there is a microscopic bubble surrounding the molecule in liquid helium. A simple approximation is proposed for the wave function of the valence electron of the molecule and the parameters of the bubble are determined for various experimental conditions. The coefficient of molecular recombination in liquid ~3He and ~4He was determined experimentally at various pressures and in dense cold ~3He gas. The results show good agreement with the theory of mutual recombination limited by molecular diffusion under conditions of strong van der Waals interaction. It is shown that in the condensed phases of helium the polarization of the molecules under the action of the magnetic field does not lead to suppression of their mutual recombination, and this is confirmed experimentally.