Diffusion and excitation transfer of metastable helium in normal gaseous helium

Abstract

The resonance collision of normal and metastable helium atoms has been investigated, and cross-sections calculated for total elastic scattering, diffusion and transfer of excitation. The theoretical diffusion coefficient of metastable atoms in normal helium agrees reasonably well with experimental results of Ebbinghaus and Biondi. As a consequence of a potential barrier in the interaction of the atoms at large separations, the transfer cross-section shows an unusual variation, being small for low collision energies and reaching a maximum of the order of 10$\pi $a$_{0}^{2}$ for collisions about 0$\cdot $25 eV energy. Comparison is made with experiments by Reynolds.