Collisional Excitation Transfer between Atoms in the Resonant Process

Abstract

The excitation transfers through collision between hydrogen atoms and between other simple identical atoms are considered theoretically by an impact parameter method. A rotating atom approximation and a fixed atom approximation (concerned with the direction of electronic polarization) are applied to the problem. The cross-section for the transfer of the excitation (2 p 2 P ) of a hydrogen atom with thermal velocity (kinetic energy of 0.025 ev) to the other hydrogen atom in the ground state is estimated to be 3065 A 2 with the rotating atom approximation and 680 A 2 with the fixed atom approximation. In the case of helium atoms, the cross-section for the transfer of the excitation (2 p 1 P ) is also estimated to be 606.7 A 2 with thermal velocity.