Fine-structure transitions in sodium-rare-gas collisions

Abstract

An impact-parameter treatment is used to obtain cross sections for reactions such as Na ²P₁2/+He to Na²P₃2/+He. The coupled equations with and without rotational coupling are numerically solved. The reaction between this work and the Landau Zener formula is discussed. It is shown that rotational coupling cannot be neglected even at low velocities. The effect of repulsive exchange interaction is shown to be much more important, at temperatures exceeding 400 K, than Van der Waals interaction for Na-He collisions. At 400 K, the cross sections are 78 AA² for Na-He, 68 AA² for Na-Ne and 62 AA² for Na-Ar.