Depopulation of low‐Rydberg Na atom in collisions with rare gases: A molecular‐state treatment

Abstract

Total quenching of the low-Rydberg state of Na in collision with thermal Ne and Ar was investigated, for the first time, employing a molecular approach in the impact parameter formalism. A large basis set of Slater-type orbitals was used to calculate the molecular structure of the transient quasimolecule formed during the collision; pseudopotentials were used to incorporate the effective binding of the distant electron. A 14-channel calculation was carried out to evaluate the total depopulation cross sections for Na(9s) colliding with the ground-state Ne and Ar atoms in the thermal-energy region. The two colliding pairs not only differ from each other, but also show wide variations from the previously studied NaHe pair, in terms of details of the collision dynamics. In the case of the NaAr system, a unique feature that leads to appreciably larger quenching cross sections shows qualitative agreement with the measurement. A comparative study of three (He/Ne/ArNa) colliding pairs reveals that the simplified approach like the free-electron model or the impulse approximation fails to provide details of such state-changing reactions. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 307–316, 1999