Nascent state distributions of Ca(4s3d 1D2), Ca(4s3d 3D J), and Ca(4s4p 3P J) in the collisional deactivation of Ca(4s4p 1P1) by the rare gases

Abstract

The collisional deactivation of Ca(4s4p 1P1) by the rare gases results in essentially exclusive production of the Ca(4s3d 3DJ) states. The collisional production of the Ca(4s3d 1D2) and Ca(4s4p 3PJ) states was negligible, within experimental error, compared to production of the Ca(4s3d 3DJ) states for He, Ne, Ar, and Kr. For Xe a relative branching ratio of 0.02±0.01 was determined for Ca(4s3d 1D2) collisional production. The nascent distributions of Ca(4s3d 3D3,2,1) multiplets were nonstatistical, and varied slightly from gas to gas. The lowest-lying Ca(4s3d 3D1) multiplet was always very underpopulated. A general mechanism is proposed whereby there are avoided crossings between slightly attractive Ca⋅RG(1Π1) potentials correlating with Ca(4s4p 1P1) and repulsive Ca⋅RG(3Σ1) potentials correlating with Ca(4s3d 3DJ). Possible reasons for the preferential production of the 3DJ vs the 1D2 or 3PJ states, and the nonstatistical nascent populations of the 3DJ multiplets, are discussed.