Exclusive production of Ba(6s6p 3P2) in the collisional deactivation of Ba(6s6p 1P1) by the rare gases

Abstract

The collisional deactivation of Ba(6s6p 1P1) by He, Ne, Ar, Kr, and Xe results in the exclusive production of Ba(6s6p 3P2). The lower-lying Ba(6s6p 3P1,0), Ba(6s5d 1D2), and Ba(6s5d 3D3,2,1) states are produced in negligible yield, within experimental error. From the known rate of radiative production of the Ba(6s5d 3D2) and Ba(6s5d 1D2) states from Ba(6s6p 1P1), absolute cross sections from the production of Ba(6s6p 3P2) in the collisional deactivation of Ba(6s6p 1P1) by the rare gases were determined and found to lie in the 0.4–4.0 Å2 range. A general mechanism is proposed in which there are avoided crossings between slightly attractive Ba⋅RG(1Π1) molecular potential curves correlating with Ba(6s6p 1P1) and repulsive Ba⋅RG(3Σ1) curves correlating with Ba(6s6p 3P2).