Quenching ofNa(4p)by He andH2:A molecular-state treatment

The collisional quenching of excited Na(4p) by He and H{sub 2} has been studied using the semiclassical, impact-parameter, close-coupling method based on a molecular expansion augmented by the plane-wave translation factor. Interactions between the colliding partners are approximated using suitable pseudopotentials. At low velocities 0.0005{le}v{le}0.001thinspa.u., interference oscillations which depend on the spatial alignment of the electron charge distribution before the collision are present in the cross sections for H{sub 2} quenching perturber. The cross sections due to H{sub 2} are larger than those of He atoms throughout the energy region. At T=470thinspK the present quenching rate coefficients show good agreement with the experimental data of Kleiber {ital et al.} [J. Chem. Phys. {bold 98}, 1101 (1993)]. {copyright} {ital 1997} {ital The American Physical Society}