Inelastic collisions of CaF(A 2Π) with He and Ar: Quantum calculations and adiabatic analysis

We present coupled-states (CS) calculations for collisions of CaF(A 2Π) with He and Ar. These calculations are based on potential energy surfaces determined by use of the Gordon–Kim electron–gas method [J. Chem. Phys. 56, 3122 (1972)]. The theoretical CS cross sections for rotationally inelastic transitions are compared with the experimental results of Dufour and co-workers [Chem. Phys. 98, 315 (1985)]. We obtain theoretical cross sections significantly greater than the experimental values. In order to discuss and interpret the results of our scattering calculations, we make use of a fully adiabatic description of the collision dynamics. This adiabatic analysis shows that the long-range part of the potential plays a key role in determining the sizes of the theoretical cross sections, and in underlying the failure of the energy sudden scaling relation to describe the calculated cross sections.