The elastic and inelastic scattering of diatomic molecules by atoms: CsI+Ar, CsCl+Ar, CsI+Xe

Abstract

Measurements of differential cross sections for the elastic and inelastic scattering of CsI by Ar, of CsI by Xe, and of CsCl by Ar are reported at three relative translational energiesE in the range 4–17 kJ mol−1. Both excitation and de‐excitation of the molecules, which have internal energies approximately those of a gas at 844 K, occur with cross sections approaching those of elasticscattering for center‐of‐mass angles of 40° or greater. No rainbow structure is apparent; presumably either E is below the threshold for the transition from orbiting to rainbow scattering, or E is so high that any rainbow structure is obscured by the scattering near the primary beam, or more probably the molecular asymmetry and dipole moment cause complicated trajectories. The absence of structure corresponding to purely vibrational transitions, even when this would be resolved by the apparatus, suggests that a substantial fraction of the inelastic events involve changes in rotational energy.