Scattering of state-selected molecules in the sudden approximation

Abstract

It is shown that in the sudden approximation the differential cross section for scattering by state-selected molecules can be factored into a geometrical part depending on the experimental arrangement and the quantum numbers and a dynamical part which depends on the harmonic coefficients of the cross section for scattering by a fixed target. The importance of the dependence of the cross section on the azimuthal angle of scattering is emphasised. The Glauber approximation is employed to obtain the small-anisotropy limit of the cross section for forward, diffraction and classical scattering. The subsidiary infinite-order sudden (IOS), body-fixed and m-conserving approximations are investigated. The usual IOS approximation is found to be particularly poor and the other approximations satisfactory only for the azimuthal dependence of the cross section.