Influence of first collisions on the passage of laser-excited molecules through capillaries

An analysis is made of the diffusion of molecules excited by a laser field through a porous plate in the approximation of a single channel represented by a capillary. It is shown that the first few collisions of a molecule with the walls of the capillary, which cause deactivation if the molecule is excited, have a considerable influence on the ratio of the permeabilities of the capillary to excited and unexcited molecules. Several conclusions are drawn on the permeability of a capillary under various conditions and these may be confirmed or contradicted by experiments.