Mechanisms of surface chemiluminescence excitation accounting for nonequilibrium desorption and diffusion

Based on the results obtained on a device with molecular beams we propose the mechanism for excitation of heterogeneous chemiluminescence (HCL) on the ZnS-Tm and CaO-Bi surfaces, which takes into account nonequilibrium emission of activator ions into the vacuum during recombination of hydrogen atoms, diffusion of luminescent centers from the bulk to the surface, and aging of specimens in the course of the experiment. The formation and relaxation of strongly excited oscillating states on the surface and their participation in luminescent center excitation and nonequilibrium desorption are also considered. The kinetics of HCL are found to be related to the variations in the quantum yield of atomic recombination rather than to dynamic blocking of the surface. It is shown that auto-oscillations of the HCL intensity result from a nonequilibrium energy exchange between excited and unexcited admolecules.