CN DESORPTION FROM POTASSIUM-METAL SURFACES UNDER ELECTRON-BOMBARDMENT

First measurements of the energy-dependent desorption cross sections n ear threshold energy for electron-stimulated desorption of excited CN molecules from potassium-metal surfaces are presented. Threshold energ ies were observed to be different when the alkali metal surface was ex posed to a CO2 + N-2 mixture from that when exposed to H-2 gas, leadin g to the conclusion that two different chemical processes are involved . The rotational energy distribution was observed to be independent of incident electron energy. We postulate a desorption model similar to the Antoniewicz model.