Direct detection of neutral atoms photodesorbed from monolayers and multilayers of rare gases on a metal surface by excitonic and ionic primary processes

Neutral atoms photodesorbed by monochromatic synchrotron radiation between 7 and 30 eV from monolayers and multilayers of Ar and Kr on Ru(001) have been detected by positionization and lock-in mass spectrometry. From multilayers, primary processes leading to desorption are surface and bulk excitons of various orders, ionic excitations, and two-step processes (photoelectron-induced excitons). Ar monolayers show surface excitons besides ionic excitations. The acting mechanisms are briefly discussed.