Recent results from photon stimulated desorption of rare gas solids excited with synchrotron radiation

Abstract

Desorption of neutral rare gas atoms following selective excitonic excitation of rare gas solids (Ne, Ar, Kr, Xe) by VUV photons underlines the crucial role of excitons concerning (i) transport of excitation energy from the bulk to the surface, and (ii) the microscopic desorption mechanism itself. All rare gas solids yield desorption of ground state atoms which stem from relaxation of molecular-type excitons after their radiative decay. In addition, solid Ne and Ar yield desorption of 3P1, 1P1, and metastable (3P2, 3P0) atoms. Total desorption yields as well as partial yields of excited atoms will be presented. The dominating role of primary excitation of surface excitons is obvious for excited atoms. Primary creation of free electron-hole pairs favours desorption of ground state atoms. The kinetic energy distributions of metastable Ne and Ar atoms were determined by a time-of-flight technique. Maxima were found at 0.2 eV (Ne) and 0.04 eV (Ar) which establish a new desorption mechanism of excitonic origin.