Photon stimulated ion desorption of condensed CO2 at ∼ 85 K studied by synchrotron radiation

Abstract

Photon stimulated ion desorption (PSID) from condensed carbon dioxide has been studied for photon excitation energies ranging from 93 to 193 eV. PSID studies have been performed at the Brazilian synchrotron light source (LNLS), Campinas, during a multi-bunch operation mode of the storage ring. The results showed that after photon excitation several ions desorbed from the CO 2 films: C+, O+, CO+ and O 2+. PSID experiments showed that ion desorption was enhanced only at the Si resonance excitations. When the thickness of the CO 2 was ∼ 500 L or higher, almost no desorption yield was observed. The study of the dependence of the relative partial ion yield on the photon excitation showed that the X-ray induced Electron Stimulated Desorption (XESD) mechanism has to be invoked to explain the origin of the desorbed ions in the energy region studied.