Photon stimulated ion desorption from condensed chloroform on Si(100) at the Cl and Si K-edges

Photon stimulated ion desorption (PSID) studies have been performed in chloroform condensed on Si(100) at ∼85 K using synchrotron radiation at the chlorine and silicon 1s-edges. Data acquisition was performed at the Brazilian synchrotron light source (LNLS), during a single-bunch operation mode of the storage ring. It was found that hydrogen ion is the main ionic species to desorb after photon excitation followed by other fragments with lower intensities. Desorption ion yields for H+ and Cl+ were obtained as a function of the photon energy. A pronounced enhancement of the Cl+ yield was observed at the first Cl 1s resonance, which may be related to a spectator Auger process. In order to verify the influence of the substrate in the ionic desorption of condensed chloroform, PSID spectra were also measured at the silicon 1s-edge. The indirect X-ray induced electron stimulated desorption (XESD) mechanism seems to dominate.