Dissociative electron attachment and dipolar dissociation of H- electron stimulated desorption from hydrogenated diamond films - art. no. 045401

In this work we report, a study of the mechanism of H- electron stimulated desorption (ESD) from hydrogenated diamond films for incident electron ener gies in the 2-45 eV range. Two types of experiments were carried out in ord er to assess the nature of the ESD processes leading to desorption as a fun ction of incident electron energy: (i) kinetic energy distribution (KED) of H- and (ii) H- anions yield at fixed ion energy (FIE) measurements. The KE D measurements show that for incident electrons of up to similar to 11 eV t he most probable kinetic energy of H- ions monotonically increases from abo ut 1.7 to 3.3 eV. For higher incident electron energies, the ion energy dis tribution peaks at about 1.5 eV and is nearly constant. From these measurem ents it is derived that the H- ESD cross section has a resonance behavior d isplaying two well-defined peaks at 9 and 22 eV and a monotonic increase wi th a threshold at similar to 14 eV as a function of incident electron energ y. From the KED and FIE spectra the 9- and 22-eV peaks are interpreted as d ue to dissociative electron attachment via a single Feshbach anion resonanc e state, albeit accessed directly and indirectly, respectively. A possible intermediate process involving a well-known electronic excitation of the hy drogenated diamond at 13 eV is suggested. For incident electron energies hi gher than similar to 14 eV, H- ESD proceeds also via dipolar dissociation p rocesses.