Dissociative electron attachment and dipolar dissociation ofH−electron stimulated desorption from hydrogenated diamond films

Surface versus Sub-Surface D? Electron Stimulated Desorption from Diamond Surfaces

“…2, the D --ion yield presents two components: a peak centred at 8 eV and a monotonic increase from a threshold at 14 eV. A similar dependence for the H --ion yield ESD was obtained in our previous work on hydrogenated diamond films [20]. We can attribute these components to two different mechanisms of ESD: The peak at 8 eV is attributed to a DEA process, namely the excitation of a core hole Feschbach resonance state.…”

“…In our previous low energy ESD studies we could not discern between the contribution of surface and sub-surface hydrogen (deuterium) to the ESD processes [20]. However, one should expect different kinetic energy distributions for these two cases.…”

“…In addition to the 9 eV DEA peak and the DD process, a broad peak was also measured at 22 eV in the ion yield. This peak was assigned to an indirect DEA process [20]. In this case the 22 eV incident electrons interact with the solid loosing a part of their energy to a 13 eV excitation, that can be followed by resonant electron attachment.…”

“…In that case the films were prepared by the chemical vapor deposition (CVD) method, the surface is expected to be fully hydrogenated alongside with some sub-surface hydrogen [18,19]. We reported the mechanisms responsible of the observed H --ESD for incident electron energies in the 5-45 eV range [20]. In this energy range two processes are involved: dissociative electron attachment (DEA) via a Feschbach anion resonance state and dipolar dissociation (DD) resulting in fragmentation into an ion pair.…”

“…The MKE values measured as a function of E i were found to display a dependence, that can be described by the thermodynamic limit using a simple gas phase model [23]. The KED curve shapes, on the other hand, were found to reflect the dynamic of desorption in which there is a strong coupling of the outgoing ion and the solid surface and near surface region [24]. In addition to the 9 eV DEA peak and the DD process, a broad peak was also measured at 22 eV in the ion yield.…”