Hyperthermal rare-gas ion-stimulatedCN−desorption from a nitrogenated graphite surface

Abstract

The mechanism of hyperthermal (2--30 eV) rare-gas (RG) ions induced ${\mathrm{CN}}^{\ensuremath{-}}$ desorption from a nitrogenated graphite surface is investigated. ${\mathrm{CN}}^{\ensuremath{-}}$ desorption occurs at an incident energy as low as 2 eV and gains a relatively high energy from the desorption process in comparison with the incident kinetic energy. A strong correlation is observed between the ${\mathrm{CN}}^{\ensuremath{-}}$ maximum translational energy (MTE) and the incident RG ion energy, suggesting a localized interaction between the incident ion and surface CN species. A MTE of \ensuremath{\sim}5 eV is obtained at 0-eV incident energy, and is found independently of the incident ion species. It is proposed that ${\mathrm{CN}}^{\ensuremath{-}}$ emission occurs as a result of the potential desorption of chemisorbed surface CN species mediated by the formation of a localized hole at its bonding or nonbonding orbital via (quasi)resonant neutralization of an incident RG ion.