Photon-stimulated desorption of solid neopentane

Abstract

The positive-ion yields and kinetic-energy distributions resulting from the photon bombardment of solid neopentane [${\left({\mathrm{CH}}_3\right)}_4$C] have been measured for photon excitation energies between 17 and 45 eV. The ion (>94%${\mathrm{H}}^{+}$) appearance potential is at 20 (±1) eV with a yield maximum at 24 (±1) eV of $2\times {10}^{-7\mathrm{}}$ ions/photon. For all photon energies, the ion-kinetic-energy distribution peaks at 1.9 (±0.25) eV and is broadened asymmetrically to higher kinetic energies. These results indicate that the process responsible for${\mathrm{H}}^{+}$ desorption near threshold is a C $2s\to$ Rydberg-type level excitation followed by decay to a final state involving several valence holes and at least one electron in a Rydberg-type level.