Photon-stimulated desorption of solid neopentane

The positive-ion yields and kinetic-energy distributions resulting from the photon bombardment of solid neopentane [(CH3)4C] have been measured for photon excitation energies between 17 and 45 eV. The ion (>94% H+) appearance potential is at 20 ( +- 1) eV with a yield maximum at 24 ( +- 1) eV of 2 x 10-7 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 H+ desorption near threshold is a C 2s→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