Translational Energy Distribution of Si Atoms Desorbed by Laser-Induced Electronic Bond Breaking of Adatoms onSi(111)−(7×7)

The desorption of Si atoms caused by the laser-induced electronic bond breaking of adatoms of $\mathrm{Si}\left(111\right)-(7\times 7)$ was studied upon exciting the surface with nanosecond and femtosecond laser pulses. The translational energy distribution of desorbed Si atoms is characterized by a peak energy of 0.06 eV with an onset energy of 0.02 eV; the feature is independent of wavelengths, fluences, and temporal widths of excitation laser pulses. This energy distribution, as well as other characteristic features of the process, is well described by a proposed model of phonon-kick mechanism following the two-hole localization on adatom sites.