Deexcitation Model for Sputtered Excited Neutral Atoms

Velocity distributions of In atoms in their ground (${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$) and excited (${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$) states ejected from In foils by bombardment with 5-keV ${\mathrm{Ar}}^{+}$ ions are measured with a multiphoton resonance-ionization technique. We show for the first time that the ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ level is not significantly populated during sputtering and that the only path for population of this state is via laser-induced photodissociation of ${\mathrm{In}}_2$ during the detection process. A new deexcitation model for sputtered excited neutral atoms is proposed which is based on the electronic localization of the fine-structure orbital.