Electronic processes during the sputtering of atoms from metallic surfaces studied by resonance laser ionization spectroscopy

We demonstrate how resonance laser ionization spectroscopy can be applied to investigate the electronic processes that lead to the sputtering of neutral atoms in different quantum states upon keV-ion bombardment of metallic surfaces. Key information about the electronic processes is contained in the population probability of a specific atomic state and the state-specific escape velocities of the emitted particles. State-selective laser probing allows one to measure the population partition and velocity distributions of sputtered atoms, which is exemplified for Ni. It is demonstrated that the trends in these experimental observables can be qualitatively interpreted within the framework of the resonant electron transfer model. Furthermore, we show that our data are in good quantitative agreement with the outcome of a rate-equation approach based on this model.