Double-resonant photoionization spectroscopy of SrI

We report on the investigation of the double-resonant photoionization of Sr atoms out of the ground state 5s2 1S0 and the metastable triplet states 5s5p 3PoJ. Specifically, the saturation behavior of both the excitation steps to intermediate states, and the ionization steps to auto-ionizing states have been studied, and the photoionization cross-sections from the intermediate levels into auto-ionizing states were determined. The ionization schemes were applied in saturation conditions to estimate the ratio of atoms sputtered in the ground and metastable states during Ar+ ion-beam sputtering from a polycrystalline strontium target.