Quantitative laser mass spectroscopy of sputtered versus evaporated metal atoms

Abstract

We demonstrate that the presence of excited states in sputtered surface atoms after ion bombardment affects the measured ion yield of a subsequent post multiphoton-ionization processes. This effect was investigated using an advanced time-of-flight mass-spectroscopic technique. This work reports a comparison of two-photon ionization spectra of metallic atoms obtained from solid samples via sputtering and thermal evaporation that reveals the role of excited states. Furthermore we experimentally determine the cross sections for the two photon ionization processes of evaporated Mg, Zn, and In through quantitative ion yield measurement. Numerical configuration interaction calculations for Mg and Zn are presented and the resulting theoretical two-photon ionization cross sections are compared with the measured ones.