A new approach to the determination of the ionization yield of atoms by laser-enhanced ionization

Abstract

Two convenient and simple means of measuring the ionization yield of excited atoms in flames are proposed. Both techniques make use of two laser pulses, one of which is delayed in time with respect to the other. The ionization yield for each technique is then given by an expression containing a combination of various one- or two-step signals. The proposed methods are suitable for the determination of ionization yields in the interval 0.1–0.9. Experiments in Na and Li are presented. The ionization yields in an air-acetylene flame of the 3 s → 3 p → 7 d transitions in Na and 2 s → 2 p → 3 d transitions in Li were determined to be 0.35 and 0.78, respectively. A collisional ionization rate of 0.2 GHz was evaluated for Li.