Abstract

A study of the application of resonance ionization mass spectrometry (RIMS) to the lanthanide elements, except promethium, has been initiated. The spectral range for this investigation has been generally 430-455 nm. The lanthanide atoms are generated at a thermal source and are excited and ionized by a single- or two-color process using a N₂-pumped laser and/or one or two dye lasers of broad bandwidth, 1 cm^–1. The purpose of the survey is severalfold: to evaluate analytically useful RIMS transitions, to gain further understanding of possible resonant optical mechanisms that can generate ions, and to gain experience in spectral interpretation that can be applied to a broad study of the heavier actinides. Several types of optical process have been identified. Many of the RIMS transitions can be assigned to single-color, resonant, two- or three-photon transitions. Other optical mechanisms for generating ions are also observed, however, such as two-photon processes to a bound state, two-photon transitions to an autoionizing level, etc. At least some of the transitions seen in europium and previously assigned to a possible hybrid resonant effect are due to two-photon transitions to apparently new levels. The implications of these results to RIMS are discussed.

© 1985 Optical Society of America