Instrumental factors in resonance enhanced multi-photon ionization of FIB-sputtered atoms

Resonance enhanced multi-photon ionization (REMPI) is a promising ionization technique for realizing both the high sensitivity and selectivity. The authors developed an apparatus equipped with a gallium focused ion beam (FIB) and a tunable pulsed dye laser system for REMPI for micro- and nano-scale analysis of solid surfaces. For the practical application of REMPI method to FIB-sputtered atoms, many factors affecting REMPI intensity should be considered and optimized. This paper will discuss sensitivity and stability in relation to the laser beam stability, and the optimization of the extraction of laser-ionized species into time-of-flight mass spectrometry (TOF-MS).