Comparison of secondary ion mass spectrometry and resonance ionization mass spectrometry

Abstract

Resonance ionization mass spectrometry (RIMS) of neutral atoms sputtered from a solid is an analytical technique that is complementary to secondary ion mass spectrometry (SIMS). Potential advantages of RIMS include: (1) high sensitivity; (2) rejection of mass interferences while retaining high sensitivity; (3) reduced matrix effects. A modified commercial double-focusing, magnetic sector SIMS instrument is used for photoionization-based measurements. Comparisons of SIMS and RIMS are directly possible. Examples of RIMS' ability to overcome matrix effects and interferences are given. Factors affecting relative sensitivity and detection limits of the two techniques examined are in part: duty cycle, secondary ion yield vs. secondary atom yield, photoionization efficiency ion transmission efficiency and detection mode. In RIMS, the geometrical overlap of laser and sputtered atoms must be optimized, and a three-dimensional formalism is discussed. Because of the pulsed nature of RIMS, duty cycle restrictions can limit the sensitivity relative to SIMS. Absolute ion yields for SIMS and RIMS are presented.