Quantitative surface composition analysis using very high intensity nonresonant multiphoton ionization

Abstract

The subject of this article is quantitative surface and material analysis under high sensitivity conditions. Various gases and one solid sample were studied, using high intensity (1014–1015 W/cm2), nonresonant multiphoton postionization in tandem with time-of-flight mass spectrometry. These atomic and molecular gases (Ar, Kr, NO, Xe, N2 and O2) possess high ionization potentials, requiring high photon flux density for ionization saturation. The solid sample SiO2, studied using 5 keV Ar+ sputtering, places a stringent test on quantitative analysis. Si and O have exceedingly different ionization potentials that require four and six photons for ionization, respectively. The experimental results demonstrate that it is possible not only to saturate species with high ionization potentials, but also to perform quantitative analysis by establishing a well-defined ionization volume for all species evolved from the surface.