Resonance ionization mass spectrometry of sputtered osmium and rhenium atoms

Abstract

The mass spectrometric analysis of Os and Re was investigated
\nby use of a pulsed primary Ar^+ ion beam to provide
\nsputtered atoms for resonance ionization mass spectrometry.
\nA useful yield of 10^(-2) and a detection limit of 8 ppb were
\ndemonstrated for Os concentration measurement. In situ
\nmeasurements of Os concentration are obtainable by this
\nmethod at the sub-part-per-million level in conducting and
\nsemiconducting materials with a full width at half maximum
\nbeam diameter of ~70 µm. An ionization scheme for Os that
\nutilizes three resonant energy levels (including an autoionizing
\nenergy level) was investigated and found to have superior
\nsensitivity and selectivity compared to nonresonant and one
\nand two energy level resonant ionization schemes. An elemental
\nselectivity for Os over Re of ≥10^3 was demonstrated.
\nIt was found that detuning the ionizing laser from the autoionizing
\nenergy level to an arbitrary region in the Ionization
\ncontinuum resulted in a 5-fold decrease in signal intensity and
\na 10-fold decrease in elemental selectivity.
\n