Comparison of one- and two-color ionization schemes for the analysis for osmium and rhenium isotopic ratios by sputter-induced resonance ionization mass spectrometry

Sputter-Induced resonance Ionization mass spectrometry Is a technique In which atoms sputtered from a sample are Ionized using a pulsed laser beam. To maximize sample utilization, a pulsed Ion beam Is used to atomize the sample so there is a high temporal and spatial overlap between the atom plume and laser beam. The frequency of the laser Is tuned to resonantly excite electrons In the atoms Into an excited state and then nonresonantly Into the continuum. A two-color scheme which uses a portion of the excimer pump laser to excite the Ionization step was Investigated as a method of Increasing the ionization signal. Ionization Intensity enhancements In many transitions In Re and Os were measured. Isotope ratio measurements of Re filaments showed more sample to sample variations due to varying conditions of the laser beams and a higher bias than corresponding analyses of loaded samples