- Conference date: 8-12 October 2000
- Location: Knoxville, Tennessee (USA)
We report on progress in development and application of ultratrace determination by diode-laser-based RIMS. Applications include biomedical isotope-tracer studies of human calcium kinetics, cosmochemical investigations of meteorites, environmental dosimetry and radiodating. Depending on the application, needs to be determined at isotopic abundance in the range of to relative to the major stable isotope We use either a double- or triple-resonance excitation scheme and subsequent non-resonant photoionization of calcium atoms in a collimated atomic beam. All resonant steps are excited with narrow bandwidth extended cavity diode lasers, non-resonant photo-ionization is attained with either an argon ion laser or a laser. The resulting photo-ions are detected with a quadrupole mass spectrometer. With double-resonance excitation, the optical isotopic selectivity for against is while the triple-resonance scheme provides optical selectivity of more than By adding the third resonant step, overall detection efficiency increases from to and the detection limit for relative abundance improves from to Both schemes have been applied to various sample types and accuracy and reproducibility of the resulting isotope ratios have been determined to be better than 5%.
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