This award is for the support of an instrument development project at the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. A laser resonance ionization source mass spectrometer is being developed for the purpose of measuring Os isotopic ratios and Re and Os concentrations in natural samples via the isotope dilution method. Currently, the laser ionization of Re and Os takes place in an atom cloud above the sample that is produced by pulsed tantalum filament heating. The relatively slow thermal pulse of the filament compared to the short duration of the pulsed laser causes premature depletion of the atom cloud and limits the ultimate accuracy of the instrument. The goal of this project is to improve the ion source system by incorporating a pulsed sputtering gun to replace the thermal source.
