Atomic mass ratios for some stable isotopes of platinum relative to 197 Au

. The Canadian Penning Trap mass spectrometer was designed to determine precisely the masses of stable and unstable isotopes. To date, such measurements have been carried out on approximately 60 short-lived species. A laser ablation ion source is also available to produce ions of stable isotopes, intended for use in calibrations, checks for systematic effects and for measurements involving stable isotopes. Mass ratios for the isotopes 194,195,196,198 Pt relative to 197 Au have been determined to a precision of better than 3 × 10 -8 . These measurements were motivated, in part, by the long-standing discrepancy between earlier mass measurements and the Atomic Mass Evaluations in the mercury region. The results also demonstrate the stability of the measurement system and set limits on the magnitude of systematic effects. No significant deviations from accepted values were found.