CONTINUOUS-WAVE LASER RESONANCE IONIZATION MASS-SPECTROMETRIC ANALYSIS OF STRONTIUM

Resonance ionization mass spectrometric analysis of strontium has been performed through a simple two colour 1 + 1 cw laser excitation schem e, using a portion of the pump Ar+ ion laser to excite the non-resonan t ionization step, and the first results of precise isotope ratio meas urements of Sr are presented. These measurements made in an ion microp robe, employing both thermal evaporation and primary ion beam sputteri ng for producing neutral Sr atoms, have exhibited strong even-odd effe cts for the Sr-87/Sr-86 ratio, with a near 10% depletion of the Sr-87 isotope, and the dependence of this anomalous isotopic effect on laser output power has been studied. In sputter-induced RIMS experiments, p rimary ion beams of oxygen, argon and xenon, were used for sputtering pure Sr metal targets, and the calculated ionization yields are compar ed with the results of a simple mathematical analysis of the resonance ionization process. Possible reasons for the quantitative differences observed between the measured and the predicted results are suggested and discussed.