Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)

Resonance ionization mass spectroscopy (RIMS) is well suited for trace analysis of long-lived radioisotopes in environmental, biological and technical samples. By multiple resonant laser excitation and ionization of the elemental atoms under investigation, an extremely high element selectivity can be achieved. In addition, isotope selectivity is obtained by subsequent mass analysis. The excellent sensitivity results from the large atomic cross-sections in the excitation-ionization process and the good detection efficiency for ions. The element selectivity of RIMS allows a simplified procedure for the chemical preparation of the samples compared to the requirements of thin sources for alpha-spectroscopy. Various samples have been determined by RIMS with respect to their content and the isotopic composition of plutonium in the ultra-trace regime. A detection limit of 10(6) to 10(7) plutonium atoms has been achieved for all isotopes, independent of their half-life and decay mode. For Pu-239, this value is distinctly below the radiometric detection limit. (C) 1998 Elsevier Science S.A.