Application of laser mass spectrometry for trace analysis of plutonium and technetium

Resonance ionization mass spectrometry (RIMS) is a highly selective and sensitive method for trace analysis of radiotoxic elements in environmental, biological or technical samples. By multiple resonant laser excitation and ionization of the element under investigation, an extremely high element selectivity is achieved. Additionally, isotope selectivity is obtained by subsequent mass analysis in a magnetic, time-of-flight or quadrupole mass spectrometer which serves for efficient background suppression as well. High sensitivity results from the large optical cross sections in the photo-ionization process and the high detection efficiency for ions. The outstanding element selectivity of RIMS permits a simplification of the chemical separation method. RIMS has been used for ultra-trace analysis of long-lived radioisotopes of Pu and Tc in various samples. The detection limit determined experimentally is of the order of 10 6 atoms per sample. For some of the most important long-lived radioisotopes, this value is distinctly below the radiometric detection limit.