APPLICATION OF LASER MASS-SPECTROMETRY FOR TRACE ANALYSIS OF PLUTONIUM AND TECHNETIUM

Resonance ionization mass spectrometry (RIMS) is a highly selective an d sensitive method for trace analysis of radiotoxic elements in enviro nmental, biological or technical samples. By multiple resonant laser e xcitation and ionization of the element under investigation, an extrem ely high element selectivity is achieved. Additionally, isotope select ivity is obtained by subsequent mass analysis in a magnetic, time-of;f light or quadrupole mass spectrometer which serves for efficient backg round suppression as well. High sensitivity results from the large opt ical cross sections in the photo-ionization process and the high detec tion efficiency for ions. The outstanding element selectivity of RIMS permits a simplification of the chemical separation method. RIMS has b een used for ultra-trace analysis of long-lived radioisotopes of Pu an d Tc in various samples. The detection limit determined experimentally is of the order of 10(6) atoms per sample. For some of the most impor tant long-lived radioisotopes, this value is distinctly below the radi ometric detection limit.