Resonance ionization mass spectrometry for ultratrace analysis of plutonium with a new solid state laser system

Resonance ionization mass spectrometry (RIMS) is well-suited for isotope selective ultratrace analysis of long-lived radioactive isotopes due to its high element and isotope selectivity and good sensitivity. For the analysis of plutonium with a pulsed RIMS apparatus, a powerful, reliable and easy to handle Nd:YAG pumped titanium-sapphire laser system has been developed and combined with a time-of-flight mass spectrometer. Spectroscopic measurements led to an efficient three step excitation and ionization scheme for plutonium with lambda(1) = 420.76 nm, lambda(2) = 847.28 nm and lambda(3) = 767.53 nm. The isotope shifts in this scheme for the Plutonium isotope P-238 through Pu-244 have been determined. An overall efficiency of the RIMS apparatus of I x 10(-5) is routinely achieved resulting in a detection limit of 2 x 10(6) atoms of plutonium for single isotope measurements. The application of RIMS for isotope ratio measurements is outlined. (C) 2004 Elsevier B.V. All rights reserved.