On the basis of the observed cluster stoichiometry distributions, it was concluded that trivalent metal sites were dominant in each series of LnO. A distinctive sequence more » of cluster compositions was found for each Ln, apparently reflecting the relative accessibilities of the +2, +3, and +4 oxidation states. In each case, ions with metal contents (m) of up to at least 26 were detected, with the largest cluster identified being TbO (mass = 11 516 amu). Cluster ions, LnO, were identified for all of the lanthanides studied: Ln = Sm, Eu, Gd, Tb, and Yb. Pulsed XeCl excimer laser ablation ( = 308 nm irradiance approximately 10 MW cm2]) of hydrated lanthanide oxalates into vacuum has been found to generate significant yields of lanthanide oxide cluster ions, the compositions of which were analyzed by reflection time-of-flight mass spectrometry. Some analytical performances of this method were determined under optimum conditions and were = co-ablated from a multicomponent target circumvented effects of experimental variables and provided especially reliable comparative reactivities. This effect was considered for optimization for isotope selection and analysis. Under helium gas environment, Doppler splitting was caused from particle motion. The relaxation rate of high-lying metastable state was found to be higher than that of the ground state, which suggests that higher analytical sensitivity can be obtained using low-lying state transition. The measured minimum line width of about 0.9 GHz was close to the Doppler width of the Gd atomic transition at room temperature. Isotope-selective absorption spectra were measured by observing the slow component of the plume produced under low-pressure rare-gas ambient. To improve isotopic selectivity and detection sensitivity of the ablated species, various experimental conditions were optimized. For remote isotope analysis of low-decontaminated trans-uranium (TRU) fuel, absorption spectroscopy has been applied to a laser-ablated plume of lanthanide elements.
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