Filament chemistry of uranium in thermal ionisation mass spectrometry

Advances in atomic spectrometry and related techniques

“…Experimental results of instrumental isotopic fractionation of Sr in NIST SRM-987 tended to confirm a linear model of isotope fractionation, and hence Rayleigh's distillation law. Kraiem et al 313 have investigated the vaporisation and ionisation of U from a rhenium filament and found it to be consistent with the formation of UO 2 on the surface. In a related paper the same group 314 have investigated the ionization mechanism of U in the presence of carbon and found that the uranyl nitrate sample turned into a uranium carbide compound, independent of the type of carbon used as ionization enhancer; and on further heating this led to formation of uranium metal ions and a small amount of uranium carbide ions.…”

Improved sample utilization in thermal ionization mass spectrometry isotope ratio measurements: refined development of porous ion emitters for nuclear forensic applications

“…The addition of carbon has been shown to boost ionization efficiency in two has since been confirmed [76,77]. The formation of refractory metal carbides delays sample volatilization allowing for analysis at higher temperatures than would normally be achievable lending to increased ion yield [68,73,74,76,77].…”

Critical need for plutonium and uranium isotopic standards with lower uncertainties

“…45 The addition of ionization enhancers like carbon improves the ionization yield of uranium. 46,47 U and Pu isotopic standards with lower uncertainties in the major and minor ratios are required for the preparation of particle standards for analysis of swipe samples or environmental samples. Environmental monitoring is identied by the IAEA as a useful tool to strengthen the safeguards mechanisms associated with additional protocol (INFCIRC) and for identication of undeclared nuclear material processes.…”