Isotopic fractionation studies of uranium and plutonium using porous ion emitters as thermal ionization mass spectrometry sources

Graphene Oxide Carburization Enhanced Ionization Efficiency for TIMS Isotope Ratio Analysis of Uranium at Trace Level

“…As the mass ratio of Re powder and GO was raised, the ionization efficiency increased slightly and then reached a plateau (Figure ), illustrating that Re powder could promote the formation of Re-carbide in the GO layers, generating a better property for ion emitting. It also provides another possibility for further improvement of ionization enhancer by integrating other ion emitters with this porous layered nanomaterial. − …”

“…Although this method could get an ionization efficiency of 0.2–0.3% for uranium and was much more reproducible, it always required a special vacuum instrument to expose the filaments to benzene vapor at high temperature, which is time-consuming, expensive and has a potential risk of benzene toxicosis. Recently, a porous ion emitter (PIE) technique was developed for the analysis of trace quantities of actinides. − Rhenium and platinum powders were mixed in a gluing agent, and then heated to form a porous Pt/Re alloy as the thermal ionization emitter. Although the preparation was a little time-consuming and required operation skill, these works showed the porous micro- and nanostructures of ion emitter could remarkbly enhance the ion yields.…”

Task-Specific Supported Liquid Membrane for Actinide Assay in Aqueous Streams by Thermal Ionization Mass Spectrometry

“…The choice of the filament material is based on high melting point and high work function of Re that aids in the formation of positive ions during TIMS analysis according to the Saha–Langmuir equation . However, the traditional solution loading technique is reported to have extremely poor sample utilization efficiency, i.e., the fraction of analyte atoms loaded on a filament that is detected as ions, for actinides. − This poses a major limitation to the precision and accuracy of Pu analysis by TIMS, especially when the sample amount is either less or limited as in the cases of nuclear forensic, nonproliferation, and safeguards. Conventionally, the loading of actinides as acidic solution produces more volatile oxide ions, apart from the elemental ions, during TIMS analysis which further degrades the analysis performance.…”

“…Kelley and Robertson in 1985 carried out extensive studies on the reaction possibilities and diffusion kinetics involved in Pu ion emission from carburized Re filaments and suggested that carbon modifiers tend to form plutonium-carbides which are stable at higher temperatures and, thus, promote ionization over vaporization during TIMS analysis. In recent times, Thermal Ion Cavity (TIC) and Porous Ion Emitters (PIE) emerged as yet another promising substrate for loading of actinides in TIMS. ,,, PIEs are reported to be well suited for precise isotopic analyses owing to the fact that PIE renders controlled ion emission with minimum isotopic fractionation . Baruzzini et al have reported an average boost in ionization efficiency of ∼550% for Pu and ∼1100% for Am by using Pt and Pt/Re PIEs …”

“…In recent times, Thermal Ion Cavity (TIC) and Porous Ion Emitters (PIE) emerged as yet another promising substrate for loading of actinides in TIMS. 11,12,19,20 PIEs are reported to be well suited for precise isotopic analyses owing to the fact that PIE renders controlled ion emission with minimum isotopic fractionation. 9 Baruzzini et al have reported an average boost in ionization efficiency of ∼550% for Pu and ∼1100% for Am by using Pt and Pt/Re PIEs.…”