Substrate selection for product deposition in the enrichment of lanthanides for medical applications

The Lanthanide isotope, viz., ¹⁷⁷Lu has application in the medical field as a nuclear medicine with high specific activity. One route for obtaining this isotope is by irradiation of highly enriched ¹⁷⁶Yb in the nuclear reactor followed by chemical separation. Enrichment of this naturally occurring isotope viz., ¹⁷⁶Yb, by Laser Isotope Separation (LIS) based on selective photo-ionization is being pursued by BTDG, BARC. In the LIS process, the target isotope from the atomic vapour of the natural ytterbium feed, is excited from ground state to higher energy states, and subsequently photoionized using combination of high-power dye lasers. The photo-ions of the targeted isotope are collected on a negatively biased collector substrate. The product, deposited as solid, is recovered from the substrate by acid elution to bring it in to aqueous phase and analyzed for quantity and quality by ICPOES and TIMS methods respectively. This work addresses the selection of the substrate for product collection. The quantity of collection of photo-ions on the product collection segment is ~16% more on the tantalum substrate than on the stainless-steel substrate. As this minor variation in collection can be due many factors mentioned in paper, it can be concluded that there is no predominant effect of the selected substrate material of the collection of photo-ions of the chosen lanthanide for the separation of isotopes through LIS. Selection of tantalum as a substrate is however advantageous, as compared to stainless steel, due to excellent inertness to acid used for product recovery and hence nearly nil elemental impurity addition to the product