The application of laser-assisted condensation repression method for the enrichment of medical isotopes

An investigation into the feasibility of the laser condensation repression technique for the enrichment of sulfur isotopes was conducted. The condensation repression technique involves selectively exciting molecules within a population that differs only by the isotopes of a specific element used in their composition. These excited molecules would have their tendency to condense repressed compared to the unexcited molecules.; The process involved a batch process of the gas, containing the element to be separated, in an evacuated chamber at a low pressure, then subjecting the gas to infrared radiation of a predetermined frequency using a CO 2 laser. The radiation from the laser vibrationally excites the molecules containing one of the particular isotopes of interest. While the gas is irradiated by the tuned laser beam, the chamber walls and baffles are cooled with liquid nitrogen. The excited molecules, because of their higher internal average kinetic energy, will not condense to the cooled wall of the container as readily as those that are not excited by the laser beam. This mechanism would cause enrichment of the molecular isotopes of interest in the gaseous phase.; The work was conducted on sulfur hexafluoride (SF6). Sulfur is a target isotope for the production of the medically useful radioisotope 33P (i.e. 33S + n → 33P + p).; A Fourier Transform Infrared Spectrometer (FTIR) was used to determine the abundances of the isotopic molecules in the gaseous SF6. The analysis of the data obtained from the experiments to demonstrate the validity of this concept to enrich 33SF6 indicates an enrichment factor of about 2.0 +/- 0.6, i.e. the 33S isotope was enriched from its 0.7% natural abundance to 1.4%. Experiments conducted to enrich 32SF6 succeeded in enhancing the fractional concentration of this naturally 95.0% abundance isotope to about 96.2%. It is suggested that future work investigate the feasibility of the technique on other useful isotopes and on making the process more efficient and economically viable on a pilot plant scale.