VERFAHREN ZUM TRENNEN VON ISOTOPEN

1526512 Producing selective excitation by electromagnetic radiation EXXON RESEARCH & ENG CO 27 Feb 1976 [23 April 1975] 07828/76 Heading G6P In a process of isotope separation involving isotopically selective excitation (by irradiation with electromagnetic radiation) under conditions in which vibrational excitation by multiple photon absorption occurs, thermal electrons are attached to the excited species to form negative ions which decompose to form ion fragments which can be separated out. The mixture to be separated comprises a molecular gas of a compound whose general formula is MF 6 where M is one of U, S, W, Se, Te, Mo, Re and Tc. Helium may be added as a buffer gas. The process involves three stages, namely :- (1) Irradiation by infrared (e.g. pulsed CO 2 ) laser for less than 10-3 sec. Such that at least 0À1% of the molecules of one isotope are excited to a vibrational energy content of 4v3 by multiphoton absorption. (2) Thermal electrons (e.g. generated by an electron gun) are contacted with the mixture and become attached to both excited and unexcited molecules to form negative ions MF 6 - (unexcited) and *MF 6 - (excited). The ratio of thermal electrons to total MF 6 molecules is at least 0À1. Contact occurs for less than 10-3 sec. in order to minimize thermal dilution. (3) The MF 6 - ions do not dissociate, but the *MF 6 - do so rapidly (i.e. *MF 6 -#MF 5 -+F). If a chemical reaction is used to separate the fractions, MF 6 will remain in the gaseous phase while MF 5 will precipitate. Electromagnetic separation can be used.