Theoretical Considerations Concerning the Separation of Isotopes

Abstract

The relative importance of effusion processes, the half quanta due to van der Waals forces, and half quanta associated with homopolar bonds is considered with respect to the question of the separation of isotopes. Specific reaction rate constants for various isotopic molecules in effusion processes have been calculated. It is shown that only in the neighborhood of liquid hydrogen temperatures or lower are the half quanta due to van der Waals forces important. Specific reaction rate constants involving the zero point energy of homopolar molecules have been calculated for various isotopic molecules, principally those in which a hydrogen atom is one constituent, at temperatures of 20°K, 90°K, and 273°K. The advantage of working at as low a temperature as possible is rendered apparent. Even at ordinary temperatures the differences in the constants are in general much greater than in the case of effusion or van der Waals processes. A general equation is derived relating the concentration of the light and heavy isotopes, valid for any one of the three processes considered.