Maria Goeppert Mayer

Calculation of Equilibrium Constants for Isotopic Exchange Reactions

It is pointed out that the possibility of chemical separation of isotopes is a quantum effect. This permits a direct calculation of the difference in the free energies of two isotopic molecules. Tables and approximation methods are given which permit a rapid calculation of equilibrium constants if the frequency shifts on isotopic substitution are known. Several applications are discussed.

Vibrational Spectrum and Thermodynamic Properties of Uranium Hexafluoride Gas

The Raman spectra of liquid UF6 and of UF6 dissolved in C7F16 have been photographed. Three Raman lines are found for UF6 at 200, 511, and 656 cm−1. The infra‐red spectrum of the gas has been obtained in the region between 2 and 17μ. A vibrational assignment of all the fundamental frequencies is made on the basis of the regular octahedral model. The calculated infra‐red active overtones are in good agreement with experiment. Using 2.0A as the U–F distance from electron diffraction measurements, the entropy, heat capacity and — (F° — E0°/T) are calculated from 100°K to 1000°K for the gas. The calculated and experimental entropies are in good agreement.