The magnetic susceptibility of oxygen in a clathrate compound

Summary

Cooke, Meyer, Wolf, Evans andRichards (Proc. Roy. Soc.,225, 112 (1954)) have measured at low temperatures the susceptibility of oxygen dissolved in aβ-quinol compound, wherein the oxygen molecules are 8 Å apart, and the deviation of the susceptibility from that in the gaseous state may hence be small. They find that¹⁶O¹⁸O and¹⁶O¹⁶O have the same susceptibility, although at low temperatures the magnetic behavior in the gaseous state should be different, inasmuch as only odd values ofK are allowed for¹⁶O¹⁶O. The present paper shows that the magnetic behavior can be explained on the assumption that at helium temperatures the O₂ molecules do not rotate freely, but instead are aligned along a particular spatial direction. Calculations by MissO’Brien show that the susceptibility curves can be fitted by assuming the axis of the O₂ molecule is «frozen» in space and that the spin-spin parameter is about 25 percent lower than in the gas. This apparent reduction can be explained on the basis that the molecule is not rigidly frozen, and instead has a potential barrier of about 50 cm⁻¹.