Magnetic Susceptibility of Sodium—Ammonia Solutions

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Abstract
Magnetic susceptibilities of sodium—ammonia solutions with concentrations ranging from 0.36 to 3.85 mole/liter have been measured at room temperature using Gouy's force method. At the low concentration end, atomic susceptibilities of sodium derived from the measurements fit Hutchison and Pastor's data which were measured at lower molarities. The general trend of the atomic susceptibility as a function of concentration indicates a transition in the electronic structure at a critical interatomic distance dm of 15 Å. This transition is discussed in relation to the transition from the nonmetallic to the metallic state which has been predicted by Mott for crystalline arrays of hydrogen‐like atoms. At concentrations c above 2.0 mole/liter, the atomic susceptibility exhibits a c−2/3 dependence as expected for Pauli's paramagnetism of a degenerate electron gas. Observed deviations of metal—ammonia solutions from Curie's law can be accounted for by a temperature dependence of dm.