Electron Localization in Dense Ammonia Vapor

Electron mobility measurements have been performed in subcritical and supercritical ammonia vapor in the density range from 6×${10}^{18}$ to 3×${10}^{21}$ molecules/${\mathrm{cm}}^3$ and in the temperature range of 210 to 440 K. In the density range from 2×${10}^{20}$ to about 3×${10}^{21}$ molecules/${\mathrm{cm}}^3$ an anomalous decrease of electron mobility by more than two powers of ten is observed with increasing vapor density, indicating a "transition" from the delocalized to the localized electron state.