Electron Localization in Dense Ammonia Vapor

Electron mobility measurements have been performed in subcritical and supercritical ammonia vapor in the density range from 6×{}10¹⁸ to 3×{}10²¹ molecules/cm³ and in the temperature range of 210 to 440 K. In the density range from 2×{}10²⁰ to about 3×{}10²¹ molecules/cm³ 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.