Definite Evidence for Population Inversion of Hot Electrons in Silver Halides

Hot-electron kinetics and distribution in pure AgCl and AgBr at crossed electric and magnetic fields have been studied at 4.2 K up to $E_x=3.4\mathrm{}$ kV/cm and $H_z=58\mathrm{}$ kOe by detecting a response current $Q_z$ to a perturbing electric field $E_z$ in the transient condition. The results of measurements on $Q_z(E_x,H_z)$ established the pictures of an ideal streaming motion of electrons in the range $\frac{c{E}_x}{H_z}>V_{\mathrm{LO}}$ (where $\frac{1}{2}{m}^{*}{V_{\mathrm{LO}}}^2\equiv \hslash {\omega }_{\mathrm{LO}}$) and of a population inversion of hot electrons in the range $\frac{c{E}_x}{H_z}<V_{\mathrm{LO}}$.