Stimulated and spontaneous transitions between discrete levels of electrons channeled in crystals

The dependence of the spectrum of the quasicharacteristic radiation from channeled particles on the crystal parameters, energy and directivity of the beam is investigated. A theory of dechanneling is developed in which elastic scattering of the channeled electrons by atomic nuclei is taken into account. It is shown that the dependence of the dechanneling length on the form of the wave function pronouncedly alters the relation between the intensities of separate spectral lines in ''thick'' crystals. A procedure is proposed for creating population inversion between the transverse motion levels. The band structure of superbarrier leVels of a channeled electron is investigated. The pulsations of the forbidden and allowed superharrier band widths are calculated on variation of the beam energy or of the crystal parameters. The magnitudes of the matrix transition elements between superbarrier and sub-barrier levels are compared