Effect of Collective Electron Channeling and Features of Quasicharacteristic Radiation in the Bragg Diffraction Mode

The features of quasicharacteristic radiation based on direct radiative transitions between the above-barrier energy levels corresponding to the dynamic diffraction of electrons and the levels of channeled electron motion in crystals are considered. The structure and features of such radiative transitions are studied using diffraction in the Laue and Bragg geometry. The main advantages of these transitions in relation to channeling are associated with a high probability of excitation of the diffraction state, low scattering and deceleration of moving particles, long duration of the orientational (i.e., not chaotic, related to certain planes) motion regime, and large corresponding matrix element of the dipole momentum of the radiative transition. It is shown that the radiation based on these transitions can display a large integral and spectral intensity and can be implemented at a lower particle energy than the traditionally considered quasicharacteristic radiation between channeling levels.