This thesis analyzes two effects associated with the passage of charged particles through crystals; resonant nuclear excitation and generation of laser radiation.; Resonant transitions to excited nuclear states are predicted when relativistic nuclei are directed along a crystal axis. The periodic field of the crystal can be treated as a flux of photons; therefore, this process is analogous to photo-excitation. Resonance occurs when the velocity of the nucleus and the periodicity of the lattice lead to a field at the nucleus whose frequency corresponds to a nuclear excitation frequency.; Numerical calculations identify {dollar}sp{lcub}19{rcub}{dollar}F, {dollar}sp{lcub}57{rcub}{dollar}Fe and {dollar}sp{lcub}236{rcub}{dollar}U as the best candidates for observation of this effect among low, medium and high mass nuclei, respectively. The predicted resonant excitation rate is not large, but should be observable experimentally.; Also, laser radiation may be produced by two different mechanisms when electrons or positrons channel in crystals. The feasibility of both suggestions is evaluated by calculation of the gain. The calculations suggest that the probability of laser production by either proposal is not large.
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