Features of coherent excitation of 229mTh

The paper studies the effects that arise at the coherent excitation of the anomalously low-lying isomeric level 3/2+(8.19±0.12 eV) in the 229Th nucleus driven by laser radiation in wide band gap dielectrics. It is shown that in such an excitation a) the appearance of additional decay channels with a width Γ of the 229mTh isomer due to electron states in the band gap leads to an effective “freezing” of the system in the ground state (the repopulation process at relatively small Γ and the Zeno effect at large Γ), making the process of nuclear excitation practically impossible, b) the probability of the α decay of a coherent superposition of the ground and isomeric states becomes equal to the half-sum of the α widths of both levels and is increased by about a factor of two in comparison with the probability of the α decay of 229Th, c) the intensity of the main α lines oscillates with the Rabi frequency and the total α spectrum shifts towards higher energies for long time measurements, d) the inverse population of nuclear levels required for the Thorium γ ray laser is achieved relatively quickly within the π pulse duration, e) the observation of the Zeno effect according to the Cook's scheme is possible for the system of three lower levels of the 229Th nucleus.