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The excitation processes of the low energy isomeric level in nucleus 229Th by optical photons are investigated for different values of relations between energies of nuclear transition and photons. The role of the atomic shell, which "works" as electron bridge, is considered. The cross-sections of the resonance nuclear excitation by laser beam (the narrow line) and by special lamp (the wide line) are calculated. The possibilities of experimental researches are discussed.

Lead potassium niobate crystals were grown by our pulling down method and tube-seed Czochralski method. Evaporation of lead and potassium was observed. Crystal growth was not so difficult despite the evaporation. Grown crystals were brownish and transparent. Cleavage was observed in the Czochralski grown crystals on the c-plane. After heat treatment, the dielectric constant along the c-axis was about 500–1000. A large dielectric constant above 10000 was observed on the a b-plane. On the a b-plane, almost isotropic properties were obtained on the basis of the dielectric constant and the thermal expansion coefficient.