Multiple Excitation and Decay of the 229mTh(3/2+, 8.4 eV) Isomer during the Electron Transition in the Shell of Thorium Ions

Abstract

Excitation of the nucleus ²²⁹Th to a low-lying isomeric state 3/2+ (8.356 eV) during the transition of an electron between bound states in a Th ion in the case of proximity of energies and coincidence of the multipolarities of the nuclear and electronic transitions can lead to multiple coherent transfer of excitation energy from the electron shell to the nucleus and back. Thus, the electron shell plays the role of a kind of resonator for the virtual photon emitted by the nucleus. At the same time, it “breathes,” periodically decreasing and increasing in size. Such energy oscillations between the doublet of nuclear levels and the electron shell are a consequence of the relatively large interaction energy of the electron and nuclear currents. Due to the coherent nature of the phenomenon, the process under consideration becomes the main, but at the same time reversible, channel for the “decay” of both the nuclear isomer and the excited ion.