Abstract: The new clock based on atomic nucleus transition,nuclear clock,has important research value.Its principle is to use the electromagnetic wave frequency generated by atomic nucleus transition to accurately measure time.At present,the most promising nucleus for nuclear clock is considered to be the first excited state of ²²⁹Th nucleus ^229mTh.How to excite ²²⁹Th nucleus to the first excited state and obtain the parameters of the first excited state ^229mTh are the focus of current research.The latest measurement data of the excited state energy is E_is=8.28±0.17 eV,which corresponds to the direct laser excitation of ²²⁹Th to ^229mTh with a wavelength of 149.7±3.1 nm.This provides a data reference for the direct laser excitation of the excited state.In addition to direct laser excitation,electron bridge excitation is also an indirect excitation method worth considering.Some potential applications of nuclear clock technology are also introduced,such as the new definition of second,the study of time variation of fundamental constants and dark matter detection.

Key words: Nuclear clock structure, Nuclide selection of nuclear clock, ^229mTh excitation mode, ^229mTh excitation state parameter measurement