The nuclear transition between the ground and the low-energy isomeric state in the ²²⁹Th nucleus is of interest due to its high sensitivity to a hypothetical temporal variation of the fundamental constants and a possibility to build a very precise nuclear clock, but precise knowledge of the nuclear clock transition frequency is required. In this work, we estimate the probability of an electronic bridge (EB) process in ²²⁹Th³⁵⁺, allowing to determine the nuclear transition frequency and reduce its uncertainty. Using configuration interaction methods, we calculated energies of the low-lying states of Th³⁵⁺ and determined their uncertainties. Our calculations showed that the transition energy from the J = 15/2 state to the ground state, 8.31eV, is close to the central value of the experimentally determined nuclear isomer energy, 8.19eV, and practically coincides with the upper edge value, 8.31eV. It opens new possibilities for a more precise measurement of the nuclear isomer energy using an EB process.

²²⁹ Th 核中基态和低能异构状态之间的核跃迁很有趣，因为它对基本常数的假设时间变化高度敏感，并且有可能建立一个非常精确的核时钟，但对需要核时钟转换频率。在这项工作中，我们估计了²²⁹ Th ^{35+ 中}电子桥 (EB) 过程的概率，从而可以确定核跃迁频率并降低其不确定性。使用构型相互作用方法，我们计算了 Th ³⁵⁺低位态的能量并确定了它们的不确定性。我们的计算表明，J的跃迁能= 15/2 态到基态，8.31eV，接近实验确定的核异构体能量的中心值 8.19eV，实际上与上边缘值 8.31eV 重合。它为使用 EB 过程更精确地测量核异构体能量开辟了新的可能性。