⁶Li原子跃迁频率和超精细分裂的精密测量

In this paper, we report a precision measurement of hyperfine splitting and absolute frequency of D₁ line in cold ⁶Li atoms. The gray molasses is realized in the experiment and the tempreature is cooled to about 50μK, which is lower than the Doppler cooling limit, 140μK. By use of an optical comb, the absolute frequencies and corresponding hyperfine splitting are measured. We obtain frequencies of 446789503.080(35) MHz, 446789529.198(36) MHz, 446789731.316(50) MHz and 446789757.476(29) MHz for the D1 line. The results are in reasonable agreement with the theoretical calculations and consistent with earlier measurements. They could provide an important foundation for future frequency measurement, α constant and nuclear radius.