摘要
We report an experimental investigation on the Doppler-free saturated absorption spectroscopy of buffer-gas-cooled Barium monofluoride(BaF)molecules in a 4 K cryogenic cell.The obtained spectra with a resolution of 19 MHz,much smaller than previously observed in absorption spectroscopy,clearly resolve the hyperfine transitions.Moreover,we use these high-resolution spectra to fit the hyperfine splittings of excited A(v=0)state and find the hyperfine splitting of the laser-cooling-relevant A^(2)Π_(1/2)(v=0,J=1/2,+)state is about 18 MHz,much higher than the previous theoretically predicted value.This provides important missing information for laser cooling of BaF molecules.
基金
support from the National Key Research and Development Program of China under Grant No.2018YFA0307200
the National Natural Science Foundation of China under Grant Nos.U21A20437 and 12074337
the Natural Science Foundation of Zhejiang Province under Grant No.LR21A040002
Zhejiang Province Plan for Science and technology No.2020C01019
the Fundamental Research Funds for the Central Universities under No.2021FZZX001-02.