Energy Levels and Transition Rates for Laser Cooling Os$^{-}$ and a General Approach to Produce Cold Atoms and Molecules
Yuzhu Lu1, Rui Zhang1, Changxian Song2, Chongyang Chen2, Ran Si2*, and Chuangang Ning1,3*
1Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China 2Shanghai EBIT Lab, Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China 3Frontier Science Center for Quantum Information, Tsinghua University, Beijing 100084, China
Abstract：High-resolution photoelectron energy spectra of osmium anions are obtained using the slow-electron velocity-map imaging method. The energy levels of excited states $^{4}\!F_{7/2}$, $^{4}\!F_{5/2}$ and $^{4}\!F_{3/2}$ of Os$^{-}$ are determined to be 148.730(13), 155.69(15), and 176.76(13) THz [or 4961.09(41), 5193.4(49), and 5896.1(42) cm$^{-1}$], respectively. The lifetime of the opposite-parity excited state $^{6}\!D_{9/2}^{\rm o}$ is determined to be 201(10) µs using a cold ion trap, about 15 times shorter than the previous result 3(1) ms. Our high-level multi-configuration Dirac–Hartree–Fock calculations yield a theoretical lifetime 527 µs. Our work shows that the laser cooling rate of Os$^{-}$ is as fast as that of Th$^{-}$. The advantages of Os$^{-}$ are its near-IR range cooling transition and simple electronic structure, which make Os$^{-}$ a promising candidate for laser cooling of negative ions. We propose a general approach to produce cold atoms and molecules based on the sympathetic cooling of negative ions in combination with a threshold photodetachment.
. [J]. 中国物理快报, 2023, 40(9): 93101-.
Yuzhu Lu, Rui Zhang, Changxian Song, Chongyang Chen, Ran Si, and Chuangang Ning. Energy Levels and Transition Rates for Laser Cooling Os$^{-}$ and a General Approach to Produce Cold Atoms and Molecules. Chin. Phys. Lett., 2023, 40(9): 93101-.
2023, Vol. 40 
