基于A^(2)Π_(1/2)←X^(2)Σ_(1/2)跃迁的CaH分子激光冷却光谱理论研究  

Theoretical investigation into spectrum of A2Π1/2←X2Σ1/2 transition for CaH molecule toward laser cooling

作　　者：尹俊豪 杨涛 印建平[1] Yin Jun-Hao;Yang Tao;Yin Jian-Ping(State Key Laboratory of Precision Spectroscopy,East China Normal University,Shanghai 200062,China)

机构地区：[1]华东师范大学,精密光谱科学与技术国家重点实验室,上海200062

出　　处：《物理学报》2021年第16期118-127,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11834003,11874151)资助的课题。

摘　　要：冷分子是当下物理学的前沿领域和热点研究方向之一,早在2004年就有科学家提出将CaH分子作为激光冷却与磁光囚禁的候选分子.本文首先用三种方法(莫尔斯势法、闭合近似法和RKR反演法)计算CaH分子的弗兰克-康登因子,证实了CaH的X^(2)∑_(1/2)态和A^(2)∏_(1/2)态之间具有高度对角化的弗兰克-康登因子矩阵.随后,采用有效哈密顿量的方法研究了基态X^(2)∑_(1/2)的超精细能级结构和A^(2)∏_(1/2)(J=1/2,+)←X^(2)∑_(1/2)(N=1,-)跃迁的超精细跃迁分支比,并提出可同时覆盖超精细能级的边带调制方案.最后,为探究CaH分子磁光囚禁的相关性质,计算了|X,N=1,->态的塞曼效应和J混合下的朗德g因子.以上工作不仅证明了激光冷却和磁光囚禁CaH分子的可行性,而且对天体物理学中的光谱分析、超冷分子碰撞以及探索基本对称性破缺等基础物理学的相关研究也具有一定的参考意义.Laser cooling and trapping of neutral molecules has made substantial progress in the past few years.On one hand,molecules have more complex energy level structures than atoms,thus bringing great challenges to direct laser cooling and trapping;on the other hand,cold molecules show great advantages in cold molecular collisions and cold chemistry,as well as the applications in many-body interactions and fundamental physics such as searching for fundamental symmetry violations.In recent years,polar diatomic molecules such as SrF,YO,and CaF have been demonstrated experimentally in direct laser cooling techniques and magneto-optic traps(MOTs),all of which require a comprehensive understanding of their molecular internal level structures.Other suitable candidates have also been proposed,such as YbF,MgF,BaF,HgF or even SrOH and YbOH,some of which are already found to play important roles in searching for variations of fundamental constants and the measurement of the electron’s Electric Dipole Moment(eEDM).As early as 2004,the CaH molecule was selected as a good candidate for laser cooling and magneto-optical trapping.In this article,we first theoretically investigate the Franck-Condon factors of CaH in the A^(2)∏_(1/2)←X^(2)∑_(1/2) transition by the Morse potential method,the closed-form approximation method and the Rydberg-Klein-Rees method separately,and prove that Franck-Condon factor matrix between X^(2)∑_(1/2) state and A^(2)∏_(1/2) state is highly diagonalized,and indicate that sum of f00,f01 and f02 for each molecule is greater than 0.9999 and almost 1×104 photons can be scattered to slow the molecules with merely three lasers.The molecular hyperfine structures of X^(2)∑_(1/2),as well as the transitions and associated hyperfine branching ratios in the A^(2)∏_(1/2)(J=_(1/2),+)←X^(2)∑_(1/2)(N=1,-)transition of CaH,are examined via the effective Hamiltonian approach.According to these results,in order to fully cover the hyperfine manifold originating from|X,N=1,->,we propose the sideband modulati

关 键 词：冷分子 激光冷却 CaH分子 弗兰克-康登因子 

分 类 号：O561[理学—原子与分子物理]