-
作为非对称多原子分子制冷的一个重要目标分子, CaSH的冷却有望打破双原子分子及线性三原子分子在激光冷却中的技术局限. 本文使用高精度的EA-EOM-CCSD (electron attachment equation-of-motion coupled cluster singles and doubles)方法, 通过cc-pV XZ/cc-pCV XZ ( X= T, Q)系列基组外推至基组极限, 得到了CaSH基态和3个最低激发态精确的几何结构及基态到激发态的跃迁能. 其中, 基态
$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}' $ 几何结构参数分别为 R CaS= 2.564 Å; R SH= 1.357 Å; ∠CaSH= 91.0°; 从$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ 到$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ ,$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{{\prime\prime} } $ 和$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ 的垂直激发能分别为1.898, 1.945和1.966 eV, 与已有实验符合得很好. 进一步, 在3ζ级别基组上, 计算了该分子4个最低电子态的势能面, 并通过求解核运动方程给出CaS键伸缩、CaSH弯曲两个振动模的频率. 最后, 理论计算给出的$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0, 0}}, 0) $ 态到激发态$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0, 0}}, 0) $ ,$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{{\prime\prime} }({\mathrm{0, 0}}, 0) $ 和$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0, 0}}, 0) $ 跃迁的Frank-Condon (FC)因子分别为0.9268, 0.9958和0.9248. 结合Frank-Condon因子和激发态寿命分析, 本文给出了可能用于CaSH冷却的光学循环, 为CaSH的激光冷却提供了理论参考.-
关键词:
- 激光冷却/
- 激发态/
- Franck-Condon因子/
- 光学循环
The CaSH molecule is an important target in the field of laser cooling non-linear polyatomic molecules. Successful cooling of such molecules marks a breakthrough of the technical limitations of laser cooling diatomic and linear triatomic molecules. To identify the possible optical cycle in cooling CaSH, precise geometries of the CaSH ground state and the three lowest excited states, along with their excitation energy, are determined by utilizing the EA-EOM-CCSD (electron attachment equation-of-motion coupled cluster singles and doubles) method, in combination with energy extrapolation using cc-pV XZ/cc-pCV XZ ( X= T, Q ) serial basis sets. Geometric parameters of the ground state$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ are found to be R CaS= 2.564 Å, R SH= 1.357 Å, and ∠CaSH= 91.0°. Additionally, the equilibrium geometries of three excited states are also obtained. The$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ state has a similar equilibrium structure to the ground state, while the$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ and$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ states exhibit significant conformer distortions. Specifically, the CaS bond of the$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ state and$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ state tend to contract, and the CaSH angel bends by 5° relative to the ground state. The vertical excitation energy from the ground state to$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ ,$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ and$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ are of 1.898, 1.945 and 1.966 eV, respectively, which are in good agreement with the previous experimental results. Moreover, the potential energy surfaces of the four lowest electronic states of CaSH are calculated by EA-EOM-CCSD with 3ζ level of basis sets. The nuclear equations of motion are solved to obtain the vibrational frequencies of the CaS bond stretching and CaSH bending. The vibrational frequencies of the (0,1,0) mode and the CaS stretching frequency of four states are 316 cm –1, 315 cm –1, 331 cm –1and 325 cm –1, which are in close agreement with the available experimental results. The frequencies of the CaSH bending mode are presented for the first time, with the values of 357 cm –1, 396 cm –1, 384 cm –1, 411 cm –1for the$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ ,$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ ,$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ and$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ states, respectively. Theoretical calculations give the Frank-Condon factors of 0.9268, 0.9958 and 0.9248 for the$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0,0}},0) $ to$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0,0}},0) $ ,$ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{{{\prime} }{{\prime} }}({\mathrm{0,0}},0) $ and$ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0,0}},0) $ transitions. All three excited states are the bright states with considerable oscillator strength relative to the ground state. Based on the Frank-Condon factor and lifetime of excited states, the$ {{\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0,0}},0)\to \tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{{{\prime} }{{\prime} }}({\mathrm{0,0}},0) $ transition is regarded as the main cooling cycle for the CaSH molecule. The corresponding pump light wavelength is 678 nm. By exciting the vibrational excited states (0,1,0) and (0,0,1) of the$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ state to$ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} ({\mathrm{0,0}},0) $ using lasers at 666 nm and 668 nm, respectively, the optical cooling branch ratio of CaSH is expected to exceed 0.9998.-
Keywords:
- laser cooling/
- excited state/
- Franck-Condon factor/
- optical cycle
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] -
State r0(Ca-S)/Å r0(S—H)/Å θ(Ca—S—H)/(°) Method Ref. $ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ 2.557 1.338 91.0 EA-EOM-CCSD This work 2.614 1.346 100.0 MP2 Calc.[23] 2.607 1.339 97.1 Calc.[25] 2.647 1.347 93.1 CCSD(T) Calc.[24] 2.560 1.346 96.6 Expt.[22] 2.564 1.357 91.0 Expt.[26] $ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ 2.528 1.343 86.0 EA-EOM-CCSD This work 2.513 1.346 94.6 Expt.[22] 2.517 1.357 89.1 Expt.[26] $ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ 2.554 1.338 91.0 EA-EOM-CCSD This work 2.550 1.357 89.1 Expt.[26] $ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ 2.525 1.345 86.0 EA-EOM-CCSD This work 2.562 1.357 91.0 Expt.[26] 
下载:
导出CSV
$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} \to {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ $ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} \to {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ $ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} \to {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ EA-EOM-CCSD VEEa) 1.945 2.000 2.093 3ζ 1.915 1.966 2.016 4ζ 1.898 1.945 1.966 Basis set limit AEEb) 1.894 1.944 1.961 Basis set limit SA-CASSCF VEE 1.884 1.937 2.216 3ζ fc) 0.2628 0.2589 0.1621 Expt. 1.907 1.966 1.993 Ref. [26] 1.905 1.960 1.987 Ref. [21] Calc. 1.860 1.930 2.110 Ref. [23] VEEa) 2.000 2.060 2.330 Ref. [43] 注:a)垂直激发能;b)绝热激发能;c)偶极跃迁振子强度. 下载:
导出CSV
$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} $ $ {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ $ {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ $ {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ (0, 1, 0) 316 (326)b) 315 (318)b) 331 (320)b) 326 (312)b) (0, 0, 1) 357 396 384 411 (0, 2, 0) 634 632 661 653 (0, 1, 1) 681 724 722 742 (0, 0, 2) 704 785 760 808 (0, 3, 0) 953 949 990 981 (0, 2, 1) 1007 1051 1058 1074 (0, 1, 2) 1034 1122 1102 1145 (0, 0, 3) 1039 1167 1130 1188 (0, 4, 0) 1271 1266 1318 1308 注:a)(0, 1, 0)CaS 伸缩振动模式, (0, 0, 1)CaSH键角弯曲振动模式;b)括号内值为实验值[23]. 下载:
导出CSV
$ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} {\to} {\tilde{{\mathrm{A}}}}^{2}{{\mathrm{A}}}^{\prime} $ $ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} {\to} {\tilde{{\mathrm{B}}}}^{2}{{\mathrm{A}}}^{\prime\prime} $ $ {\tilde{{\mathrm{X}}}}^{2}{{\mathrm{A}}}^{\prime} {\to} {\tilde{{\mathrm{C}}}}^{2}{{\mathrm{A}}}^{\prime} $ (0, 0, 0) →
(0, 0, 0)0.9268 0.9958 0.9248 (0, 1, 0) →
(0, 0, 0)0.0627 0.0011 0.0626 (0, 0, 1) →
(0, 0, 0)0.0094 0.0002 0.0114 (0, 1, 1) →
(0, 0, 0)0.0006 2.4×10–7 0.0008 (0, 2, 0) →
(0, 0, 0)0.0001 0.0006 2.2×10–5 (0, 0, 2) →
(0, 0, 0)6.0×10–5 0.0003 5×10–6 下载:
导出CSV
-
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] -
[1] 李多多, 张嵩.五氟吡啶激发态非绝热弛豫过程中的分子结构. 必威体育下载 , 2024, 73(4): 043101.doi:10.7498/aps.73.20231570 [2] 朱宇豪, 李瑞.基于组态相互作用方法对AuB分子低激发态电子结构和光学跃迁性质的研究. 必威体育下载 , 2024, 73(5): 053101.doi:10.7498/aps.73.20231347 [3] 邢凤竹, 崔建坡, 王艳召, 顾建中.激发态丰质子核的双质子发射. 必威体育下载 , 2022, 71(6): 062301.doi:10.7498/aps.71.20211839 [4] 尹俊豪, 杨涛, 印建平.基于 ${{\bf{A}}}^{{\boldsymbol{2}}}{{{\boldsymbol{\Pi}} }}_{{\boldsymbol{1/2}}}{\boldsymbol{\leftarrow }}{{\bf{X}}}^{{\boldsymbol{2}}}{{{\boldsymbol{\Sigma }}}}_{{\boldsymbol{1/2}}}$ 跃迁的CaH分子激光冷却光谱理论研究. 必威体育下载 , 2021, 70(16): 163302.doi:10.7498/aps.70.20210522[5] 张树东, 王传航, 唐伟, 孙阳, 孙宁泽, 孙召玉, 徐慧.TiAl电子态结构的ab initio计算. 必威体育下载 , 2019, 68(24): 243101.doi:10.7498/aps.68.20191341 [6] 张锦芳, 任雅娜, 王军民, 杨保东.铯原子激发态双色偏振光谱. 必威体育下载 , 2019, 68(11): 113201.doi:10.7498/aps.68.20181872 [7] 万明杰, 李松, 金成国, 罗华锋.激光冷却SH–阴离子的理论研究. 必威体育下载 , 2019, 68(6): 063103.doi:10.7498/aps.68.20182039 [8] 万明杰, 罗华锋, 袁娣, 李松.激光冷却KCl–阴离子的理论研究. 必威体育下载 , 2019, 68(17): 173102.doi:10.7498/aps.68.20190869 [9] 陈涛, 颜波.极性分子的激光冷却及囚禁技术. 必威体育下载 , 2019, 68(4): 043701.doi:10.7498/aps.68.20181655 [10] 邢伟, 孙金锋, 施德恒, 朱遵略.AlH+离子5个-S态和10个态的光谱性质以及激光冷却的理论研究. 必威体育下载 , 2018, 67(19): 193101.doi:10.7498/aps.67.20180926 [11] 张云光, 张华, 窦戈, 徐建刚.激光冷却OH分子的理论研究. 必威体育下载 , 2017, 66(23): 233101.doi:10.7498/aps.66.233101 [12] 赵翠兰, 王丽丽, 赵丽丽.有限深抛物势量子盘中极化子的激发态性质. 必威体育下载 , 2015, 64(18): 186301.doi:10.7498/aps.64.186301 [13] 刘晓军, 苗凤娟, 李瑞, 张存华, 李奇楠, 闫冰.GeO分子激发态的电子结构和跃迁性质的组态相互作用方法研究. 必威体育下载 , 2015, 64(12): 123101.doi:10.7498/aps.64.123101 [14] 田原野, 郭福明, 曾思良, 杨玉军.原子激发态在高频强激光作用下的光电离研究. 必威体育下载 , 2013, 62(11): 113201.doi:10.7498/aps.62.113201 [15] 孙羽, 冯高平, 程存峰, 涂乐义, 潘虎, 杨国民, 胡水明.利用激光冷却原子束测量氦原子精密光谱. 必威体育下载 , 2012, 61(17): 170601.doi:10.7498/aps.61.170601 [16] 张宝武, 张萍萍, 马艳, 李同保.铬原子束横向一维激光冷却的蒙特卡罗方法仿真. 必威体育下载 , 2011, 60(11): 113701.doi:10.7498/aps.60.113701 [17] 高双红, 任兆玉, 郭平, 郑继明, 杜恭贺, 万丽娟, 郑琳琳.石墨烯量子点的磁性及激发态性质. 必威体育下载 , 2011, 60(4): 047105.doi:10.7498/aps.60.047105 [18] 周业宏, 蔡绍洪.氯乙烯在外电场下的激发态结构研究. 必威体育下载 , 2010, 59(11): 7749-7755.doi:10.7498/aps.59.7749 [19] 魏 群, 杨子元, 王参军, 许启明.轴对称晶场中d3离子激发态对4A2基态自旋哈密顿参量的影响. 必威体育下载 , 2007, 56(1): 507-511.doi:10.7498/aps.56.507 [20] 汤乃云, 陈效双, 陆 卫.尺寸分布对量子点激发态发光性质的影响. 必威体育下载 , 2005, 54(12): 5855-5860.doi:10.7498/aps.54.5855
下载:
计量
- 文章访问数:1689
- PDF下载量:56
- 被引次数:0