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采用多参考组态相互作用方法结合全电子基组计算了LiCl -阴离子5个电子态 (X 2Σ +, A 2∏, B 2Σ +, 3 2Σ +, 2 2∏) 的电子结构. 为了得到精确的光谱常数, 计算中考虑了Davidson 修正、芯-价电子关联效应和自旋-轨道耦合效应. 拟合得到各电子态的光谱常数、分子常数、自发辐射速率和自发辐射寿命. 基态的光谱常数与实验值和其他理论值符合较好, 同时报道了LiCl –阴离子激发态的光谱常数以及其到基态的跃迁性质. 计算结果表明A 2∏
$\leftrightarrow $ X 2Σ +跃迁具有高对角分布的弗兰克-康登因子 f 00, 第一激发态A 2∏有较短的自发辐射寿命. 构造A 2∏ ( ν′)$\leftrightarrow $ X 2Σ +($\nu''$ )准循环跃迁进行激光冷却LiCl –阴离子需要一束主激光和两束抽运激光. 以上结果预测了激光冷却LiCl –阴离子是可行的.The electronic structure of the X 2Σ +, A 2Π, B 2Σ +, 3 2Σ +, and 2 2Π state of LiCl –anion are performed at an MRCI+Q level. Davison correction, core-valence correction and spin-orbit coupling effect are also considered. The ground state X 2Σ +of LiCl –anion correlates with the lowest dissociation channel Li( 2S g) + Cl –( 1S g); the A 2∏ state and B 2Σ +state correlate with the second dissociation channel Li( 2P u) + Cl –( 1S g); the 3 2Σ +state and 2 2Π state correlate with the third dissociation channel Li –( 1S g) + Cl –( 2P u). Spectroscopic parameters are calculated by solving the radial Schröedinger equation. The equilibrium internuclear distance R eof the ground state X 2Σ +is 2.1352 Å, which is a little bigger than the experimental datum, with an error being 0.5%. It is a deep potential well, and the dissociation energy D eis 1.886 eV. These values are in good agreement with experimental data. The A 2∏ state is at 13431.93 cm –1above the X 2Σ +state. The R eis 2.1198 Å, which is only 0.0154 Å smaller than that of the X 2Σ +state. The values of energy level G νand rotational constant B νof five Λ-S states are also calculated. The values are in good agreement with available theoretical ones. The electronic structures of the excited states are also reported. The SOC effect weakly influences the spectroscopic parameters for the $ {\text{X}}{}^2\Sigma _{1/2}^ + $ ,$ {\text{A}}{}^2{\Pi _{1/2}} $ ,$ {\text{A}}{}^2{\Pi _{3/2}} $ , and$ {\text{B}}{}^2\Sigma _{1/2}^ + $ state. From the analysis of the SO matrix, it can be seen that the SOC effect plays a little role in realizing the A 2Π$\leftrightarrow $ X 2Σ +transition, so, it can be ignored.The scheme of laser cooling of LiCl –anion has constructed at a spin – free level. The A 2∏( ν ′) $\leftrightarrow $ X 2Σ +($v'' $ ) transition has a highly diagonally distributed Franck-Condon factor f 00= 0.9898, the calculated branching ratio of the diagonal term R 00is 0.9893, and spontaneous radiative lifetime of A 2∏ is 35.45 ns. A main pump laser and two repumping lasers for driving the A 2∏( ν ′)$\leftrightarrow $ X 2Σ +($v'' $ ) transitions are required. The laser wavelengths are 744.10, 774.30 and 772.42 nm, respectively. Owing to the summation of R 00, R 01, and R 02being closer to 1, the A 2∏( ν ′)$\leftrightarrow $ X 2Σ +($v'' $ ) transition is a quasicycling transition. These results imply that the LiCl –anion is a candidate for laser cooling.-
Keywords:
- spin-orbit coupling effects/
- spectroscopic parameters/
- molecular parameters/
- laser cooling
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电子态 Re/Å ωe/cm–1 ωeχe/cm–1 Be/cm–1 De/eV D0/eV Te/cm–1 X2Σ+ 2.1352 535.33 5.8173 0.7205 1.8886 1.856 0 实验值[20] 2.18(4) 0 实验值[21] 2.123(15) 1.75(2) 0 理论值[22] 2.12a 0 理论值[23] 2.1354 537.7b 6.34b 0.7203b 1.81 0 A2∏ 2.1198 554.65 5.7157 0.7310 1.9902 1.9559 13431.93 B2Σ+ 2.0282 652.79 6.1252 0.7985 1.6653 1.6250 17491.75 32Σ+ 5.8594 30.19 0.8483 0.0963 0.0362 0.0353 38607.64 22∏ 7.1411 39.08 0.5616 0.0638 0.0136 0.0112 38855.32 a采用HF方法计算得到基态的核间距. 
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ν X2Σ+ A2∏ B2Σ+ 32Σ+ 22∏ Gν Bν Gν Bν Gν Bν Gν Bν Gν Bν 本文工作 文献[23] 本文工作 文献[23] 本文工作 本文工作 本文工作 本文工作 本文工作 本文工作 本文工作 本文工作 0 266.72 264.07 0.7146 0.7143 276.48 0.7252 325.33 0.7927 14.96 0.0940 6.12 0.0631 1 790.93 791.77 0.7029 0.7023 820.21 0.7136 966.07 0.7811 43.02 0.0893 18.15 0.0618 2 1303.27 1307.01 0.6911 0.6903 1352.13 0.7021 1594.23 0.7697 68.84 0.0857 28.92 0.0572 3 1803.71 1809.92 0.6794 0.6784 1872.34 0.6907 2210.02 0.7584 93.22 0.0826 29.30 0.0095 4 2292.31 2300.65 0.6677 0.6666 2380.97 0.6793 2813.56 0.7471 116.24 0.0796 31.32 0.0112 5 2769.15 2779.34 0.6560 0.6548 2878.13 0.6680 3404.89 0.7359 138.17 0.0765 33.19 0.0125 6 3234.29 3246.11 0.6444 0.6430 3363.87 0.6567 3984.09 0.7247 158.98 0.0725 35.07 0.0140 7 3687.83 3701.10 0.6328 0.6313 3838.29 0.6455 4551.20 0.7135 178.26 0.0678 36.53 0.0310 8 4129.88 4144.45 0.6212 0.6197 4301.42 0.6343 5106.17 0.7023 195.60 0.0626 37.33 0.0257 9 4560.61 4576.29 0.6097 0.6081 4753.37 0.6231 5648.95 0.6911 210.77 0.0571 39.11 0.0188 下载:
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Ω态 Re/Å ωe/cm–1 ωeχe/cm–1 Be/cm–1 De/eV Te/cm–1 $ {\text{X}}{}^2\Sigma _{1/2}^ + $ 2.1352 535.32 5.8172 0.7205 1.8886 0 $ {\text{A}}{}^2{\Pi _{1/2}} $ 2.1196 554.87 5.7153 0.7311 2.0094 13419.77 $ {\text{A}}{}^2{\Pi _{3/2}} $ 2.1200 554.41 5.7160 0.7308 2.0059 13444.07 $ {\text{B}}{}^2\Sigma _{1/2}^ + $ 2.0282 652.79 6.1253 0.7985 1.6679 17491.75 下载:
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SO矩阵元 $ {\text{S}}{{\text{O}}_1} = - {\text{i}}\left\langle {{{\text{X}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_2} = \left\langle {{{\text{X}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_3} = - {\text{i}}\left\langle {{{\text{B}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_4} = \left\langle {{{\text{B}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_5} = - {\text{i}}\left\langle {{3^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_6} = \left\langle {{3^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_7} = - {\text{i}}\left\langle {{{\text{X}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_8} = \left\langle {{{\text{X}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_9} = - {\text{i}}\left\langle {{{\text{B}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_{10}} = \left\langle {{{\text{B}}^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_{11}} = - {\text{i}}\left\langle {{3^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_{12}} = \left\langle {{3^2}{\Sigma ^ + }} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_{13}} = {\text{i}}\left\langle {{{\text{A}}^2}{\Pi _x}} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_{14}} = {\text{i}}\left\langle {{2^2}{\Pi _x}} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _y}} \right\rangle $ $ {\text{S}}{{\text{O}}_{15}} = {\text{i}}\left\langle {{2^2}{\Pi _y}} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{{\text{A}}^2}{\Pi _x}} \right\rangle $ $ {\text{S}}{{\text{O}}_{16}} = {\text{i}}\left\langle {{2^2}{\Pi _x}} \right|\hat H_{{\text{SO}}}^{{\text{BP}}}\left| {{2^2}{\Pi _y}} \right\rangle $ 下载:
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跃迁 f00 f01 f02 f03 A00 A01 A02 A03 τ= 1/ΣA f10 f11 f12 f13 A10 A11 A12 A13 A2∏ $\leftrightarrow $ X2Σ+ 0.9898 0.0101 0.0001 8.70(–7) 27904200 298313 3848.85 44.60 35.45 0.0102 0.9686 0.0209 0.0004 269660 27336600 607335 12332 35.43 B2Σ+$\leftrightarrow $ X2Σ+ 0.5908 0.2909 0.0894 0.0225 18316800 7658290 2038730 452210 34.99 0.3266 0.1286 0.2888 0.1671 12279600 4261780 7988480 3979390 33.00 下载:
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