Laser cooling of the alkaline-earth-metal monohydrides: Insights from an ab initio theory study
Laser cooling of the alkaline-earth-metal monohydrides: Insights from an ab initio theory study
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DOI：
10.1103/physreva.90.052506
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发表时间：
2014-11-10
影响因子：
2.9
通讯作者：
Gao, Tao
中科院分区：
文献类型：
--
作者：
Gao, Yufeng;Gao, Tao
用量子化学从头算方法研究了激光冷却MH（M = Be，Mg，Ca，Sr，Ba）的可行性。用多参考组态相互作用（MRCI）理论水平计算了MH分子的基态X（2）Sigma（+）和第一激发态A（2）Pi.对于CaH，SrH和BaH，自旋轨道耦合效应也被考虑在MRCI水平的电子结构计算。计算的（BeH）-Be-9、（MgH）-Mg-24、（CaH）-Ca-40、（SrH）-Sr-86和（BaH）-Ba-138的光谱常数与现有的理论和实验结果具有良好的一致性。在MRCI水平上计算了MH分子X（2）Sigma（+）和A（2）Pi态的永久偶极矩和跃迁偶极矩，与前人的理论结果符合较好.利用获得的势能曲线和TDM，高度对角分布的Franck-Condon因子f无穷大（（BeH）-Be-9：0.998，（MgH）-Mg-24：0.954，（CaH）-Ca-40：0.961，（SrH）-Sr-86：0.978，和（BaH）-Ba-138：0.971）。计算了A（2）Pi（v' = 0）态的辐射寿命（9 BeH：82.0ns，（MgH）-Mg-24：48.6ns，（CaH）-Ca-40：33.3ns，（SrH）-Sr-86：33.2ns，和（BaH）-Ba-138：68.6ns），发现它们的辐射寿命短得足以满足激光快速冷却的要求。所提出的主循环激光器在波长处驱动X（2）Sigma（+）（v = 0）-> A（2）Pi（v' = 0）跃迁.λ无限（（BeH）-Be-9：497.2 nm，（MgH）-Mg-24：525.5 nm，（CaH）-Ca-40：675.4 nm，（SrH）-Sr-86：740.3 nm，和（BaH）-Ba-138：952.6 nm）。研究结果表明激光冷却MH物种的可能性，为进一步开展碱土金属单晶的理论和实验研究提供了理论参考。
The feasibility of laser cooling MH (M = Be, Mg, Ca, Sr, and Ba) is investigated using ab initio quantum chemistry. The ground state X (2)Sigma(+) and first excited state A (2)Pi of MH species are calculated using the multireference configuration interaction (MRCI) level of theory. For CaH, SrH, and BaH, the spin-orbit coupling effects are also taken into account in electronic structure calculations at the MRCI level. Calculated spectroscopic constants for (BeH)-Be-9, (MgH)-Mg-24, (CaH)-Ca-40, (SrH)-Sr-86, and (BaH)-Ba-138 show good agreement with available theoretical and experimental results. The permanent dipole moments and transition dipole moments (TDMs) of the X (2)Sigma(+) and A(2)Pi states of MH species are also calculated at the MRCI level of theory, and they are in good agreement with previous theoretical results. With the potential energy curves and TDMs obtained, the highly diagonally distributed Franck-Condon factors f infinity ((BeH)-Be-9 : 0.998,(MgH)-Mg-24 : 0.954,(CaH)-Ca-40 : 0.961,(SrH)-Sr-86 : 0.978, and (BaH)-Ba-138 : 0.971) for the A (2)Pi (v' = 0) -> X (2)Sigma(+) (v = 0) transition are determined. Radiative lifetime calculations of theA (2)Pi (v' = 0) state (9BeH : 82.0ns, (MgH)-Mg-24 : 48.6 ns, (CaH)-Ca-40 : 33.3ns, (SrH)-Sr-86 : 33.2 ns, and (BaH)-Ba-138: 68.6 ns) are found to be short enough for rapid laser cooling. The proposed main cycling laser drives the X (2)Sigma(+) (v = 0) -> A (2)Pi (v' = 0) transition atwavelength. lambda infinity ((BeH)-Be-9 : 497.2 nm, (MgH)-Mg-24 : 525.5nm, (CaH)-Ca-40 : 675.4nm, (SrH)-Sr-86 : 740.3nm, and (BaH)-Ba-138 : 952.6 nm). The results demonstrate the possibility of laser cooling MH species, and provide a promising theoretical reference for further theoretical and experimental research on alkaline-earth-metal monohydrides.