Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr
Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr
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AlBr 激光冷却中的振动分支比和辐射寿命
DOI：
10.1039/c6cp08181a
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发表时间：
2017
影响因子：
3.3
通讯作者：
Wan Mingjie
中科院分区：
文献类型：
--
作者：
Gao Yufeng;Wan Mingjie
用量子化学从头算方法研究了激光冷却AlBr分子的可行性。采用多参考组态相互作用加Davidson修正（MRCI+ Q）方法，在ACVQZ基组下计算了基态X1 S +和前两个激发态（a（3）Pi和A（1）Pi）的势能曲线、永久偶极矩和跃迁偶极矩，并在MRCI水平上考虑了自旋轨道耦合效应.基于获得的势能曲线和跃迁偶极矩，确定了跃迁A（1）Pi 1（nu）-> X-1 Sigma（1）（0）+（nu”）的高度对角分布的Franck-Condon因子（f（00）= 0.9540，f（11）= 0.8172）和振动分支比（R-00 = 0.9708，R-11 = 0.8420）。计算了A（1）Pi（1）（nu' =0.4）态的辐射寿命（9.16- 11.48ns），这对于激光快速冷却是足够的。所提出的主循环激光器在波长λ（00）= 279.19 nm处驱动X-1 Sigma（1）（0）+（nu”-0）-> A（1）Pi（1）（nu'-0）跃迁。A（1）Pi（1）（nu ′）态与中间态a（3）Pi（0）+和a（3）Pi（1）的振动分支损失比小到足以忽略不计（<5.2 × 10（-6））。目前的理论结果表明，溴化铝分子是一个有前途的候选激光冷却。
The feasibility of laser cooling of the AlBr molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the ground state X1 S + and the first two excited states (a(3)Pi and A(1)Pi) are calculated using the multi-reference configuration interaction plus Davidson corrections (MRCI+ Q) method with the ACVQZ basis set; the spin- orbit coupling effects are also taken into account in electronic structure calculations at the MRCI level. Based on the acquired potential energy curves and transition dipole moments, highly diagonally distributed Franck- Condon factors (f(00) = 0.9540, f(11) = 0.8172) and vibrational branching ratios (R-00 = 0.9708, R-11 = 0.8420) for the transition A(1)Pi 1(nu)-> X-1 Sigma(1)(0)+(nu")are determined. Radiative lifetime calculations of the A(1)Pi(1)(nu' =0.4) state are found to be short (9.16- 11.48 ns) enough for rapid laser cooling. The proposed main cycling laser drives the X-1 Sigma(1)(0)+(nu" -0)-> A(1)Pi(1)(nu' - 0)transition at the wavelength lambda(00) = 279.19 nm. The vibrational branching loss ratios of the A(1) Pi(1)(nu')state to the intervening states a(3)Pi(0)+ and a(3)Pi(1) are small (<5.2 x 10(-6)) enough to be negligible. The present theoretical results indicate that the AlBr molecule is a promising candidate for laser cooling.