AlH^+离子5个Λ-S态和10个?态的光谱性质以及激光冷却的理论研究  

Theoretical study of spectroscopic properties of 5 Λ-S and 10 Ω states and laser cooling for AlH^+ cation

作　　者：邢伟 孙金锋[1,3] 施德恒 朱遵略 Xing Wei;Sun Jin-Feng;Shi De-Heng;Zhu Zun-Lüe(School of Materials Science and Engineering,Henan University of Science and Technology Luoyang 471023,China;College of Physics and Electronic Engineering,Xinyang Normal University,Xinyang 464000,China;College of Physics and Materials Science,Henan Normal University,Xinxiang 453007,China)

机构地区：[1]河南科技大学材料科学与工程学院,洛阳471023 [2]信阳师范学院物理电子工程学院,信阳464000 [3]河南师范大学物理与材料科学学院,新乡453007

出　　处：《物理学报》2018年第19期123-134,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61275132;274097)资助的课题~~

摘　　要：利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH^+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X^2Σ_(1/2)^+和A^2Π_(3/2)→X^2Σ_(1/2)^+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)^(第一势阱)(υ′=0, 1)→X^2Σ_(1/2)^+(υ′′)和A^2Π_(3/2)(υ′=0, 1)→X^2Σ_(1/2)^+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)^(第一势阱)(υ′=0, 1)和A^2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH^+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH^+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH^+离子的影响.In this paper, we calculate the potential energy curves of 5 Λ-S and 10 ？, which arise from the first two dissociation limits of the AlH＋ cation. The calculations are done using the complete active space self-consistent field method, which combines with the valence internally contracted multireference configuration interaction plus the Davidson modification （icMRCI＋Q） approach with the aug-cc-pV6Z basis set. To improve the reliability and accuracy of the potential energy curves, the core-valence correlation and scalar relativistic correction, as well as the extrapolation of potential energy to the complete basis set limit are taken into account. The spin-orbit coupling is computed using the state interaction approach with the Breit-Pauli Hamiltonian. Employing the potential energy curves obtained in this study, we evaluate the spectroscopic parameters and vibrational levels for the bound and quasi-bound 4 Λ-S and 8 ？ states. The computed spectroscopic constants of X^2Σ^＋ and A^2Π states are all in agreement with the available experimental data. Moreover,the present theoretical energy separations between each higher channel （Al^＋（^3P0） ＋ H（^2S（1/2））, Al^＋（^3P1） ＋ H（^2S（1/2））,and Al^＋（^3P2） ＋ H（^2S（1/2）） and the lowest one （Al^＋（^1S0） ＋ H（^2S（1/2））） are in excellent agreement with the experimental values. The transition dipole moments are calculated using the valence internally contracted multireference configuration interaction approach with the aug-cc-pV6Z basis set for the 2（1/2） → X^2Σ（1/2）^＋ and A^2Π（3/2）→ X^2Σ（1/2）^＋. Based on the obtained potential energy curves and transition dipole moments, highly diagonally distributed Franck-Condon factors （f（00） and f（11）） and large vibrational branching ratios are determined for the 2（1/2）^（1st well）（υ′= 0, 1） → X^2Σ（1/2）^＋（υ′′） and A^2Π（3/2）（υ′= 0, 1） → X^2Σ（1/2）^＋（υ′′） transitions

关 键 词：光谱常数 自旋轨道耦合 Franck-Condon因子和辐射寿命 激光冷却 

分 类 号：O562[理学—原子与分子物理]