Jiang Jun, Barnum Timothy J, Coy Stephen L, Field Robert W
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Chem Phys. 2019 Apr 21;150(15):154305. doi: 10.1063/1.5091526.
We report calculations of vibrational autoionization rates of CaF Rydberg states, based on the results of a global multi-channel quantum defect theory (MQDT) fit. Our goal is to use intuitive physical models to interpret and extend the results from the MQDT calculations and, in particular, to characterize the physical mechanisms for the interaction between the Rydberg electron and the ion-core. The calculations indicate that, among the six strongly l-mixed core-penetrating (CP) Rydberg series of CaF, the n.36 p^Π Rydberg series has the fastest Δv = 1 vibrational autoionization rate, which is at least four times larger than that for the other CP Rydberg series, in agreement with experimental results. We first demonstrate that the rotational level dependence of the vibrational autoionization rate of the n.36 p^Π series is satisfactorily explained by l-uncoupling interactions, which differ for the positive and negative Kronig symmetry levels. Next, we interpret the relative vibrational autoionization rates of all six CP Rydberg series in the context of a valence-precursor (VP) model. The VP model is a consequence of Mulliken's rule, which states that the innermost lobe of the Rydberg wavefunction remains invariant in both the nodal position and shape for members of the same Rydberg series. The electronic properties of the six VP states, which are the terminus states (lowest-n) of each of the six CP Rydberg series, are further characterized in terms of a ligand-field model, providing insight into the intimate relationship between the Rydberg electron density in the ion-core region and the vibrational autoionization rate.
我们基于全局多通道量子亏损理论（MQDT）拟合结果，报告了CaF里德堡态的振动自电离速率计算。我们的目标是使用直观的物理模型来解释和扩展MQDT计算结果，特别是表征里德堡电子与离子实之间相互作用的物理机制。计算表明，在CaF的六个强l - m混合芯穿透（CP）里德堡系列中，n.36 p^Π里德堡系列具有最快的Δv = 1振动自电离速率，比其他CP里德堡系列至少大四倍，这与实验结果一致。我们首先证明，n.36 p^Π系列振动自电离速率的转动能级依赖性可以通过l解耦相互作用得到令人满意的解释，正、负克罗尼格对称能级的这种相互作用有所不同。接下来，我们在价前驱体（VP）模型的背景下解释所有六个CP里德堡系列的相对振动自电离速率。VP模型是穆利肯规则的结果，该规则指出，对于同一里德堡系列的成员，里德堡波函数的最内叶在节点位置和形状上都保持不变。六个VP态（即六个CP里德堡系列中每个系列的终态（最低n））的电子性质，通过配体场模型进一步表征，从而深入了解离子实区域里德堡电子密度与振动自电离速率之间的密切关系。
