Laboratoire Collisions Agrégats Réactivité (LCAR), IRSAMC, Université de Toulouse, CNRS UMR 5589, Toulouse, France.
Phys Chem Chem Phys. 2019 Feb 13;21(7):3626-3636. doi: 10.1039/c8cp05253k.
We study the photodissociation of the potassium atom from a superfluid helium nanodroplet upon 5s 2S or 4p 2P excitation using the time-dependent helium density functional method (He-TDDFT). The importance of quantum effects is assessed by comparing the absorption spectrum obtained for a classical or a quantum description of the K atom. In the case of the 5s 2S ← 4s 2S excitation the difference is rather large, and we use a quantum description for the ensuing direct dissociation dynamics. In the case of the 4p 2P ← 4s 2S absorption spectrum, the difference is much smaller, hence a classical description of K is used to describe 4p 2P excitation dynamics. Excitation to the 4p 2Σ1/2 state leads to the direct dissociation of the K atom, while the 4p 2Π3/2 state initially leads to the formation of an exciplex and the 4p 2Π1/2 state to a bouncing atom above the droplet surface. Remarkably, electronic relaxation can be observed for the latter two states, leading to spin-orbit relaxation and the binding of the initially departing one-atom excimer as a ring excimer for the 2P3/2 state and to the formation of a bound, ring excimer for the 2Π1/2 state.
我们使用时间相关的氦密度泛函方法（He-TDDFT）研究了超流氦纳米液滴中钾原子在 5s 2S 或 4p 2P 激发下的光解。通过比较经典或量子描述的 K 原子的吸收光谱来评估量子效应的重要性。对于 5s 2S ← 4s 2S 激发，差异相当大，因此我们对随后的直接解离动力学采用量子描述。对于 4p 2P ← 4s 2S 吸收光谱，差异要小得多，因此使用经典描述来描述 K 的 4p 2P 激发动力学。激发到 4p 2Σ1/2 态会导致 K 原子的直接解离，而 4p 2Π3/2 态最初会导致形成激合体，4p 2Π1/2 态会导致在液滴表面上方反弹的原子。值得注意的是，对于后两种状态可以观察到电子弛豫，导致自旋轨道弛豫，并将最初离解的单原子激合体结合为 2P3/2 态的环状激合体，并为 2Π1/2 态形成束缚的环状激合体。
