Kristensen Henrik H, Kranabetter Lorenz, Schouder Constant A, Stapper Christoph, Arlt Jacqueline, Mudrich Marcel, Stapelfeldt Henrik
Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
Phys Rev Lett. 2022 Mar 4;128(9):093201. doi: 10.1103/PhysRevLett.128.093201.
Rubidium dimers residing on the surface of He nanodroplets are doubly ionized by an intense femtosecond laser pulse leading to fragmentation into a pair of Rb^{+} ions. We show that the kinetic energy of the Rb^{+} fragment ions can be used to identify dimers formed in either the X ^{1}Σ_{g}^{+} ground state or in the lowest-lying triplet state, a ^{3}Σ_{u}^{+}. From the experiment, we estimate the abundance ratio of dimers in the a and X states as a function of the mean droplet size and find values between 4∶1 and 5∶1. Our technique applies generally to dimers and trimers of alkali atoms, here also demonstrated for Li_{2}, Na_{2}, and K_{2}, and will enable femtosecond time-resolved measurements of their rotational and vibrational dynamics, possibly with atomic structural resolution.
位于氦纳米液滴表面的铷二聚体被强飞秒激光脉冲双电离，导致分裂成一对Rb⁺离子。我们表明，Rb⁺碎片离子的动能可用于识别在X¹Σ₉⁺基态或最低三重态a³Σᵤ⁺中形成的二聚体。通过实验，我们估计了a态和X态中二聚体的丰度比作为平均液滴尺寸的函数，并得到了4∶1到5∶1之间的值。我们的技术普遍适用于碱金属原子的二聚体和三聚体，这里也对Li₂、Na₂和K₂进行了演示，并且将能够对它们的旋转和振动动力学进行飞秒时间分辨测量，可能具有原子结构分辨率。
