Attosecond XUV probing of vibronic quantum superpositions in Br2+
Attosecond XUV probing of vibronic quantum superpositions in Br2+
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Br2 中电子振动量子叠加的阿秒 XUV 探测
DOI：
10.1103/physreva.102.051102
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发表时间：
2020
影响因子：
2.9
通讯作者：
Leone, Stephen R.
中科院分区：
文献类型：
--
作者：
Kobayashi, Yuki;Neumark, Daniel M.;Leone, Stephen R.
超快激光激发可以在分子中产生电子态的相干叠加，并在几飞秒时间尺度上触发电子密度的超快流动。虽然最近的阿秒实验已经解决了这些初级光化学过程的实时观察问题，但同时核运动的潜在作用以及它们如何修改和干扰价电子运动仍然不确定。在这里，我们使用阿秒瞬态吸收光谱研究了离子溴 () 的多个电子振动能级之间诱导的相干电子振动动力学，包括自旋轨道 () 和价 () 电子叠加。电子相干性的衰变、复兴和表观频移是通过 Br 核心级吸收信号上的特征量子拍来测量的。量子力学模拟将观察到的电子退相干归因于非谐势上核波包的加宽相位分布。分子振动结构被进一步揭示为电子拍频的离散级数。这些结果为解释多原子系统中复杂的电荷迁移动力学提供了未来的基础。
Ultrafast laser excitation can create coherent superpositions of electronic states in molecules and trigger ultrafast flow of electron density on a few femtosecond timescale. While recent attosecond experiments have addressed real-time observation of these primary photochemical processes, the underlying roles of simultaneous nuclear motions and how they modify and disturb the valence electronic motion remain uncertain. Here, we investigate coherent electronic-vibrational dynamics induced among multiple vibronic levels of ionic bromine (), including both spin-orbit () and valence () electronic superpositions, using attosecond transient absorption spectroscopy. Decay, revival, and apparent frequency shifts of electronic coherences are measured via characteristic quantum beats on the Br-core-level absorption signals. Quantum-mechanical simulations attribute the observed electronic decoherence to broadened phase distributions of nuclear wave packets on anharmonic potentials. Molecular vibronic structure is further revealed to be imprinted as discrete progressions in electronic beat frequencies. These results provide a future basis to interpret complex charge-migration dynamics in polyatomic systems.