论文标题
飞秒对称性破裂和甲烷阳离子在碳k边缘处的相干放松
Femtosecond Symmetry Breaking and Coherent Relaxation of Methane Cations at the Carbon K-Edge
论文作者
论文摘要
了解光激发分子的松弛途径对于获得光化学的原子水平至关重要。本文中，我们通过甲烷阳离子上的几何弛豫（Jahn-Teller失真）对超快分子对称性的破坏进行了时间分辨研究。 Attsond瞬时吸收光谱在碳k边缘处具有软X射线，这表明失真发生在$ 10 \ pm 2 $ pm toseconds之内，几乎没有甲烷的强场电离。失真在X射线信号中检测到的对称性折断阳离子的剪刀振动模式中激活相干振荡。这些振荡在$ 58 \ pm13 $ femtoseconds之内被抑制，因为振动连贯性随着能量重新分配到低频振动模式而损失。这项研究完全重建了该原型例子的分子松弛动力学，并为探索复杂系统开辟了新的途径。
Understanding the relaxation pathways of photoexcited molecules is essential to gain atomistic level insight into photochemistry. Herein, we perform a time-resolved study of ultrafast molecular symmetry breaking via geometric relaxation (Jahn-Teller distortion) on the methane cation. Attosecond transient absorption spectroscopy with soft X-rays at the carbon K-edge reveals that the distortion occurs within $10\pm 2$ femtoseconds after few-femtosecond strong-field ionization of methane. The distortion activates coherent oscillations in the scissoring vibrational mode of the symmetry broken cation, which are detected in the X-ray signal. These oscillations are damped within $58\pm13$ femtoseconds, as vibrational coherence is lost with the energy redistributing into lower-frequency vibrational modes. This study completely reconstructs the molecular relaxation dynamics of this prototypical example and opens new avenues for exploring complex systems.
