Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland.
National Research Council of Canada, Ottawa, ON, Canada.
Science. 2021 Jan 29;371(6528):489-494. doi: 10.1126/science.abf1656.
Conical intersections allow electronically excited molecules to return to their electronic ground state. Here, we observe the fastest electronic relaxation dynamics measured to date by extending attosecond transient-absorption spectroscopy (ATAS) to the carbon K-edge. We selectively launch wave packets in the two lowest electronic states (D and D) of CH The electronic D → D relaxation takes place with a short time constant of 6.8 ± 0.2 femtoseconds. The electronic-state switching is directly visualized in ATAS owing to a spectral separation of the D and D bands caused by electron correlation. Multidimensional structural dynamics of the molecule are simultaneously observed. Our results demonstrate the capability to resolve the fastest electronic and structural dynamics in the broad class of organic molecules. They show that electronic relaxation in the prototypical organic chromophore can take place within less than a single vibrational period.
锥形交叉允许电子激发的分子回到它们的电子基态。在这里，我们通过将阿秒瞬态吸收光谱（ATAS）扩展到碳 K 边缘，观察到迄今为止测量到的最快的电子弛豫动力学。我们选择性地在 CH 的两个最低电子态（D 和 D）中启动波包。电子 D→D 弛豫发生在 6.8±0.2 飞秒的短时间常数内。由于电子相关导致 D 和 D 带的光谱分离，ATAS 可以直接观察到电子态的转换。同时观察到分子的多维结构动力学。我们的结果证明了在广泛的有机分子中解析最快的电子和结构动力学的能力。它们表明，在典型的有机发色团中，电子弛豫可以在不到一个振动周期的时间内发生。
