Svoboda Vít, Ram Niraghatam Bhargava, Baykusheva Denitsa, Zindel Daniel, Waters Max D J, Spenger Benjamin, Ochsner Manuel, Herburger Holger, Stohner Jürgen, Wörner Hans Jakob
Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland.
Department of Physics, Indian Institute of Science Education and Research-Bhopal, Bhauri, Bhopal 462066, India.
Sci Adv. 2022 Jul 15;8(28):eabq2811. doi: 10.1126/sciadv.abq2811.
Understanding the chirality of molecular reaction pathways is essential for a broad range of fundamental and applied sciences. However, the current ability to probe chirality on the time scale of primary processes underlying chemical reactions remains very limited. Here, we demonstrate time-resolved photoelectron circular dichroism (TRPECD) with ultrashort circularly polarized vacuum-ultraviolet (VUV) pulses from a tabletop source. We demonstrate the capabilities of VUV-TRPECD by resolving the chirality changes in time during the photodissociation of atomic iodine from two chiral molecules. We identify several general key features of TRPECD, which include the ability to probe dynamical chirality along the complete photochemical reaction path, the sensitivity to the local chirality of the evolving scattering potential, and the influence of electron scattering off dissociating photofragments. Our results are interpreted by comparison with high-level ab-initio calculations of transient PECDs from molecular photoionization calculations. Our experimental and theoretical techniques define a general approach to femtochirality.
理解分子反应途径的手性对于广泛的基础科学和应用科学至关重要。然而，目前在化学反应基础初级过程的时间尺度上探测手性的能力仍然非常有限。在此，我们展示了利用桌面光源产生的超短圆偏振真空紫外（VUV）脉冲进行的时间分辨光电子圆二色性（TRPECD）。通过解析来自两个手性分子的碘原子光解离过程中手性随时间的变化，我们展示了VUV-TRPECD的能力。我们确定了TRPECD的几个一般关键特征，其中包括沿着完整光化学反应路径探测动态手性的能力、对不断演化的散射势的局部手性的敏感性以及电子从解离光碎片散射的影响。通过与分子光电离计算的瞬态光电子圆二色性的高水平从头计算进行比较，对我们的结果进行了解释。我们的实验和理论技术定义了一种飞秒手性的通用方法。
