Jiang Xiang, Nam Yeonsig, Rouxel Jérémy R, Yong Haiwang, Mukamel Shaul
Department of Chemistry, Department of Physics & Astronomy, University of California Irvine California 92697 USA
Chemical Sciences and Engineering Division, Argonne National Laboratory Lemont Illinois 60439 USA.
Chem Sci. 2023 Sep 11;14(40):11067-11075. doi: 10.1039/d3sc02807k. eCollection 2023 Oct 18.
Molecular chirality, a geometric property of utmost importance in biochemistry, is now being investigated in the time-domain. Ultrafast chiral techniques can probe the formation or disappearance of stereogenic centers in molecules. The element-sensitivity of X-rays adds the capability to probe chiral nuclear dynamics locally within the molecular system. However, the implementation of ultrafast techniques for measuring transient chirality remains a challenge because of the intrinsic weakness of chiral-sensitive signals based on circularly polarized light. We propose a novel approach for probing the enantiomeric dynamics by using the orbital angular momentum (OAM) of X-ray light, which can directly monitor the real-time chirality of molecules. Our simulations probe the oscillations in excited chiral formamide on different potential energy surfaces and demonstrate that using the X-ray OAM can increase the measured asymmetry ratio. Moreover, combining the OAM and SAM (spin angular momentum) provides stronger dichroic signals than linearly polarized light, and offers a powerful scheme for chiral discrimination.
分子手性是生物化学中极为重要的一种几何特性，目前正在时域中进行研究。超快手性技术能够探测分子中手性中心的形成或消失。X射线的元素敏感性增加了在分子系统内局部探测手性核动力学的能力。然而，由于基于圆偏振光的手性敏感信号的固有弱点，用于测量瞬态手性的超快技术的实施仍然是一个挑战。我们提出了一种利用X射线光的轨道角动量（OAM）探测对映体动力学的新方法，该方法可以直接监测分子的实时手性。我们的模拟探测了激发态手性甲酰胺在不同势能面上的振荡，并表明使用X射线OAM可以提高测量的不对称比。此外，将OAM和SAM（自旋角动量）相结合比线偏振光提供更强的二向色性信号，并为手性鉴别提供了一个强大的方案。
