北京大学物理学院

报告人简介

李铮，北京大学物理学院研究员。主要从事第一性原理原子分子结构理论，分子动力学，自由电子激光，和光与物质相互作用领域的理论研究，着重于研究与自由电子激光相关的理论，在Science, Phys. Rev. Lett., Nature Commun., J. Am. Chem. Soc., Sci. Adv.等期刊发表研究论文七十余篇。

报告摘要

The Jahn-Teller effect is a fundamental mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to directly image the onset of Jahn-Teller symmetry breaking remains unreached. Here we employ ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution and unambiguously image the ultrafast dynamics of Jahn-Teller deformations of CH4+ cation in symmetry space. It is unraveled that the Jahn-Teller deformation from C3v to C2v geometries takes a characteristic time of 20+/-7 fs for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C2v structure involving complex revival process of multiple vibrational pathways of the CH4+ cation.

At the same time, we have proposed an analysis method for ultrafast diffraction imaging, which can be used to reconstruct the quantum state of molecular dynamics processes. And through external field control and quantum Zeno effect, we have achieved a selection of quantum states in the molecular dynamics process.

报告地点：中国科学院物理研究所怀柔园区X1南楼204会议室

腾讯视频会议号：449-712-076，会议密码：2025

邀请人：方少波 副研究员

联系人：万源  研究员

　　　　汪非凡 副研究员

　　　　田春璐 cltian@iphy.ac.cn

主办方：中国科学院物理研究所、松山湖材料实验室