超快电子衍射系统的时间空间分辨能力研究及其优化

Development and optimization on spatiotemporal resolution of ultrafast electron diffraction

超快电子衍射技术是研究物质瞬态结构变化及超快结构动力学的有效手段.研制了国内第一套同时具有超快时间分辨及超高空间分辨能力的超快电子衍射系统,并研究了在该超快电子衍射系统上实现超快时间分辨及超高空间分辨能力的技术手段及其优化方法.实验结果表明:经过优化后该系统可以具有优于500fs的时间分辨能力,其空间分辨能力达到0.04%的衍射峰位置变化,对应的晶面变化为0.0005.该系统可以为实时测量超快光脉冲激发的物质瞬态结构变化,特别是为研究晶体材料的超快动力学行为提供了强有力的实验工具.

Uhrafast electron diffraction is a powerful technique for the measurement of transient structure at atomistic level and on ultrafast timescale. Here we report the development of the first such an ultrafast electron diffraction system in China. With careful design and after performing optimization of its spatiotemporal resolution, we are able to detect a sub-milli-~ingstrom lattice spacing change with a sub-picosecond temporal resolution in an ultrafast heated A1 film. This achievement offers great promise to conduct real-time measurements of transient structures in many dynamical processes that can be initiated by ultrafast optical excitation.