超快电子衍射研究及发展综述

Review on Research and Development of Ultrafast Electron Diffraction

原子运动及相应的结构改变是自然界中化学反应、生命过程等现象的本质。因此,在原子层面实时间、实空间观测物质非平衡态的原子运动和结构演化过程,能深刻地解释这些现象的本质,将物质的微观动力学过程和其物理化学等特性联系起来,为科学突破创造了巨大的机遇。原子层面的动态过程的特征时间在皮秒、飞秒、甚至阿秒量级,目前只有泵浦-探测技术可以实现该量级的时间分辨率。超快电子衍射使用电子作为泵浦-探测技术中的探针,具有高弹性散射截面、低能量沉积、造价及维护成本低等优势,在近十余年间获得快速发展。该文总结近年来超快电子衍射中关键技术的发展,并对新一代超快电子衍射的发展趋势进行展望。

Atomic motion and structural changes are the essences of chemical reactions and life processes in nature. Therefore, observing the atomic motion and structural evolution of the nonequilibrium state of matter at the atomic level in real time and space can profoundly explain the essence of these phenomena, link the microscopic dynamic process of matter with its physical and chemical characteristics, and create great opportunities for scientific breakthroughs. The characteristic time of the dynamic process at the atomic level is in the order of picosecond, femtosecond, and even attosecond. At present, only the pump-probe technique can achieve the temporal resolution of such anorder. Ultrafast electron diffraction uses electrons as the probe in the pump-probe technique. It has the advantages such as high elastic scattering cross section, low energy deposition, and low maintenance cost, and thus has achieved rapid development in the past decade. This paper summarizes the development of key technologies in ultrafast electron diffraction in recent years and looks forward to the development trend of the new generation of ultrafast electron diffraction.