Picosecond Time Resolved X-Ray and Electron Diffraction

在实验物理化学项目光学科学与工程项目的支持下，加州大学欧文分校的Peter Rentzepis将使用皮秒激光x射线和电子源来探测液体和固体相的瞬态结构。要解决的具体问题包括金属和半导体中晶格畸变的机制以及从热电子到晶格的能量转移的研究。气相物质的时间分辨电子衍射将用于研究光解离和异构化过程。这些研究将使通过直接观察键和角的变化来识别超快中间体和亚稳态基态物质的结构成为可能。这些技术将在蛋白质和酶动力学、分子电子器件以及晶格中的热输运物理等领域得到应用。x射线和电子衍射研究提供了有关分子结构的丰富信息。Rentzepis教授将使用超快x射线和电子脉冲来实时探测由光激发引起的结构变化。这种新技术将用于研究化学和生物系统中涉及主要事件的熔化、结晶、热传递和瞬态结构等基本现象。

In this project supported under the Optical Science and Engineering initiative in the Experimental Physical Chemistry Program, Peter Rentzepis of the University of California at Irvine will use picosecond laser based x-ray and electron sources to probe the structures of transients in the liquid and solid phases. Specific problems to be addressed include the mechanism of lattice distortion in metals and semiconductors and studies of energy transfer from hot electrons to the lattice. Time resolved electron diffraction of gas phase species will be used to investigate photodissociation and isomerization processes. These studies will make it possible to identify structures of ultrafast intermediates and metastable ground state species by directly observing bond and angle changes. These techniques will have application in areas such as protein and enzyme kinetics, molecular electronic devices, and the physics of thermal transport in crystal lattices. X-ray and electron diffraction studies have provided a wealth of information concerning molecular structure. Professor Rentzepis will use ultrafast x-ray and electron pulses to probe, in real time, the structural changes caused by optical excitation. Basic phenomena such as melting, crystallization, heat transport, and the transient structures involved in primary events in chemical and biological systems will be studied by means of this new technique.