Time Resolved Electron Energy Loss Spectroscopy of Surface Kinetics

本研究项目的主要目的是在分子水平上详细了解气体-表面相互作用的动力学和机理。结合快速温度和压力扰动的时间分辨电子能量损失谱(TREELS)研究了吸附化学键性质的变化。这种激发和探测技术可以研究广泛的表面过程，包括吸附/解吸、解离和吸附产物的反应。更具体地说，拟议的项目将解决以下领域的问题：1.碱促进的离解和反应，2.杂质对表面动力学的影响，3.合成反应，以及4.电子和光子诱导的反应。将把实验时间分辨率从毫秒范围延长到微秒范围。除了为TREELS临时配备更快的96通道多路探测器和数据采集电子设备外，还将分别通过在脉冲分子束中添加斩波器和用微秒脉冲激光直接加热来实现更快的压力和温度微扰。负电子亲和势的砷化镓光电阴极将产生脉冲电子源。

The main goal of this research project is to obtain a detailed understanding at the molecular level the kinetics and mechanisms of gas - surface interactions. Changes in the nature of the adsorbate chemical bond are studied by time resolved electron energy loss spectroscopy (TREELS) coupled with fast temperature and pressure perturbations. A wide range of surface processes can be studied by this excite - and - probe technique, including adsorption/desorption, dissociation, and reaction of adsorbate. More specifically, the proposed project will address problems in the following areas: 1. alkali-promoted dissociations and reactions, 2. effects of impurities on surface kinetics, 3. synthesis reactions, and 4. electron and photon induced reactions. Extension of the experimental time resolution from millisecond to microsecond range will be undertaken. In addition to improvise a faster 96-channel multidector and data acquisition electronics for TREELS, the more rapid pressure and temperature perturbations will be achieved by the addition of a chopper to the pulsed molecular beam and direct heating with a microsecond pulsed laser, respectively. A pulsed electron source will be generated from a negative electron affinity GaAs photocathode.