Direct Comparsion of Thermal Desorption from Supported Metals and Metal Single Crystals

单晶的热解吸通常在与负载金属的热解吸完全不同的条件下进行。为了进行直接比较，正在研究在相同压力和温度条件下测量两种形式金属的热解吸的方法。克努森积液池用于测量相对高压下单晶的热解吸。此外，还研究了从负载金属直接解吸到超高真空中的方法。以往的单晶研究表明，一氧化碳的热解吸对金属表面结构很敏感；这里开发的技术可能允许用这一事实来识别支撑金属的表面结构。首先，研究了铂族金属。支撑材料表面的纳米金属结构在微电子和催化领域有着重要的应用。有几种方法可用于测量这种小结构的整体组成和结构，但大多数表面分析方法缺乏这种尺度所需的分辨率。该项目开发的技术可以提供非常小的金属颗粒表面构象的信息。

Thermal desorption from single crystals is normally performed under radically different conditions from thermal desorption from supported metals. In order to make direct comparisons, methods are being developed for measuring thermal desorption from the two forms of metal under identical conditions of pressure and temperature. Knudsen effusion cells are used to measure thermal desorption from single crystals under relatively high pressure. Also being investigated is desorption from supported metals directly into ultrahigh vacuum. Previous single-crystal studies have shown that thermal desorption of carbon monoxide is sensitive to metal surface structure; the techniques developed here may permit this fact to be used to identify surface structures on supported metals. Initially, the platinum-group metals are studied. Nanometer-sized metal structures on the surface of support materials have important applications in microelectronics and in catalysis. Several methods are available to measure bulk composition and structure of such small structures, but most surface analysis methods lack the resolution needed for this scale. This project develops techniques that provide information on surface conformations in very small metal particles.