CHROMIUM COATING FOR HIGH RESOLUTION CRYO SEM

生物大分子结构的高质量成像 将高分辨率扫描电子显微镜与扫描电子显微镜相结合，可获得样品 先进的金属薄膜镀膜技术。因为它的产量 生物样品的二次电子(SE)信号很低，很薄 通常需要一层细晶金属膜来浓缩SE-1 信号的产生和增强感兴趣特征的对比度。 表面地形对比度取决于SE-USE-11I的比率 收集，SE-II信号产量取决于数量和 背向散射电子(BSE)信号的相互作用体积(彼得斯， 1982年)。因此，应选择BSE产率较低的金属作为 高分辨率扫描电子显微镜涂层。铬，具有低铬的特点 原子量(Z-24)和足够的SE‘信号产额，是一个 适当的选择，它首先被彼得斯(1982)用来表示高 分辨率扫描电子显微镜成像。为了制造可重现的纯铬膜， 清洁的真空是最关键的要求，因为铬将 只要有氧气存在，就会很快被氧化。氧化铬 化合物是一种完全不同的金属，在SE产量和 低质量的。因此，在这个项目中，我们将尝试解决 渗漏和氧化问题，使我们可以得到一致和清洁 镀铬层。

ffigh quality imaging of macromolecular structure of biological samples can be obtained when combining high resolution SEM with advanced thin metal film coating techniques. Because the yield of secondary electron (SE) signal from biological samples is low, a thin layer of fine grain metal film is often necessary to enrich the SE-1 signal yield and enhance the contrast of features of interest. Surface topographic contrast depends on the ratio of SE-USE-11I collection, and the SE-II signal yield depends on the amount and interaction volume of the backscattered electron (BSE) signal (Peters, 1982). Therefore the metals with low BSE yield should be chosen for high resolution SEM coating. Chromium, which has the features of low atomic weight (Z--24) and sufficient SE'signal yield, is an appropriate choice and it was first used by Peters (1982) for high resolution SEM imaging. To create a reproducible pure chromium film, a clean vacuum is the most crucial requirement because Chromium will be oxidized very quickly whenever oxygen exists. Oxidized chromium compound is a totally different metal and is low in the SE yield and low in mass. So, in this project, we will attempt to solve the leaking and oxidation problem so that we can get consistent and clean chromium coating.