Technician Support for Geoscience Research in Transmission Electron Microscopy

这笔拨款为一名电子显微镜学家提供部分工资支持，他将帮助最大限度地提高两个tem的地质、矿物学和地球化学能力，这两个tem将于2001年安装在亚利桑那州立大学高分辨率电子显微镜中心。获得这些仪器是为了开发材料科学和物理领域的新技术和新测量方法，新职位的目标是熟悉这些技术并将其应用于地质科学的研究。其中一种仪器的电子束可以小于0。直径2纳米。我们将利用这种能力在原子尺度上分析晶界、位错核心和表面层，并将通过电子纳米衍射从单元胞内获得晶体学数据。另一种仪器将包含一个用于测量的Gatan成像滤波器，该滤波器将允许在亚纳米尺度上进行元素映射。它还将有一个环境单元，用于在受控气氛下进行研究。该电池将在样品室中保持高达50 torr的相对较高的气体压力，同时保留TEM的高分辨率能力。试样加热和动态图像记录将允许在接近原子尺度上跟踪化学反应。我们将用它来研究在电子显微镜的真空中不稳定的矿物。这些包括粘土矿物、绿锈、石膏和相关的水合硫酸盐，以及矿物中的脱羟基反应和价态变化

0113345BuseckThis grant provides partial salary support for an electron microscopist who will help maximize the geological, mineralogical, and geochemical capabilities of two TEMs that will be installed in 2001 within the ASU Center for High Resolution Electron Microscopy. These instruments were obtained to develop new techniques and measurements in materials science and physics, and the goal of the new position is to become familiar with those techniques and adapt them for research in the geological sciences. One of the instruments will have an electron beam that can be made less than 0. 2 nm in diameter. We will use this capability to analyze grain boundaries, dislocation cores, and surface layers on the atomic scale and will obtain crystallographic data from within unit cells through electron nanodiffraction. The other instrument will contain a Gatan imaging filter for measurements that will allow elemental mapping on the sub-nanometer scale. It will also have an environmental cell for studies under controlled atmospheres. This cell will maintain a relatively high gas pressure of up to 50 torr in the sample chamber, while retaining the high-resolution capabilities of the TEM. Specimen heating and dynamic image recording will allow chemical reactions to be followed at close to the atomic scale. We will use this to study minerals that are unstable in the vacuum of the electron microscopes. These include clay minerals, the green rusts, gypsum and related hydrated sulfates as well as dehydroxylation reactions and valence changes in minerals.***