Quantitative X-Ray Microanalysis of Bulk Materials at High Energy (60-400 keV)

本项目的目标是开发一种简单、可靠和有效的工具，用于电子能量为60~400keV的透射电子显微镜中块状样品的X射线定量分析。目前还不存在这样的工具。2009年，Bruker推出了第一个可安装在瞬变电子显微镜中的硅漂移探测器(SDD)，该探测器提供至少50万个/S的光子计数率，能量分辨率类似于Si(Li)EDS探测器。魁北克水电研究中心的日立HD-2700场发射扫描电子显微镜(FE-STEM)安装了第一台SDD探测器。现在可以在电子能量超过60keV的电子显微镜上获得大块样品的X射线能谱。然而，对电子能量高于60keV的X射线能谱进行定量的X射线显微分析是不可能的，因为现有的块状样品的定量模型是针对低于30keV的电子束能量开发的，这是电子探针和扫描电子显微镜所使用的电子能量。这项合作研究拨款是为了与Bruker公司和魁北克水电公司合作，开发一种在60-400keV范围内对大宗样品进行定量X射线显微分析的方法。预计在透射电子显微镜中对大块样品进行定量X射线微区分析将降低痕量元素的检测下限。最后，对30keV和200keV的块状材料的分析进行了比较，以显示这些能量在块状样品的定量X射线微区分析中的优势和局限性。

The objective of this project consists of elaborating a simple, reliable and efficient tool for quantitative x-ray microanalysis of bulk specimen in the transmission electron microscope (TEM) for electron energies from 60 to 400 keV. Such tools do not exist presently. In 2009, Bruker introduced the first Silicon Drift Detector (SDD) that can be installed in a TEM that provides, at least, a photon count rate of 500 000 counts/s with energy resolution similar to Si(Li) EDS detectors. The first SDD detector was installed to the Field Emission Scanning Transmission Electron Microscope (FE-STEM) Hitachi HD-2700 of Hydro-Québec Research Center. It is now possible to acquire x-ray spectra of bulk specimen in the TEM for electron energy above 60 keV. However, quantitative x-ray microanalysis of x-ray spectra acquired for electron energies above 60 keV is not possible because the quantitative models that already exist for bulk specimen were developed for electron beam energy below 30 keV, the electron energies used by the electron microprobe and the SEM. This collaborative research grant is to develop, in collaboration with Bruker and Hydro-Québec, a method to perform quantitative x-ray microanalysis of bulk specimen in the 60 - 400 keV range. It is expected that quantitative x-ray microanalysis of bulk specimen in the TEM will lower the detection limit of trace elements. Finally, comparisons will be performed for the analysis of bulk materials between 30 and 200 keV in order to show the advantages and limitations of these energies for quantitative x-ray microanalysis of bulk specimens.