Development of new methods for the characterization of bio and nanomaterials

开发生物和纳米材料表征的新方法

• 批准号: 121420-2008
• 负责人: Gauvin, Raynald
• 金额: $ 2.38万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=451505
• 关键词: Development; new; methods; characterization; bio

Characterization of the microstructure of materials with a spatial resolution of the order of 1 nm is normally performed using field emission transmission electron microscopy (FE-TEM). This characterization includes quantitative chemical analysis using x-ray microanalysis, the determination of the crystalline structure with electron diffraction and the nature of the atomic bonds using electron energy loss spectroscopy (EELS). FE-TEM requires specimens that must be transparent to the electron beam. Preparing thin foils for FE-TEM observation can be a long and tedious process. However, since it was reported that Fast Secondary Electrons (FSE) can degrade the resolution of X-Ray microanalysis in FE-TEM for the quantification of light elements, the ultimate resolution of this technique is still an issue. Auger electrons were reported recently to have potentially the same effect. Since the mid 1990's, the Field Emission Scanning Electron Microscope (FE-SEM) are available on the market. Low voltage FE-SEM has an image resolution of 2 nm. Since specimen preparation is easier in FE-SEM than in FE-TEM, this explains the increasing popularity of low voltage FE-SEM. Also, transparent thin films for FE-TEM observations have an observable area of 0.25 where polished specimens inserted in the FE-SEM have area of the order of 1cm2. Therefore the area observable in the FE-SEM is 400,000,000 greater than in the TEM, leading to vastly superior statistical information about the microstructure of a given material. However, FE-TEM can determine the microstructure of nanomaterials in three dimension using electron tomography and software development is needed to improve its spatial resolution. This project will develop the scientific software that will allow FE-SEM to perform chemical quantitative x-ray analysis of heterogeneous materials, to determine their crystalline structure by simulating electron backscattered diffraction patterns and to develop a new x-ray detector for soft x-ray spectroscopy. The effect of FSE and Auger electrons on x-ray microanalysis and a new tomography method will also be developed for the FE-TEM.

通常使用场发射透射电子显微镜 (FE-TEM) 以 1 nm 量级的空间分辨率表征材料的微观结构。该表征包括使用 X 射线微量分析进行定量化学分析、使用电子衍射确定晶体结构以及使用电子能量损失光谱 (EELS) 确定原子键的性质。 FE-TEM 要求样品必须对电子束透明。准备用于 FE-TEM 观察的薄箔可能是一个漫长而乏味的过程。然而，据报道，快速二次电子 (FSE) 会降低 FE-TEM 中用于轻元素定量的 X 射线微量分析的分辨率，因此该技术的最终分辨率仍然是一个问题。最近有报道称俄歇电子可能具有相同的效果。自 20 世纪 90 年代中期以来，市场上出现了场发射扫描电子显微镜 (FE-SEM)。低压 FE-SEM 的图像分辨率为 2 nm。由于 FE-SEM 中的样品制备比 FE-TEM 更容易，这解释了低压 FE-SEM 越来越受欢迎的原因。此外，用于 FE-TEM 观察的透明薄膜的可观察面积为 0.25，而插入 FE-SEM 中的抛光样品的面积约为 1cm2。因此，FE-SEM 中的可观察面积比 TEM 中大 400,000,000，从而获得有关给定材料微观结构的极其优越的统计信息。然而，FE-TEM 可以使用电子断层扫描确定纳米材料的三维微观结构，并且需要开发软件来提高其空间分辨率。该项目将开发科学软件，使 FE-SEM 能够对异质材料进行化学定量 X 射线分析，通过模拟电子背散射衍射图确定其晶体结构，并开发用于软 X 射线光谱的新型 X 射线探测器。 FSE 和俄歇电子对 X 射线微量分析的影响以及新的断层扫描方法也将针对 FE-TEM 进行开发。