电子能量损失谱的数据采集和谱图处理及在3d过渡族元素谱图中的应用

Data acquisition and processing in electron energy loss spectroscopy and its application to 3d transition elements analysis

本工作以有序Ni3Fe样品的电子能量损失谱EELS(electron energy loss spectroscopy)的采集、处理和分析为例,叙述了内置(Ω型)与后置能量过滤器在采集和处理电子能量损失谱的工作原理、处理步骤及注意要点。实验结果表明:在采集谱图过程中,内置Ω型能量过滤器零峰非常稳定,后置GIF(gatan image filter)能量过滤器可以节约采集过程中处理谱图的时间。在处理谱图时发现,利用Ω型能量过滤器采集的电子能量损失谱中谱图的背底曲线与理论拟合结果偏差很大;本文提出了通过数据处理给出的校正因子可以很好地弥补这一偏差。由于Ω型能量过滤器的物距较小,在零峰附近常伴随有衍射点,所以无论样品厚度如何,由Ω型能量过滤器采集的电子能量损失谱必须扣除多重散射的影响。

In this study, we took example for Ni3Fe ahoy to explain the principles, processes and key points in the data acquisition and processing of electron energy loss spectroscopy （EELS） spectra obtained by in-column （Ω-type） and post-column energy filter. The experimental results showed that the zero-loss peak obtained by in-column energy filter was very stable, while the time of data processing was retrenched when using post-column Gatan image filter （GIF）. The background curve in the spectrum obtained by in-column energy filter did not fit with the theoretical prediction. To solve this problem, the correction factor was introduced during processing the experimental data. Because of the small objective distance in the in-column energy filter, the diffraction pattern was usually accompanied by the zero-loss peak. Whatever the sample thickness is, the plural scattering effect must be removed from the EELS spectra obtained by in-column energy filter.