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本文详细讨论了EXAFS测定的分辨本领、信噪比与实验参数间的相互关联;提出了实验参数临界条件的概念及其确定的方法;在临界条件下分别讨论了分辨本领、信噪比与临界实验参数值的相互关系并由此导出如下结论:1.当入射狭缝,出射狭缝宽度均为临界参数时,EXAFS测定的分辨本领与分光晶体摆动曲线的宽度无关,而信噪比则取决于分光晶体摆动曲线宽度所表征的嵌镶块大小对强度分布和消光效应的影响。2.当接收狭缝,分光晶体摆动曲线的宽度均为临界参数时,入射狭缝可增至最佳宽度,其分辨本领不仅保持不变,还能显著提高信噪比。当入射狭缝继续增大,超过最佳宽度时,信噪比不再增加。文中由此指出:当所用分光晶体完整性欠佳时,以采用结论1的条件为宜;当分光晶体完整性较好则应采用用结论2所提出的条件。
This paper discusses in detail the resolving power of the EXAFS measurement, the correlation between the signal-to-noise ratio and the experimental parameters, the concept of the critical conditions of the experimental parameters and the method of determining the critical parameters, and respectively discusses the resolution, signal to noise ratio and critical The experimental results show the following conclusions: 1. When the entrance slit and the exit slit width are both critical parameters, the resolving power of EXAFS has nothing to do with the width of the wiggle curve of the SP crystal, and the signal to noise ratio depends on The influence of the size of the embedded patch on the intensity distribution and the extinction effect, which is characterized by the width of the wobble curve of the optical crystal. 2. When receiving the slit, the width of the optical crystal swing curve are critical parameters, the incident slit can be increased to the optimal width, its resolution not only remains unchanged, but also significantly improve the signal to noise ratio. When the entrance slit continues to increase, beyond the optimal width, the signal to noise ratio does not increase. This paper pointed out: When the use of spectroscopic crystal integrity is poor, in order to adopt the conclusions of the conditions of 1 is appropriate; when the spectroscopic crystal integrity is better, the conditions proposed in Conclusion 2 should be used.