Correction for counting losses in X-ray diffractometry
Correction for counting losses in X-ray diffractometry
复制标题
X 射线衍射中计数损失的校正
DOI：
10.1107/s0021889805005637
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发表时间：
2005
影响因子：
6.1
通讯作者：
Y. Iwata
中科院分区：
文献类型：
--
作者：
T. Ida;Y. Iwata
比较了非扩展死区模型和扩展死区模型、脉冲幅度分析器(PHA)加窗模型以及介于非扩展死区模型和扩展死区模型之间的一个模型。通过对箔片法测量的粉末衍射峰强度分布的分析，验证了该方法的有效性。包含时滞和延伸度参数的中间模型可以再现非扩展模型和扩展模型，也可以再现两个模型之间的中间依赖关系。对于最大相对偏差为0.0003的中间模型，还给出了一个简便的近似公式。通过应用近似模型，可以很容易地确定参数和对测量强度进行校正，因为它提供了表示为初等函数组合的校正函数的简单公式。文中还给出了精确计算计数损失参数的实验和分析方法。通过对实验数据的精确分析，发现了观测到的依赖关系与非扩展死区模型和扩展死区模型的系统偏差，而PHA窗口模型、中间模型及其近似在实验误差范围内重现了观察到的依赖关系。
Non-extended and extended dead-time models, a pulse-height analyser (PHA) windowing model, and a model intermediate between the non-extended and extended models for losses in counting methods are compared. The validities of the methods are examined by application to the analysis of powder diffraction peak intensity profiles measured by a foil method. The intermediate model including parameters for the dead-time and degree of extension can reproduce both the non-extended and the extended models and also intermediate dependence between the two models. A convenient approximate formula for the intermediate model, the maximum relative deviation of which is 0.0003, is also proposed. The determination of the parameters and a correction for the measured intensities can easily be achieved by applying the approximate model, because it provides simple formulae for the correction function expressed as a combination of elementary functions. Experimental and analytical methods for precise evaluation of the parameters to specify the counting losses are also presented. Systematic deviations of the observed dependence from the non-extended and extended dead-time models have been detected by the precise analyses of experimental data, while the PHA windowing model, intermediate model and its approximation have reproduced the observed dependence within the experimental errors.