An Improved Method for the Normalization of the Scattered Intensity and Accurate Determination of the Macroscopic Density of Noncrystalline Materials

During the past few years, several studies have been carried out of the structural characterization of amorphous materials using the Monte Carlo method. It has been shown that a variety of errors gives rise to pronounced artifacts in the R-space correlation functions, which may hinder the accurate interpretation of the Monte Carlo results. The elimination of these ambiguities, particularly for heteroatomic systems, demands very careful experiments in association with careful error analysis. Recently, Kaszkur [J. Appl. Cryst. (1990), 23, 180-185] presented a theory describing some convolutional properties of the reduced interference function. This procedure enables an estimation of the normalization constant (in all probability, nowadays, one of the more serious limitations in obtaining significant and reproducible radial distribution functions) with a high degree of accuracy. Since the Kaszkur formulation is limited to monoatomic substances, the present work recalls his basic arguments with the aim of extending them to the most general case of heteroatomic materials. In addition, the proposed procedure allows an overall insight into the quality of the measured data and determination of the macroscopic density on the basis of the scattered intensities. The success of the procedure is proved by its application to two experimental data sets and one simulated example.