Preliminary data processing

In order to obtain a reduced pattern, scattered intensity maxima should be located and their relative intensities (either as peak height values or, most commonly, as peak areas) should be established together with the 

Peak search, which is unbiased by any kind of structural information. 

The background should never be subtracted prior to full pattern decomposition and full profile-based Rietveld refinement. In these cases it is approximated using various analjdical functions with coefficients, which are refined along with other parameters. Thus computed background is then added to the intensity calculated as a function of Bragg angle. 

In the majority of preliminary data processing algorithms, the background is handled in two different ways  

Indeed, it is possible and always recommended to save a backup copy of the unmodified experimental data file. If for any reason the background should be reevaluated, it is easy to do so, provided a copy of the original data file exists. 

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Figure 4.1. The flowchart illustrating common steps employed in a structural characterization of materials by using the powder diffraction method. It always begins with the sample preparation as a starting point, followed by a properly executed experiment both are considered in Chapter 3. Preliminary data processing and profile fitting are discussed in this chapter in addition to common issues related to phase identification and analysis. Unit cell determination, crystal structure solution and refinement are the subjects of Chapters 5,6, and 7, respectively. The flowchart shows the most typical applications for the three types of experiments, although any or all of the data processing steps may be applied to fast, overnight and weekend experiments when justified by their quality and characterization goals.

All the above components are placed undo computer control and data logging and preliminary data processing is implemented in real time. 

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