Some General Hints for Phase Identification from Powder

The most important issue you should keep in mind when using Match! is that the quality of your results strongly depends on the quality of the peak data that are derived from your initial raw data during the so-called "raw data processing" step. For example, if your peak data contain 2theta-errors (e.g. caused by sample displacement or 2theta-shift of the detector), or if there are far too many peaks detected because your raw data contain a lot of noise, you most certainly will get poor results (if any).

The background is that during the first step of the phase identification process (search), only the peak data are compared to the reference database. This is reasonable since the reference databases themselves (like the PDF or the COD) also contain peak data only. Hence, it should be clear that the quality of your peak data is most important to get good results.

What does this mean in practice? Although the determination of the peak data from the raw data can be run automatically using Match!, the computer is still not able to equal the "eye" of an experienced powder diffraction specialist, who is normally much better in distinguishing between noise and peaks. Hence, it is definitely worth while to invest some time in a critical evaluation of the peak data with regard to the raw data. Match! offers several functions which make this procedure as comfortable as possible.

Here are some suggestions for a reasonable workflow: