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A Powder Diffraction File

Although cards are no longer a purchasable medium for the Powder Diffraction File, they still present a useful visual display of the type of information contained within the PDF database. In the images below we show two typical card entries, the first displaying a full range of information, the latter showing the bare minimum:

(151 kBytes)
(144 kBytes)

Taking the first case, we can find the following sets of information on the card:

The intensities of the peaks in the powder pattern are normalised with respect to the intensity of the strongest peak, which has relative intensity 1.0 (= 100%) and is labelled I1. The observed intensities of the other peaks are therefore listed as I/I1 values.

In the second case, much of the above information is missing. In principle the barest workable minimum would be:

The crystallographic and other information are extremely useful but not vital for identification purposes. Indeed the crystal structure of the material need not even be known for identification purposes and crystallographic parameters and hkl indices will not be found in every case.


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© Copyright 1997-2006.  Birkbeck College, University of London.
 
Author(s): Paul Barnes
Martin Vickers