If I have an XRD pattern, it typically consists of a peak and some background noise. We usually try to remove the background noise, but I wonder if it contains any specific information about the material. Additionally, what are the possible reasons for the presence of background data, aside from noise or distortion caused by the sample holder?
Dear Akash Marsalin ,
... 'background noise', 'background "Noise" ', 'background data'...
we have to clearly define what we are talking about;
An XRD pattern mainly is a superposition of
a) quite narrow peaks arising from the crystalline part of the sample,
b) very boad peaks or humps having some structure like shoulder(s) arising from the x-ray scatter at the amorphous part of the sample,
c) peaks and background from the sample in the case of thin sample (you already mentioned it),
d) background due to x-ray fluorescence , if no measures have been taken to reduce or even avoid it, and
e) the noise N, which is the comb-like structure on top of the XRD pattern; it is due to the statistics of the counting process in the detector (N = sqrt(I); with I being the collected number of counts at a given theta/2theta). A more convenient term is the relative noise Nr , i.e. the noise relative to the intensity Nr = N/I = 1/sqrt(I). The relative noise goes down for increasing I.
The noise N arises from the XRD peaks as well as from the background. From the noise you cannot get any additional informations about the sample. It is just dependent on the x-ray flux and the (local) acquisition time.
The background is the sum of b) , c) and d).
If c) and d) can be neglected, the background is solely due to the amorphous part of the sample.
From that part one may estimate the amorphous fraction of the sample and a term, which is called 'crystallinity' or 'crystallinity index'.
Structural information can also be gathered from the amorphous part, but this task is not an easy one.
See for example:
https://www-ssrl.slac.stanford.edu/conferences/workshops/scatter2006/talks/hufnagel.pdf
Best regards
G.M.
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