Re: [sdpd] Automatic peak position hunting

[Armel Le Bail <armel...@fluo.univ-lemans.fr>]

Lachlan wrote :

>Do you have an example file of this on the web
>that can be tried out?

Yes, this occurs for a synchrotron powder pattern
already discussed at this mailing list about indexing, in email :
http://www.egroups.com/message/sdpd/113
with a link to a compressed file containing the data :
http://www.cristal.org/sdpd/indexrr.zip
with name biesrf.*

The two not separable peaks are close to 4.2°(2-theta).

I think that, owing to the small FWHM, the step (0.01°2-theta) is 
too large for the derivative method working well. 

Going to a 0.005° step, by adding intensities by a simple
interpolation, makes that the 2 adjacent peaks are then located 
by the automatic hunting without problem. 

Anyway, these peak hunting methods really cannot see 2 peaks 
if their maximum are only separated by one step, even if the valley
is deep. This was noticed by the 13th (unlucky ?) student 
subscribing to the SDPD Internet  Course (and note that the email 
number above is 113 ;-).

Best,

Armel Le Bail
http://www.cristal.org/course/

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