[Ifeffit] Re Iffeffit LCF

fred.mosselmans at diamond.ac.uk fred.mosselmans at diamond.ac.uk
Wed Feb 8 01:24:41 CST 2012

Dear Niken,
To my untutored eye your normalisation and fitting look OK so thus it comes down to the data or whether the treatment is valid:
Did you collect the data in fluorescence mode? Two possible problems occur to me.
As thiophene is a liquid at RT unless you did the experiment cryogenically I think 2 is unlikely.

1) Most probably there is an inherent self-absorption problem with S XANES LCF which was written about by G. Almkvist, K. Boye and I. Persson
J. Synchrotron Rad. (2010). 17, 683-688    [ doi:10.1107/S0909049510022946 ]
K-edge XANES analysis of sulfur compounds: an investigation of the relative intensities using internal calibration. The self-absorption seen can affect the results of simple LCF data quite alot.

2) the samples were not well enough mixed, hence the data collected does not reflect the real mixture but a fraction that is more like the values you obtain by the LCF.
S K-edge measurements don't sample much sample (sorry for that) so mixing solid standards is not necessarily trivial but for liquids/solutions this should not apply.


Prof.  J F W Mosselmans
Principal Beamline Scientist I18
Diamond Light Source
Diamond House
Harwell Campus

T 00 44 1235 778568
M 00 44 7785510211
E fred.mosselmans at diamond.ac.uk
F 00 44 1235 778448

Never mind the W it's the tax that counts

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