Dear Wahyu,

As well as the points that David has pointed out, the background could be
due to fluorescence from elements in your sample. For example iron
fluoresces under excitation from copper x-rays and so if you have access
to another wavelength / source then it may be more successfull. Or if you
have the facility for a secondary monochromator in your setup?

Regards
Ross Colman

David Lee wrote:
> I would suggest that you do the background refinement with GSAS.   Try
using Expgui, a graphical
> interface to gsas written by Brian Toby, to select background points and
do a background fit.
> There are excellent tutorials on doing this available at: 
http://www.ncnr.nist.gov/xtal/software/expgui/
>
> Also,  you need to find out why your background is so high and rough. 
Do you have
> other phases present?   Is your material not fully crystallized?   Is
your sample
> (if a powder) ground finely enough?   Is your sample surface smooth and
flat?
>
> Good Luck,
>
> David Lee, Ph.D.
> DTLee Scientific, llc
> http://www.dtlee.com
> 614-562-6230
>
> On May 19, 2009, at 6:16 AM, wahyu bambang wrote:
>
>> Dear all rietvelder,
>>
>> Please give me a suggestion about my problem.
>> I want to do quantitative analysis using GSAS, however my diffraction
>> pattern has very high and rough background which makes me difficult to
>> do preliminary qualitative works to determine the available phases.
>>
>> Is it alright if I substract the background and refine it a little
>> first using another refinement software before I go through GSAS?
>>
>> I really appreciate your kindness to answer.
>>
>> regards,
>>
>> wahyu
>>
>
>

-- 
________________________________

Ross Colman

G19 Christopher Ingold Laboratories

University College London

Department of Chemistry

20 Gordon Street

London

WC1H 0AJ

Phone: +44 (0)20 7679 4636

Internal: 24636

Email:  ross.col...@ucl.ac.uk <mailto:ross.col...@ucl.ac.uk>



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