[Ifeffit] doubts

[Marcos Eleoterio]

good afternooon,

My name  is Marcos Eleotério, i am undergraduate  in physics and i have  a
scholarship at  Brazilian Synchroton Light Laboratory, nearly one month ago  i
start using  the  software Athena and  Artemis, to analyse some X-ray absorption
data  that i have, to  make  my  problem more  easy  to you understand i list
below the steps that i use in those  programs:

1) After a  normalization of  the  data, i  put the data in "Athena" turn  on
 the  options: "pre-edge line", "post-edge line" and then "normalized" (in fact
i usually turn the  option "flatten" on, in dispite of  the  fact  that i don´t
know  what that means, what  that means?), i save  using  the  option "Save
chi(k)" in "file".

2)Then i  open  the  program "Artemis" and  insert the  data  saved  in  the
step "1)" in the column of the middle i click  with  the  right button of the
mouse and  select the  option "theory", "atoms" and  insert the  spatial group,
unit cell parameter, and atomic  location (here  its important to say that  the
compound that  i'm studying is LaCaMnRuO6 the measure  of x-ray  absorption was
performed in the  K-edge of  the  Mn, we are  interested in
Mn-O ligands so  in  "Artemis" i only put  the  data  of  the  Mn and O, right?)

3)I click  in the option "run atoms" for  each atoms  that i  inserted the
information, choosing 10 paths in  each  step, i click  the  in the  option
"run feff" for  each atom that i inserted the  information (again), after  that,
i click  in "Fit" then  appears  in the  screem  the  advise: "there is
something  wrong  with your math expressions" (or something like that) i  ignore
that  advise and  go on, but the  big problem is  that   the fit  appears  very
poor!

I have  to  say  that  the  information that  i use  to  insert  the atomic
position, unit cell parameters, was obtained from  a  Riteveld  refinament,
that i performed with  the  data  from  a cooper  x-ray tube, do i need a  data
 from a beam line, at  synchroton?


Do you  have some idea of  my problem? Have i make the  correct steps?

I'm sorry  for  my  english, i will  be  very thankful if  you answer  my
e-mail or give  to me someone  who  can do it!


REGARDS