Quick fitting

This is an example how to fit a segment of diffraction pattern containing a few overlapped peaks.

  1. Start the program
  2. Go to Environment - Directories and check/modify the working directory. This is not necessary, if the correct directories are defined in Configuration file. In principle, only the DAT and PRN directories must be defined.
  3. Go to Files - Load - Run (short-cut FLR) and select the data file from the list (pathname can also be modified here).
  4. Go to Graphics (G) main menu
  5. Select the segment, if necessary, by X-scale change (XL) in some way - window, explicit left and right limits. Go back to main Graphical menu (ESC).
  6. Give zero approximation of background - Corrections - Background - Global (CBG), select left and right points by Graphical cursor. Go back to main Graphical menu (ESC).
  7. Find the peaks - Lines - Search peak - Find peaks (LSF), modify the threshold level with graphical cursor if necessary, give typical line width for smoothing. Markers of found peaks are shown on the top. Go back one level in the menu.
  8. Delete false peaks if necessary with Erase peak (select a peak with graphical cursor and press Delete for approapriate peak). Peak parameters can be viewed and changed under Parameters menu. Peaks also can be added by Add peak.
  9. Go back to main text menu (ESC) and go to Fitting - Fit (TF). Iterations are started and can be repeated, if unsatisfactory results are obtained. Global parameters and analytical function can be defined under Global parameters. Starting profile parameters can be modified and/or fixed in Peaks.
  10. Go to Graphics and look at the results (separated Ka1 lines can be viewed by Alt K, differences by Alt D, separated doublets can be switched on only in Fitting-Graphics). If you are unsatisfied, you can again go to Fit (TF).
  11. Finally go to Output - Write - File - Run (OWF). Give filename, select parameters which will be listed in the table and press Run. Graph can be saved in HPGL format in Plot - Filename - Run.

This may be the fastest way of fitting the profiles. As the non-linear regression is applied, zero-estimate of parameters must be given (background - item 6, profile parameters - item 7). Always the peaks which are contained in the latest graphical window are fitted.