Using fityk to determine flank positions

[Ben Buse]

Hi

As I've just tried this I thought I'd write it down, in case of use to anyone else

(1) Load program
(2) Data > Load File (For PFE .dat export file - enter column numbers for x and y - in this case x 23 y 33) > Open slot > Click on each file & repeat open slot (4 andradite repeats, and 4 almandine repeats)
(3) Select 4 andradite repeats - go to Data > Merge Points - output to new dataset
(4) Repeat for 4 almandine repeats
(5) Data > Edit transformations - add new function to normalise data e.g.

Code Select Expand

y=y[n]/max(y)*100 and apply to both merged datasets
(6) Create difference spectra - type in command line

Code Select Expand

@+ =@10-@11 where10 and 11 are the spectra numbers

(7) Duplicate Difference Spectra (see sum button)
(8.) Fit peak to the maximum difference and identify centroid giving a flank position - it only fits peak to positive values so shift spectra to positive values using edit transformations - add new function

Code Select Expand

Y=y[n]+25 - using data-range mode deselect parts of spectra not relevant to fitting - select split pearson7 - auto-add - start fitting - either write down centre of fitting peak (the flank position) or Functions>Export peak parameters

(9) Duplicate Difference Spectra (see sum button)
(10) Fit peak to the minimum difference and identify centroid giving a flank position - use Data > Edit Transformations > Invert - to make negative peak a positive peak - select region for fitting - fit and record peak position as before

[Probeman]

For others interested in the Flank method, please search for "flank" in this user forum to see more on this method. For example:

https://smf.probesoftware.com/index.php?topic=1605.msg12395#msg12395