How to fit Gaussian/Lorentzian lines
Example :
Spectrum showing overlapping gaussian/lorentzian lines
Step 1 : Setting up the starting solution (the different lines)
-
Open the file in dmfit [Menu/File/Open] or drag it to dmfit
window from file manager
-
Initiate a decomposition [Menu/Decomposition/New Fit]
-
Select a nucleus by Clicking the
button or calling the [Spec Parameters]
dialog.
-
Click
the [Add] button to add
a new line
-
Click
the [Drag]
button to drag this new line to a convenient position, widht and amplitude,
click left to accept (click right toggles between Amp/Pos and Amp/Width modes).
-
Check or modify the lines parameters in the [Fit Pannel] (bottom
of screen)
-
Press
the [Compute] button to
recompute the model spectrum
-
Repeat this procedure for all the lines that you expect.
Line Parameters (Bold parameters are selected for
automatic optimization):
Amplitude : height of the maximum of the line
Position : Position of the line (in Hertz, ppm or point depending on the current
unit)
Width : full width at half maximum of the line
xG/(1-x)L : Gaussian/Lorentzian ratio (1 for Gaussian, 0 for Lorentzian)
You can always click use the
Fit Parameters Pannel buttons
Step 2 : Optimizing the fit
-
Check the different lines and their parameters (only
Bold face parameters will be optimized)
-
If necessary click
the [Parameters] button to call the [Model
Parameters full list] dialog and modify the list of variable paramters
-
Click
the [Optimize] button to
optimize the current solution
Step 3 : Reporting and Saving
Fit parameters can be saved in machine readable binary
format [Menu/Decomposition/Save Fit] or [Menu/Decomposition/Save as Fit] and
thus retrieved later exactly in same state.
Parameters can be reported in human readable format by clicking
the [Report] button to report the current line
paramters in a dialog box from which you can Select/Copy and further Paste word
processing or SpreadSheet programs.