When you have a spectrum ready to fit, use the ‘Peak Fitting’ button to open the peak add window in Avantage.

This brings up a new window, and in the add peaks tab we can begin adding peaks to our data. Avantage helps you by suggesting where you might want to add new peaks, but be careful not to add too many! You should still use your judgement to make sure you can justify every peak you add in your data, and use as few peaks as possible unless you have very good reason.

Once you have peaks in place, you can see the peak fitting properties in the peak fit tab of the fitting window. If you open the peak add window again, and go to the fitting tab, you’ll see an option to ‘Fit this level’, or ‘Fit all levels’. Peak fitting is an iterative process – and you can set the max iterations at the top of the window. If you click ‘Fit All Levels’, Avantage will perform an iterative fit to match the spectral envelopes to the data as best it can.

Once you have a fit in place, you can organise this by renaming peaks simply by clicking on the name column and typing in. If you want to rename the labels on the spectra, you’ll have to go to the ‘Peaks’ tab and rename there.

Sometimes you might wish to manually lock certain peak parameters so that Avantage does not adjust it. For example, if you are basing a fit from standard reference data you may wish to lock the exact peak parameters from this data in order to extract a lineshape from small differences compared to the reference data.

You can manually adjust the peak parameter by typing into the appropriate parameter box, and then right click on this and select ‘Fix Selected Cells’. When you perform subsequent iterative fits this will not be adjusted.

Peak constraints are in cells below the relevant parameter. Typically these appear in the form of X : Y, where X is the lower limit, and Y is the upper limit. You can edit these by typing in new values, and Avantage will only fit between this range.

You can also lock peaks to another peak value, for example if we want to lock the FWHM of all peaks in a fit – we can type ‘A’ into the peak constraint boxes of peaks B and C and hit enter, and this will lock these peaks together. This is critical for more advanced fits, or if you want to reduce the number of variables in a fit in a system where we expect the core-hole lifetime to be very similar (e.g. in Carbons/Organics).