Advanced Peak-fitting Examples

Peak-fitting C (1s) signal from clean PET (Mylar)

The spectrum at the left shows the expected theoretical peak area ratio ( 3:1:1). The spectrum at the right did not give a 3:1:1 ratio. After noticing that the valley (dip) between Peak A and B was not as strong as the spectrum on the left, we thought that maybe the surface was contaminated with a very thin layer of Hydrocarbon. After adding a second peak to the Hydrocarbon BE, we found that the Chi-Square (and residual fit) were not optimized, so we added another small Alcohol/Ether type peak. After constraining the FWHM to be similar and constraining the BE positions, we finally obtained a good fit on the right which reveals the presence of a thin layer of a carbon material that has hydrocarbon and alcohol components.