Note that aligning the spectra to the C 1s peak of adventitious carbon is a highly risky procedure and was recently shown to lead to unphysical results. Therefore, I strongly suggest to avoid it. Adventitious carbon is in general an unknown compound, not an inherent part of the sample, does not make proper electrical contact to the analyzed sample, BE of the C1s peak varies in a wide range.
Mohamed Abdelhamid I'm not completely sure that I agree with 'Note that aligning the spectra to the C 1s peak of adventitious carbon is a highly risky procedure'. While there is significant and justifiable debate about the 285 eV C 1s peak, the concept and use has been since the early days of XPS - indeed I was 'taught' this in the late 1970's during my Ph.D. It's a simple concept, easy to understand, and any 'replacement' should be of a similar nature. As long as the raw peaks are displayed then anyone can use any route to derive oxidation states. I don't consider this 'highly risky' - will people die if this old method is employed?
What is more interesting (to me, at least) is that any sample contained in air has a huge proportion of C on the surface - and that's where the material/particle interacts with its environment.
Whilst the C(1s) peak calibration has issues recently revisited by Greczynski et al (see for example https://www.researchgate.net/project/Why-you-should-not-use-the-C-1s-peak-for-referencing-XPS-spectra). Whilst this work is valid, very well done and the problems have been known for years, its has created some sensationalist headlines and unncessary worry in the literature at the moment
A key point is that the energies you are dealing with are essentially 'realtive energies'. There is nothing wrong with using the C(1s) at all- you just need to be careful on your model as a lot of GO samples are poorly fitted as there is generally still a graphitic contirnution in many of them which is ignored
You are right to doubt the C1s method, especially for GO. The carbon signal you get from GO is not from adventitious carbon, it's the actual material and consists mostly of sp2 while sp3 comes from the oxide locations, so the premise of the method isn't even given here. If your films are thin enough and you are working on a highly conducting substrate, it would probably be the best to apply no shifting at all.
- Badges
- Science topic