Dear scientific society,
In my XPS results of Ru-zeolite catalyst, there's no carbon however in the spent catalyst there is a chance of carbon deposition. I spent catalyst XPS, Ru 3d3/2 at 284.6 can overlap with carbon. These signals do interfere with one another. How can I deal with the interference?
Thanks in advance
Dear Adarsh,
It is highly probable or almost a fact that you have adventitious carbon in your Ru/zeolite. Adventitious carbon is found in almost all samples, to corroborate this I suggest that you acquire the survey spectrum from 1300 eV to detect the C KLL signal. And the spent catalyst is very likely to have more carbon than the fresh catalyst.
Regarding the overlapping problem, you have two options:
The first is to acquire a Ru signal that does not overlap with any other signal in your sample, it could be the second strongest Ru signal which is Ru 3p (only Ru 3p3/2 could be enough, however I recommend acquire the entire region as much as possible). However, chemical analysis can be complicated since there may not be enough information in the literature about this signal. The other problem is that you would be completely excluding carbon for quantification.
The second is to acquire two Ru signals, Ru 3d, the most intense and most studied signal, and an alternative signal, Ru 3p. Then you do the peak fitting of the Ru 3d also including the C 1s, then you do the peak fitting of the Ru 3p and you start to compare the corrected areas of the Ru 3d and the Ru 3p, and when you reach a ratio ~ 1:1 your peak fitting will be correct, and after this you can make the assignation of the species and the quantification, remember that you must to use one signal per element for quantification.
Dear Adarsh,
It is highly probable or almost a fact that you have adventitious carbon in your Ru/zeolite. Adventitious carbon is found in almost all samples, to corroborate this I suggest that you acquire the survey spectrum from 1300 eV to detect the C KLL signal. And the spent catalyst is very likely to have more carbon than the fresh catalyst.
Regarding the overlapping problem, you have two options:
The first is to acquire a Ru signal that does not overlap with any other signal in your sample, it could be the second strongest Ru signal which is Ru 3p (only Ru 3p3/2 could be enough, however I recommend acquire the entire region as much as possible). However, chemical analysis can be complicated since there may not be enough information in the literature about this signal. The other problem is that you would be completely excluding carbon for quantification.
The second is to acquire two Ru signals, Ru 3d, the most intense and most studied signal, and an alternative signal, Ru 3p. Then you do the peak fitting of the Ru 3d also including the C 1s, then you do the peak fitting of the Ru 3p and you start to compare the corrected areas of the Ru 3d and the Ru 3p, and when you reach a ratio ~ 1:1 your peak fitting will be correct, and after this you can make the assignation of the species and the quantification, remember that you must to use one signal per element for quantification.
You should be able to distinguish between the two 3d spin-orbit splitted peak, the taller of wich is the 3d5/2 one located at about 280 ev BE in the Ru metal case.
If so, you may try a model route:
1. Isolate the above said 3d5/2 peak and subtract out any possible background contribution due to C-bands tail.
2. Consider the pure Ru metal 3d spectrum which is available everywhere and shows the BE, width and relative height of both components. You will use this model doublet in your fit of the carbon-overlapping range after having aligned the 3d5/2 peak of the model with your real one and having normalised to the same peak area in the ereal and model cases.
3- perform a series of fits including the expected carbon contributions in the due range-
You should so extract a significant carbon spectrum, including all type of C in the chosen BE range.
However, the above method suffers of some weaknesses. For example, this procedure is of course approximatw and valid in case Ru is in its mtallic state. If Rux+ would dominate the surface chemistry, the method could be no longer applied because of the occurrence of not easily modelled satellites of the two 3d peaks at a couple of Ev higher BE from each of the main peaks.
You should look for other peaks Ru 3d 5/2 and Ru 3p1/2. Fitting the spectra with spin orbit splitting will help you to analyse the data properly by keeping the delta value in mind for metallic sample. I hope this paper can help you........
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