You can of course have defective materials, however you wont be getting signals for oxygen vacancies. Instead you will be seeing signals for where a (high energy) defect site has undergone adsorption of water or similar, forming surface OH groups or similar.

What peaks are you ascribing to carbon defects? A similar argument will be true as the oxygen.

Dear David,

Many thanks for your reply.

In C1s, i have ascribed peak at 283.9 eV for carbon defects.

similarly in O1s, i have ascribed peak at 532.2 eV for oxygen vacancies.

I also want to know the mechanism of formation of such defects.

Faiza

It would be good to see your raw data and/or fitting. The O 1s at ~532 eV is likely C-O-C, C-OH or aromatic C=O (i.e. bound directly to the phenyl ring).

The peak at 283.9 could be carbide, but is a little high, although if you have a silicon contaminant it could be Si-C. Perhaps therefore its likely broadening of the sp2 carbon peak due to damage, but to say its a defect peak should made with caution - perhaps its better to say its more evidence of distortion?

We can say more if we can see images of the spectra or the spectral data itself

Hello David,

Thanks for your response.

I have sent the Excel data to your email.

Thanks

Hi Faiza Rehman

I have looked at the data, and the first thing I would say is that it needed calibrating to make sense - which I have done in the attached image.

As I do not know any acquisition parameters, such as pass energy etc, it is a limited interpretation I give from the fitting I present , but the C 1s spectrum does make some sense to me in terms of speciation etc (see labels on the image).

However, I am a little more concerned by the O1s spectrum as the peak at 534.3 eV is rather large and higher that I would expect in binding energy.

I therefore suspect there is some charging on this sample or some regions have been calibrated whilst others haven't.

Personally, I would repeat the measurement ensuring the sample is insulated from the XPS system and that the charge compensation is sufficient and at a lower pass energy to help improve resolution.

Dear Dr. David J. Morgan , thanks alot.