Hi everyone,
For a part of my study on TiO2 nanoparticles, I need to perform atomic ration calculation (O to Ti stoichiometry calculation) using core emissions data from XPS. I have access to SDP software and was wondering if anyone possibly knows how to perform such analysis. Additionally, I have heard that the stoichiometric analysis needs to use the cross section factor for Ti and O to correct the integrated area from XPS data, and how can I get the value of these factors? It can be very tricky.
So, any help to show me how this can be performed and how to get reliable results is greatly appreciated.
Thanks indeed.
I think, you also need to consider two parameter. First is the relative sensitivity factor for each element. Second is the ration for each series of doublet....p1/2 & p 3/2 = 1:2 ; d3/2 & d5/2= 2:3 and f5/2 & f7/2= 3:4....
The atomic sensitivity factors for the Ti2p and O1s peaks are part of the instrument that took the data. Whoever took the measurements for you should provide them to you. Otherwise, when you use tabulated values from some other reference, your calculated ratios will be inaccurate.
I suggest a contact with professor A. Herrera from Cinvestav Queretaro Mexico, He is an expert in this topi.c In your group developed a software analyze.
email adress: [email protected]
For quantitative XPS you need the subshell cross section (Yeh, Lindau), the transmission function of your spectrometer and some assumptions on the cleanliness of your sample. As Ti 2p and O1s are pretty close, you can in first order assume the photoelectrons come from the same depth in your sample, Ti 2p is a spin orbit doublet so you have to take both lines to compare with O1s. Looking closer to the spectra you need to identify chemically different phases as e.g. Ti4+ in TiO2 and Ti3+ at defects (shows up as a shoulder in the 2p emission). The same for O in TiO2 and adsorbed water etc. As the kinetic energies are close you can omit the energy dependent transmission function of the spectrometer if you calculate Ti/O as it canceles out.
1. All details of the quantitative analysis are well represented in the International standard ISO 18118 “Surface chemical analysis – Auger electron spectroscopy and X-ray photoelectron spectroscopy – Guide to the use of experimentally determined relative sensitivity factors for the quantitative analysis of homogeneous materials”
2. Usually the O1s spectrum of TiOx, 1,8
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