What is an LA lineshape? I don't see that in the manual:

http://www.casaxps.com/help_manual/manual_updates/peak_fitting_in_xps.pdf

Jürgen Weippert

LA(a,b,m) and LF(a,b,w,m) are two asymetric Voigt-functions introduced in version 2.3.14 (see http://www.casaxps.com/help_manual/manual_updates/LA_Lineshape.pdf).

Aman Baunthiyal

The LA lineshape introduces asymetric tailes, giving you undefined areas (not sure exactly how CasaXPS determines the area, probably cutting off at the region edges). I would recommend to use GL in your case.

Dear all,

I've learned some time ago, that a tail-function is not appropriate for oxides, as the tail physically originates from inelastic scattering / excitation of conducting electrons by the photoelectron on the way to the surface of the sample. Since oxides typically have a band gap larger than about 1-2 eV, and in that particular case, Ga2O3 has even more than 4.5 eV, excitation of core electrons with continuous losses in the range from e.g. 0 to 3 eVs would be rather unexpected. Thus, an asymmetric tail can be excluded here. I agree with Thorsten Schultz that a "simple" Gauss-Lorentzian is appropriate here! best regards, Dirk

Thorsten Schultz Dirk Luetzenkirchen-Hecht Dear Dr. Schultz and Prof. Dr. Luetzenkirchen-Hecht,

Thank you for your response. It made me clear about it now. For me, GL fits best with very low residue STD value as compared to LA shapeline.

Thank you again.

Regards

Aman Baunthiyal

Aman Baunthiyal be very careful on relying on the residual STD. This means that statistically your synthetic peaks fit the data envelope well, but could be chemically meaning less. On a point of note, its very easy to get more Gaussian charter in the LA (or LF) line shapes. These Voight-like derivations are less prone to variance if you have noisier spectra.

Note you should check your relative percentage of oxygen calculated from the O(2s) with that from the O(1s) as a "sanity check" of your fitting - assuming these aren't films, then you would expect the O(1s) and O(2s) concentrations be be equal (or equal within error)

The comparison between O1s and O2s can lead to substantial differences if you have surface contaminations, due to the different attenuations. Account properly for this is rather tricky.

Therefore a quantification from the Ga3d and the O2s should lead to the most accurate results if surface contaminations are present, due to the same attenuation.

Thorsten Schultz Whilst that is of course true, if its just adventitious carbon then the difference isn't that big - from my experience of looking at Ga2O3 as a catalytic support then the at% comparison is ~ +-2%, same goes for the Ga(3d) vs Ga(2p3/2). If the materials are films then that's a different issue

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Have a nice day

Claude Le Gressus Are you sure you didn't want to post this in a different discussion? Seems a bit off-topic for this one.

Sorry

There was this paper I have gone through recently related to asymmetric fitting in XPS, and it provides a lot of interesting references. DOI: 10.1002/sia.7215. Good luck.