Powder samples are not good for XPS analysis. If you make a pellet out of the powder and sinter it, it will work better. Powder particles are covered with adsorbed contaminants like carbon, oxygen etc. When it is in the form of pellet, you can remove contamination by scrapping the surface in UHV. Powder as such can not be cleaned in-situ. In any case, many people carry out XPS studies on powder samples. XPS signals are influenced by contamination. Your interpretation may be wrong if XPS is taken on powder as it is. If you have no option than doing on the powder, for usual XPS(no-monchromatic), X-ray spot size is about 5 to 10 mm, you should have enough powder to cover whole of this area. It cannot be mentioned in terms of mass, as it depends on the kind of sample you have.
It depends on the geometry of the beam you use.
I use 50 - 200 mg, but less could work as well.
Well its depends upon the spot size of the X-Ray as well as your sample mounting procedure. If you are going to use carbon tape then i would suggest to use enough powder to cover the entire tape. else you would get additional carbon (from the tape) in your spectra.. as well as it would give you false information.
As said before, it depends.
If you have d=1 cm2 as a spot diameter and if you detect the electrons having energies
Practically, for any type of the instrument is enough to have a few mg of the powder. About 5 - 10 mg is the maximum amount that will be used even for large spot XPS analysis.
Powder samples are not good for XPS analysis. If you make a pellet out of the powder and sinter it, it will work better. Powder particles are covered with adsorbed contaminants like carbon, oxygen etc. When it is in the form of pellet, you can remove contamination by scrapping the surface in UHV. Powder as such can not be cleaned in-situ. In any case, many people carry out XPS studies on powder samples. XPS signals are influenced by contamination. Your interpretation may be wrong if XPS is taken on powder as it is. If you have no option than doing on the powder, for usual XPS(no-monchromatic), X-ray spot size is about 5 to 10 mm, you should have enough powder to cover whole of this area. It cannot be mentioned in terms of mass, as it depends on the kind of sample you have.
Dear,
I agree with Dr. Medicherla that power samples are not good for XPS analysis. You can make a pellet using a press in your university.
just wondering incase the sample is so porous that it cannot make the pellet what would be receommend?
kindly suggest if I want to prepare the sample for lyophilized bacterial culture for the analysis of surface of gram positive bacteria...........how can I prepare the sample ...........
Abhijit N Kadam , usually I take a snip of carbon tape ~3x5mm and place it onto the sample holder. then add enough sample to cover the carbon tape at all. It's not hard to do it always it is just enough sample material and even better as long as it is not electrostatic.
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