Dear colleagues,
In our XPS instrument, most of the time when we acquire the Pd3d region (for a wide range of materials containing Pd) it overlaps with a strong signal from Ca2p. Nonetheless, those samples are totally free of any Ca-containing contamination and it appears regardless of the anode used (Mg/Al). So, any ideas about where that contamination might be found and how to get rid of it?
Instrument and acquisition details:
SPECS spectrometer equipped with a Phoibos 150MCD-9 analyzer and using a non-monochromatic MgKα (1253.6 eV) source operating at 100 W. An analyzer pass energy of 30 eV, with a 0.1 eV energy step and an operating pressure of 10−9 mbar.
Thanks in advance.
In order to verify that it's actually Ca, can you check if is Ca2s also observed?
Otherwise you might have some sort of satellite in your Pd signal.
If your data isn't fully secret, could you maybe post a spectrum so we can have a look at it?
Hi Jürgen, thanks for your kind response.
Yes, the Ca2s also appear in the Survey spectrum. We believe it's the sample holder which has been contaminated by calcium so that we are currently checking this hypothesis. Unfortunately, after asking for it, I'm not allowed to share the spectrum. Let's see if by changing the sample holder we might get rid of this contamination.
Many thanks.
How big is your sample? A modern XPS detector should be able to gather just the electrons from a millimeter-sized sample region. I once saw lots of sample holder signal and it turned out there was a control error which caused the front lenses of the detector not to get any voltage.
Calcium is contained in sweat, so handling samples by hand might introduce such contaminations.
Have you checked with other samples, if the calcium contamination is present as well?
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