Sample should be 100% PbSO4, but peaks found at 160.38 and 163.26 eV. Does anyone have any idea what these XPS peaks could indicate?

Hello, I purchased a manufactured bottle of PbSO4 from Alfa Aesar and according to the XRD it's 100% PbSO4, however when I ran it through the XPS I have low energy S2p peaks (160.38 eV and 163.26...

26 May 2019 3,338 4 View