X-ray Degradation

It is important to remember that for certain samples the action of sample irradiation can change the sample chemistry - affecting the spectra obtained. This X-ray induced degradation is important to remember in the analysis of polymers and has been seen in the analysis of metal oxides. For polymers, keeping analysis time to a minimum can help negate this issue as can lowering the X-ray flux.

Metal oxides/hydroxides can also be susceptible to this effect. As local heating may play a role here one option to help mitigate this effect (in addition to minimizing analysis time or lowering the X-ray source flux) is to cool the samples using an in situ cooling stage (generally cooled using liquid nitrogen).  This has been shown to help in the analysis of copper and vanadium oxides [1].

Reference:
[1] M.C. Biesinger, L.W.M. Lau, A.R. Gerson, R.St.C. Smart, Resolving Surface Chemical States in XPS Analysis of First Row Transition Metals, Oxides and Hydroxides: Sc, Ti, V,Cu and Zn, Applied Surface Science, 257 (2010) 887-898.