X-ray Degradation of Cu(OH)2

X-ray induced degradation of copper (II) species can complicate interpretation of results. One way to mitigate this issue is to perform the analysis of the Cu 2p (and Cu LMM Auger line) first and in as few scans as possible, then perform subsequent needed analysis afterward (e.g. other high resolution spectra, survey scans).  If the mechanism of reduction is due to thermal effects, as it appears to be for Cu(OH)2, cooling of the material can reduce the amount of degradation significantly. The charts below for copper (II) hydroxide samples analyzed by XPS at normal operating temperatures (top) and cooled to -100C (bottom) using the same X-ray source (15 kV, 14 mA, monochromatic Al K(alpha)) and charge neutralizer conditions (Kratos AXIS Ultra system) show that degradation is slowed significantly for the cooled sample.  Notably, degradation is minimal for the cooled sample for the initial window of analysis. 

X-ray induced degradation of Cu(OH)2 - normal operating temperatures.

X-ray induced degradation of Cu(OH)2 - sample cooled to -100C.