Synthesis and surface characterization of a patterned cuprite sample: Preparatory step in the evaluation scheme of an X-ray-excited optical microscopy system

The synthesis and characterization of a reference sample containing a distinct geometrical pattern of Cu2O (cuprite) are described. The sample is to be used as an assessment sample to evaluate a newly developed X-ray-excited optical luminescence (XEOL) microscope, built for non-destructive chemical imaging of metal and other surfaces. The sample was produced by heating in a reducing flame and subsequent air exposure. It was characterized both qualitatively and quantitatively using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy in both fluorescence mode (XAS) and optical luminescence mode (XEOL-XAS) and X-ray diffraction (XRD). Results indicate the presence of a layered structure comprising a heterogeneous mixture of cuprite and tenorite (CuO) with mainly cuprite (91.4%) in the near-surface regions and larger amounts of tenorite in the top 1-3 nm. The cuprite produced via this protocol was found to provide intense optical luminescence upon X-ray bombardment, which is particularly useful during the evaluation of the microscope.