Quantitative AES and XPS: calibration of electron spectrometers for true spectral measurements—VAMAS round robins and parameters for reference spectral data banks

Abstract

A fully instrumented electron spectrometer has been developed to measure absolute spectral intensities for AES and XPS. The spectra do not contain contributions from the energy dependencies of the analyser transmission or the detector efficiency and therefore provide the true spectrum, n( E), with a known uncertainty. Data from this instrument have been built into the protocols for VAMAS round robins. The result for a VAMAS AES intensity round robin involving 38 laboratories have now been analysed. Certain instruments may be calibrated through this protocol over the full energy range from 40 to 2000 eV to provide spectra diverging from the true spectrum, n( E), to a standard deviation of less than 2%. This figure should be compared with the value of over 200% found in earlier round robins. Absolute intensities are also transferable with an uncertainty of 2%. These results lead directly to (i) a methodology to calibrate the intensity scale of all AES instruments for direct spectra, (ii) reference conditions for acquiring AES data banks, and (iii) the launch of a new round robin for XPS.