Quantitative Model of Internal Analyzer Scattering in a Hemispherical Electron Analyzer and Its Application to Improve the Accuracy of the Transmission Function

Internal scattering within hemispherical electron analyzers (HEA) is common when operating at low pass energies, where the instrument resolution of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy experiments are at their best. Such scattering contributes extrinsic signal to the measurement, complicating quantitative analysis of peak shapes and areas and precluding accurate analysis of the inelastic XPS background signal. In certain circumstances, internal analyzer scattering can make it very difficult or even impossible to properly calibrate specific instrument operating modes. Typically, the advice is to avoid modes where internal scattering is present. Here, we directly measure the internal scattering within the analyzer and develop a general and quantitative model that describes its contribution to the measured spectrum. We show that application of this model can be used to correct the spectrum for internal analyzer scattering and recover quantitative information on the underlying photoelectron spectrum. Moreover, we use the quantitative model to accurately calibrate the transmission function of otherwise difficult lens modes. Our approach to transmission function calibration is based on a combination of existing methods and our model of internal analyzer scattering, and is traceable to external standards. The approach is relatively fast, requires no assumptions or parameters as input, and is general to HEAs used in XPS as well as other photoemission and Auger spectroscopies.