XPS spectra associated with surface core-level shifts (SCLS) for the InSb{111}A, B-(2×2) surfaces are fitted with the curves represented by the Voigt function. While testing as to how the Voigt function changes with detection angle, the Lorentzian width included in the function remains almost unchanged, whereas the Gaussian width becomes broadened with an increase in detection angle. This Voigt function allows to decompose a spectrum of interest into bulk and SCLS component with sufficient intensity, realizing quantitative estimation for the SCLS intensity.
