The evolution of near-edge X-ray absorption fine structure in the vicinity of the
K-absorption edge of oxygen for HfO2 over a wide range of incidence angles is
analyzed by simultaneous implementation of the total-electron-yield (TEY)
method and X-ray reflection spectroscopy. It is established that the effect of
refraction on the TEY spectrum is greater than that of reflection and extends
into the angular region up to angles 2c . Within angles that are less than the
critical angle, both the reflection and refraction strongly distort the shape of
the TEY spectrum. Limitations of the technique for the calculation of optical
constants from the reflection spectra using the Kramers–Kronig relation in the
limited energy region in the vicinity of thresholds are discussed in detail.