Differential reflection phase shift under conditions of attenuated internal reflection

The angle-of-incidence dependence of the differential reflection phase shift Delta between p and s polarizations is considered a function of the real and imaginary parts of the relative complex dielectric function epsilon of an interface in the domain of fractional optical constants, i.e., under conditions of internal reflection. The constraint on complex epsilon such that oscillatory and monotonic angular responses are obtained is determined. A sensitive and stable technique, which is based on attenuated internal reflection ellipsometry between the Brewster angle and the critical angle, is proposed for measuring small induced absorption(epsilon(i) similar to 10(-5)) in the medium of refraction. (C) 1999 Optical Society of America [S0740-3232(99)01407-6].