The influence of the structure of different germanium chalcogenide glasses on the molar refraction and its wavelength dependence

The wavelength dependence of the molar refraction of different germanium chalcogenide glasses is analyzed by use of a two-term Sellmeier dispersion relation. Whereas a single-oscillator model, which neglects the contribution of the oscillation transitions to the molar refraction in contrast to the electron transitions, clearly reflects the discontinuous change of the structure in the series GexSe1−x at x = 0.33, a two-oscillator model allows the differentiation between a substitution of isostructural units in the series (Ge2S3)1−x(Ge2Se3)x and a continuous change of the structure in the series GexSe1−x in the ranges 0 < x < 0.33 and 0.33 < x < 0.4.