Dispersion analysis with inverse dielectric function modelling

• The Berreman effect applies also reflectance spectra of bulk materials described by scalar dielectric functions.
• For p-polarized light, the reflectance is then increasingly influenced by the inverse dielectric function.
• Dispersion analysis can therefore strongly benefit from inverse dielectric function modelling.
• In particular p-polarized reflectance spectra can be modelled with higher accuracy.
• The dispersion parameters of perpendicular modes can be evaluated with unparalleled precision and easiness.

We investigate how dispersion analysis can profit from the use of a Lorentz-type description of the inverse dielectric function. In particular at higher angles of incidence, reflectance spectra using p-polarized light are dominated by bands from modes that have their transition moments perpendicular to the surface. Accordingly, the spectra increasingly resemble inverse dielectric functions. A corresponding description can therefore eliminate the complex dependencies of the dispersion parameters, allow their determination and facilitate a more accurate description of the optical properties of single crystals.

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