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Spectroscopic ellipsometry was used to determine the real and imaginary parts of the dielectric function of ZnSe thin films grown on (001) GaAs substrates by molecular-beam epitaxy, for energies between 1.5 and 5.0 eV. A sum of harmonic oscillators is used to fit the dielectric function in order to determine the values of the threshold energies at the critical points. The fundamental energy gap was determined to be at 2.68 eV. The E0+Δ0 and E1 points were found to be equal to 3.126 and 4.75 eV, respectively. Below the fundamental absorption edge, a Sellmeir-type function was used to represent the refractive index. At the critical points, E0 and E0+Δ0, the fitting was improved by using an explicit function combining the contributions of these two points to the dielectric function.

We present a series of measurements characterizing the dependence of polarized thermal emission on surface roughness. In particular, we measure the spectrally resolved degree of linear polarization (DOLP) for a series of roughened borosilicate (Pyrex) glass substrates as a function of the roughness parameter Ra, the root-mean-square slope distribution, and observation angle theta. Also measured are a series of smooth glass substrates coated with two particular polymers of interest, i.e., a common commercially available Krylon paint and a chemical-agent-resistant coating paint. The DOLP is measured over a 4-13 microm wave band by using a modified Fourier transform IR spectrometer in which a wire-grid polarizer and a quarter-wave Fresnel rhomb are used in conjunction to measure all four Stokes parameters. In addition, we show an enhanced DOLP due to anomalous dispersion exhibited by the surface material.

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