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Surface nanostructure organizational entropy and spectral antireflective functionality relations have been recently suggested. They result from correlations between the onset of spectral transmission enhancement and surface grouped-feature separation collective disorder. Random antireflective surface structures (rARSS) enhance transmission by effectively reducing the electromagnetic impedance between optical indices across a boundary. Effective-medium approximation emulates the “random” structure surface layer with homogeneous films, failing to predict the critical wavelength above which the enhancement effect is observed. It is not clear as to what qualifies the “randomness” of rARSS, other than conventional profilometry measurements. We fabricated various rARSS silica surface modifications and quantified their randomness through Shannon’s measure of nano-structural entropy. A surface organization state variable, granule population distributions, and spectral reflectivity suppression were related to disorder phase-transitions. Surface disorder parameter trends were compared to spectral measurements and simulations, to distinguish short-wavelength uncooperative nanostructure effects (bi-directional scatter) from cooperative effects (transmission enhancement.)
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