Polyelectrolyte multilayer films were fabricated via layer-by-layer deposition using polyallylamine hydrochloride lightly functionalized (similar to 1%) with a covalently bound polypyridyl Ru(II) chromophore dye (RuPAH) and polystyrenesulfonate (PSS). Absorbance oscillations were noted in the UV-visible spectra of these films as functions of the number of PSS/RuPAH bilayers and identified as optical interference effects. The interference effects were modeled according to a Fabry-P rot cavity and a powerful conversion methodology was developed capable of correcting many spectra from relatively few fits. It is recommended that this method be applied as a standard to enable accurate analysis of absorbance spectra in thin films containing chromophores. Published by Elsevier B.V.