Optical interference effect corrections for absorbance spectra of layer-by-layer thin films bearing covalently bound dye

Polyelectrolyte multilayer films were fabricated via layer-by-layer deposition using polyallylamine hydrochloride lightly functionalized (∼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-Pérot 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.