Transmission spectra of bilayers of a strongly absorbing dye molecule on thin semitransparent metallic films show a pronounced variation of the shape as a function of the thickness of the metal film. The shape changes with increasing thickness of the metal film from the form of an absorption spectrum as determined by the imaginary part of the dielectric function to an antisymmetric shape characteristic of the dispersion of the real part of the dielectric function in the vicinity of a resonance. These different spectra shapes were exploited to derive the complex dielectric function of a dye layer from transmission spectra of the layer on metal films of a different thickness. This method proved to be a simple alternative to determination of the dielectric function of a thin film of a dye by spectroscopic ellipsometry.
© 2003 Optical Society of America
(020.3690) Atomic and molecular physics : Line shapes and shifts
(120.4530) Instrumentation, measurement, and metrology : Optical constants
(120.7000) Instrumentation, measurement, and metrology : Transmission
(240.0310) Optics at surfaces : Thin films
(310.6860) Thin films : Thin films, optical properties
Eugene G. Bortchagovsky and Ulrich C. Fischer, "Method for Determination of the Dielectric Function of a Thin Absorbing Film on Variable Substrates from Transmission Spectra," Appl. Opt. 42, 6915-6918 (2003)