Exciton and polarization contributions to optical transition energies in an epitaxial organic monolayer on a dielectric substrate

Abstract

Optical emission and excitation spectra of the model molecule perylene-3,4,9,10-tetracarboxylic acid dianhydride adsorbed on an NaCl(100) surface were measured in the limit of isolated monomers and for two epitaxial monolayer phases (Q and HB${}^{*}$). Intermolecular dipole-dipole coupling and molecular polarization lead to distinct and structure-dependent relative shifts of the exciton energies with respect to the monomer. In combination with calculations of the exciton band structures, this gives insight into the relevant contributions to the transition energies for an interfacial organic film.