Leakage radiation spectroscopy of organic nanofibers on metal films: evidence for exciton-surface plasmon polariton interaction

Leakage radiation spectroscopy of organic nanofibers composed of self-assembled organic molecules (para-Hexaphenylene, p-6P) deposited on a thin (40-60 nm) Ag film has been performed in the spectral range 420-675 nm which overlaps with the nanofiber photoluminescence band. Using a soft transfer technqiue, domains of mutually parallel oriented organic nanofibers were initially grown under high-vacuum conditions by molecularbeam epitaxy onto a cleaved muscovite mica substrate and afterwards transferred onto a silver film prepared on the glass carrier. The sample placed on a flat side of a hemisphere prism with an index matching liquid was illuminated by either a He-Cd 325 nm laser or by white light from a bulb. In the case of laser excitation two orthogonal linear polarizations and two different configurations of p-6P nanofibers were applied, both parallel and perpendicular to the plane of detection. The leakage radiation was observed on the opposite side of the Ag film at the phase matching angle. The spectrally resolved intensity of the scattered radiation has been measured as a function of scattering angle at normally incident light. The spectrum contains a distinct peak at an wavelength dependent angle above the critical angle. By analyzing this dispersion curve one can argue that it originates from the interaction between the nanofiber excitons and surface plasmon polaritons of the metal film.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.