Scanning near-field optical microscopy/spectroscopy of thin organic films

We have used a scanning near-field optical microscope to investigate the optical properties of a thin organic film consisting of poly(phenylene vinylene) and tris(8-hydroxy)quinoline aluminum. Near-field optical images taken in transmission mode using a 488 nm laser light revealed numerous ''dark spots'' scattered randomly across the filmy however, the dark spots were not related to the surface topography. These dark spots ranged in size from 100-300 nm in diameter. The nature of the dark spots was attributed to an increase in the absorption at 488 nm as a result of local variations in the poly(phenylene vinylene) film. (C) 1996 American Vacuum Society.