ABSTRACT
We observed Förster resonance energy transfer (FRET) with a covalently linked donor-acceptor pair D-A consisting of two naphthalene groups acting as the donors and a benzofurazan group acting as the acceptor and adsorbed onto Ag or Au nanoisland films. The use of metal nanoisland films, which caused a strong enhancement of the Raman signal, permitted description of the adsorption mechanism onto the two metals. The intense fluorescence response of molecular adsorbates and the different behavior of the antenna on Ag and Au nanoislands are partly explained in terms of the radiating plasmon model.
ABSTRACT
UV polymerization of self-assembled monolayers of a novel carbazolyl-diacetylene (CDS9) chemisorbed on silver films was demonstrated by surface plasmon resonance (SPR) and surface enhanced Raman scattering (SERS) experiments. SPR tests performed during UV exposure permitted one to observe the growth of the absorption coefficient, associated with the formation of the polymeric backbone. The Raman spectra of polymerized monolayers exhibited the bands associated with the C=C stretching modes of the conjugated backbone, typical of the blue and red polymeric phases usually present in polydiacetylenes, with a clear predominance of the red form. Moreover, the strong surface enhancement of the Raman band corresponding to the aromatic C=C stretching modes suggested that carbazolyl groups arrange nearly perpendicularly to the metal surface. In contrast, the absence of a SERS signal in the region of conjugated C[triple bond]C bond stretchings confirmed a polymerization scheme with conjugated triple bonds nearly parallel to the plane of the metal.
