Surface-enhanced Raman scattering: Imaging and mapping of Langmuir-Blodgett monolayers physically adsorbed onto silver island films

The point-by-point mapping of the surface-enhanced resonance Raman scatteri ng (SERRS) and surface-enhanced Raman scattering (SERS) spectra obtained fr om Langmuir-Blodgett (LB) monolayers of bis(n-butylimido)perylene (BuPTCD) on silver island films are reported. Wide field global images of the SERRS signal are also discussed. The mapping and global Raman images of the LB-co ated silver surfaces, obtained using the 514.5 nm and the 780 nm laser line s, give a visual picture of the variation of the intensity of the SERRS/SER S signal on the rough metal surface with ca. 1 mu m(2) spatial resolution. Neat and mixed LB monolayers of BuPTCD with arachidic acid of 20% and 1% mo lecular concentration of the analyte were used as samples in the SERRS and SERS experiments. This is the first report of SERS and SERRS mapping and im aging of single Langmuir-Blodgett monomolecular layers. The use of BuPTCD i s particularly important, since the molecules are not chemically hound to t he surface. SERRS spectra with large signal-to-noise ratio (100) are observ ed from a maximum of 40000 molecules of the analyte with a collection time of 10 s.