Surface-enhanced Raman scattering and imaging of Langmuir-Blodgett monolayers of bis(phenethylimido)perylene on silver island films

The optical spectra of bis(phenethylimido)perylene (PhPTCD) are discussed. Surface-pressure area isotherms of floating Langmuir monomolecular layers have been obtained, and Langmuir-Blodgett (LB) molecular monolayers of the material have been fabricated on silver island substrates for surface-enhanced vibrational studies. The electronic absorption and emission spectra of solutions and thin solid films are described. The vibrational spectra, infrared and Raman for the bulk, and the surface-enhanced Raman (SERS) and resonance Raman scattering (SERRS) spectra of LB monolayers have been obtained. Surface-enhanced fluorescence (SEF) for LB films is also demonstrated. Given the unique properties of the LB coated silver surfaces, the mapping of the SERS/SERRS signal and global Raman images, at a particular vibrational wavenumber, were obtained by using the 780 and 514.5 nm laser lines. The images give a visual picture of the variation of the SERRS and SERS signal intensity on the rough metal surface.