Single-molecule detection using surface-enhanced resonance Raman scattering and Langmuir-Blodgett monolayers

The Langmuir-Blodgett (LB) technique has been used to obtain spatially reso lved surface-enhanced resonance Raman scattering (SERRS) spectra of single dye molecules dispersed in the matrix of a fatty acid. The experimental res ults presented here mimic the original electrochemical surface-enhanced Ram an scattering (SERS) work where the background bulk water did not interfere with the detection of the SERS signal of molecules adsorbed onto the rough silver electrode. LB monolayers of the dye in fatty acid have been fabrica ted on silver island films with a concentration, in average, of one probe m olecule per micrometer square. The properties of single-molecule spectrosco py were investigated using micro-Raman including mapping and global images. Blinking of the SERRS signal was also observed.