DIRECT INVESTIGATION OF SURFACE PLASMON SENSITIVE SURFACE ENHANCED RAMAN SCATTERING USING SINGLE Ag NANO-AGGREGATES

Abstract: We investigated polarization dependences of surface enhanced resonance Raman scattering (SERRS) and surface plasmon resonance (SPR) to identify the SERRS yielding SPR bands. We also studied SERRS excitation spectra for single Ag nano-aggregates with the SPR bands to explore the electromagnetic (EM) and resonance contribution to SERRS. Surface enhanced resonance Raman scattering (SERRS) has recently been a matter of great interest from the points of its applications as well as basic science because it allows one single molecule detection due to its enormous enhancement factor by 1010 to 1014. However, the varieties of molecules and metal substrates that yield SERRS are quite limited and its mechanism is still unclear. Recently, experimental studies on relationship between surface plasmon resonance (SPR) and SERRS have rapidly been advanced because several groups achieved SERRS detections using single Ag nano-aggregate and/or single adsorbed dye molecule systems [1-5]. These SERRS researches are valuable to optimize the electromagnetic (EM) interactions at metal nano-structure/adsorbed molecule systems for single-molecule bioanalysis and nano-biodevice. In the present study, polarization dependences of SERRS and SPR are investigated for identification of the SERRS yielding SPR bands. SERRS excitation spectra are investigated fo