Polarization effects in surface-enhanced resonant Raman scattering of single-wall carbon nanotubes on colloidal silver clusters - art. no. 081401

Polarization effects are studied in surface-enhanced resonant Raman scatter ing (SERRS) experiments on single-wall carbon nanotubes (SWNT's) in contact with silver colloidal clusters. For metallic SWNT's the very low depolariz ation ratio of the G band observed in normal resonant Raman scattering (RRS ) is nearly completely preserved in SERRS, and this is ascribed to the stro ng antenna effect of metallic carbon nanotubes. For semiconducting SWNT's, the depolarization ratio is a factor of 2 larger in SERRS compared to RRS. This is attributed to a lowering of symmetry for the resonant Raman scatter ing properties of the SWNT's arising from the very large field gradients on the metal colloidal clusters. The polarization directions of the local opt ical fields, as seen by the SWNT's on metallic clusters, are preserved.