A significant enhancement of the second harmonic generation (SHG) from second-order nonlinear optical (NLO) dyes in solution has been evidenced when these dyes were grafted onto the surface of spherical gold nanoparticles (AuNPs), as compared to their NLO response without AuNPs. The length, as well as the nature of the spacers between the gold particle and the chromophore, is shown to play an important role, a benzene linker being more favorable to AuNP-4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) interactions, as illustrated by a higher exaltation of the NLO response for DAST molecules linked to AuNP via a phenyl ring as compared to their equivalent with a CH2–CH2 link.
Origin of optical second-harmonic generation in spherical gold nanoparticles: Local surface and nonlocal bulk contributions
