Surface-enhanced raman scattering platforms on the basis of assembled gold nanorods

Abstract

This study investigates the surface-enhanced Raman scattering (SERS) of rhodamine 6G (R6G) on the surface of gold nanorods (GNRs) assembled on silicon. Two samples of GNRs were synthesized, notably, GNR-670 and GNR-810, with the average (length × thickness) dimensions of 64 × 23 and 45 × 11 nm and with plasmon resonances at 670 and 810 nm, respectively. Three types of substrates were fabricated, namely, a low-density monolayer (S1), a densely packed monolayer with regions of the side-by-side assembly of nanorods (S2), and a fractal film (S3). The extinction spectra of densely packed substrates showed the appearance of new maxima and the broadening and the red-shift of plasmon resonances, as was consistent with the typical behavior of plasmonic particles interacting at an interparticle distance of about 1–3 nm (data of transmission electron microscopy). The intensities of SERS peaks of the rhodamine 6G increased for substrates S1, S2, and S3 as 1: 6: 260, respectively. There was no significant difference in the SERS efficiency of the substrates based on GNR-670 and GNR-810 rods. The average enhancement of the signal over an area of 400 μm was about 105 with a reproducibility error of ±10%, thus making the obtained substrates promising platforms for sensitive SERS chemical and biological sensors.