Raman Activity of HS (CH2) NH Coumarin Molecule Adsorbed on the Surface of Gold Nanostructures with various Morphologies

Abstract

Sanele Nyembe, Poslet Shumbula, Nosipho Moloto, Gebhu Ndlovu, Nikiwe Mhlanga, Lucky Sikhwivhilu

Synthesis of gold nanowires with an average diameter of 10 nm and length of up to 20 µm was achieved through a three-step heterogeneous nucleation process. Gold nanowires were formed through coalescence of spherical nanocrystals leading to grain growth and subsequently uneven nanowires. Furthermore, the uneven gold nanowires experienced thinning driven by thermodynamics to form relatively even nanowires with smaller diameters. Gold nanowires showed enhanced Raman activity in respect to enhancement factor than respective spherical gold nanoparticles with average particle sizes of 14 nm, 30 nm and 40 nm. The better Raman activity of gold nanowires with respect to spherical morphology was attributed to how they adsorb Raman active molecules, which are surface adsorption and network entanglement.

PDF