Surface Enhanced Raman Scattering from Single-Walled Carbon Nanotube Decorated on Ag Nanowires

Abstract

Surface-enhanced Raman spectroscopy (SERS) is a surface sensitive technique which gives enhanced Raman signal intensity of the molecules by roughening metal surfaces. It can be used to detect trace amounts of analysts including heavy metals, pesticides, explosives, proteins and different biological and chemical contaminants. In this paper, we report a facile approach to synthesise highly nano-crystalline and homogeneous plasmonic wave guide of silver nanowires (Ag-NWs) by polyol method. Morphology of the synthesised Ag-NWs has been characterised using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques and suggests the homogenous formation of nanowires with an average diameter of 400–450 nm and 15–25 µm of length. Surface-enhanced Raman spectroscopy (SERS) of single-walled carbon nanotube (SWNT) when it is coupled with Ag-NW suggests that the enhancement factor is as high as ~ 103 and ~ 102 for the characteristic Raman signals (G-peak and radial breathing modes, respectively). Using numerical method of finite difference time domain (FDTD), it is shown that the enhancement depends on the orientation of the SWNTs with respect to the Ag-NWs and is maximum (~ 107) when they are at 45° to each other. The proposed approach provides an effective, reproducible and facile method for preparing high-quality SERS substrates for remote optical excitation in plasmonic devices.