Search

Au plasmonic hollow spherical nanostructures were synthesized by electrochemical reduction (GRR, the Galvanic Replacement Reaction) using Ag nanoparticles as templates. From UV-visible absorption spectroscopy, it was found that the surface plasmon resonance (SPR) of gold hollow spherical nanostructures first showed red shift and then blue shift. However, further addition of gold precursor (HAuCl) resulted into a red shift of SPR peak. The morphological changes from Ag nanoparticles to Au hollow nanostructures were assessed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX)analysis. The Mie Scattering theory based simulations of SPR of Au hollow nanostructures were performed which are in good agreement with the experimental observations. Based on the experimental observations and theoretical calculations, a complete growth mechanism for Au hollow nanostructures is proposed. [ABSTRACT FROM AUTHOR]

Tip-enhanced Raman spectroscopy (TERS) has received much attention due to excellent spatial resolution and high detection sensitivity. However, its performance depends crucially on the tip size and shape, and the tip-substrate distance. Substrates coated with roughened silver or gold films, or nanoparticles further limit its stability and reproducibility. Here, substrates with well-ordered silver nanohole arrays, were prepared for TERS by depositing silver on an anodic aluminum oxide (AAO) template. The TERS performance was investigated by varying the tip-substrate distance, position of the tip over different domains of the silver nanohole array, and changing the illumination polarization. We show that: (1) the proposed system is more efficient at controlling the distribution of Raman enhanced 'hot spots', and demonstrates a detection limit for a low concentration of 10 mol L for Rh6G and (2) the proposed approach has a high fidelity factor as the system is highly reproducible, making it suitable for probing over an area. Our experimental and theoretical results demonstrate that substrates with silver nanohole arrays are extremely promising for further application of TERS in surface plasmon resonance biosensing. [ABSTRACT FROM AUTHOR]