Etchant-based design of gold tip apexes for plasmon-enhanced Raman spectromicroscopy

In this paper, we gain insight into the design and optimization of plasmonic (metallic) tips prepared with dc pulsed voltage electrochemical etching gold wires, provided that, a duty cycle is self-tuned. Physically, it means that etching electrolyte attacks the gold wire equally for all pulse lengths, regardless of its surface shape. Etchant effect on the reproducibility of a curvature radius of the tip apex is demonstrated. It means that the gold conical tips can be designed chemically with a choice of proper etchant electrolyte. It is suggested to use a microtomed binary polymer blend consisting of polyamide and low density polyethylene, as a calibration grating, for optimizing and standardizing tip-enhanced Raman scattering performance. (C) 2016 Elsevier B.V. All rights reserved.