Electrochemical design of plasmonic nanoantennas for tip-enhanced optical spectroscopy and imaging performance

Abstract

Optical nanoantennas play a crucial role in controlling near-fields on the nanoscale and being counterparts of commonly used conventional optical components such as lens, prisms, gratings, etc. for shaping the wavefront of light in the far-field. In this paper we highlight a dc-pulsed voltage electrochemical etching method with a self-tuneable duty cycle for highly reproducible design of plasmonic (metallic) nanoantennas. With the method, we introduce such concepts as design, optimization and figure-ofmerit for evaluating fabrication efficiency. The ability of the nanoantennas to enhance and localize the optical fields beyond the diffraction limit is statistically studied with Rayleigh scattering from the tip apex and tipenhanced Raman spectroscopy of a single walled carbon nanotubes bundle.

Tip‐Enhanced Raman Spectroscopy: A Tool for Nanoscale Chemical and Structural Characterization of Biomolecules

“…The quality of the metal tip is then strongly dependent on the etchant (HCl, HNO 3 , H 2 SO 4 , …), the concentration of all reactants, the etching voltage, the etching temperature, and the method used to stop the EC etching process . Following this kind of procedure, gold tips with curvature radii of their apexes below 50 nm were manufactured in a reproducible way by several authors . Silver tips exhibiting curvature radii of their apexes below 100 nm were also produced, but the fabrication process was not always easy to control .…”

Optimizing the near‐field and far‐field properties of tips in tip‐enhanced Raman scattering

“…The sharp metallic cone is the most commonly used probe in near-field scanning probe microscopy, including in TERS. Electrochemical etching of metal nanowires [37][38][39][40][41][42] is a low-cost, simple, and widely used method for nanotip preparation. However, due to the presence of a large number of governing parameters, such as the nature and concentration of the electrolyte and solvent, the applied voltage frequency and amplitude, etching time, and immersion depth of the wire, it remains difficult to consistently produce sharp tips with radii well below 50 nm.…”

Исследование Структуры Объемного Гетероперехода В Полимерных Солнечных Элементах С Помощью Комбинации Ультрамикротомирования И Атомно-Силовой Микроскопии

“…Для этой цели была использована ин-вертированная оптическая схема и СЗМ-конфигурация c измерением боковых сил, использующая кварцевый резонатор с приклеенной золотой наноантенной. Оп-тическая наноантенна конусной формы была получена с помощью адаптивного электрохимического травле-ния золотой проволоки в растворе соляной кислоты (37%) и этилового спирта (96%) в объемной пропор-ции 1 : 1 [23,24]. Для измерений использовался лазер с длиной волны 532 нм.…”

“…В работах [23,24] было показано, что оптическое разре-шение данного метода на полимерных образцах состав-ляет 50−60 нм. Измеренный нами сигнал соответствует области спектра 1515−1570 см −1 , в которой находятся спектральные максимумы и полимера, и фуллерена.…”