Silver nanowires: synthesis, characterization and optical properties
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1144-LL20-17
Silver nanowires: synthesis, characterization and optical properties. Yu. A. Barnakov, H. Li, G. Zhu, M. Mayy, E. Robinson, C. Bonner and M. A. Noginov Center for Materials Research, Norfolk State University, Norfolk, VA 23504, USA ABSTRACT We describe electrochemical synthesis of a bulk metamaterial, consisting of silver nanowires in Porous Anodic Alumina membrane and its characterization. We have found that the quality of the synthesized metamaterial depends on the metal used as a working electrode at the optimal conditions of the electroplating process. The dissolution of the thin layer of working electrode is occurred during the electrochemical reaction. It suggests an important role of interfacial phenomena taking place between the working electrode and the sample holder. INTRODUCTION In the past few years, artificial sub-wavelength metal nanostructures embedded into dielectric media, known as Metamaterials (MMs), have received enormous attention of scientific community [1,2]. They do not exist in nature and their extraordinary properties are determined by the interplay of their underlying materials properties and their structural arrangement. This opens up the possibilities to engineer materials by the tailoring and controlling of the values of relative electric permittivity, and magnetic permeability, ยต. The interaction of electromagnetic waves with such materials results in a number of unprecedented phenomena, such as the negative refraction [3], sub-wavelength imaging (superlens and hyperlens) [4, 5], and optical cloaking [6]. Current progress towards the fabrication of MMs has been enabled by advances in nanofabrication technology. Several structures that have been proposed have been synthesized for operation in the both microwave and optical frequencies ranges, such as split ring resonators [7], paired metal stripes [8], fishnet [9]. However, until now, the creation of 3D bulk MMs operating in the optical frequencies range has remained a major challenge because of significant optical losses and difficulties in fabrication. Recently, it has been shown that a metamaterial based on the regular array of silver nanowires embedded into Porous Anodic Alumina (PAA) membrane can be considered as the 3D bulk photonic metamaterial [3, 10]. In this work, we report on the synthesis of this type of metamaterial. Since it was first reported, the use of PAA membrane as template for the synthesis of nanowires has a long history [11, 12]. A range of methods for the synthesis of nanowires of different metals, including silver, gold and copper were developed [13-15]. Also in those reports, the relationship between synthesis, structure, and basic optical properties was established. A typical synthesis procedure [13] involves the deposition of a metal thin film on one of the sides of membrane, which serves as working electrode, followed by electrochemical deposition into the pores of the membrane where the pores are used to restrict the dimensions of the metal rods that form. The technique is reliable, simple and
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