Electrotunable nanoplasmonic liquid mirror. Nature Materials, 2017; DOI: 10.1038/nmat4969
By finely tuning the distance between nanoparticles in a single layer, researchers have made a filter that can change between a mirror and a window. The development could help scientists create special materials whose optical properties can be changed in real time. These materials could then be used for applications from tuneable optical filters to miniature chemical sensors. Creating a ‘tuneable’ material has been a challenge because of the tiny scales involved. In order to tune the optical properties of a single layer of nanoparticles – which are only tens of nanometres in size each – the space between them needs to be set precisely and uniformly.
To form the layer, the team from Imperial College London created conditions for gold nanoparticles to localise at the interface between two liquids that do not mix. By applying a small voltage across the interface, the team have been able to demonstrate a tuneable nanoparticle layer that can be dense or sparse, allowing for switching between a reflective mirror and a transparent surface.
The distance between the nanoparticles determines whether the layer permits or reflects different wavelengths of light. At one extreme, all the wavelengths are reflected, and the layer acts as a mirror. At the other extreme, where the nanoparticles are dispersed, all wavelengths are permitted through the interface and it acts as a window. In contrast to previous nanoscopic systems that used chemical means to change the optical properties, the team’s electrical system is reversible.
Professor Alexei Kornyshev, from the Department of Chemistry at Imperial, said: “Finding the correct conditions to achieve reversibility required fine theory; otherwise it would have been like searching for a needle in a haystack. It was remarkable how closely the theory matched experimental results.”
http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_5-9-2017-11-56-31</a
Recent Comments