A team from Rice University in Texas, USA, has developed a method to manufacture stable, 3D nanoclusters that could be used to impart metamaterial optical properties into unstructured substrates such as liquids, glasses and plastics.
This work could lead to a new generation of optical emitters and sensors, molecular contrast agents, nanoscale lasers, and super lenses, the latter being optics that can potentially overcome the diffraction limit associated with traditional lenses.
The team, led by Professor Halas and Professor Nordlander, chose an Andor iKon-M NIR-enhanced CCD camera coupled to a hyperspectral imaging system to collect the dark-field scattering spectra of individual nanoclusters. Their results reveal a very strong agreement between the experimental spectral characterisation of 3D nanoclusters with varying configurations (number, geometry, and orientation of the cluster) and the team's theoretical calculations based on finite element analysis.
According to Professor Peter Nordlander: ‘The precise way in which the nanoparticles are arranged, rather than their composition, dictates the optical characteristics through an effect called localised surface plasmon resonance. The Andor iKon-M camera played a key role; the very low dark current due to the advanced thermoelectric cooling, combined with high sensitivity over a large wavelength regime, allowed us to image even very weakly-scattering nanoparticles to determine their optical properties.’
Professor Naomi Halas added: ’The universality of the fabrication method could extend the use of plasmonic nanoclusters to other regions of the spectrum by incorporating different materials, for example, aluminium for the UV. They are also compatible with easily applied material coating methods, such as aerosols, and could lead to materials with transparency windows at specific frequencies and with constant ratios and linewidths. They could also enable electromagnetic characteristics not yet achievable in current types of metamaterials, as well as new approaches to current technological challenges, such as high-throughput chemical and biological sensing.’