Jan 22, 2010
Tunable surface plasmon resonance inside metals
Resonant absorption due to surface plasmons on conducting nanoparticles within an optically transmitting insulator is well known. Now, two Australian researchers have demonstrated that tunable surface plasmon resonance can also occur inside a reflecting conductor, if material is separated from the host by a thin insulating layer down to ~1 nm in thickness.
This sharp resonance is stronger than its well known counterpart, and tunable by varying shell thickness or having metal heterostructures. It exemplifies an important growing field – "Babinet's (principle) plasmonics" – in which the structure is mainly metal.
A metal-in-metal system is the Babinet's counterpart of insulator systems containing metal shells or rings, which have been studied for a decade for their geometric tunability and hybrid plasmon modes.
Exciting science and numerous applications for this new resonant class of materials are envisaged. For example, large-area flexible 2D examples mass produced in thin metal layers should be practical, with the challenge to see how thin the insulator rings can go.
The researchers presented their work in the journal Nanotechnology.
About the author
This work was performed at the Institute of Nanoscale Technology at the University of Technology, Sydney. Prof. Geoff Smith and his group have made many contributions to basic and applied nanoscience, thin films, solar energy and energy efficiency in buildings for 30 years. The group's nanoparticle and coating work currently spans optical control in the solar spectrum and thermal infrared, with the latter aimed at night sky cooling. Alan Earp is a research fellow whose recent PhD focused on fluorescent solar concentrators, daylighting and special paints. He then worked for a new technology start-up, Fluorosolar, from 2006 to 2008. This paper is relevant to energy-efficient windows and some of the samples studied were produced by Dr John Ridealgh at Pilkington laboratories, Lancashire, UK.