14 January 2011

Plasmonics: From metallic foils to cancer treatment

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In a timely review paper, scientists from Japan, Germany, and Spain provide a highly relevant overview of the history, physical interpretation and applications of plasmons in metallic nanostructures

The authors provide an extensive overview of the properties of plasmons in nanomaterials with emphasis on pioneering work of Ruthemann and Lang on electron energy loss spectroscopy (EELS) of electron motion in thin metal foils; recent infrared analysis of nanoscale metallic nanorods and nanoislands produced by ‘top-down’ photolithography; and the potential of metallic atomic wires for supporting plasmonic resonating modes. The review includes detailed explanations of plasmons for in vivo biosensing and nanoantennas.

A plasmon can be visualized as a collective oscillation of electronic ‘liquid’ in metals, similar to waves in lake, which are collective mode of the water molecules. Furthermore, surface plasmons are such oscillations confined to the surfaces of metals, which display a strong interaction with light, leading to the formation of so-called ‘polaritons’. Futuristic applications of plasmons include ideal lenses and even invisibility cloaks.

Research in the 1940s by Ruthemann and Lang on electrons flowing in thin metal foils using EELS yielded the first experimental sign of the presence of the theoretically predicted ‘plasma oscillations’ in metals. In 1957 Richie and colleagues predicted the existence of ‘surface localized’ plasmons, which was confirmed by Powell and Swan by EELS a few years later. In the 1960s researchers determined optical dispersion curves using optical spectroscopy, thereby opening up the possibility of optical applications of plasmon structures.

(Nanotechwire)

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