Cathodoluminescence Used to Probe Metamaterials

True-color cathodoluminescence image taken with the Cameca SX100. Fluorite (blue-violet) is shown associated with calcite (yellow-orange) in a carbonatite from India. Credit: Natural History Museum UK

The phenomenon of cathodoluminescence gave geologists an easy way to identify quartz and other minerals in rock samples. Cathodoluminescence allows a piece of quartz to glow icy blue when put under an electron scanning microscope. Now, scientists have used this phenomenon to probe into nanostructures.

The scientists published their findings in the journal Physical Review Letters¹. The light, emitted after a beam of electrons kicks a material’s own electrons in to a higher-energy state, is faint and diffuse, thus discouraging scientists from harnessing it for fine-scale imaging. A Dutch group has found a way to collect and focus this light, which was previously ignored. They used it to probe a material’s nanoscale structure. The technology will reach the market early this year, giving scientists another tool to investigate the behavior of light in the interiors of the complex nanostructures used in lasers, light-based circuits and solar cells.

The technique has the advantage of combining optical and electron-based imaging. An electron beam can achieve a resolution of less than one nanometer, but a beam of light achieves a few hundred nanometers. Maps made by scattered or reflected electrons are not typically sensitive to the way light behaves in the sample. Cathodoluminescence can map the interaction of light and matter and since it’s triggered by a narrow beam of electrons, it can achieve the same nanoscale resolution.

Source: Ernst Jan Vesseur & Toon Coenen (Amolf)

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