New Compound Can Transform Infrared into Visible Light

A team of scientists in Germany has developed a compound that can transform infrared into warm, white-colored light.

The new compound emits a broadband spectrum of light upon excitation with an infrared laser. Image credit: Nils Wilhelm Rosemann.

The team, headed by Dr. Nils Wilhelm Rosemann of the Philipps-Universität Marburg, designed their compound of tin and sulfur, and with a diamondoid-like structure, then coating this scaffolding with organic ligands.

“The compound [(R^delocSn)₄S₆](R^deloc=4–(CH₂=CH)–C₆H₄) was obtained as a fine amorphous powder,” Dr. Rosemann and co-authors said.

This compound is non-volatile, air-stable, and thermally stable up to 572 degrees Fahrenheit (300 degrees Celsius).

“Inorganic nanocrystals form the core of this compound and are coated with organic ligands on the surface,” they explained.

When a laser directs near-infrared light into the compound, the structure of the compound alters the wavelength of the light through a non-linear interaction process, producing light at wavelengths that are visible to the human eye.

“The visible part of the spectrum resembles the color of a tungsten-halogen lamp at 2,900 Kelvin while retaining the superior beam divergence of the driving laser,” the researchers said.

“The emitted light is also exceedingly directional, a desirable quality for devices like microscopes that require high spatial resolution, or for applications with high throughput, such as projection systems.”

This development could open up new routes for advanced directed illumination technologies, especially since the materials used in this system are cheap, readily available, and easily scalable.

Dr. Rosemann and co-authors published their findings in the journal Science.

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Nils W. Rosemann et al. 2016. A highly efficient directional molecular white-light emitter driven by a continuous-wave laser diode. Science, vol. 352, no. 6291, pp. 1301-1304; doi: 10.1126/science.aaf6138