By Patricia Daukantas

For hundreds of years, stained-glass windows have decorated medieval cathedrals and awed onlookers with their intricate, translucent designs. Now a researcher in Australia has discovered that some windows that date back to the Middle Ages contain 21^st-century-style light-activated nanotechnology.

Medieval windows painted with pigments containing gold particles actually purify the air when lit by sunlight, according to Huai Yong Zhu, associate professor of chemistry at Queensland University of Technology in Brisbane.

Zhu and colleagues found that the gold nanoparticles found in many pigmented glass windows in Europe become activated when struck by sunlight and remove volatile organic compounds (VOCs) from the air. VOCs are light hydrocarbons that vaporize easily, and many of them are considered pollutants in the gas phase.

In Zhu’s words, sunlight causes the small gold particles to act like a “photocatalytic air purifier.” The solar energy boosts the magnetic field on the surface of the nanoparticles and this in turn breaks apart airborne VOCs. Zhu is interested in the process because it is solar-powered and thus energy-efficient.

2008-08 August, Optics history optics history, nanotechnology