The team, led by Prof. Koichi Komatsu of the Kyoto University Institute for Chemical Research, made a hole in a fullerene with a diameter of 0.7 nanometer, put a hydrogen molecule inside, and closed the opening, all through the molecular surgical method, which relies on chemical and thermal reactions. One nanometer is a billionth of a meter. They achieved a yield of 8.8 pct, dramatically improving productivity compared with conventional methods based on physical techniques, such as high-pressure and high-temperature treatment with gasses, which are difficult to control.

The technology may lead to the controlled production of "endohedral fullerenes," which are nano-sized closed-cage carbon molecules that have atoms or a molecule trapped inside them.

The researchers reported that a fullerene that contained a hydrogen molecule was as stable as the one without the molecule: the molecule did not escape even when heated to 500 degrees Centigrade for 10 minutes.

Their method may be applied to encapsulate other types of atoms and molecules. Organic synthesis can be a "powerful means" for the production of "yet unknown classes of endohedral fullerenes," they said in the report.