Singled-walled carbon nanotubes are graphene sheets wrapped into tubes, and are typically made up of various sizes and with different amounts of twist (also known as chiralities). Each type of nanotube has its own electronic and optical properties. Physicists at Osaka University in Japan used colored light to selectively manipulate different types of carbon nanotubes. They found that some of nanotubes displayed a tendency to cluster at the focal area of a focused laser beam.