Structure of Carbon Nanotube (CNT). (IMAGE) Institute for Basic Science Caption (Left) Illustration of rolling graphene into CNTs of different structures, denoted by two indices, like (8,4). (Right) Microscope images of an array of CNTs with the mean diameter of 1.21 nm. Credit IBS Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.