FLUORO 1 (IMAGE) Rice University Caption Rice University chemist Han Xiao and his colleagues have discovered a simple method to turn fluorescent tags on and off with visible light by switching one atom. Credit Jeff Fitlow/Rice University 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.