Researchers at Ohio State University published a paper in the Proceedings of the National Academy of Sciences demonstrating their studies of high-energy states of DNA and RNA using ultraviolet light, rather than fluorescence, illustrating what they call the "dark state" of these molecules. Since UV light can lead to genetic alterations, it is posited that these "dark states" may cause damage to DNA.
Access to the full article requires a subscription to PNAS. Click here for the abstract or here for the layman's version on the Buckeye website.