Primary processes induced in DNA multimers (single and double strands, guanine quadruplexes) by direct UV radiation absorption are studied using time-resolved optical spectroscopy. Most studies are conducted within the framework of the European project LightDyNAmics.

The ubiquity of high-energy emission with a nanosecond lifetime in double helices has been highlighted [Vaya2022, Gustavsson2023], as illustrated in the figure, and has also been detected in a guanine quadruplex [Balanikas2022]. Additionally, by combining femtosecond transient absorption and quantum chemistry calculations, the effect of DNA polarity (the way bases are linked from the 5' to the 3' position) on electronic relaxation has been demonstrated for the first time [Petropoulos2023]. Finally, structural parameters that could be useful for the development of biosensors using optical and electrical signals, associated with intrinsic fluorescence and low-energy photoionization of guanine quadruplexes, have been cataloged [Markovitsi2023].