Multi-octave continuum and X-ray probes to explore DNA base excited state dynamics
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Multi-octave continuum and X-ray probes to explore DNA base excited state dynamics
Tue, 16/06/2026 - 14:00 to 15:00
Location:
Speaker:
Stephen Bradforth
Affiliation:
University of Southern California
Synopsis:
Femtosecond supercontinua that simultaneously cover the visible, near and deep-ultraviolet open up new possibilities to probe photochemistry in the aqueous phase, particularly for molecular systems whose photoproducts only absorb in the ultraviolet. This spectral region contains key absorptions associated with amino acids and the nucleobases, the building blocks of DNA. We demonstrate this capability in transient absorption on the UV photohydration reaction of RNA derivative, 1,3-dimethyluracil and complement our study with time-resolved X-ray absorption employing the Stanford X-FEL, LCLS. We detect a <2% channel, demonstrating that the photohydration reaction occurs via a twisted ground-state intermediate.
Biography:
Stephen Bradforth is Professor of Chemistry at the University of Southern California. His lab designs experiments to understand how the inter-connected motions of molecules, and their quantum mechanical correlations, impact chemical reactions in complex environments. These include solution reaction media for chemical synthesis, biochemical environments, water-air interfaces or in functional molecular materials. Research in the Bradforth lab applies ultrafast laser techniques to address challenges such as UV damage to DNA, photochemistry, radical pairs, the mechanisms for solar energy conversion and photocatalysis as well as condensed phase ionization. Recent honors include the Research Corporation STAR award and the ACS Senior Experimental Physical Chemistry Award. He is Fellow of the American Physical Society, the Royal Society of Chemistry and the American Association for the Advancement of Science. He is a Benjamin Meaker visiting professor at Bristol University in 2026.
He earned his Ph.D. in physical chemistry from the University of California, Berkeley in 1992 after completing his undergraduate education at Cambridge University in 1987 where he read Natural Sciences.