Charge‐Tagged DNA Radicals in the Gas Phase Characterized by UV/Vis Photodissociation Action Spectroscopy.

Adenosine radicals tagged with a fixed‐charge group were generated in the gas phase and structurally characterized by tandem mass spectrometry, deuterium labeling, and UV/Vis action spectroscopy. Experimental results in combination with Born–Oppenheimer molecular dynamics, ab initio, and excited‐state calculations led to unambiguous assignment of adenosine radicals as N‐7 hydrogen atom adducts. The charge‐tagged radicals were found to be electronically equivalent to natural DNA nucleoside radicals. [ABSTRACT FROM AUTHOR]