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Subnanosecond Emission Dynamics of AT DNA Oligonucleotides
Author(s) -
Skowron David J.,
Zhang Yuyuan,
Beckstead Ashley A.,
Remington Jacob M.,
Strawn Madison,
Kohler Bern
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600566
Subject(s) - excited state , picosecond , excimer , ultrafast laser spectroscopy , relaxation (psychology) , atomic physics , chemistry , absorption (acoustics) , emission spectrum , photochemistry , fluorescence , molecular physics , materials science , spectroscopy , optics , laser , physics , spectral line , psychology , social psychology , quantum mechanics , astronomy , composite material
UV radiation creates excited electronic states in DNA that can decay to mutagenic photoproducts. When excited states return to the electronic ground state, photochemical injury is avoided. Understanding of the available relaxation pathways has advanced rapidly during the past decade, but there has been persistent uncertainty, and even controversy, over how to compare results from transient absorption and time‐resolved emission experiments. Here, emission from single‐ and double‐stranded AT DNA compounds excited at 265 nm was studied in aqueous solution using the time‐correlated single photon counting technique. There is quantitative agreement between the emission lifetimes ranging from 50 to 200 ps and ones measured in transient absorption experiments, demonstrating that both techniques probe the same excited states. The results indicate that excitations with lifetimes of more than a few picoseconds are weakly emissive excimer and charge transfer states. Only a minute fraction of excitations persist beyond 1 ns in AT DNA strands at room temperature.