High-Energy Long-Lived Excited States in DNA Double Strands

International audienceDark DNA light: Dark excited states of alternating GC double strands emit fluorescence at 4000 cm-1 higher energy (see spectrum) and with four orders of magnitude longer lifetime compared to the bright * states. Such high-energy long-lived excited states are expected to play a key role in the DNA photoreactivity associated with the appearance of carcinogenic mutations

Fluorescence of Natural DNA: From the Femtosecond to the Nanosecond Time Scales

International audienceThe fluorescence of calf thymus DNA is studied by steady-state and time-resolved spectroscopy combining fluorescence upconversion and time-correlated single photon counting. The fluorescence spectrum is very similar to that of a stoichiometric mixture of monomeric chromophores, arising from bright ππ* states, and contrasts with the existing picture of exciplex emission in natural DNA. Yet, the DNA fluorescence decays span over five decades of time, with 98% of the photons being emitted at times longer than 10 ps. These findings, in association with recent studies on model duplexes, are explained by the involvement of dark states, possibly related to charge separation, serving as a reservoir for the repopulation of the bright ππ* states

Guanine : From the mononucleotide to quadruplexes. A femtosecond fluorescence study

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Femtosecond studies of monomeric nucleic acid bases

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The local structure in the BmimPF(6)/acetonitrile mixture: the charge distribution effect

The effect of the charge distribution on the local structure in the binary mixture of 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF 6 ) ionic liquid and acetonitrile is investigated over the entire composition range