Ultrafast internal conversion of excited cytosine via the lowest pipi electronic singlet state.
Computational evidence at the CASPT2 level supports that the lowest excited state pipi* contributes to the S1/S0 crossing responsible for the ultrafast decay of singlet excited cytosine. The computed radiative lifetime, 33 ns, is consistent with the experimentally derived value, 40 ns. The nOpi* state does not play a direct role in the rapid repopulation of the ground state; it is involved in a S2/S1 crossing. Alternative mechanisms through excited states pisigma* or nNpi* are not competitive in cytosine.
Merchán
Manuela
M
Departamento de Química Física, Instituto de Ciencia Molecular, Universitat de València, Dr. Moliner 50, Burjassot, ES-46100 Valencia, Spain. manuela.merchan@uv.es
Serrano-Andrés
Luis
L
D003596:Cytosine / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D008956:Models, Chemical; D012313:RNA / Q000737:chemistry; D013816:Thermodynamics
D012313:RNA; D003596:Cytosine; D004247:DNA