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UV Spectra and Excitation Delocalization in DNA: Influence of the Spectral Width
Author(s) -
Emanuele Emanuela,
Markovitsi Dimitra,
Millié Philippe,
Zakrzewska Krystyna
Publication year - 2005
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.200500014
Subject(s) - delocalized electron , excited state , exciton , chemistry , oscillator strength , absorption spectroscopy , spectral line , molecular physics , atomic physics , excitation , dipole , singlet state , physics , condensed matter physics , optics , quantum mechanics , organic chemistry
The singlet excited states of the model DNA duplex (dA) 10 .(dT) 10 are studied. Calculations are performed in the exciton theory framework. Molecular dynamics calculations provide the duplex geometry. The dipolar coupling is determined using atomic transition charges. The monomer transition energies are simulated by Gaussian functions resembling the absorption bands of nucleosides in aqueous solutions. Most of the excited states are found to be delocalized over at least two bases and result from the mixing of different monomer states. Their properties are only weakly affected by conformational changes of the double helix. On average, the highest oscillator strength is carried by the upper eigenstates. The duplex absorption spectra are shifted a few nanometers to higher energies with respect to the spectra of noninteracting monomers. The states with larger spatial extent are located close to the maximum of the absorption spectrum.