Hole interactions with molecular vibrations on DNA.
We report on a study of the interactions between holes and molecular vibrations on dry DNA using photoinduced infrared absorption spectroscopy. Laser photoexcited holes are found to have a room-temperature lifetime in excess of tau > 1 ms, clearly indicating the presence of localization. However, from a quantitative model analysis of the frequency shifts of vibrational modes caused by the holes, we find the hole-vibrational coupling constant to be relatively small, lambda approximately 0.2. This interaction leads to a change in the conformational energy of DeltaE0 approximately 0.015 eV, which is too small to cause self-trapping at room temperature. We conclude that, at least in the dry (A) form, DNA is best understood in terms of a double chain of coupled quantum dots arising from the pseudorandom chain sequence of base pairs, in which Anderson localization prevents the formation of a metallic state.
Omerzu
Ales
A
Department of Complex Matter, Institute Jozef Stefan, Jamova 39, 1000 Ljubljana, Slovenia.
Licer
Matjaz
M
Mertelj
Tomaz
T
Kabanov
Viktor V
VV
Mihailovic
Dragan
D
D004247:DNA / Q000737:chemistry*; D010777:Photochemistry; D013055:Spectrophotometry, Infrared / Q000379:methods; D013816:Thermodynamics
D004247:DNA