Berlin 2005 – wissenschaftliches Programm
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MO: Molekülphysik
MO 15: Biomolecules II
MO 15.4: Vortrag
Freitag, 4. März 2005, 17:45–18:00, HU 2097
Excited state H-transfer and conical intersections in 2-aminopyridine: A model for DNA base pairs — •Thomas Schultz, E. Samoylova, W. Radloff, and I.V. Hertel — Max-Born-Institut Berlin, Max-Born Strasse 2a, 12489 Berlin, Germany
2-Aminopyridine (2AP) dimer allows the investigation of basic photochemical reaction mechanisms in hydrogen bonded chromophores. Time resolved ionization spectroscopy revealed nanosecond excited state lifetimes for the 2AP monomer and larger clusters (2APn ≥ 3), but a remarkably accelerated excited state relaxation (τ = 65 ps) for the H-bound dimer. This fast relaxation was assigned to an excited state H-transfer and subsequent relaxation via conical intersections to the electronic ground state. Calculated cluster structures indicated that the H-transfer occurs only in near-planar doubly H-bound structures. The same process may occur in the Watson-Crick base pair guanine-cytosine and could thus contribute to the photochemical stability of DNA.