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Updated: Jul 15, 2026

Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
Dynamics of photoinduced processes in adenine and thymine base pairs
E Samoylova1, H Lippert, S Ullrich
1Max-Born-Institut, Max-Born-Strasse 2a, D-12489 Berlin, Germany.
Abstract:
The excited-state dynamics of adenine and thymine dimers and the adenine-thymine base pair were investigated by femtosecond pump-probe ionization spectroscopy with excitation wavelengths of 250-272 nm. The base pairs showed a characteristic ultrafast decay of the initially excited pi pi* state to an n pi* state (lifetime tau(pi pi*) approximately 100 fs) followed by a slower decay of the latter with tau(n pi*) approximately 0.9 ps for (adenine)2, tau(n pi*) = 6-9 ps for (thymine)2, and tau(n pi*) approximately 2.4 ps for the adenine-thymine base pair. In the adenine dimer, a competing decay of the pi pi* state via the pi sigma* state greatly suppressed the n pi* state signals. Similarities of the excited-state decay parameters in the isolated bases and the base pairs suggest an intramonomer relaxation mechanism in the base pairs.
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