Hannover 2016 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 1: Quantum Control and Femtosecond Spectroscopy 1
MO 1.1: Vortrag
Montag, 29. Februar 2016, 11:00–11:15, f102
Controlling the ultrafast relaxation dynamics of uracil: A theoretical study — •Daniel Keefer1, Sebastian Thallmair1, Spiridoula Matsika2, and Regina de Vivie-Riedle1 — 1Department Chemie, LMU München — 2Department of Chemistry, Temple University, Philadelphia, USA
The RNA nucleobase Uracil exhibits ultrafast relaxation dynamics after optical excitation to the second electronically excited state S2 (first bright state) 1. With the constantly increasing capabilities of experimental pulse shaping techniques at hand, it is an obvious question how the dynamics of such a biologically relevant molecule can be influenced. We will give theoretical insights on this issue by designing laser pulses with the help of quantum optimal control theory (OCT).
The 2D potential energy surface for the S2 state of Uracil exhibits a double well structure and contains a conical intersection (CoIn) seam. After excitation to the S2 state, the nuclear wave packet evolves via a local minimum to the CoIn seam, and subsequently relaxes to the S1 state. This relaxation process happens on the femtosecond timescale. We optimized laser pulses to influence the ultrafast dynamics in two extreme ways: One goal was to directly steer the wave packet to the conical intersection seam, and thereby to shorten the time for relaxation to the ground state. Another optimization aim was to keep the wave packet in the S2 state as long as possible by trapping it in the local minimum and potentially prevent relaxation via the CoIn seam.
1 S. Matsika et al., J. Phys. Chem. A 117 (2013), 12796.