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MO: Fachverband Molekülphysik

MO 5: Quantenkontrolle 1

MO 5.3: Vortrag

Montag, 2. März 2009, 14:30–14:45, VMP 6 HS-G

Investigation of electronic and vibrational coherence in molecules by phase-locked double pulses — •Nils Krebs¹, Peter Baum¹, Jürgen Hauer², and Eberhard Riedle¹ — ¹Lehrstuhl für BioMolekulare Optik, LMU München — ²Institut für Physikalische Chemie, Universität Wien

We investigated the femtosecond coherence dynamics of organic molecules in solution in a coherent control experiment based on transient absorption with double pulse excitation. The first pump pulse induces polarization oscillating with the transition frequency connecting ground and excited state. The second pulse with a well determined relative phase interacts constructively or destructively with the previously induced polarization. Hence, the obtained interference signal is a measure for electronic dephasing. A third pulse probes the excited state population at a ps delay time. The pulses were generated as identical copies of Fourier limited 11 fs visible pulses via a stabilized Michelson interferometer. In agreement with the expectation for a simple two-level system (here Perylene Orange in solution) the results are interpreted with the aid of homogeneous and inhomogeneous broadening mechanisms affecting the absorption line width. Extension of the pumping wavelength to the UV (350 nm, 22 fs pulse duration) allowed for the investigation of transient electronic and the vibrational phase effects during the excited state intramolecular proton transfer (ESIPT) of HBT. The double pulse temporal spacing was found to be the decisive control parameter for vibrational wavepacket control.