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SYFM: Symposium Quantenkontrolle funktionaler Moleküle

SYFM 1: Quantum control of functional molecules I

SYFM 1.3: Hauptvortrag

Mittwoch, 21. März 2007, 15:00–15:30, 6C

Mode-selective control in complex molecules with shaped femtosecond pulses — •Marcus Motzkus¹, Tiago Buckup¹, Jürgen Hauer¹, and Carles Serrat² — ¹Physikalische Chemie, Philipps-Universität Marburg, D-35032 Marburg, Germany — ²Departament de Fisica, Universitat Politecnica de Catalunya, 09822 Terrassa, Spain

Coherent control of vibrational modes is essential for manipulating photochemistry on ground and excites states since such oscillations may represent motion along the desired reaction coordinate. One well established mechanism for optimizing vibrations in time domain exploits pulse sequences with temporal spacing between the sub pulses equal to an integer multiple of the vibrational period. To explore the underlying mechanism it is important to understand if an optimally shaped laser pulse can overcome the limitations defined by Fourier-limited laser pulse of equal laser energy, i.e. the shaped pulse does not act merely as a filter but actual enhancement of population and coherence is obtained. We show that excitation with electronically resonant or far off-resonant laser pulse spectra cause no enhancement, while with near resonant excitation (blue or red shifted) the vibrational modes can be amplified by almost a factor of 2. A four-level density matrix simulation supports the experimental findings and underlines the crucial role of electronic resonances for effective mode-control.