Title: Coherent high-harmonic spectroscopy of electronic dynamics in molecules Speaker: Hans Jakob Wörner Laboratorium für Physikalische Chemie, ETH Zürich, Switzerland Time: Thursday, October 6, 15.15 to 16.00 Place: Fysisk Auditorium Abstract: Electrons determine most properties of matter, yet observing their motion is a major challenge. In the past years, the emerging tools of attosecond science have enabled major progress towards this goal. In this presentation we will discuss recent advances in the development of high-harmonic spectroscopy as a method for probing electronic structure and dynamics in molecules. Exploiting the coherence properties of high-harmonic generation in a transient grating geometry enables one to measure both the amplitude and phase of the emitted extreme-ultraviolet radiation in a self-referenced (homodyne) detection. Aligned molecules can be measured relative to a randomly aligned sample, giving access to the complex photorecombination dipole moments. The dynamics of photoexcited molecules can be temporally resolved against the unexcited molecules of the sample, resulting in a high sensitivity. Recent experiments on the photodissociation of Br2 showed that high-harmonic spectroscopy probes the evolution of the electronic structure of the molecule along the dissociation coordinate [1]. In NO2, the method reveals the change in electronic symmetry that occurs when the photoexcited wave packet crosses a conical intersection and the subsequent statistical photodissociation dynamics [2]. [1] H. J. Wörner, J. B. Bertrand, D. V. Kartashov, P. B. Corkum and D. M. Villeneuve, "Following a chemical reaction using high-harmonic interferometry", Nature 466, 604 (2010). [2] H. J. Wörner, J. B. Bertrand, B. Fabre, J. Higuet, H. Ruf, A. Dubrouil, S. Patchkovskii, M. Spanner, Y. Mairesse, V. Blanchet, E. Mével, E. Constant, P. B. Corkum and D. M. Villeneuve, "Conical intersection dynamics in NO2 probed by homodyne high-harmonic spectroscopy", Science, accepted (2011). Jacob Sherson and Aurélien Dantan Coffee, tea and cake will be served at 15.05 ----------------------------------- Aurelien Dantan Ion Trap Group Department of Physics and Astronomy University of Aarhus Ny Munkegade, bygn. 1520 8000 Aarhus Denmark +4589423602