Darmstadt 2008 – scientific programme
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MO: Fachverband Molekülphysik
MO 4: Femtosekundenspektroskopie II
MO 4.1: Talk
Monday, March 10, 2008, 16:30–16:45, 3G
Monitoring Electron Tunneling Dynamics in Molecules with Attosecond Precision — •Stefanie Graefe and Misha Yu. Ivanov — Steacie Insitute for Molecular Sciences, National Research Council Canada, Canada
Recent experiments have demonstrated control of electron localization during strong-field induced ionization and subsequent dissociation of molecular deuterium (D2) (Kling et al., Science 2006). As the molecular ion D2+ created after strong-field ionization vibrates, the returning electron excites the molecular ion into the dissociative σu state. Re-collision and excitation of the σu state occur in the presence of the strong laser field, which creates a coherent superposition of the σu and σg states. This superposition corresponds to an electron localized on one of the two protons, breaking the symmetry in molecular dissociation.
To observe electronic dynamics, the spectroscopic techniques have to be on the same time-scale as the dynamics to be observed - the attosecond time-scale. Although attosecond pulses are spectrally very broad (several eV), we demonstrate that information about electronic tunneling motion can be extracted by monitoring asymmetries in the time-resolved photoelectron distribution. A theoretical description for calculating time-resolved spectra in the presence of a strong laser field is given. Taking the electronic localization dynamics as an example, it is demonstrated that electron tunneling can be observed by interferences in the photoelectron spectra, based on a mechanism similar to interfering pathways in coherent control (double-slit setup).