Hannover 2013 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 14: Poster 1: Cluster, Femtosecond Spectroscopy
MO 14.6: Poster
Dienstag, 19. März 2013, 16:00–18:30, Empore Lichthof
Attosecond electronic coherence in molecular dissociation — •Lukas Medišauskas1, 2 and Misha Ivanov1, 2 — 1Imperial College London, UK — 2Max-Born-Institute Berlin, Germany
We show that electronic coherence can significantly influence nuclear dynamics when interference of paths associated with vibrational motion along different potential energy surfaces becomes important.
We consider attosecond XUV pump - IR probe setup. A N2 molecule is first ionized by an XUV pump pulse. Ionization creates a coherent superposition of two excited electronic states in N2+ ion. The dissociation of the molecular ion then takes place over two different potential energy surfaces. Interaction with IR field ensures that both of them lead to the same dissociation limit. The fragment spectrum obtained depends significantly on how the two paths interfere.
Interference is observed if the continuum electron wavepackets correlated with each of the paths have an overlap. This condition is set during ionization, which happens in a fraction of a femtosecond and is given by the length of the XUV pump pulse. However, it determines the appearance of molecular dissociation spectrum hundreds of femtoseconds later.
When one of the pathways involves a direct and the other a sequential transition to a dissociative state, the phase acquired along the propagation on sequential path creates a chirp in the interference pattern. This chirp encodes information on the initial wavepacket and the potential energy surface.