Hamburg 2009 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 34: Poster II
A 34.15: Poster
Donnerstag, 5. März 2009, 16:30–19:00, VMP 9 Poster
Origin for the high harmonic spectral minimum in N2 — •Markus Gühr, Brian K. McFarland, Joseph P. Farrell, and Philip H. Bucksbaum — Stanford PULSE Institute, SLAC National Accelerator Lab, Menlo Park, CA 94025 and Physics Department, Stanford University, Stanford CA 94305, USA
High harmonic generation is decomposed into three steps including 1) ionization from the highest occupied orbital, 2) acceleration of the ionized electron in the laser field and 3) recombination of that electron with the ionized orbital transferring the electron kinetic energy into a photon. Destructive interferences between the recombining free electron wave and the ionized molecular orbital modulate the high harmonic amplitude and phase according to a geometrical model [1].
We observe a phase jump accompanied by a spectral minimum for HHG in N2. In alignment experiments, the minimum shifts to lower harmonics for increasing the angle between the molecular axis and harmonic generation polarization. Furthermore, the minimum shifts to higher harmonics with increasing harmonic generation intensity. We find that the features observed in N2 cannot be fully explained by a geometrical model and discuss alternative approaches via a multi-orbital model [2].
Lein et al., Phys. Rev. A, 66, 023805 (2002)
B. K. McFarland, J. P. Farrell, P. H. Bucksbaum and M. Gühr, Science 322, 1232 (2008)