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Author: Bruner, B.D. × Type: Article ×

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    Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation
    ([London] : Nature Publishing Group UK, 2015) Ferré, A.; Boguslavskiy, A.E.; Dagan, M.; Blanchet, V.; Bruner, B.D.; Burgy, F.; Camper, A.; Descamps, D.; Fabre, B.; Fedorov, N.; Gaudin, J.; Geoffroy, G.; Mikosch, J.; Patchkovskii, S.; Petit, S.; Ruchon, T.; Soifer, H.; Staedter, D.; Wilkinson, I.; Stolow, A.; Dudovich, N.; Mairesse, Y.
    High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20-26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected.
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    Attosecond time-resolved photoelectron holography
    ([London] : Nature Publishing Group UK, 2018) Porat, G.; Alon, G.; Rozen, S.; Pedatzur, O.; Krüger, M.; Azoury, D.; Natan, A.; Orenstein, G.; Bruner, B.D.; Vrakking, M. J.J.; Dudovich, N.
    Ultrafast strong-field physics provides insight into quantum phenomena that evolve on an attosecond time scale, the most fundamental of which is quantum tunneling. The tunneling process initiates a range of strong field phenomena such as high harmonic generation (HHG), laser-induced electron diffraction, double ionization and photoelectron holography - all evolving during a fraction of the optical cycle. Here we apply attosecond photoelectron holography as a method to resolve the temporal properties of the tunneling process. Adding a weak second harmonic (SH) field to a strong fundamental laser field enables us to reconstruct the ionization times of photoelectrons that play a role in the formation of a photoelectron hologram with attosecond precision. We decouple the contributions of the two arms of the hologram and resolve the subtle differences in their ionization times, separated by only a few tens of attoseconds.
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    When does an electron exit a tunneling barrier?
    (Les Ulis : EDP Sciences, 2013) Shafir, D.; Soifer, H.; Bruner, B.D.; Dagan, M.; Mairesse, Y.; Patchkovskii, S.; Ivanov, M.Y.; Smirnova, O.; Dudovich, N.
    We probe the dynamics of tunnel ionization via high harmonic generation. We characterize the ionization dynamics in helium atoms, and apply our approach to resolve subtle differences in ionization from different orbitals of a CO 2 molecule.