Attosecond dynamics through Fano resonances

Monday, October 9, 2017 - 3:00pm to 4:00pm

Speaker:  Lou Barreau of CEA

Program Description:

Autoionization arises when an atom or a molecule is excited to a quasi-bound state above its ionization potential. The interferences between the quasi-bound state and the neighboring continuum through configuration interaction, first described by Fano [1], lead to an asymmetric line shape in the spectral domain and a typical lifetime of tens of femtoseconds in the temporal domain. The lifetime is not sufficient to describe entirely the autoionization dynamics, in particular the above-mentioned interferences at birth time. This information is encoded in the complex transition amplitude, and thus requires the measurement of its amplitude and phase [2].

The recent progress in attosecond spectroscopy is making possible the spectral characterization of this resonant electron wave packet. Using spectrally-resolved electron interferometry, the so-called Rainbow RABBIT method, we fully characterize the electron wave packet emitted through a Fano resonance [3]. This allows reconstructing the complete ionization dynamics, including the resonance buildup. This evidences how photoelectron wave packets are born and morph into asymmetric Fano profiles.

[1] U. Fano, Phys. Rev. 124, 1866 (1961).

[2] M. Kotur et al., Nat. Commun. 7, 10566 (2016).

[3] V. Gruson et al., Science 354, 734 (2016).

Attosecond dynamics through Fano resonances
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