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arXiv · 1405.4732

Modulation of attosecond beating in resonant two-photon ionization

Álvaro J. Galán·Luca Argenti·Fernando Martín
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Abstract

We present a theoretical study of the photoelectron attosecond beating at the basis of RABBIT (Reconstruction of Attosecond Beating By Interference of Two-photon transitions) in the presence of autoionizing states. We show that, as a harmonic traverses a resonance, its sidebands exhibit a peaked phase shift as well as a modulation of the beating frequency itself. Furthermore, the beating between two resonant paths persists even when the pump and the probe pulses do not overlap, thus providing a sensitive non-holographic interferometric means to reconstruct coherent metastable wave packets. We characterize these phenomena quantitatively with a general finite-pulse analytical model that accounts for the effect of both intermediate and final resonances on two-photon processes, at a negligible computational cost. The model predictions are in excellent agreement with those of accurate ab initio calculations for the helium atom in the region of the N=2 doubly excited states.

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Álvaro J. Galán, Luca Argenti, Fernando Martín. 2014-05-19. Modulation of attosecond beating in resonant two-photon ionization. https://doi.org/10.1103/physrevlett.113.263001

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