Attosecond timing of electron emission from a molecular shape resonance

Abstract

Shape resonances in physics and chemistry arise from the spatial confinement of a particle by a potential barrier. In molecular photoionization, these barriers prevent the electron from escaping instantaneously, so that nuclei may move and modify the potential, thereby affecting the ionization process. By using an attosecond two-color interferometric approach in combination with high spectral resolution, we have captured the changes induced by the nuclear motion on the centrifugal barrier that sustains the well-known shape resonance in valence-ionized N${}_2$. We show that despite the nuclear motion altering the bond length by only $2\%$, which leads to tiny changes in the potential barrier, the corresponding change in the ionization time can be as large as $200$ attoseconds. This result poses limits to the concept of instantaneous electronic transitions in molecules, which is at the basis of the Franck-Condon principle of molecular spectroscopy.

arXiv comment24 pages, 5 figures

References in corpus (7)

• Probing single-photon ionization on the attosecond time scale
• Photoionization in the time and frequency domain
• Observation of Quantum Effects in sub Kelvin Cold Reactions
• Attosecond dynamics through a Fano resonance: Monitoring the birth of a photoelectron
• Theory of attosecond delays in laser-assisted photoionization
• Attosecond delays in molecular photoionization
• Phase-resolved attosecond near-threshold photoionization of molecular nitrogen

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