Attosecond timing of electron emission from a molecular shape resonance

S. Nandi (1, 2) , E. Plésiat (3) , S. Zhong (1) , A. Palacios (3) , D. Busto (1) , M. Isinger (1) , L. Neoričić (1) , C. L. Arnold (1) , R. J Squibb (4) , R. Feifel (4) , P. Decleva (5) , A. L’huillier (1) , F. Martin (3, 6, 7, 8) , M. Gisselbrecht (1)

1 Skane University Hospital [Lund]
2 iLM - DYNAMO - iLM - Structure et dynamique multi-échelle des édifices moléculaires
3 UAM - Universidad Autónoma de Madrid
4 GU - Göteborgs Universitet = University of Gothenburg
5 Dipartimento di Scienze Chimiche e Farmaceutiche
6 Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
7 IFIMAC - Condensed Matter Physics Center
8 DIPC - Donostia International Physics Center

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 N2. 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.

Domaines: Sciences de l'ingénieur [physics]; Chimie; Physique [physics]

S. Nandi, E. Plésiat, S. Zhong, A. Palacios, D. Busto, et al.. Attosecond timing of electron emission from a molecular shape resonance. Science Advances , 2020, 6 (31), pp.eaba7762. ⟨10.1126/sciadv.aba7762⟩. ⟨hal-02920123⟩