• • Researchers from the TomATTO project use attosecond spectroscopy to explore the ultrafast dynamics of biphenyl.
  • Charge transfer in molecules occurs on ultrafast timescales and is closely linked to the movement of atoms.

Madrid, 13^th January 2026.

A new study reveals the ultrafast movements of electronic charge in a complex donor-acceptor molecule, 4-amino-4′-nitrobiphenyl (ANB). Researchers used attosecond pulse spectroscopy to observe how charge moves between donor and acceptor groups within this molecule. This method allows phenomena occurring on attosecond timescales, millions of times faster than a human blink, to be captured.

The results, published in the journal Ultrafast Science, show that charge transfer in biphenyl occurs in several stages. First, the molecule ‘flattens,’ facilitating ultra-fast charge movement. Then, oscillations in the charge distribution occur as a result of two factors: the electronic coherence generated by the pulse and the interaction with the movement of atoms. These observations highlight how electronic and nuclear dynamics are closely connected.

The study combines attosecond spectroscopy experiments with advanced theoretical simulations of density functional theory (DFT) and surface hopping, revealing a detailed picture of charge transfer at the atomic level as a function of time. These findings deepen our fundamental understanding of molecular chemistry, highlighting the relationship between structural transformations and their electronic footprints, and paving the way for innovations in ultrafast spectroscopy and controlled manipulation of molecular systems.

The work is the result of the European TomATTO project, funded by an ERC Synergy grant (G.A. 951224). TomATTO aims to capture the ultrafast dynamics of electrons with the goal of improving solar energy conversion efficiency.

Reference

Mocci, D; González, JR; Wu, YX; Vázquez, JG; Vismarra, F; Fernandez-Villoria, F; Urieta-Mora, J; Palacios, A; Recio, P; Cachon, J; Bañares, L; Lucchini, M; Reduzzi, M; Borrego-Varillas, R; Martín, N; Martín, F; Nisoli, M. Ultrafast Structural Reorganization and Charge Dynamics in a Photoionized Donor–Acceptor Biphenyl Molecule. Ultrafast Science 5, 0108 (2025). DOI: 10.34133/ultrafastscience.0108

Link to the paper in a Repository: https://hdl.handle.net/11311/1301277