Observation of molecular dipole excitations by attosecond self-streaking

TL;DR

This paper introduces a method to observe ultrafast molecular dipole excitations using the molecule's own near-field as a streaking probe, enabling real-time tracking of electronic coherence in molecules.

Contribution

It presents a novel protocol combining ab-initio simulations and analytical modeling to detect molecular dipole oscillations via self-generated streaking fields.

Findings

Self-streaking accurately traces dipole oscillations.

Time-dependent near-field modulates photoelectron momentum.

Method applicable to ultrafast molecular dynamics studies.

Abstract

We propose a protocol to probe the ultrafast evolution and dephasing of coherent electronic excitation in molecules in the time domain by the intrinsic streaking field generated by the molecule itself. Coherent electronic motion in the endohedral fullerene \Necsixty~is initiated by a moderately intense femtosecond UV-VIS pulse leading to coherent oscillations of the molecular dipole moment that persist after the end of the laser pulse. The resulting time-dependent molecular near-field is probed through the momentum modulation of photoemission from the central neon atom by a time-delayed attosecond XUV pulse. Our ab-initio time-dependent density functional theory and classical trajectory simulations predict that this self-streaking signal accurately traces the molecular dipole oscillations in real time. We discuss the underlying processes and give an analytical model that captures the essence of our ab-initio simulations.