Strong-field ionization of complex molecules

Abstract

Strong-field photoelectron momentum imaging of the prototypical biomolecule indole is disentangled in a combined experimental and computational approach. Experimentally, strong control over the molecules enables the acquisition of photoelectron momentum distributions in the molecular frame for a well-defined narrow range of incident intensities. A highly efficient semiclassical simulation setup based on the adiabatic tunneling theory quantitatively reproduces these results. Jointly, experiment and computations reveal holographic structures in the asymptotic momentum distributions, which are found to sensitively depend on the alignment of the molecular frame. We identify the essential molecular properties that shape the photoelectron wave packet in the first step of the ionization process and employ a quantum-chemically exact description of the cation during the subsequent continuum dynamics. The detailed modeling of the molecular ion, which accounts for its polarization by the laser electric field, enables the accurate description of the photoelectron dynamics in close vicinity of the molecule. Our approach provides full insight into the photoelectron's dynamics in terms of semiclassical trajectories and aims at the simulation and unraveling of strong-field diffractive imaging of biomolecular systems on femtosecond timescales.