We demonstrate an experimental method to record snapshot diffraction images of polyatomic gas-phase
molecules, which can, in a next step, be used to probe time-dependent changes in the molecular geometry during
photochemical reactions with femtosecond temporal and angstrom spatial resolution. Adiabatically laser-aligned
1-ethynyl-4-fluorobenzene (C8H5F) molecules were imaged by diffraction of photoelectrons with kinetic energies
between 31 and 62 eV, created from core ionization of the fluorine (1s) level by ≈80 fs x-ray free-electronlaser
pulses. Comparison of the experimental photoelectron angular distributions with density functional theory
calculations allows relating the diffraction images to the molecular structure
