X-ray induced Coulomb explosion images of toluene and its isomers*

We present the progress of an experiment on the soft x-ray induced Coulomb explosion of toluene and other C7H8 isomers. Coulomb explosion imaging is a powerful technique that can intuitively link fragment ion momenta to the full three-dimensional molecular geometry. This technique is particularly suited to high-repetition-rate XFEL facilities and has proven effective when probing polyatomic molecules with planar symmetry and ”marker atoms” with high x-ray absorption cross sections that help define a fragmentation within the molecular plane [1]. We show that Coulomb explosion imaging can also be extended to the aforementioned pure hydrocarbons, some of which are not planar, and note that the kinetic energies and angular distributions of the ensuing fragments vary depending on the cyclic or acyclic geometries of the molecule. We additionally show promising results employing time-resolved Coulomb explosion imaging to observe ultrafast ring reconfiguration of toluene upon strong-field ionization.

[1] R. Boll., et al. X-ray multiphoton-induced Coulomb explosion images complex single molecules. Nat. Phys. 18, 423–428 (2022).