  Filming atomic motion within molecules is an active pursuit of molecular
physics and quantum chemistry. A promising method is laser-induced Coulomb
Explosion Imaging (CEI) where a laser pulse rapidly ionizes many electrons from
a molecule, causing the remaining ions to undergo Coulomb repulsion. The ion
momenta are used to reconstruct the molecular geometry which is tracked over
time (i.e. filmed) by ionizing at an adjustable delay with respect to the start
of interatomic motion. Results are distorted, however, by ultrafast motion
during the ionizing pulse. We studied this effect in water and filmed the rapid
"slingshot" motion that enhances ionization and distorts CEI results. Our
investigation uncovered both the geometry and mechanism of the enhancement
which may inform CEI experiments in many other polyatomic molecules.

Chemical Physics;Atomic Physics;Optics;Quantum Physics