Time-resolved Coulomb Explosion Imaging of the Ultrafast Ring-opening Reaction of Furan

The ultrafast molecular dynamics of gas-phase furan were investigated by time-resolved Coulomb explosion imaging (CEI). The ultrafast nonadiabatic transitions leading to ring opening were initiated by ultraviolet (200 nm) excitation. The transient molecular geometries were probed by CEI induced by near-infrared laser pulses and visualized as Newton plots. These Newton plots displayed clearly changing structures as a function of pump-probe delay. Molecular dynamics simulations revealed that the ring-opening reaction led to an isomer with a carbon-chain structure that is responsible for the observed changes in the Newton plot.