Investigating Enhanced Multiple Ionization Near Conical Intersections in C2H2$+$

Nonadiabatic behavior near conical intersections (CIs) leads to strong nonradiative mixing between different electronic states in polyatomic molecules. Recently, evidence was shown that strong field multiple ionization was significantly enhanced near the CI driving the isomerization of CHD [1]. An interesting question is if it is a general feature that conical intersections enhance ionization rates. In this talk, we investigate the possibility of enhanced multiple ionization near the CI between the $A $and $X $states of the C2H2 cation, which is involved in the isomerization pathway to vinylidene. The cation is prepared in the $A $state nonlinearly using 50 fs pulses at 266 nm. The evolution of the nuclear wavepacket through the CI is then probed by a strong ultrafast pulse at 800 nm. Using a newly designed system to reconstruct the momenta of all ion fragments from a single Coulomb explosion event, we are able to see any enhancement of highly charged channels over doubly charged ones from events that are probed near the CI. [1] V.S. Petrovich et. al, J. Chem. Phys. 139, 184309 (2013)