Multi-body fragmentation dynamics explored using coincidence momentum imaging with native frames analysis*

As both detector and light source technologies progress, experimental studies of the multi-body fragmentation of polyatomic molecules using coincidence momentum imaging become more feasible. Our goal is to gain detailed insight into both concerted and sequential (i.e. step-wise) molecular dynamics, which we accomplish by using native frames analysis [1].  

The advantage of the native frames method is that it provides a framework to analyze and interpret multi-body fragmentation, which is typically challenging due to the high dimensionality inherent to such data. In one example, we study the sequential fragmentation of D₂O molecules into D⁺ + D⁺ + O + 2e^- following double ionization. Specifically, we pinpoint the precise electronic states involved in each sequential breakup step, image the internal energy of the OD⁺ intermediate above the D⁺ + O (³P) dissociation limit, and show how the angular momentum of the intermediate manifests as a threshold behavior in the kinetic energy release of the second step.  In addition, we discuss experimental progress towards imaging four-body sequential fragmentation and towards time-resolved studies where the strong-field pump and probe initiate each breakup step.

This work is in collaboration with the groups of Itzik Ben-Itzhak, Daniel Rolles, Artem Rudenko, Thorsten Weber, Bill McCurdy, Robert Lucchese, Daniel Slaughter, Joshua Williams, Allen Landers, and Reinhard Dörner.

[1] Phys. Rev. Lett. 120, 103001 (2018)