Quantum-mechanical treatment of sequential three-body fragmentation

We study the sequential fragmentation process of a triatomic molecule $ABC$ into its constituent atoms $A$, $B$, and $C$ --- e.g., $ABC$$\rightarrow$$AB$+$C$$\rightarrow$$A$+$B$+$C$, where the $AB$ intermediate is a ro-vibrational resonance. The initial $ABC$ may be charged or neutral, ground- or excited-state, and produced via collision or photon absorption. Our quantum-mechanical treatment yields the full momentum distribution of the atomic fragments. With this, we will identify the conditions under which the long-used experimental signature of sequential fragmentation --- namely, a uniform angular distribution of the relative motion of $A$ and $B$ relative to $C$ --- are valid. In particular, we analyze in general terms what properties of $ABC$ and $AB$ are needed to produce the isotropic angular distribution.