Recombination of N Atoms in a Manifold of Electronic States Simulated by Time-Reversed Nonadiabatic Photodissociation Dynamics of N₂

Following a singlephoton VUV absorption, the N-2 moleculedissociates into distinct channels leading to N atoms of differentreactivities. The optically accessible singlets are bound, and dissociationoccurs through spin-orbit induced transfer to the triplets.There is a forest of coupled electronic states, and we here aim totrace a path along the nonadiabatic couplings toward a particularexit channel. To achieve this, we apply a time-reversed quantum dynamicalapproach that corresponds to a dissociation running back. It beginswith an atom-atom relative motion in a particular product channel.Starting with a Gaussian wave packet at the dissociation region ofN(2) and propagating it backward in time, one can see thepopulation transferring among the triplets due to a strong nonadiabaticinteraction between these states. Simultaneously, the optically activesinglets get populated because of spin-orbit coupling to thetriplets. Thus, backward propagation traces the nonradiative associationof nitrogen atoms.