Formation of fragment momentum correlations in three-body predissociation of triatomic hydrogen: The interplay of geometry-dependent nonadiabatic coupling and ground-state dynamics

Abstract

Momentum correlations in three-body predissociation of triatomic hydrogen are investigated by quasiclassical trajectory calculations. It is shown that nonadiabatic couplings that trigger predissociation of the 2sA 1 state of H 3 imprint their geometric properties on the momentum correlation structures observed after dissociation. A simple symmetry-based model of the geometric coupling properties succeeds in reproducing most of the experimentally observed patterns. The ground-state dynamics that transform the geometric properties of the coupling into the final momentum correlations are identified.

Momentum vector correlations in three-particle fragmentation of triatomic hydrogen

“…The configuration space can be for both momentum and spatial arrangement [2]. While the hyperradius ρ controls the overall size of the configuration triangle, ϑ and ϕ describe its shape; see Fig.…”

“…1 of [2]. plane [2,6,16]. Hyperspherical coordinates can be used for representation of dissociative potential energy surfaces [17], as well as for the calculation of rovibrational levels in a potential well [18].…”

“…For C 2v symmetry the angle ϕ has values ϕ = n × 60 • (n integer) and the hyperangle ϑ characterizes various isosceles triangles; it varies from 0 • (obtuse linear) to 180 • (acute linear) with 90 • for the equilateral triangle. These coordinates are explained in detail in the appendices of [2] and [6].…”

“…Recently two publications predicted entire Dalitz maps for the three-body decay of triatomic hydrogen [1,2] for the 2sA 1 electronic initial state. Both approaches are semiclassical, combining the quantum description of the bound 2s state and its nonadiabatic transition operator with classical trajectories on the two Jahn-Teller-split ground-state surfaces.…”

“…In this context it is most exciting that predictions for momentum vector correlation maps of the three-particle decay of H 3 and D 3 have recently become available from theory [1,2]. Theory specifically considered the short-lived 2sA 1 Rydberg state, neglecting rotation, as the electronic initial state, and has combined the quantum description of the bound Rydberg state and its nonadiabatic transition operator with classical trajectories on the two Jahn-Teller-split ground-state surfaces.…”