Bi- and unimolecular resonances of the collinear reaction F+DBr⇄FDBr⇄FD+Br

Abstract

The reaction probability function P(ν′←ν‖E) of the bimolecular collinear reaction F+DBr(ν)→FD(ν′)+Br shows sharp resonance peaks at certain collision energies Ebi. On the other hand, the unimolecular dissociation FDBr*(ν1ν3)→F+DBr(ν), FD+Br(ν) exhibits long-lived behavior for particular resonance wave functions Ψν1ν3 at energies Euni. Good numerical agreement is found in a comparison of bi- and unimolecular resonance energies and lifetimes by two complementary methods: (i) S-matrix propagation in hyperspherical coordinates for the bimolecular reaction; (ii) the diagonally corrected vibrational adiabatic hyperspherical (DIVAH) method to determine unimolecular resonances, coupled with the fast Hankel transform (FHT) method to propagate them in time. The agreement found suggests a correlation between bi- and unimolecular resonances by the reaction mechanism F+DBr(ν)⇄FDBr*(ν1ν3)⇄FD(ν′)+Br, where the unimolecular resonance states Ψν1ν3 serve as traps or doorway states, blocking or catalyzing the bimolecular reaction.