Staircase patterns of nuclear fluxes during coherent tunneling in excited doublets of symmetric double well potentials
Tunneling isomerization of molecules with symmetric double well potentials are associated with periodic nuclear fluxes, from the reactant R to the product P and back to R. Halfway between R and P the fluxes achieve their maximum values at the potential barrier. For molecules in the lowest tunneling doublet (v = 0) the rises and falls to and from the maximum values are approximately bell-shaped. Upon excitation to higher tunneling doublets v = 1, 2, etc., however, this shape is replaced by symmetric “staircase patterns” of the fluxes, with v + 1 stepping up and down in the domains of R and P, respectively. The quantum derivation of the phenomenon is universal. It is demonstrated here for a simple model of nuclear fluxes during tunneling isomerization of ammonia along the umbrella inversion mode, with application to separation of isotopomers.