Momentum vector correlations in three-particle fragmentation of triatomic hydrogen

The correlation pattern in the center of mass motion of the three fragments from dissociation of well-defined Rydberg states of H{sub 3} and D{sub 3} is studied. Dissociation of the molecules is induced by an external electric field. Through a comparison with results obtained in radiative cascading we can show that the correlation pattern is that of the short-lived 2s {sup 2}A{sub 1}{sup '} electronic state, of which a tiny amplitude is admixed by the external electric field. A comparison of our results with the predictions by M. Lehner and M. Jungen [J. Phys. B 42, 065101 (2009)] and U. Galster [Phys. Rev. A 81, 032517 (2010)] for predissociation of the 2s {sup 2}A{sub 1}{sup '} state is made. We show that the experimental vector correlation maps are direct images of the spatial symmetry of the product of the vibrational wave function and spatial dependence of the nonadiabatic coupling operator.