Momentum vector correlation maps for three-particle fragmentation of neutral triatomic hydrogen near its ionization threshold

Three-particle dissociation of high-lying Rydberg states of H-3, in the immediate vicinity of the ionization threshold, is induced by an external electric field. We observe that the momentum vector correlation map of the center-of-mass motion of the fragments changes rapidly with electronic energy. Near-and above-threshold substantial contributions of fragment orientations which are characteristic of near-linear geometry appear, i.e., two atoms with opposing momenta, the third atom being nearly at rest. This finding is similar to observations by Strasser et al. [Phys. Rev. A 66, 032719 (2002)], who studied dissociative recombination of cold H-3(+) ions with slow electrons. We discuss the likely dissociation paths responsible for the observed correlation.