Hydrogen and deuterium negative ions produced by collisional dissociation of H3(+), D3(+) and HD2(+)

We have measured the absolute angular differential cross section and the energy distribution of the negative monatomic ions produced by the collisions of H3(+), D3(+) and HD2(+) on HE. The relevance of the negative ion production of the mentioned reaction has been widely discussed, not only for its relation with thermonuclear research but also because recently the process H3(D3(+) or HD2(+)) + He yields H(-)(D(-)) + 2H(+)(or D(+)) was considered as a heavy particle analog to the threshold ionization process e(-) + He yields (He(-))(*) yields He(+) + 2e. In the heavy particle alternative, at keV energies, the charge transfer is unlikely and the negative atomic ions are assumed to be formed as a result from three body coulomb break up. It is supposed that the triatomic molecules are excited through a collision with He. We made use of the intimate correlation between the center of mass velocity distributions of the fragments and their angular spread in the laboratory frame. By the analysis of the energy spectra and by a computer iteration method correlating the angular and energy spectra, the best W and E values were determined. The results for H(-)(D(-)) are W = 4.5 +/- 0.4 eV for its maximum energy spread and E = 21.8 +/- 1 eV for the inelastic energy loss of the molecule, necessary to produce the negative fragment. A complete determination of the final state must be accomplished by coincidence method of the charged monatomic ionic products.