Associative detachment of H- + H → H2 + e-

Using a merged-beams apparatus, we have measured the associative detachment (AD) reaction of H-+H→H2+e- for relative collision energies up to Er≤4.83 eV. These data extend above the 1-eV limit of our earlier results. We have also updated our previous theoretical work to account for AD via the repulsive 2Σg+ H2- potential energy surface and for the effects at Er≥0.76 eV on the experimental results due to the formation of long-lived H2 resonances lying above the H+H separated atoms limit. Merging both experimental data sets, our results are in good agreement with our new theoretical calculations and confirm the prediction that this reaction essentially turns off for Er(greater-or-similar sign)2 eV. Similar behavior has been predicted for the formation of protonium from collisions of antiprotons and hydrogen atoms.