Measurements of cross sections for the production of protons by collisions between electrons and vibrationally de-excited H3+ions

The results of two experiments are reported. In the first, cross sections were measured for the production of protons by collisions between electrons and vibrationally de-excited H 3 + ions for interaction energies between 29 and 611 eV. This experiment employed electron and ion beams which intersected at right angles ( theta =90 degrees ). In the second experiment inclined beams ( theta =10 degrees ) were used to investigate lower interaction energies (19.2 to 29.5 eV) because it was found that the cross section increased rapidly with energy between 20 and 30 eV. The cross section reached a maximum value of 7.6*10 -16 cm 2 at 79 eV and the systematic errors were assessed to be less than +or-6%. There is excellent accord between the present results and earlier measurements (Peart and Dolder, abstr. A72242 of 1974) at near-threshold energies.