Angular dependence of proton kinetic-energy distributions from dissociative ionization of ${\mathrm{H}}_2$

Results are reported on the angular dependence of the ${\mathrm{H}}^{+}$ translational kinetic-energy distributions resulting from electron-induced dissociative ionization of ${\mathrm{H}}_2$. These measurements confirm a fact clearly implied by earlier measurements, namely, that considerable variation of the energy distributions with angle can occur even for electron energies as much as 40 eV above threshold, and bring into question conclusions previously drawn from comparison of ion and/or high-Rydberg-excited fragment energy distributions measured at widely separated angles.