Electron detachment ofH−in collisions with argon at 0.5 and 1.0 MeV

${\mathrm{H}}^{-}$ ions with energies of 0.5 and 1.0 MeV were passed through a crossed beam of Ar atoms. Secondary electron energy spectra in the energy region of $v_e\approx v_i$ were measured in the forward direction. These spectra seemed to manifest characteristics of two types of ionization processes. The results are discussed within the framework of theories of electron loss. A group of electrons was tentatively identified as being produced by the single-electron-loss process. Another group of electrons was interpreted as respresenting only a small portion of the electrons from double-electron-loss collisions.