Large-angle collisions of Ar+ ions with Ar atoms are studied in which the inelastic energy loss Q is measured as a function of incident energy and scattering angle. Measurements are made at 3-, 6-, 12-, 25-, 50-, 75-, and 100-keV incident energies and the recoiling target particles are studied at several angles φ between 84° and 52°, corresponding to collisions where the scattered incident particle is scattered through angles θ between about 6° and 38°. The kinetic energies and scattering angles of the recoils are accurately measured, and this, together with the conservation equations, permits determination of the inelastic energy. The average value of the inelastic energy loss Q̄ is plotted vs recoil angle φ and a separate curve is obtained for each incident energy. However, when the various Q̄ values are plotted vs the calculated distance of closest approach, a universal curve is obtained which has an abrupt rise when this distance is 0.23 Å irrespective of energy. The Q̄ values are a weighted average of the energy losses associated with the various charge states found among the recoil particles at a given angle, the energy loss Q̄n of a particular charge state n being weighted in accordance with its abundance. The several values of Q̄n are presented for each of several angles φ at each energy studied. In a few cases a fine structure was seen in the data. For example, in 12-keV Ar+ on Ar collisions, the recoils at φ=52° are found to contain Ar2+ ions (as well as Ar+, Ar3+, etc.). Here these Ar2+ ions arise from collisions where the average value is Q̄2=234 eV. However, this is a weighted average of three just resolved groups of slightly different energies and these correspond to Q's of 90, 318, and 620 eV. These are interpreted as arising from collisions where the (unobserved) scattered incident particle is Ar+, Ar3+, and Ar5+, respectively. Thus, individual Q values are obtained for these reactions. There is evidence that the electrons usually leave in groups of two during these violent collisions.