The velocity and angular distributions of Mg+(P-2(3/2)) produced by photolysis of Mg+-Ar complex at 4.66 eV were observed using an apparatus set up for imaging fragment ions from mass-selected ions. The translational energy E-t and the anisotropy parameter beta were measured to be 640 +/- 80 cm(-1) and 1.03 +/- 0.05, respectively. The binding energy of Mg+-Ar in the ground state, estimated to be 1180 +/- 80 cm(-1), agreed with those reported in the literature. We have demonstrated that the recoil energy as small as 100 meV can be resolved using this apparatus. (C) 2015 Elsevier B.V. All rights reserved.