Steric effects are reported for the chemiluminescent CaCl(B (2) Sigma) and CaBr(A (2) Pi) exit channels of the reaction of Ca(D-1(2)) with oriented CH3Cl (JKM = 111) and CH3Br (JKM = 111), respectively. The translational energy dependence of the total chemiluminescence and the steric effect of the CaCl(B (2) Sigma) channel was measured, An enhanced CaCl(B) chemiluminescence is observed for a tails (methyl end) approach and an enhanced CaBr(A) production for a heads (Br end) approach geometry. The observed energy dependence of the steric effect : is attributed mainly to a correlation between the projection of the electronic angular momentum of the Ca(D-1(2)) on the intermolecular axis and the projection of the electronic angular momentum of the diatomic product on the diatomic axis. A full report of semiclassical trajectory calculations on a long-range potential is presented in the accompanying paper by Meijer et al.