Collision-induced near-IR emission of O-2 a(1)Delta(g) was investigated in O-2/M (M = Ar, Kr, Xe, N-2, or CO2) gas total mixtures, where the pressure ranged from 10 to 100 atm, and gaseous O-2 dimol was excited with a pulsed dye laser at 630 nm through the simultaneous two-electron transition to prepare O-2 in the a(1)Delta(g) state. The a(1)Delta(g) -> X-3 Sigma(-)(g) emission intensity around 1270 nm increased with the number density of foreign gas (M) under constant O-2 number density. Emission enhancement efficiencies were in the order Xe > CO2 > O-2 > Kr > N-2 > Ar; they are controlled by collisional enhancement during the near-IR emission at 1270 nm but not during photo-absorption at 630 nm. Efficiencies were converted into bimolecular rate constants to enhance the radiative a -> X transition for the added gases. The rate constants were estimated as quadratically dependent on the molar refraction (or polarizability) of collision gas. The self-quenching rate constant was determined from the Stern-Volmer plot of the emission lifetimes measured in pure O-2.