The dimol absorption of O-2 at 630 nm was performed to generate O-2 a(1)Delta(g) in the gas phase. The pure collision-induced phosphorescence spectrum was recorded around 1260 nm at the O2 pressure of 130 atm. The excitation spectrum, recorded by measuring the near-IR emission intensity, had the same spectral shape as that of the dimol absorption spectrum in 620-640 nm. The quadratic pressure dependence of the phosphorescence intensity evidenced that the emission was induced by collision. The self-quenching rate constant of O-2 a(1)Delta(g) has been estimated to be (1.7 +/- 0.2) x 10(-18) cm(3) molecule(-1) s(-1). (C) 2009 Elsevier B.V. All rights reserved.