This letter reports a study on producing gas-phase O 2(a 1Δ) by decomposition of triphenyl phosphite ozonide ((C 6H 5O) 3PO 3, TPPO 3) under a number of reaction conditions. For the first time, the cooperative emission at wavelengths 634 and 703 nm of O 2(a 1Δ) generated by TPPO 3 decomposition are observed. Specifically, under the condition of catalyzed decomposition by pyridine of TPPO 3 solution in CFCl 3 at low temperature, the emission spectrum is the same as that from the basic hydrogen peroxide plus chlorine reaction. This shows the feasibility of developing a new source for singlet delta oxygen. However, in the experiments of spontaneous decomposition of solid TPPO 3 and thermal decomposition of TPPO 3 solution on a high temperature surface, the spectra have a wide emission background around the 634 and 703 nm peaks, which indicates the production of some excited species than O 2(a 1△). Besides, there are about 2%～3%CO and 1.5%～2%CO 2 in the gaseous products together with a small amount of insoluble in acetone solid product, which imply that other than the formation of O 2(a 1△) and TPPO by unimolecular decomposition of TPPO 3, more complicated reactions may take place. The study of the reaction mechanism, the optimization of the expertise of O 2(a 1△) generation by TPPO 3 decomposition as well as measurement of absolute concentration of O 2(a 1△) are under way.
