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.
The dynamics of the Cl＋SiH4 reaction has been studied using the universal crossed molecular beam method. Angular resolved time-of-flight spectra have been measured for the channel SiH3Cl＋H. Product angular distributions as well as energy distributions in the center-ofmass frame were determined for the channel. Experimental results show that the SiH3Cl product is mainly backward scattered relative to the Cl atom beam direction, suggesting that the channel takes place via a typical SN2 type reaction mechanism.
