The Si(P-3(J))+O-2 reaction: A fast source of SiO at very low temperature;CRESU measurements and interstellar consequences

The rate coefficient of the reaction Si(P-3(J)) + O-2 --> SiO + O has been measured at temperatures down to 15 K using a CRESU (Cinetique de Reaction en Ecoulement Supersonique Uniforme) apparatus coupled with the PLP-LIF (Pu lsed Laser Photolysis - Laser Induced Fluorescence) technique. The temperat ure dependence of the rate coefficient is well fitted using the expression: 1.72 x 10(-10) (T/300 K)(-0.53) exp(-17 K/T) cm(3) molecule(-1) s(-1) in t he temperature range 15-300 K. The silicon chemistry in interstellar clouds is reviewed and possible consequences of our study are stressed.