The Si(3PJ) + O2 reaction: A fast source of SiO at very low temperature; CRESU measurements and interstellar consequences

Abstract

The rate coefficient of the reaction Si(3PJ) + O2 → SiO + O has been measured at temperatures down to 15 K using a CRESU (Cinétique de Réaction en Écoulement Supersonique Uniforme) apparatus coupled with the PLP-LIF (Pulsed Laser Photolysis - Laser Induced Fluorescence) technique. The temperature dependence of the rate coefficient is well fitted using the expression: 1.72 × 10-10 (T/300 K)-0.53 exp(-17 K/T)cm3 molecule-1 s-1 in the temperature range 15-300 K. The silicon chemistry in interstellar clouds is reviewed and possible consequences of our study are stressed.