KINETICS OF THE INITIATION STEP OF THE THERMAL-DECOMPOSITION OF SICL4

The initiation reaction of the thermal decomposition of silicon tetrac hloride SICl4 + M -->(k1) SiCl3 + Cl + M was studied behind reflected shock waves at temperatures between 1550 K and 2370 K and pressures be tween 1 and 1.5 bar. Atomic resonance absorption spectrometry (ARAS) w as applied for time-resolved measurements of H atoms at the L-alpha-li ne in SiCl4/H-2/Ar systems. Additional experiments were performed in t he SiCl4/Ar system following the absorption of SiCl4 at the L-alpha-li ne. Rate coefficients for the reaction (RI) were determined to be: k(1 ) = 4.8 x 10(16)exp(-40954 K/T)cm(3)mol(-1)s(-1). The choice between t wo possible alternatives of the first decomposition step, namely elimi nation of either Cl-2 or Cl, has been made in favor of the second reac tion on the basis of kinetic and energetic considerations. (C) 1997 Jo hn Wiley & Sons, inc.