FLOW-TUBE INVESTIGATION OF THE HIGH-TEMPERATURE REACTION BETWEEN BCL3AND NH3

The reaction between BCl3 and NH3 to produce dichloroboramine (Cl2BNH2 ) and HCl was probed using a flow-tube reactor interfaced to a molecul ar-beam mass-sampling system. A composite method that couples the deta iled simulation of the fluid mechanics and chemical reactions occurrin g in the flow tube to an algorithm for nonlinear least-squares optimiz ation was used to extract the kinetic parameters from the experiment. The rate constant for this gas-phase reaction is k (cm(3) mol(-1) s(-1 )) = 4.21 x 10(11) exp[-(8350 cal mol(-1))/(RT)] with an estimated unc ertainty of 10-15% over the temperature range 670-920 K. The results i ndicate that surface reactions involving BCl3 and NH3 occur in the flo w tube, but their contributions to the observed chemical behavior of t he system can be quantified and therefore do not affect the kinetic me asurements reported here. In addition, the low-energy barrier to this gas-phase reaction has important implications for the chemical vapor d eposition of boron nitride from BCl3 and NH3.