KINETICS OF THE REACTIONS OF HCO WITH H AND D ATOMS

The rate constants for the reactions HCO+H-->products (1) and HCO+D--> products (2) were determined at room temperature in an isothermal disc harge flow reactor. Atom and radical concentrations in the reactions w ere monitored using Electron Paramagnetic Resonance (EPR) for H and D atoms and Far Infrared Laser Magnetic Resonance (FIR-LMR) and Laser In duced Fluorescence (LIF) for HCO. The overall rate constants describin g the decay of the HCO concentrations with H and D, respectively, were found to be k(1)=(6.8+/-2.0)x10(13) cm(3) mol(-1) s(-1) and k(2)=(8.3 +/-2.5)x10(13) cm(3) mol(-1) s(-1). The results are discussed assuming a mechanism that allows for parallel reaction pathways via a direct H atom abstraction reaction or via an addition-elimination reaction thr ough a short-lived highly vibrationally excited formaldehyde complex.