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 discharge flow reactor. Atom and radical concentrations in the reactions were monitored using Electron Paramagnetic Resonance (EPR) for H and D atoms and Far Infrared Laser Magnetic Resonance (FIR-LMR) and Laser Induced Fluorescence (LIF) for HCO. The overall rate constants describing 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 through a short-lived highly vibrationally excited formaldehyde complex.