Temperature dependence and deuterium kinetic isotope effects in the HCOÂ +Â NO reaction

The reactions of HCO and DCO with NO have been measured by the laser photolysis/continuous-wave (CW) laser-induced fluorescence (LIF) method from 296 to 623 K, probing the (B˜2A′←X˜2A′) HCO (DCO) system. The HCO + NO rate coefficient is (1.81 ± 0.10) × 10−11 cm3 molecule−1 s−1 and the DCO + NO rate coefficient is (1.61 ± 0.12) × 10−11 cm3 molecule−1 s−1 at 296 K. Both rate coefficients decrease with increasing temperature between 296 and 623 K. The kinetic isotope effect is kH/kD = 1.12 ± 0.09 at 296 K and increases to 1.25 ± 0.15 at 623 K. The normal kinetic isotope effect supports abstraction as the principal mechanism for the reaction, in agreement with recent computational results.