Absolute Rate Coefficient of the Gas-Phase Reaction between Hydroxyl Radical (OH) and Hydroxyacetone: Investigating the Effects of Temperature and Pressure

The rate coefficient (k1) of the reaction between hydroxyl radical and hydroxyacetone, which remained so far controversial, was determined over the temperature range 290–500 K using pulsed-laser photolysis coupled to pulsed-laser induced fluorescence (PLP-PLIF). Hydroxyl radical was generated by pulsed photolysis of H2O2 at 248 nm. The results show that at a pressure of 50 Torr He, the rate coefficient obeys a negative temperature dependence k1(T) = (1.77 ± 0.19) × 10–12 exp((353 ± 36)/T) cm3 molecule–1 s–1 for temperatures between 290 and 380 K, in good agreement with the results of Dillon et al. (Phys. Chem. Chem. Phys. 2006, 8, 236) at 60 Torr He. However, always at 50 Torr He but for the higher temperature range 410–500 K, a positive temperature dependence was found: k1(T) = (1.14 ± 0.25) × 10–11 exp(−(378 ± 102)/T) cm3 molecule–1 s–1, close to the expression obtained by Baasandorj et al. (J. Phys. Chem. A 2009, 113, 10495) for pressures of 2 and 5 Torr He but at lower temperatures, 280–360 K, where t...