Temperature dependence of the rate coefficient for the α-pinene reaction with ozone in the range between 243 K and 303 K

Abstract

The absolute rate coefficient for the reaction of α-pinene with ozone was determined in the temperature range between 243 K and 303 K at atmospheric pressure. In total, 30 experiments were performed in the large (85 m³) temperature-controlled simulation chamber AIDA, where the concentrations of the reactants ozone and α-pinene were measured directly. An Arrhenius expression for the α-pinene + ozone reaction was derived with a pre-exponential factor of (1.4 ± 0.4) × 10⁻¹⁵ cm³ s⁻¹ and a temperature coefficient of (833 ± 86) K. This rate coefficient is in good agreement (−5%) with the current IUPAC (IUPAC 2007) recommendation at 298 K. The IUPAC recommendation is significantly larger (+27%), around 243 K where the recommended values were extrapolated from higher temperatures. This finding is relevant for tropical regions where strong updrafts can rapidly transport reactive hydrocarbons like α-pinene from the boundary layer into the cold regions of the free troposphere.