A visible and FTIR spectrometric study of the nighttime chemistry of acetaldehyde and PAN under simulated atmospheric conditions

An atmospheric simulation chamber equipped with both a long path UV-visible spectrometer and an in situ Fourier transform infrared (FTIR) analysis device has been used to study the complete scheme of the nitrate radical initiated oxidation of acetaldehyde. This study constitutes one of the first evidence under simulated atmospheric conditions of the existence of reaction: NO3+CH3C(O)O2→CH3C(O)O+NO2+O2 which has been pointed out as an atmospherically important process in the nighttime OH production. Its rate constant at 298±2 K has been found equal to k=(3.2±1.4)×10−12 molecule−1 cm3 s−1. onstants for the following reactions have also been determined at 298±2 K; HCHO+NO3→HNO3+HCO with k=(5.2±0.9)×10−16 molecule−1 cm3 s−1 and CH3CHO+NO3→HNO3+CH3CO with k=(2.1±0.7)×10−15 molecule−1 cm3 s−1.