Reaction Kinetics of CH 2 OO and syn -CH 3 CHOO Criegee Intermediates with Acetaldehyde

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2024-06, Vol.128 (25), p.4956-4965
• Main Authors: Jiang, Haotian, Liu, Yue, Xiao, Chunlei, Yang, Xueming, Dong, Wenrui
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/acs.jpca.4c01374

Criegee intermediates exert a crucial influence on atmospheric chemistry, functioning as powerful oxidants that facilitate the degradation of pollutants, and understanding their reaction kinetics is essential for accurate atmospheric modeling. In this study, the kinetics of CH OO and -CH CHOO reactions with acetaldehyde (CH CHO) were investigated using a flash photolysis reaction tube coupled with the OH laser-induced fluorescence (LIF) method. The experimental results indicate that the reaction of -CH CHOO with CH CHO is independent of pressure in the range of 5-50 Torr when using Ar as the bath gas. However, the rate coefficient for the reaction between CH OO and CH CHO at 5.5 Torr was found to be lower compared to the near-constant values observed between 10 and 100 Torr. Furthermore, the reaction of -CH CHOO with CH CHO demonstrated positive temperature dependence from 283 to 330 K, with a rate coefficient of (2.11 ± 0.45) × 10 cm molecule s at 298 K. The activation energy and pre-exponential factor derived from the Arrhenius plot for this reaction were determined to be 2.32 ± 0.49 kcal mol and (1.66 ± 0.61) × 10 cm molecule s , respectively. In comparison, the reaction of CH OO with CH CHO exhibited negative temperature dependence, with a rate coefficient of (2.16 ± 0.39) × 10 cm molecule s at 100 Torr and 298 K and an activation energy and a pre-exponential factor of -1.73 ± 0.31 kcal mol and (1.15 ± 0.21) × 10 cm molecule s , respectively, over the temperature range of 280-333 K.