2017/08/30 by Torsten Berndt, Hartmut Herrmann, Theo Kurtén · 1 voice
Chemistry · Earth and Planetary Sciences · #Atmospheric Ozone and Climate #Atmospheric chemistry and aerosols #Spectroscopy and Laser Applications
paper · doi:10.1021/jacs.7b05849
openalex publication_date 2017/08/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/25
Criegee intermediates (CIs), mainly formed from gas-phase ozonolysis of alkenes, are considered as atmospheric oxidants besides OH and NO 3 radicals as well as ozone. Direct CI measurement techniques are inevitably needed for reliable assessment of CIs’ role in atmospheric processes. We found that CIs from ozonolysis reactions can be directly probed by means of chemical ionization mass spectrometry with a detection limit of about 10 4 –10 5 molecules cm –3 . Results from quantum chemical calculations support the experimental findings. The simplest CI, CH 2 OO, is detectable as an adduct with protonated ethers, preferably with protonated tetrahydrofuran. Kinetic measurements yielded k (CH 2 OO + SO 2 ) = (3.3 ± 0.9) × 10 –11 and k (CH 2 OO + acetic acid) = (1.25 ± 0.30) × 10 –10 cm 3 molecule –1 s –1 at 295 ± 2 K, in very good agreement with recent measurements using diiodomethane photolysis for CH 2 OO generation. CIs from the ozonolysis of cyclohexene, acting as surrogate for cyclic terpenes, are followed as protonated species (CI)H + using protonated amines as reagent ions. Kinetic investigations indicate a different reactivity of cyclohexene-derived CIs compared with that of simple CIs, such as CH 2 OO. It is supposed that the aldehyde group significantly influences the CI reactivity of the cyclohexene-derived CIs. The direct CI detection method presented here should allow study of the formation and reactivity of a wide range of different CIs formed from atmospheric ozonolysis reactions.