Criegee intermediates are short-lived species formed in the ozonolysis of the unsaturated hydrocarbons in the troposphere. Collisionally stabilized Criegee Intermediates (SCIs) undergo bimolecular reactions with trace gases like H2O, SO¬2 and volatile organic compounds like carbonyls and carboxylic acids, and control the overall budget of the organic acids, secondary organic aerosols (SOAs), and other radicals. Three reported studies, mentioned below, will be discussed in detail.
1. The direct probing of the Criegee intermediate (CH2OO) and its kinetics with SO2 was studied using Cavity Ring-Down Spectroscopy (CRDS) by Chhantyal-Pun et al. (2014). The self-reaction kinetics of CH2OO and its reaction with SO2 were performed at 293 K and 10-30 Torr pressure.
2. Kinetic and Atmospheric Modeling Studies of Criegee Intermediate Reactions with Acetone was reported by Chhantyal-Pun et al. (2019). The kinetics were performed at 250-310 K and a 5-100 Torr pressure range. Computational calculations were performed to confirm the proposed mechanism and major products, and to infer the pressure dependence.
3. UV absorption probing of C2 Criegee (CH3CHOO) intermediates, and the study of their conformer-dependent reactivity towards H2O and SO2 using Cavity Enhanced Broadband UV Absorption Spectroscopy by Sheps et al. (2014).
The experimental and computational studies proposed to be performed throughout the PhD program are listed below.
 Establishment of Near Collinear-Pulsed Laser Photolysis-Cavity Ring-Down Spectroscometer (NCo-PLP-CRDS)
 Kinetics: CH2OO + Methyl ethyl ketone/2-pentanone
 Kinetics:CH2OO + N-butyraldehyde/isobutyraldehyde
 Kinetics: Anti-CH3CHOO + CH3CHO
Work progress to date will be discussed in brief.
References:
1) Chhantyal-Pun, R., et al. Phys.Chem.Chem.Phys., 2015, 17, 3617
1) Chhantyal-Pun, R., et al. ACS Earth Space Chem. 2019, 10, 2363-2371
2) Sheps, L., et al. Phys.Chem.Chem.Phys., 2014, 16, 26701