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Title: Velocity map imaging of OH radical products from IR activated (CH 3) 2COO Criegee intermediates

The unimolecular dissociation dynamics of the dimethyl-substituted Criegee intermediate (CH 3) 2COO is examined experimentally using velocity map imaging to ascertain the translational and internal energy distributions of the OH and H 2CC(CH 3)O radical products. The energy profile of key features along the reaction coordinate is also evaluated theoretically. Unimolecular decay of (CH 3) 2COO is initiated by vibrational activation in the CH stretch overtone region and the resultant OH X 2Π 3/2 (v = 0) products are state-selectively ionized and imaged. Analysis reveals an isotropic spatial distribution, indicative of a 3 ps lower limit for the timescale of dissociation, and a broad and unstructured total kinetic energy release distribution. The energy released to products is partitioned principally as internal excitation of the H 2CC(CH 3)O fragments with modest translational excitation of the fragments and a small degree of OH rotational excitation. The total kinetic energy release distribution observed for (CH 3) 2COO is compared with that predicted for statistical partitioning over product quantum states, and contrasted with recent experimental and quasi-classical trajectory results for syn-CH 3CHOO [N. M. Kidwell et al., Nat. Chem. 8, 509 (2016)].
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [2] ;  [1]
  1. Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Chemistry
  2. Emory Univ., Atlanta, GA (United States). Dept. of Chemistry
Publication Date:
Grant/Contract Number:
FG02-87ER13792; FG02-97ER14782
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Pennsylvania, Philadelphia, PA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1467883
Alternate Identifier(s):
OSTI ID: 1323993