Title: Substituent Effects on the Electronic Spectroscopy of Four-Carbon Criegee Intermediates

Abstract

Atmospheric ozonolysis of biogenic and anthropogenic alkenes generates zwitterionic carbonyl oxide intermediates (R₁R₂C=O⁺O^–), known as Criegee intermediates, with different structural motifs and conformations. This study reports a systematic laboratory study of substituent effects on the electronic spectroscopy of four-carbon Criegee intermediates (CIs) with methyl–ethyl (MECI) and isopropyl (IPCI) groups, which are isomers produced in ozonolysis of asymmetric branched alkenes. The four-carbon CIs are separately generated by an alternative synthetic route, and spectroscopically characterized on the strong π* ← π transition associated with the carbonyl oxide group in a pulsed supersonic expansion with VUV photoionization at 118 nm and UV-induced depletion of the m/z 88 signal. The resultant broad and unstructured UV spectral features for MECI and IPCI are peaked at ca. 320 and 330 nm, respectively, with large absorption cross-sections of ca. 10^–17 cm². Comparisons are made with the four-carbon CIs formed in isoprene ozonolysis, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide), which have the same backbone connectivity as MECI and IPCI but have extended conjugation across the vinyl and carbonyl groups. A remarkable 50 nm shift of the peak absorption to longer wavelength is observed for MVK-oxide and MACR-oxide compared to MECI and IPCI, respectively. Furthermore, verticalmore » excitation energies computed theoretically agree well with the experimental findings, confirming that the spectral shifts are caused by the extended π conjugation in the isoprene-derived Criegee intermediates.« less

Authors:

Liu, Tianlin  ^[1];

• Search DOE PAGES for author "Liu, Tianlin"
• Search DOE PAGES for ORCID "0000-0002-6725-8714"

Zou, Meijun  ^[1];

• Search DOE PAGES for author "Zou, Meijun"
• Search DOE PAGES for ORCID "0000-0003-2219-6107"

Caracciolo, Adriana  ^[2];

• Search DOE PAGES for author "Caracciolo, Adriana"
• Search DOE PAGES for ORCID "0000-0002-2588-7627"

Sojdak, Christopher A.  ^[1];

• Search DOE PAGES for author "Sojdak, Christopher A."
• Search DOE PAGES for ORCID "0000-0002-1176-6736"

Lester, Marsha I.  ^[1]

• Search DOE PAGES for author "Lester, Marsha I."
• Search DOE PAGES for ORCID "0000-0003-2367-3497"

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+ Show Author Affiliations

1. Univ. of Pennsylvania, Philadelphia, PA (United States)
2. Univ. of Pennsylvania, Philadelphia, PA (United States); Univ. of Colorado, Boulder, CO (United States)

Publication Date:

Thu Sep 15 00:00:00 EDT 2022

Research Org.:

Univ. of Pennsylvania, Philadelphia, PA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1903749

Grant/Contract Number:  

FG02-87ER13792; ACI-1548562; CHE-2102626

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

Additional Journal Information:

Journal Volume: 126; Journal Issue: 38; Journal ID: ISSN 1089-5639

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Absorption; Carbonyls; Energy; Molecular structure; Oxides