UV absorption spectrum of the C2 Criegee intermediate CH{sub 3}CHOO

• Published in: The Journal of chemical physics 2014-08, Vol.141 (7)
• Main Authors: Smith, Mica C., Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan, Ting, Wei-Lun, Chang, Chun-Hung, Takahashi, Kaito, Boering, Kristie A., Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, California 94720, Lin, Jim Jr-Min, Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan, Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
• Format: Article
• Language: English
• Subjects: ABSORPTION; ABSORPTION SPECTRA; COMPARATIVE EVALUATIONS; CROSS SECTIONS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LASERS; MOLECULAR BEAMS; MOLECULES; PEAKS; PHOTOLYSIS; ULTRAVIOLET SPECTRA
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4892582

The UV spectrum of CH{sub 3}CHOO was measured by transient absorption in a flow cell at 295 K. The absolute absorption cross sections of CH{sub 3}CHOO were measured by laser depletion in a molecular beam to be (1.06 ± 0.09) × 10{sup −17} cm{sup 2} molecule{sup −1} at 308 nm and (9.7 ± 0.6) × 10{sup −18} cm{sup 2} molecule{sup −1} at 352 nm. After scaling the UV spectrum of CH{sub 3}CHOO to the absolute cross section at 308 nm, the peak UV cross section is (1.27 ± 0.11) × 10{sup −17} cm{sup 2} molecule{sup −1} at 328 nm. Compared to the simplest Criegee intermediate CH{sub 2}OO, the UV absorption band of CH{sub 3}CHOO is similar in intensity but blue shifted by 14 nm, resulting in a 20% slower photolysis rate estimated for CH{sub 3}CHOO in the atmosphere.