Experimental and computational investigation of vinoxy and 1-methylvinoxy radicals from the unimolecular decay of alkyl-substituted Criegee intermediates

Abstract

Unimolecular decay of syn-alkyl substituted Criegee intermediates, which form in the atmosphere via alkene ozonolysis, is an important source of vinoxy radicals, intermediates in many atmospheric processes. Vinoxy, CH2CHO, and 1-methylvinoxy, CH3CH2CO, were previously generated from alternative photochemical pathways and investigated spectroscopically. Here, vinoxy and 1-methylvinoxy are generated from the syn-CH3CHOO and (CH3)2COO Criegee intermediates, and detected via UV laser-induced fluorescence (LIF) on the B∼2A″ - X∼2A″ transition. Comparison with previously reported LIF spectra provides definitive identification of the vinoxy and 1-methylvinoxy radicals. High level, multireference calculations of the B∼ - X∼ transition energies agree well with experiment.