Dihalogenated Methylperoxy Radicals: Spectroscopic Characterization and Photodecomposition by Release of HO..

Two atmospherically relevant dihalogenated methylperoxy radicals CHX2OO. (X=F and Cl) have been generated through O2‐oxidation of the corresponding alkyl radicals CHX2. in the gas phase. The IR spectroscopic characterization of both radicals in cryogenic Ar‐ and N2‐matrices (15 K) is supported by 18O‐labeling and ab initio calculations at the UCCSD(T)/aug‐cc‐pVTZ level. Upon 266 nm laser irradiation, both radicals decompose mainly by releasing hydroxyl radicals (→HO.+X2CO) via the intermediacy of intriguing α‐hydroperoxyalkyl radicals (.CX2OOH), implying that the photooxidation of dihalogenated hydrocarbons might serve as important sources of HO. radicals in the atmosphere. [ABSTRACT FROM AUTHOR]