LAUSR

Abstract Irradiation of a para-hydrogen (p-H2) matrix containing chloroiodomethane (CH2ClI) and O2 at 3.3 K with light at 290 nm yielded infrared absorption lines at 750.1/745.6, 891.7, 1004.6, 1090.7, 1241.3, 1315.6, 1427.8, and 2988.7 cm−1, which are assigned to the gauche-chloromethylperoxy radical (gauche-CH2ClOO). Further irradiation of the matrix at 240 nm selectively diminished these features. The assignments are based on the photolytic behavior and comparisons of the observed vibrational wavenumbers and IR intensities with those predicted with the B3LYP/aug-cc-pVTZ method. The irradiation of CH2ClOO at 240 nm was found to induce cleavage of the O–O bond to produce CH2ClO, but not cleavage of the C–Cl bond to produce the Criegee intermediate CH2OO.