10.1021/jp3026368.s001 Alexander M. Morrison Alexander M. Morrison Jay Agarwal Jay Agarwal Henry F. Schaefer Henry F. Schaefer Gary E. Douberly Gary E. Douberly Infrared Laser Spectroscopy of the CH<sub>3</sub>OO Radical Formed from the Reaction of CH<sub>3</sub> and O<sub>2</sub> within a Helium Nanodroplet American Chemical Society 2012 CH 3OO CH 3 ab initio calculations helium solvated CH 3OO gas phase band origins helium atom evaporation O 2 reaction Infrared Laser Spectroscopy Helium NanodropletHelium nanodroplet isolation O 2 CH 3OO Radical CH stretch region O 2 reactants 2012-06-07 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Infrared_Laser_Spectroscopy_of_the_CH_sub_3_sub_OO_Radical_Formed_from_the_Reaction_of_CH_sub_3_sub_and_O_sub_2_sub_within_a_Helium_Nanodroplet/2515750 Helium nanodroplet isolation and infrared laser spectroscopy are used to investigate the CH<sub>3</sub> + O<sub>2</sub> reaction. Helium nanodroplets are doped with methyl radicals that are generated in an effusive pyrolysis source. Downstream from the introduction of CH<sub>3</sub>, the droplets are doped with O<sub>2</sub> from a gas pick-up cell. The CH<sub>3</sub> + O<sub>2</sub> reaction therefore occurs between sequentially picked-up and presumably cold CH<sub>3</sub> and O<sub>2</sub> reactants. The reaction is known to lead barrierlessly to the methyl peroxy radical, CH<sub>3</sub>OO. The ∼30 kcal/mol bond energy is dissipated by helium atom evaporation, and the infrared spectrum in the CH stretch region reveals a large abundance of droplets containing the cold, helium solvated CH<sub>3</sub>OO radical. The CH<sub>3</sub>OO infrared spectrum is assigned on the basis of comparisons to high-level ab initio calculations and to the gas phase band origins and rotational constants.