H2O2+ ions in ionized O2/CH4 mixtures: Intermediacy of CH3OOH+ and CH2O+

H2O2+ ions are formed in ionized O2/CH4 mixtures from the secondary reaction of CH2O+ with O2. By high-resolution mass spectrometric techniques, the peroxide HOOH structure and the H2CO structure of ionized formaldehyde are assigned to the [H2O2]+ ions and the [CH2O]+ reactants, respectively. The reaction sequence leading to CH2O+ and H2O2+ is elucidated.