Investigating the photodissociation of H2O2 using frequency modulation laser absorption spectroscopy to monitor radical products

[Display omitted] •Detection of OH and HO2 has been demonstrated using FM laser absorption spectroscopy.•Room temperature photolysis of H2O2 at 193 nm in argon has been used as a test system.•The FM sensitivity is estimated to be on the order of 1011 molecule cm−3.•The product branching measured here is in excellent agreement with previous work. The photodissociation of H2O2 dilute in argon at 193 nm has been investigated using near infrared frequency modulation laser absorption spectroscopy on selected rotational lines of the OH vibrational overtone bands between 6500 and 7100 cm−1 to detect the OH and HO2 radical products with the same laser. Sequential OH and HO2 time-dependent profiles have been measured at room temperature and total pressures ranging from 3 to 56 Torr. Kinetic analysis gives the product distribution following H2O2 photolysis of (82 ± 1) % OH and (18 ± 1) % HO2 under the present conditions, in excellent agreement with previously reported measurements.