Near-UV photolysis cross sections of CH₃OOH and HOCH₂OOH determined via action spectroscopy

C. M. Roehl (1) , Z. Marka (1) , J. L. Fry (2) , P. O. Wennberg (1, 3)

1 Division of Geological and Planetary Sciences [Pasadena]
2 Arthur Amos Noyes Laboratory of Chemical Physics
3 EAS - Division of Engineering and Applied Science [Pasadena]

Knowledge of molecular photolysis cross sections is important for determining atmospheric lifetimes and fates of many species. A method and laser apparatus for measurement of these cross sections in the near-ultraviolet (UV) region is described. The technique is based on action spectroscopy, where the yield of a photodissociation product (in this case OH) is measured as a function of excitation energy. For compounds yielding OH, this method can be used to measure near-UV photodissociation cross section as low as 10^?23 cm² molecule^?1. The method is applied to determine the photodissociation cross sections for methyl hydroperoxide (CH₃OOH; MHP) and hydroxymethyl hydroperoxide (HOCH₂OOH; HMHP) in the 305?365 nm wavelength range. The measured cross sections are in good agreement with previous measurements of absorption cross sections.

Domaines: Océan, Atmosphère

C. M. Roehl, Z. Marka, J. L. Fry, P. O. Wennberg. Near-UV photolysis cross sections of CH₃OOH and HOCH₂OOH determined via action spectroscopy. Atmospheric Chemistry and Physics, 2007, 7 (3), pp.713-720. ⟨hal-00296144⟩