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

[摘要] Knowledge of molecular photolysis cross sections is important fordetermining atmospheric lifetimes and fates of many species. A method andlaser apparatus for measurement of these cross sections in thenear-ultraviolet (UV) region is described. The technique is based on actionspectroscopy, where the yield of a photodissociation product (in this caseOH) is measured as a function of excitation energy. For compounds yieldingOH, this method can be used to measure near-UV photodissociation crosssection as low as 10⁻²³ cm² molecule⁻¹. The method is appliedto determine the photodissociation cross sections for methyl hydroperoxide(CH₃OOH; MHP) and hydroxymethyl hydroperoxide (HOCH₂OOH; HMHP) inthe 305–365 nm wavelength range. The measured cross sections are in goodagreement with previous measurements of absorption cross sections.

[学科分类] 大气科学