title: Photodissociation cross section of ClOOCl at 330 nm.
abstract: The photolysis rate of ClOOCl is crucial in the catalytic destruction of polar stratospheric ozone. In this work, we determined the photodissociation cross section of ClOOCl at 330 nm with a molecular beam and with mass-resolved detection. The photodissociation cross section is the product of the absorption cross section and the dissociation quantum yield. We formed an effusive molecular beam of ClOOCl at a nozzle temperature of 200 or 250 K and determined its photodissociation probability by measuring the decrease of the ClOOCl intensity upon laser irradiation. By comparing with a reference molecule (Cl(2)), of which the absorption cross section and dissociation quantum yield are well-known, we determined the absolute photodissociation cross section of ClOOCl at 330 nm to be (2.31 +/- 0.11) x 10(-19) cm(2) at 200 K and (2.47 +/- 0.12) x 10(-19) cm(2) at 250 K. Impurity interference has been a well-recognized problem in conventional spectroscopic studies of ClOOCl; our mass-resolved measurement directly overcomes such a problem. This measurement of the ClOOCl photolysis cross section at 330 nm is particularly useful in constraining its atmospheric photolysis rate, which in the polar stratosphere peaks near this wavelength.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Bing
authors.initials: B
authors.lastname: Jin
authors.forename: I-Cheng
authors.initials: IC
authors.lastname: Chen
authors.forename: Wen-Tsung
authors.initials: WT
authors.lastname: Huang
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Lien
authors.forename: Nikhil
authors.initials: N
authors.lastname: Guchhait
authors.forename: Jim J
authors.initials: JJ
authors.lastname: Lin