Photodissociation dynamics of chlorine peroxide adsorbed on ice

• Published in: The Journal of Physical Chemistry B
• Main Authors: S. INGLESE, T. LAINO, GRANUCCI, GIOVANNI, PERSICO, MAURIZIO
• Other Authors: S., Inglese, Granucci, Giovanni, T., Laino, Persico, Maurizio
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2005
• Subjects: Antarc*; Antarctic
• Online Access: http://hdl.handle.net/11568/181010; https://doi.org/10.1021/jp044368k

Chlorine peroxide plays an important role in the chlorine-ozone chemistry in the antarctic stratosphere. Adsorption by ice crystals may alter its photochemistry in different ways. We have simulated the photodissociation of a ClOOCl molecule adsorbed on ice by means of a semiclassical representation of the excited state dynamics. Electronic energies and wavefunctions of ClOOCl are computed by an ad hoc reparametrized semiempirical method, and the interaction with ice is taken into account by a QM/MM strategy. The reaction mechanism is similar to what was previously found for the isolated molecule: sequential or almost simultaneous breaking of both Cl-O bonds leads to the 2Cl+O2 reaction products in most cases. The Cl atoms remain temporarily adsorbed on the ice surface, while O2 is ejected. The main effect for the overall chlorine chemistry is probably an increase of the photodissociation rates at long wavelengths, due to the change of adsorption cross sections induced by the interaction with ice.