Visible spectrum photofragmentation of O3-(H2O)n, n ≤ 16

Abstract

Photofragmentation of ozonide solvated in water clusters, O3-(H2O)n, n ≤ 16, has been studied as a function of photon energy as well as the degree of solvation. Using mass selection, the effect of the presence of the solvent molecule on the O3- photodissociation process is assessed one solvent molecule at a time. The O3- acts as a visible light chromophore within the water cluster, namely the O3-(H2O) total photodissociation cross-section exhibits generally the same photon energy dependence as isolated O3- throughout the visible wavelength range studied (430-620 nm). With the addition of a single solvent molecule, new photodissociation pathways are opened, including the production of recombined O3-. As the degree of solvation of the parent anion increases, recombination to O3--based products accounts for close to 40% of photoproducts by n = 16. The remainder of the photoproducts exist as O--based; no O2--based products are observed. Upper bounds on the O3- solvation energy (530 meV) and the O--OO bond dissociation energy in the cluster (1.06 eV) are derived.