Solvent-enabled photodissociation of in water clusters

The photofragmentation of CO 2 - ( H 2 O ) m , m = 3–20 at 355 nm yields two types of anionic products: O−(H2O)m−k, 1 ⩽ k ⩽ 3, and CO 2 - ( H 2 O ) m - k , 4 ⩽ k ⩽ 9, depending on the parent cluster size. The O−(H2O)m−k fragments, attributed to the dissociation of hydrated CO 2 - , are dominant for m = 3–7, while the water-evaporation products, CO 2 - ( H 2 O ) m - k , take precedence for m = 8–20. The dissociation of CO 2 - is proposed to proceed via a hydration-stabilized excited state, originating from a low-lying CO 2 - resonance. In the evaporation channel, the suggested routes include cluster predissociation, CO 2 - photodissociation/recombination, and charge transfer to solvent.