Photodissociation dynamics of cluster anions

Studies of the dissociation dynamics of cluster ions provide insight into the process of energy disposal for mass-selected species. Detailed investigations of the photodissociation of the cluster anions ( SO 2 ) 2 − and CO 3 − ( H 2 O ) n ( 0 ≤ n ≤ 3 ) have been accomplished for mass-selected ion species using an intracavity dye laser pumped with an argon-ion laser. in the case of CO 3 − , the unhydrated parent ion is observed to have a bound electronic excited state through which absorption of a second photon proceeds to a repulsive state leading to the ejection of O-. There are two possible mechanisms for CO 3 - hydrate dissociation: one is a repulsive and the second a predissociative mechanism. In both, cluster dissociation is initiated by the same 2 A 1 ← 2 B 1 transition from the ground to a weakly bound excited state of the core ion and leads to the loss of all water molecules within the time of observation. In the photodissociation of CO 3 - , CO 3 - ( H 2 O ) 1 , 2 , 3 , and ( SO 2 ) 2 - considerable excess energy is partitioned into relative translation of the photoproducts. Through studies of energy release in ( SO 2 ) 2 - with photons of parallel and perpendicular polarization, evidence has been obtained that the lifetime of the complex preceding photodissociation is less than a rotational period. The implications of the findings are discussed in terms of phase space theory.