Photodissociation of I 2 − (Ar) n Clusters Studied with Anion Femtosecond Photoelectron Spectroscopy

Abstract

Anion femtosecond photoelectron spectroscopy was used to follow the dynamics of the I 2 − (Ar) 6 and I 2 − (Ar) 20 clusters subsequent to photodissociation of the I 2 − chromophore. The experiments showed that photodissociation of the I 2 − moiety in I 2 − (Ar) 6 is complete by approximately 200 femtoseconds, just as in bare I 2 − , but also that attractive interactions between the departing anion fragment and the solvent atoms persisted for 1200 femtoseconds. Photodissociation of I 2 − (Ar) 20 results in caging of the I 2 − followed by recombination and vibrational relaxation on the excited à 2 Π g ,3/2 and the ground X̃ 2 Σ u + states; these processes are complete in 35 and 200 picoseconds, respectively.