Observation of the dipole-bound excited state of the I−⋅acetone ion-molecule complex

Abstract

Photofragmentation action spectra of the I−⋅acetone ion-molecule complex reveal the existence of an excited state, located just below the electron detachment threshold, which is thought to correspond to a dipole-bound state derived primarily from the electric dipole moment of acetone. The excited state relaxes by fragmentation into the acetone anion, a dipole-bound ground state anion. This type of excited state should be a general property of ion-molecule complexes, X−⋅M, where M has a significant dipole moment and X does not, and is a microscopic precursor of the charge transfer to solvent bands observed for anions in dipolar solvents.