Accurate measurement of the T-shaped and linear [formula omitted] binding energies using vibronic-specific I2(B, ν) fragment velocity-map imaging

Abstract

Ion time-of-flight slow fragment velocity imaging (SFVI) is combined with laser-induced fluorescence spectroscopy measurements to accurately determine the binding energies of the T-shaped and linear conformers of the ground-state Ar⋯I2(X,ν″=0) complex. The fluorescence-based measurements were used to optimize the conditions for preferentially stabilizing either the T-shaped or linear conformers, and to ensure proper excitation energetics for the SFVI experiments. In the ion-imaging experiments, the kinetic energy distributions of specific I2(B,ν) fragments formed with very low kinetic energies via dissociation of initially prepared Ar⋯I2(B,ν′) intermolecular vibrational levels were imaged to measure the binding energies of the linear and T-shaped conformers. The linear conformer is energetically preferred, with a binding energy of 250.3(2.7)cm−1, over the T-shaped conformer, with a binding energy of 240.5(3.6)cm−1. These values are compared with previously reported data from high-level ab initio calculations and experiments.