Photofragment spectroscopy and potential curves of Ar+2

Photofragment energy distributions have been measured for the process Ar+2(2Σ+u)+hν→Ar++Ar using a 3 keV ion beam and cw lasers both coaxial and crossed with the ion beam, polarized, respectively, perpendicular and parallel to the ion beam direction. Measurements were made at 14 wavelengths between 4579 and 7993 Å. Transitions to the dissociative states 2Πg and 2Σ+g are observed, as are the effects of the spin–orbit interaction in Ar+2. The experimental results are used along with theoretical calculations to determine the 2Σ+u, 2Σ+g, and 2Πg potentials. The effects of the spin–orbit interaction on the potential curves, the magnitude and wavelength dependence of the photodissociation cross section, and the angular distributions of the photofragments are considered.