Photodissociation of gas-phase I−3: product branching in the visible and UV regions

Photodissociation of the gas-phase triiodide anion, I−3, was investigated using photofragment mass spectrometry. The photofragment yield (PFY) and photoproduct branching fractions were determined from the observed mass spectra in the wavelength range 270–540 nm (2.3–4.6 eV). The measurement revealed that:1. otodissociation occurs with the production of I− and I−2 fragments in the whole energy range studied, anching ratio of I− versus I−2 production depends strongly on the excitation energy. experimental findings clearly demonstrate the nonadiabatic nature of the I−3 photodissociation dynamics.