Photodissociation spectroscopy of 03

The photodissociation cross section of gas‐phase O3− has been measured using a tunable dye laser over a wavelength range of 6400–5080 A. The cross section exhibits considerable structure which is consistent with dissociation from vibrational levels of a quasibound excited electronic state. Analysis of the structure indicates progressions in two vibrational modes of the excited state. Photodissociation spectra of ions prepared in both excited and ground vibrational levels also yields two vibrational frequencies for the ground X 2B1 state and an apparent rate coefficient for vibrational relaxation in O2. The molecular constants determined here for the two O3− electronic states are compared with those obtained from absorption spectra of the ion in other media. Identification of the dissociating state is discussed.