Knowledge Bank

An analysis of the population distribution in the electronic states of iodine following excitation of $I2$ by energy transfer from metastable oxygen ($O2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta g$ has been undertaken. Populations of the vibrational levels of both the ground state and excited states were obtained from emission spectra and from laser excitation techniques. It is shown that three mechanisms are chiefly responsible for the dissociation of molecular iodine. Two of these require the consumption of two molecules of $O2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta g$ per $I2$ molecule, but the predominant process is a three-step dissociation mechanism, consuming three molecules of $O21\Delta g$ to dissociate one $I2$ molecule. The measured consumption of metastable oxygen increases with the extent of vibrational relaxation occurring in the ground state.