Bound-free transitions and the dissociation limit

Abstract

Following a sequential two-photon excitation, fluorescence is observed from several selectively excited single rotational-vibrational energy levels of theE ³ π0 ⁺ _g state of molecular iodine. The re-emittedE →B fluorescence spectrum from each of the populated rovibrational level of theE state consists of a series of sharp lines terminating on the various discrete ro-vibrational levels of theB state and a few broad lines due to transitions taking place on to the continuum of theB state. The point of transition from sharp lines to broad features in the fluorescence spectrum has been utilized to determine theB state dissociation limit. This method of obtaining the dissociation limit of the molecular electronic states appears to be quite simple and straightforward.