NITROGEN RELATED EXCITATION PROCESSES IN A MERCURY BROMIDE LASER DISCHARGE.

The role of nitrogen as a buffer gas constituent in an avalance discharge mercury bromide laser has been examined, and it is shown that a change over in excitation from electron impact dissociation of HgBr//2 to energy transfer dissociation by excited nitrogen occurs at 1. 5% N//2. This is explainable in terms of excitation cross-sections if considerable pumping occurs from excited states of nitrogen which are higher in energy than the metastable A state. When excitation via nitrogen is dominant, a high discharge E/N value is needed to avoid coupling of energy to unwanted vibrational excitation.