Nitrogen related excitation processes in a mercury bromide laser discharge

The role of nitrogen as a buffer gas constituent in an avalanche discharge mercury bromide laser has been examined, and it is shown that a change over in excitation from electron impact dissociation of HgBr2 to energy transfer dissociation by excited nitrogen occurs at 1.5 percent N2. 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.