Two methods of studying the spectrum in the early afterglow of a pure mercury sample are discussed. Using a time-sampling technique, information about the intensity of the spectrum as a function of time in the afterglow can be obtained. The intensities of two molecular bands, centered at 3350A and 4850A, are studied. The method of formation of the diatomic mercury molecule and the emission of radiation in the two bands are shown to be density dependent. Mechanisms are presented which explain both the molecular formation and the radiation in the two bands. In an absorption study, the half-lives of the metastable and resonance states of mercury are measured. The half-lives indicate that there is a depopulation mechanism of the 6³P₂ state at all atom densities and that there is a definite depopulation mechanism of the 6³P₀ state at the very high densities. The depopulation of the 6³P₂ state is shown to be related to an ionization process which is the cause of the enhancement in the intensity of the line spectra. The depopulation mechanism for the 6³P₀ state is the formation of the mercury molecule which occurs with increasing frequency at high atom densities --Abstract, page [iv]