The C-X system of diatomic mercury chloride has been re-investigated in emission. The previous vibrational assignments of this system by Horne and others have been confirmed by measurement of the chlorine isotopic shift and improved vibrational constants for the ‘C’ state determined.

Doppler limited laser optogalvanic (LOG) spectra are obtained by irradiating a bromine discharge with a cw dye laser. The discrete bands of the Br₂B-X system appear superimposed on a strong continuum. The LOG spectrum is closely identical with the absorption/emission spectrum of Br₂. Some extra bands and assigned in theB-X system are also observed and their vibrational quantum number assignment is given.