The importance of molecular complexes in gas discharge lasers has long been recognised, and indeed they
are the essence in excimer lasers. For other discharge lasers operating with gas mixtures, for example
metal vapour lasers, the role of molecular complexes in the laser discharge has hardly been addressed. In
this work the emission from a cw multi-colour hollow-cathode HeCd+ laser has been investigated
spectroscopically, and emphasis was placed on the detection of molecular bands. Specifically the presence
of He2∗ in the laser discharge was confirmed which is thought to play a major role in the generation of
the green laser lines. Emission bands attributed to the Cd2∗ metal dimer were identified; however, this
dimer does not seem to be of importance in the laser process. In addition to the He2∗ and Cd2∗ emission
strong molecular continuum bands, exhibiting gain, were observed which accompany all laser lines; these
can only be interpreted as originating from transitions in the ionic complex (HeCd+)*.