Abstract

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+)*.