The Role of Molecular Complexes in a Hollow‐Cathode CW HeCd+ Laser

The importance of molecular complexes in gas discharge lasers has long been recognised, and indeed theyare the essence in excimer lasers. For other discharge lasers operating with gas mixtures, for examplemetal vapour lasers, the role of molecular complexes in the laser discharge has hardly been addressed. Inthis work the emission from a cw multi-colour hollow-cathode HeCd + laser has been investigatedspectroscopically, and emphasis was placed on the detection of molecular bands. Specifically the presenceofHe 2 ∗in the laser discharge was confirmed which is thought to play a major role in the generation ofthe green laser lines. Emission bands attributed to theCd 2 ∗metal dimer were identified; however, thisdimer does not seem to be of importance in the laser process. In addition to theHe 2 ∗andCd 2 ∗emissionstrong molecular continuum bands, exhibiting gain, were observed which accompany all laser lines; thesecan only be interpreted as originating from transitions in the ionic complex ( He Cd + ) * .