ABSTRACT
The described selection criteria also resulted in further positive results. We found diatomic molecules formed from elements of group IVa and group VIa of the periodic system to be well suited for efficient white light generation. Although this class of diatomic molecules has a very similar electronic state structure as the group Va homonuclear molecules, the electronic energy levels are located much more advantageous. The triplet states "b 3115 and "a 3Eu+ " are lying very close giving rise only to quite low IR losses. The "A t II - X 1E+" transition is now allowed and can contribute to the visible emission together with the dominating "E 1 E+ - X 1 E-" transition. Figure 4 shows the measured emission spectra of the germanium chalcogenides GeS, GeSe and GeTe, which yield a broadband emission in the visible and high efficiency. The GeTe discharge, for example, reaches at 1 kW microwave input power a plasma efficacy of 115 lm/W at a colour temperature of 4600 K and a colour rendering index Rag = 84. More details about this class of molecules are given in another contribution at this conference [23].
