there is disclosed a visible emission spectrum generating assembly for a gaseous mixture comprising a chamber for receiving the gases to be analyzed , electrodes positioned externally about the chamber and longitudinally disposed with respect to one another , an rf energy source connected to the electrodes to establish a current therebetween for generating the visible emission spectra of the gaseous mixture to be analyzed and at least one photodetector device disposed proximate the chamber to receive the thus generated light or visible emission spectra . the process and apparatus of the present invention also include a data processing device for evaluating the spectral signals received by the photodetector device and suitable display and / or recording assemblies .