The discharge systems of this disclosure are useful in the chemical analysis field, including identification and quantification of gaseous impurities. The systems utilize a pair of electrodes which apply a spark across a gap between the electrodes, the spark preferably being repetitively formed. As an inert gas flows between the electrodes, the spark creates photons of energy which are emitted and are used as described. In alternate aspects, other particles are energized in the spark gap and subsequently surrender their energy. Photon emission or loss of energy assists in identification and measurement of peaks eluted from a typical gas chromatograph. The preferred inert gas is helium with or without traces of rare inert gases.