Noise considerations, signal magnitudes, and detection limits in a hollow cathode discharge by optogalvanic spectroscopy

It is demonstrated that the noise in a hollow cathode discharge results mainly from statistical fluctuations of the electrons in the circuit. For the elements Na, U, Eu, and Zr, approximately one extra electron is produced for every one thousand photons absorbed. The nondependence of the magnitude of the optogalvanic signal on the ionization potential of the irradiated atom leads us to postulate a mechanism where the principal effect of laser irradiation is to pump energy into the electron gas.