SELECTIVE RESPONSES OF A FLAMELESS THERMIONIC DETECTOR

A flameles thermionic detector is described which uses an electrically heated bead consisting of an alkali metal compound embedded in a ceramic matrix Measurements of detector response as a function of bead polarization voltage, bead surface temperature and composition of gaseous environment surrounding the bead demonstrate that the ionization mechanism is the thermionic emission of charged particles from the surface of the hot bead. With the bead located in gaseous environment of air and dilute hydrogen, this detector provides highly specific responses to compounds containing hydrogen or phosphorus atoms. © 1978.