The Measurement of the Resonance, Radiation, and Ionization Potentials of Several Gases and Vapors

Abstract

Minimum Resonance, Radiation and Ionization Potentials for Various Gases.—A special vacuum tube was used which embodied a modification of K. T. Compton's variable-area electrode by being so designed that either a gauze or a plate electrode could be slid into the position of the fourth electrode. The resonance potentials were obtained from the difference in voltage between successive peaks of the resonance curves; the ionization potentials from Lenard current-voltage curves corrected as to zero by the resonance curves; the relative importance of radiation and ionization at various voltages from the ratio of the Lenard currents obtained with the plate, to the corresponding currents obtained with the gauze electrode having only one fourth the area. The critical potentials in volts, accurate to about 0.1 volt except for toluene, are as follows: The results for the resonance potentials for ${\mathrm{H}}_2$, ${\mathrm{N}}_2$ and ${\mathrm{O}}_2$ agree with those obtained by Foote and Mohler, but the values for the corresponding ionization potentials are about 1 volt higher than theirs. The fact that no radiation was detected in the case of ${\mathrm{O}}_2$ and of all the vapors except ether is rather remarkable; but it may be due to the method used.