PRODUCTION OF THE JOSHI EFFECT IN OXYGEN UNDER SILENT ELECTRIC DISCHARGE. PART II. INFLUENCE OF INTENSITY AND FREQUENCY OF THE INCIDENT RADIATIONS

The Joshi effect ∆i in oxygen has been studied at different exciting potentials V of so cycles frequency as a function of the light intensity I, and with different wave bands in the visible. At constant V, increase of ∆i with I is first rapid ; saturation sets in at large 1. This has been ascribed, on Joshi's theory, to the development of an opposing eIectro-static field in the immediate neighbourhood of the photo-active boundary layer on the excited electrodes. The Joshi-Lakahminarayana equation, viz., ∆i=al^b (a and b being constants) holds over a fairly wide range of moderate intensities. At higher V. the initial rise of ∆i with I and the corresponding tendency to saturation are comparatively pro­nounced than at a lower V. The non-linear dependence of ∆i on I discriminates the Joshi effect from the classical metal-in-vacuum type photo-electric phenomenon.