抄録
A new phenomenon called Joshi effect (Δi) which involved a marked diminution of gaseous conductivity under irradiation, was described. Data for the production of Δi corresponding to 100 per cent photorediction of the conductivity in mercury vapour excited by potentials near ‘threshold potential’ Vm, were presented. Light absorption of mercury vapour was studied against hydrogen discharge when a fine absorption line occurred at 2536Å whose intensity remained sensibly the same for the excited vapour; that excited near Vm, and also when irradiated to give appreciable Δi. Results using the tungsten lamp and mercury arc also showed no noticeable difference between normal and excited vapour under conditions causing large Δi. It is considered that Joshi effect is not a consequence of selective light absorption by the gaseous phase.
