Photoelectric Properties of Bismuth

Photoelectric threshold determinations with Fowler plots were made for six bismuth surfaces evaporated on glass under high vacuum conditions. The values obtained for the work function were all between 4.22 and 4.25 ev. There was no significant temperature variation over the range -70^∘{}C to 200^∘{}C for the wave-length 2537A, but the data indicated contamination at the lower temperatures. Values of the parameter α, the number of electrons that strike unit area of the surface per second and absorb a quantum of energy when the light intensity is unity, were obtained for the bismuth surfaces and found to be 0.03 to 0.1 as great as those of sodium surfaces investigated by Maurer. Like those of sodium, the values of α are {~}10^-2 as great as the upper limit set by DuBridge if the number of free electrons per bismuth atom is assumed to be five.