The Thermionic and Photoelectric Work Functions of Molybdenum

The photoelectric and thermionic emission from pure molybdenum was studied during a prolonged process of outgassing by heat treatment at temperatures up to 2100°K. In a sealed-off tube an equilibrium condition was reached which was not changed by further treatment extending up to 1600 hours. Photoelectric curves taken at room temperature and at 940°K and analyzed by Fowler's method yielded a true work function for the outgassed Mo of 4.15±0.02 volts. Thermionic data for the same specimen also yielded a work function of 4.15 volts, and a value of the constant $A$ close to the theoretical value of 60 amp./${\mathrm{cm}}^2$ ${\mathrm{deg}.\mathrm{}}^2$.