The Photoelectric and Thermionic Work Functions of Outgassed Platinum

In extending results previously reported the photoelectric and thermionic work functions for platinum were studied while the specimen was put through an extended outgassing process. With monochromatic light the final value of the photoelectric threshold was found to be 1962A (6.30 v.) The thermionic work function increases during outgassing, reaching a final value of 6.35 volts, within 1 percent. The two work functions are thus in agreement within the limits of error. The thermionic constant $A$ of the Richardson $T^2$ law also increases as the work function increases, reaching a final value which is 200 times or more greater than Dushman's theoretical value of 60.2 amp/${\mathrm{cm}}^2$ ${\mathrm{deg}}^2$.