Photoelectric Response of Metal Surfaces in Ambient Atmospheres

Experiments are described which examine variations in the photoelectric response of metal surfaces immersed in gas atmospheres. Work-function changes have been produced by gas bombardment, electrode heating, and the deposition of small amounts of K onto the surface. By operating the electrode under study as the cathode of a Geiger-Mueller photon counter, photocurrents as low as 10−21 A could be measured. Variations in the spectral tail could be observed with great sensitivity. Factors which influence the well-known irreversible changes in work function have been explored. A less well-known increase in the work function, which is reversible and thermally activated, has been demonstrated. Emphasis is given to the W/H2 system, but similar phenomena were observed for Ni, Fe, Pt, Pd, and Re in atmospheres of H2, N2, Ne, Ar, and NH3.