Abstract
The photoelectric currents from freshly prepared metal films have been compared with photocurrents from the same metal exposed to air for the spectral region of the volume photoelectric threshold. The fresh films were evaporated onto air-exposed films with initial pressures in the low 10−8 torr region, and pressures during evaporation in the 10−6 to 10−7 torr region. Using the data of Walker, Rustgi, and Weissler, photoelectric yields per incident photon were obtained for fresh films of aluminum, bismuth, and indium. The steep slope in the photoelectric yield per incident photon as a function of wavelength, usually found in air-exposed evaporated films, films evaporated at higher pressures than reported here, and bulk samples, and interpreted as the onset of the volume photoelectric effect, almost disappears for the fresh films, but reappears when air is admitted into the chamber. Moreover, the quantum yield per incident photon for Al, the only one of the three metals for which reflectance data are available for films evaporated at soft ultrahigh vacua, is constant within 15% over the whole measured range. These data strongly suggest that previously measured volume photoelectric thresholds in metals between 8 eV and 9.5 eV are the result of gaseous contamination of the metals.
© 1966 Optical Society of America
Full Article | PDF ArticleMore Like This
R. B. Cairns and J. A. R. Samson
J. Opt. Soc. Am. 56(11) 1568-1573 (1966)
F. Wooten and T. Huen
J. Opt. Soc. Am. 57(1) 102-103 (1967)
W. C. Walker, O. P. Rustgi, and G. L. Weissler
J. Opt. Soc. Am. 49(5) 471-475 (1959)