Metal Photocathodes as Secondary Standards for Absolute Intensity Measurements in the Vacuum Ultraviolet*

Abstract

The photoelectric yields of W, Ni, Al, Zn, Cu, Be, Fe, Ti, Ta, In, Pt, Sn, Mo, Ag, Au, and Pb have been measured over the wavelength range 1200 to 200 Å. Results obtained from different samples of the same metal are compared and the feasibility of using photocathodes of normally available metal foil in the measurement of absolute intensities in the vacuum ultraviolet is discussed. It is concluded that untreated photocathodes can be used with a probable uncertainty of about ±30% in the wavelength range 1100 to 400 Å. Changes in both the photoelectric yield and the reflectance of heated tungsten have been measured. Finally, some comments are made concerning the surface and volume photoelectric effects.