Investigations of aluminum films with synchrotron radiation of wavelengths 500 to 1000 Å

Abstract

Measurements of the photocurrent from thin Al cathodes in a windowless electron multiplier as a function of wavelength, polarization, angle of incidence, and film thickness have been carried out in the extreme vacuum ultraviolet. A normal incidence monochromator utilizing synchrotron radiation provided highly polarized light. A marked difference is found between the photocurrent measured during irradiation of thin films with “s” and “p” polarized light at wavelengths near the Al plasma wavelength (835 Å). For films thicker than about 500 Å pronounced interference effects are found in both “p” and “s” light at wavelengths less than the plasma wavelength. The observations can be explained by assuming the photocurrent is related to the photon density (electromagnetic energy density) in the photocathode. Calculations of the energy density in films irradiated with light give the structure found in the measured photocurrent. The measurements indicate our monochromator yields light with a degree of polarization consistent with the calculated polarization of the synchrotron radiation incident upon our grating (about 85%).