Temperature and Thickness Dependence of Transition Radiation From Thin Silver Foils

Abstract

The transition radiation from vacuum evaporated silver foils bombarded by 25-, 40-, and 60-keV electrons was investigated as a function of foil thickness and temperature. The intensity at the wavelength of maximum emission was found to oscillate with foil thickness as predicted theoretically. The peak in the spectrum was observed to increase in intensity and also to be shifted to shorter wavelengths when the foil temperature was decreased. The observed shift in wavelength was much greater than the value predicted on the basis of a change in the electronic density alone as would be the case for a pure plasma oscillation. The additional shift may be due to the change in the Fermi distribution of electrons which participate in the interband transition. The emission from silver thus appears to arise from a hybrid type of resonance with the pure plasma resonance being shifted in energy by the interband transition.