INTENSITY VARIATION OF TRANSITION RADIATION-INDUCED BY ADSORPTION OF NITROGEN ON W(100) SURFACE

The intensity of p-polarized ultraviolet radiation emitted from a nitrogen-covered W(100) surface irradiated with 1.5 keV of electrons has been measured at high observation angles, where the observed radiation is dominated by transition radiation. The intensity varies about 1% upon nitrogen adsorption. Its dependence on exposure agrees with the well-established fact that there are two kinds of adsorption sites. The variation of the complex dielectric function (Delta epsilon) is then obtained from the intensity variations at two observation angles. Difference in Delta epsilon between lambda=300 nm and 380 nm is briefly discussed concerning surface electronic states.