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

The intensity of p-polarized ultraviolet radiation emitted from a nitr ogen-covered W(100) surface irradiated with 1.5 keV of electrons has b een measured at high observation angles, where the observed radiation is dominated by transition radiation. The intensity varies about 1% up on nitrogen adsorption. Its dependence on exposure agrees with the wel l-established fact that there are two kinds of adsorption sites. The v ariation of the complex dielectric function (Delta epsilon) is then ob tained from the intensity variations at two observation angles. Differ ence in Delta epsilon between lambda=300 nm and 380 nm is briefly disc ussed concerning surface electronic states.