The analysis of surface-adsorbed organic molecules by alkali-assisted MIES combined with UPS(Hel)

Metastable Impact Electron Spectroscopy (MIES) in combination with UPS (Hel) is applied to the study of s-triazine and triethoxytriazine molecules adsorbed on Si(100) either alone or in combination with cesium atoms. It is demonstrated that the presence of the Cs atoms facilitates the identification of the adsorbed species considerably. It is concluded that (i) non-dissociative adsorption of the studied organic molecules occurs whereby the basal rings of the molecules lie flat on the silicon surface, in accordance with previous studies by Y. Bu and M.C. Lin, (ii) the binding of the molecules to the surface is mainly via the lone pair orbitals oft the nitrogen in the ring, and (iii) s-triazine reacts strongly with oxygen which bonds to the carbon atoms of the triazine ring.