New approach to high-resolution electron-energy-loss spectroscopy of polar materials: Studies of water and methanol adsorption on ultrathin MgO(100) films

A novel approach to the application of high-resolution electron-energy-loss spectroscopy to polar materials is demonstrated in this Letter. By using a high-impact-energy beam and an off-specular scattering geometry, losses due to excitation of the adsorbates are observed in the 1000–4000-${\mathrm{cm}}^{\mathrm{-}1}$ range with little interference from the intense losses due to multiple surface optical phonons (Fuchs-Kliewer modes). Adsorption of water and methanol on ultrathin MgO(100) films on Mo(100) have been studied using this new approach.