High-resolution electron-energy-loss spectroscopy (HREELS) and ultraviolet photoemission (UPS) measurements of the interface of phenyl diamine (NPB) and indium tin oxide (ITO) were performed. The HREELS spectrum of the oxygen-plasma-treated ITO was characterized by dipolar-active-phonon modes at 71 and 134meV. Upon deposition of NPB on ITO, the HREELS loss peaks of ITO gradually diminished, while the NPB-derived loss peaks appeared. The negligible energy shifts of the NPB peaks with NPB thickness suggested a rather weak interaction between NPB and ITO. The remarkable intensity change of the loss band at 71-65meV gave evidence for a strong vibrational coupling between the ITO phonon mode at 71meV and the NPB-derived vibrational mode at 65meV. Annealing of the NPB/ITO interface with 20

High-resolution electron-energy-loss spectroscopy (HREELS) showed that the dominant feature in the HREELS spectrum of the 'as-received' ITO was the loss peaks associated with the CHx group. Oxygen-plasma treatment of ITO led to the disappearance of the CHx loss peaks, and a concomitant increase in the intensity of the phonon peaks at 71 and 134meV. The result indicates the removal of the CHx group and additional oxidation of the ITO surface by the oxygen-plasma treatment. Both processes are proposed to be responsible for the increase in work function of ITO by the oxygen-plasma treatment.

A densely packed 1×1-O overlayer with an oxygen coverage of 1.0 (relative to the number of substrate surface atoms) was prepared on Ru (0001) by sequential dissociation of O2 and NO2 and studied by means of high-resolution electron-energy-loss spectroscopy. Two dipole-active modes were observed at 81 and 7.3meV due to a v⊥(Ru-O) stretch mode and a new surface mode, respectively. The value of v⊥(Ru-O) is shifted to higher energy compared to that for the known 2×2-O and 2×1-O adlayers at smaller oxygen coverages. These measurements indicate that the O2 dissociation is kinetically hindered for oxygen coverages larger than 0.5.

We report a high-resolution electron-energy-loss spectroscopy study of the coverage dependence of the Cs-Ru stretch vibration at 300K. Surprisingly, the frequency of Cs-Ru stretch vibration shifts upward by about 30% with Cs coverage for 0≤θCs≤0.19. Only a quarter of this shift can be explained through lateral dipoledipole interaction. We discuss two further mechanisms that may cause the other part of the shift. A slight decrease of the stretch frequency for θCs>0.19 is associated with the metallization of the alkali-metal layer including a structural change.

The interaction between magnesium (Mg) and tris(8-hydroxy-quinoline) aluminum (Alq3) has been studied using high-resolution electron energy-loss spectroscopy (HREELS). It was found that deposition of magnesium on the Alq3 film gave rise to clear changes in the HREELS spectra. The changes are attributed to the weakly bounded Mg atoms on the Alq3 layer. Interestingly, for a given amount of magnesium (Mg to Al atoms ratio=3) on Alq3 film, remarkable changes were observed in the HREELS spectra when the sample was heated. A loss peak at 81meV, which was assigned to Mg-O stretch mode, appeared upon annealing and increased in intensity as the annealing temperature increased up to about 360K. This suggested that the diffusion of Mg atoms into the Alq3 layer and the reaction between Mg and Alq3 molecule occurred at the temperature range investigated. The present work has provided direct evidence for the strong interaction between magnesium and Alq3.