In this work we review the use of the medium-energy ion scattering ͑MEIS͒ technique to characterize nanostructures at the surface of a substrate. We discuss here how the determination of shape and size distribution of the nanoparticles is influenced by the energy loss at the backscattering collision, which leads to an asymmetrical energy-loss line shape. We show that the use of a Gaussian line shape may lead to important misinterpretations of a MEIS spectrum for nanoparticles smaller than 5 nm. The results are compared to measurements of gold nanoparticles adsorbed on a multilayered film of weak polyelectrolyte.

In the present work, we have explored the interference effects which arise when H 2 + and H 3 + cluster ions interact with a thin layer of SiO 2 in order to obtain a clear signature of plasmon excitations induced by these energetic projectiles. For this purpose, high-energy-resolution experiments were carried out as a function of the incoming projectile energy, covering an energy range between 40 and 200 keV/ amu. The ratio R n between the energy loss of the cluster and the sum of the energy loss of its constituents has a steep increase between 70 and 100 keV/ amu for both cluster ions, which is associated with the plasmon excitation threshold.

We report the quantitative compositional profiling of 3-5 nm CdSe/ZnS quantum dots (QDs) conjugated with a perfluorooctanethiol (PFOT) layer using the newly developed time-of-flight (TOF) medium-energy ion scattering (MEIS) spectroscopy with single atomic layer resolution. The collection efficiency of TOF-MEIS is 3 orders of magnitude higher than that of conventional MEIS, enabling the analysis of nanostructured materials with minimized ion beam damage and without ion neutralization problems. The spectra were analyzed using PowerMEIS ion scattering simulation software to allow a wide acceptance angle. Thus, the composition and core-shell structure of the CdSe cores and ZnS shells were determined with a 3% composition uncertainty and a 0.2-nm depth resolution. The number of conjugated PFOT molecules per QD was also quantified. The size and composition of the QDs were consistent with those obtained from high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. We suggest TOF-MEIS as a nanoanalysis technique to successfully elucidate the core-shell and conjugated layer structures of QDs, which is critical for the practical application of QDs in various nano- and biotechnologies.

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We present a thorough experimental study of electronic stopping of H, He, B, N, Ne and Al ions in TiN with the aim to learn about the energy loss mechanisms of slow ions. The energy loss was measured by means of time-of-flight medium-energy ion scattering. Thin films of TiN on silicon with a δ-layer of W at the TiN/Si interface were used as targets. We compare our results to non-linear density functional theory calculations, examining electron-hole pair excitations by screened ions in a free electron gas in the static limit, with a density equivalent to the expected value for TiN. These calculations predict oscillations in the electronic stopping power for increasing atomic number Z1 of the projectile. An increasing discrepancy between our experimental results and predictions by theory for increasing Z1 was observed. This observation can be attributed to contributions from energy loss channels different from electron-hole pair excitation in binary Coulomb collisions.