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DS: Fachverband Dünne Schichten

DS 45: Ion Interactions with Nano Scale Materials I (Focused Session -- Organisers: Diesing, Facsko)

DS 45.1: Talk

Thursday, March 17, 2011, 11:00–11:15, GER 37

Electron emission in the interaction of slow ions and electrons with nanostructured surfaces — Pierfrancesco Riccardi, Michele Pisarra, and •Antonio Sindona — Università della Calabria and INFN, Cosenza, Italy

We will discuss some case studies showing that secondary electron spectroscopy of nanomaterials reveals important electronic properties of the targets. Early studies [1] showed that a submonolayer Sodium film grown on Metal substrates can be converted into two-dimensional patches by ion bombardment. Spectroscopy of electrons, emitted by autoionization of projectiles excited in collisions with target atoms, reveals the coexistence of surface regions with very different work functions which are relatively adsorbate rich and adsorbate depleted. More recently, studies of of ion- and electron-induced electron emission have been carried out on carbon based nanomaterials [2]. Here, we will report on the energy distributions of electrons ejected by the impact keV He ions and electrons on graphene adsorbed on a Ni surface [3]. We use secondary electron spectroscopy to probe the excited states of graphene adsorbed on a Ni surface. A fine structure directly related to the empty bands above the vacuum level of the sample is resolved in the spectra excited by electrons. Ion-induced spectra reveal a high energy feature that is consistent with electron promotion from valence to conduction band states. References [1] P. Riccardi et al. Thin Solid Film 289 (1996) 177 [2] M. Commisso et al. Surface Science 601 (2007) 2832 [3] P. Riccardi et al. Applied Physics Letters 97 (2010) at press