Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 62: Posters: Surface Reactions and Dynamics, Nanostructures

O 62.24: Poster

Wednesday, April 2, 2014, 17:30–21:00, P1

Two-photon photoemission spectroscopy: The effect of cluster superlattices on the electronic structure of Ir(111)/graphene — •Kira Jochmann, Florian Knall, and Thorsten M. Bernhardt — University of Ulm, Institute of Surface Chemistry and Catalysis, 89069 Ulm, Germany

A single graphite layer - namely graphene - supported by a metal crystal surface provides an ideal template for the ordered growth of regular cluster nanostructures with equally spaced and sized clusters. The ability to synthesize such ideal model systems opens completely new opportunities for fundamental research.

Two-photon photoemission (2PPE) spectroscopy is a method to experimentally gain an insight into the unoccupied electronic structure of these systems. The rather high work function of an iridium single crystal surface decreases with increasing graphene coverage, which enables the possibility to detect image potential state electrons by 2PPE at a laser wavelength of 266 nm [1].

In this contribution we report the influence of an Ir cluster superlattice on the overall workfunction and the image potential states, observed on the Ir(111)/graphene system as a function of Iridium coverage. Furthermore the influence of these nanostructures on the lifetime of the image potential states can be monitored by the means of time-resolved 2PPE.

[1] D. Niesner, Th. Fauster, J. I. Dadap, N. Zaki, K. R. Knox, P.-C. Yeh, R. Bhandari, R. M. Osgood, M. Petrović, M. Kralj, Phys. Rev. B 85, 081402 (2012).