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The 15th International Conference on

Vibrations at Surfaces

June 22-26, 2015 ▪ Donostia-San Sebastián, Spain

Donostia Igeldotik

Program

OverviewMondayTuesdayWednesdayThursdayFriday

Tuesday June 23

09:00-10:40 Tu1: Transport in electronic devices
10:40-11:20 Coffee break
11:20-13:00 Tu2: Surface diffusion and migration
13:00-15:30 Lunch break (on your own)
15:30-16:40 Tu3: Chemistry and growth of graphene
16:40-17:20 Coffee break
17:20-18:50 Tu4: Electron-phonon coupling in graphene
19:00-21:30 Poster session A

Tu2: Surface diffusion and migration

Chair: J. Manson, Clemson, USA

11:20-11:50 J. Ellis, Cambridge, UK
The use of atom-surface band structures as a framework for considering quantum effects in surface diffusion
11:50-12:20 H. Hedgeland, London, UK
Surface diffusion of aromatics through van der Waals landscapes and beyond
12:20-12:40 W. E. Ernst, Graz, Austria
Investigation of surface structure and diffusion dynamics of hydrogen adsorbed on Sb(111)
12:40-13:00 R. Martinez-Casado, Madrid, Spain
Diffraction of helium on MgO(100) calculated from first-principles

Contributed talk

Investigation of surface structure and diffusion dynamics of hydrogen adsorbed on Sb(111)

C. Gösweiner, P. Kraus, F. Apolloner, and W. E. Ernst

Institute of Experimental Physics, Graz University of Technology, Graz, Austria

As one of the essential components in the class of topological insulators [1] (TI), the semimetal antimony (Sb) and its surfaces has received growing attention by experimental groups throughout the last years. Despite experimental advances in ultra-high-vacuum (UHV) technologies, experimental studies on pure material surfaces may still suffer from the ever-present hydrogen background in vacuum chambers. Moreover, thin layers of hydrogen are more or less invisible to electron scattering methods. Since adsorbed hydrogen atoms on the surface may alter the electronic response of the material, detecting the presence of hydrogen on the surface of a TI is of major importance.

Helium atom scattering (HAS) provides a completely surface sensitive method of materials characterization and can thus provide information on the structure and electronic properties of the very first layer of the sample material [2,3,4].

HAS experiments were performed on cold Sb(111) surfaces without and with coverage of hydrogen molecules or atoms. While the presence of H2 did not alter the surface diffraction spectrum compared to an uncovered surface, atomic hydrogen coverage resulted in a complete loss of diffraction peaks at low surface temperature. By raising the temperature, the diffraction pattern was regained. However, heating up to a temperature of 500 K was required in order to obtain the clean surface spectrum.

HAS experimental data of the surface temperature dependent diffraction patterns of ordered hydrogen on Sb(111) as well as a determination of its diffusion energy barrier will be presented.

[1] H. Zhang et al., Nature Physics 5,438-442 (2009)

[2] M. Mayrhofer-R. et al., J. Phys. Condens. Matter 25, 395002 (2013)

[3] M. Mayrhofer-R. et al., Phys. Rev. B 88, 205425 (2013)

[4] P. Kraus et al., Phys. Rev. B 87, 245433 (2013)