Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.33: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Construction of a Low Temperature Scanning Tunneling Microscope — •N. Henningsen, C. Roth, I.F. Torrente, and J.I. Pascual — Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195 Berlin, Germany

Scanning Tunnelling Microscopy has become a standard tool for analysing crystal surfaces, or single molecules, even atoms. One of the most surprising capabilities of Scanning Tunnelling Microscopes (STM) is the local measurement of electronic, magnetic and vibrational properties of surfaces and adsorbates. For such spectroscopic measurements it is important to have a very good stability of the tunnel junction, as well as high energy resolution.
Here we present the design of our new low temperature STM, which has been optimised for spectroscopic measurements demanding high stability, as it is the case for Inelastic Tunnelling Electron Spectroscopy (IETS). The system will be used for inducing reactions on individual adsorbed molecular species by means of inelastic scattering of tunnelling electrons as well as by photons. For this purpose, the system will be equipped with a light source, an arc lamp providing power regimes up to 100 mW/mm2 in a continuous spectrum, which will be inserted in the UHV system via an optical fibre.
The STM head is of the Besocke type, and the design and materials are chosen to accomplish maximum stability, required for performing slow spectroscopic measurements. The design allows also the possibility of changing the tip in vacuum. The STM is coupled with a bath cryostat and is properly shielded to reach an equilibrium temperature of 5 K.