Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 25: Zeitaufgelöste Spektroskopie II

O 25.6: Vortrag

Samstag, 5. März 2005, 16:15–16:30, TU EB420

Momentum-dependent dynamics of buried interface states in Ar/Cu(100) — •M. Rohleder, W. Berthold, J. Güdde und U. Höfer — Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg

The electronic properties of interfaces play a fundamental role in both basic and applied research. In particular, the dynamics of electrons located at solid-solid interfaces is a key to many technological applications. Only recently, we have demonstrated the existence of buried interface states in the Ar/Cu(100) system and investigated the transient decay of these image-like states by means of time-resolved two-photon photoemission [1]. In this study, we focus on momentum-dependent relaxation processes in the nearly-free-electron bands. The experiments were performed by using a hemispherical analyzer equipped with a 2d detector, allowing for single-shot E(k) measurements. The parabolic dispersion could be mapped for the first n′=1 interface state. Its effective mass is only 0.6 m_e as a consequence of the highly corrugated potential inside the Ar layer. For finite parallel momenta we found an increase of the decay rate proportional to the kinetic energy of parallel motion, Γ=ℏ/τ=6.3 meV+0.012 E_∥. Our results infer that the situation is similar to the image-potential states of clean Cu(100) [2] where inelastic interactions with metal electrons lead to interband decay into the bulk and intraband scattering inside the bands.

[1] M. Rohleder et al., submitted to Phys. Rev. Lett.

[2] W. Berthold et al., Phys. Rev. Lett. 88, 056805 (2002).