Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Time-resolved spectroscopies II

O 55.2: Talk

Thursday, March 26, 2009, 15:15–15:30, SCH A315

Decoupling of image-potential states by Ne adlayers — •Nico Armbrust¹, Jens Güdde¹, Ulrich Höfer¹, and Peter Feulner² — ¹Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg — ²Physik-Department E20, TU München, D-85748 Garching, Germany

The influence of neon adlayers on the image-potential states of Cu(100) has been investigated by time-resolved two-photon photoemission (2PPE). Ne represents a particularly interesting case for studies of the decoupling of image-potential states because its large negative electron affinity of -1.3 eV is expected to result in a large tunnelling barrier even for very thin Ne adlayers. We find that the adsorption of one monolayer of Ne reduces the binding energies of the first two image-potential states by about 30% to E₁=438 meV and E₂=139 meV and that the inelastic lifetime of the n=1 state increases from 40 fs to 300 fs. We compare these results with model calculations using a one-dimensional potential that has been developed for adlayers of the heavier rare-gases [1]. We further report on the observation of laser-induced desorption of the Ne films which is surprisingly efficient not only for the UV pump pulses (ℏω_UV=4.66 eV), but also for the near-infrared probe pulses (ℏω_IR=1.53 eV).

[1] W. Berthold et al., Appl. Phys. A 78, 131 (2004)