Regensburg 2000 – wissenschaftliches Programm

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SYUO: Ultrakurzzeitdynamik an Oberflächen

SYUO 3: Kurzvortr
äge I

SYUO 3.2: Vortrag

Donnerstag, 30. März 2000, 12:45–13:00, H45

Lifetimes of image potential states on Pt(111) — •S. Link, H.A. Dürr, and W. Eberhardt — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich

We have investigated the image potential states (IPS) on clean and oxygen covered Pt(111) surfaces. Femtosecond laserpulses with photon energies of 5.84 eV and 2.92 eV have been used to populate the IPS and photoemit electrons into the vacuum. On the clean Pt(111) surface the first two image potential states (n=1,2) were resolved at binding energies of 0.7 eV and 0.25 eV, respectively. The data show that the n=2 state lives significantly longer than the n=1 state. This is in contrast to other (111) surfaces (Cu,Ag), where the n=2 state lies just outside the band gap and is therefore resonant with short lived free electron states in the bulk. The behaviour of lifetimes on the Pt(111) surface is more comparable to (100)-surfaces, where the image potential states lie close to the middle of the band gap. Oxygen adsorption affects dramatically the number of visible Rydberg states and their lifetimes.