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Phys. Rev. Lett. 81 (1998) pp. 4464-4467

Surface state lifetime measured by scanning tunneling spectroscopy

Jiutao Li and Wolf-Dieter Schneider

Institut de Physique Experimentale, Universite de Lausanne, CH-1015 Lausanne, Switzerland

Richard Berndt

2. Physikalisches Institut, RWTH Aachen, D-52056 Aachen, Germany

O.R. Bryant and S. Crampin

Department of Physics, University of Bath, BA2 7AY, United Kingdom

Abstract
Quasiparticle interactions broaden spectral features at surfaces, which can be measured using the scanning tunneling microscope (STM). We report the first study of lifetimes effects on Shockley surface state electrons using low-temperature STM spectroscopy. Data taken from Ag(111) are analysed and understood using detailed tunneling calculations and a simple model, and found to correspond to a self-energy of Sigma=4.9 +/- 0.6 meV. This is considerably below values determined by angle-resolved photoemission, but remains higher than theoretical predictions.