SURFACE-STATE LIFETIME MEASURED BY SCANNING TUNNELING SPECTROSCOPY

Quasiparticle interactions broaden spectral features at surfaces, whic h can be measured using the scanning tunneling microscope (STM). We re port the first study of lifetime effects on Shockley surface-state ele ctrons using low-temperature STM spectroscopy. Data taken from Ag(lll) are analyzed using detailed tunneling calculations and a simple model . and are found to correspond to a self-energy of Sigma = 4.9 +/- 0.6 meV. This is considerably below values determined by angle-resolved ph otoemission, but remains higher than theoretical predictions. [S0031-9 007(98)07612-1].