S. Link, J. Sievers, H.S. Rhie, H.A. Dürr and W. Eberhardt

Using time-resolved two photon photoemission spectroscopy we have investigated the population dynamics of image-potential states on the clean and hydrogen-covered Ni(lll) surface. On the clean surface a lifetime of 7+-3 fs for the n=l state is obtained. The adsorption of hydrogen increases the lifetime by a factor of two to 14+-4 fs.