W. Wallauer et T. Fauster, 2-PHOTON EXCITATION PROCESSES AND LINEWIDTHS OF SURFACE AND IMAGE STATES ON CU(111), Surface science, 374(1-3), 1997, pp. 44-50
The occupied surface state and the first image state on Cu(111) have b
een observed by high-resolution, two-photon photoemission as a functio
n of photon energy. A pronounced narrowing of the linewidth is found f
or the resonant excitation from the occupied surface state into the fi
rst image state. The product of two Lorentzians convoluted with a Gaus
sian leads to a satisfactory description of the complete series of spe
ctra. The intrinsic linewidth of the first image state on Cu(111) is o
btained as 85 +/- 10 meV, in agreement with recent time-resolved measu
rements. The occupied surface state has an intrinsic linewidth of 65 /- 15 meV, as also observed in one-photon photoemission experiments. (
C) 1997 Elsevier Science B.V.