FEMTOSECOND PHOTOEMISSION-STUDY OF ULTRAFAST ELECTRON DYNAMICS ON CU(100)

The energy dependence of the relaxation of photoexcited electrons in c opper was measured using femtosecond time-resolved photoemission spect roscopy to within 0.3 eV above the Fermi level. By performing lifetime measurements under different surface conditions, several surface dyna mical processes were investigated. In particular, an anomalous long li fetime feature, which cannot be explained with Fermi-liquid theory, wa s observed in the lifetime-energy curve. This feature was found origin ating from the photoexcitation of the strongly localized Cu 3d electro ns.