Femtosecond-laser photoemission spectra were obtained from a Mo(100) single crystal surface covered with stoichiometric magnesia thin films of well-defined thickness. Depending on the excitation wavelength and the MgO layer thickness, either one or two photon photoemission was detected at 333 and at 402 nm. This photoemission was assigned to originate from the molybdenum d band states even for 10 monolayers MgO coverage. At 263 nm excitation, however, the photoemission power dependence indicated that the signal contained both contributions from the Mo metal d electrons and from the MgO O2p valence band. While one nominal monolayer of MgO only slightly influenced the photoemission from the molybdenum surface, a considerable reduction of the surface electronic work function was observed for ultrathin magnesia overlayers of 2 to 3 monolayers in thickness. No significant change in the work function was measured for more than 3 up to 10 monolayers.

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A method for fast spatially resolved photoactivation of fluorescence from silver oxide nanoparticle films is presented. High activation rates are achieved through fast scanning of a focused high repetition rate 800 nm femtosecond laser with a peak power of 6.5 MW/cm2 over the sample. The activated areas of the thin films show fluorescence after subsequent excitation with an Ar+/Kr+ laser. The fluorescent properties were investigated by means of scanning laser microscopy at ambient conditions. Depending on excitation wavelengths (488 or 568 nm) strong fluorescence in the green or red domain was observed. The activation efficiencies were examined both as a function of exposure time and femtosecond laser power. Sensitivity, reliability and possible mechanisms for the photoactivation process are discussed.

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A systematic analysis of the embedded atom EXAFS (AXAFS) effect is presented. This effect is explained by the backscattering of the photoelectron at interstitial charge densities. The reconstructed (2 × 1)O/Cu(110) system is an ideal prototype system in which to study the angular dependence of the AXAFS because oxygen–copper rows are formed resulting in a C2 symmetry. The scattering potential is non-spherical because of the high directionality of the O–Cu bonds. The high signal-to-noise ratio of the experimental data enables us to clearly identify the AXAFS contribution. Here we present the definite angular dependence of the experimental AXAFS for the first time, giving a unique opportunity to measure the anisotropy of the local embedded atom potential. The angular dependence demonstrates that the AXAFS effect cannot be mimicked by multi-electron excitations or experimental artifacts for this system. We compare our experiments to theoretical calculations within the muffin-tin approximation and show that future full-potential calculations are needed to model the angular dependence determined.