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    Incorporation of nitrogen into TiO2 thin films during PVD processes
    (Bristol : Institute of Physics Publishing, 2014) Asenova, I.; Manova, D.; Mändl, S.
    In this paper we investigate the possibility of incorporating nitrogen into amorphous, photocatalytic TiO2 thin films, prepared at room temperature, during the growth process. The aim is to reduce the bandgap of the UV active thin films. Physical vapor deposition experiments employing a titanium vacuum arc with gas backfill ranging from pure oxygen to pure nitrogen, are carried out. The resulting films are characterized for chemical composition, phase composition, optical properties and hydrophilicity in order to determine a correlation between gas composition and thin film properties. The experimental results point that a visible change in the band structure of the deposited layers is achieved.
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    Towards time resolved core level photoelectron spectroscopy with femtosecond x-ray free-electron lasers
    (College Park, MD : Institute of Physics Publishing, 2008) Pietzsch, A.; Föhlisch, A.; Beye, M.; Deppe, M.; Hennies, F.; Nagasono, M.; Suljotil, E.; Wurth, W.; Gahl, C.; Dörich, K.; Melnikov, A.
    We have performed core level photoelectron spectroscopy on a W(110) single crystal with femtosecond XUV pulses from the free-electron laser at Hamburg (FLASH). We demonstrate experimentally and through theoretical modelling that for a suitable range of photon fluences per pulse, time-resolved photoemission experiments on solid surfaces are possible. Using FLASH pulses in combination with a synchronized optical laser, we have performed femtosecond time-resolved core-level photoelectron spectroscopy and observed sideband formation on the W 4f lines indicating a cross correlation between femtosecond optical and XUV pulses. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
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    Ultrafast two-dimensional terahertz spectroscopy of elementary excitations in solids
    (Bristol : IOP, 2013) Woerner, M.; Kuehn, W.; Bowlan, P.; Reimann, K.; Elsaesser, T.
    Recent experimental progress has allowed for the implementation of nonlinear two-dimensional (2D) terahertz (THz) spectroscopy in the ultrafast time domain. We discuss the principles of this technique based on multiple phase-locked electric field transients interacting in a collinear geometry with a solid and the phase-resolved detection of the THz fields after interaction with the sample. To illustrate the potential of this new method, 2D correlation spectra of coupled intersubband-longitudinal optical phonon excitations in a double quantum well system and a study of ultrafast carrier dynamics in graphene are presented.