Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 46: Time-resolved spectroscopies I

O 46.8: Vortrag

Donnerstag, 26. März 2009, 12:15–12:30, SCH A315

Chirped-pulse two-photon photoemission from Cu(111): experiment and theory — •Alexander Fischer², Felix Steeb², Stefan Mathias², Martin Wiesenmayer¹, Martin Aeschlimann², and Michael Bauer¹ — ¹IEAP, Sektion Physik, Christian-Albrechts-Universität zu Kiel, 24908 Kiel — ²Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663

In the study of ultrafast processes at surfaces using femtosecond light sources the effect of the spectral phase of the excitation pulse has been considered only in a few publications, yet [1,2]. For instance, Petek et al. investigated the spectral changes in the 2PPE signal from the Cu(111) Shockley surface state as induced by a controlled variation of the spectral phase of the excitation light. In this case the findings were attributed to the specific ultrafast dynamics of the involved intermediate state and not to the chirp of the laser pulse. Here we report on an extension of these earlier studies, which considers next to the peak position further spectral signatures such as the peak FWHM and asymmetry. Additionally we develop a theoretical model, which enable us to reproduce and interpret our observations in a quantitatively very satisfactory manner. It reproduces almost perfectly the experimental observed changes in the surface state 2PPE signal for a non resonant excitation scheme under consideration of the complete spectral phase of the laser pulse, especially the interaction of GVD and TOD[3].

[1] H. Petek, et al., Phys. Rev. Lett. 79 4649 (1997) [2] M. Merschdorf, et al., Phys. Rev. B 70, 1934401 (2004) [3] M. Bauer, et al, The nature of a nonlinear excitation..., New J. of Phys., in print