Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 43: Poster Session II - MA 141/144 (Surface Spectroscopy on Kondo Systems; Frontiers of Surface Sensitive Electron Microscopy; Methods: Scanning Probe Techniques+Electronic Structure Theory+Other; Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation; joined by SYNF posters)

O 43.44: Poster

Dienstag, 26. Februar 2008, 18:30–19:30, Poster F

An angle-resolved time-of flight spectrometer for low-energy photoelectron spectroscopy — •Laurenz Rettig, Patrick S. Kirchmann, Uwe Bovensiepen, and Martin Wolf — Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin

We developed and constructed a two-dimensional position-sensitive time-of-flight spectrometer (pTOF) for the angle-resolved analysis of low-energy electrons photoemitted from a metal surface by femtosecond laser pulses. The spectrometer design combines a field-free drift tube with 22^∘ acceptance angle and a microchannel plate stack with a delay-line anode [1] for position encoding. The pTOF spectrometer allows to determine both surface in-plane electron momentum components p_x and p_y along with the kinetic energy. The pTOF concept is optimized to study the electron scattering dynamics of laterally anisotropic electronic systems such as self-assembled quasi-1D atomic nano-wires or stepped surfaces.

Here, we present the working principles as well as the hard- and software implementation of the pTOF, which includes real-time analysis of multiple electron hits per laser pulse. This multihit capability is crucial for pulsed laser spectroscopy with repetition rates of ∼100 kHz. To demonstrate the performance of the spectrometer measurements on a Cu(111) single-crystalline surface were performed using UV femtosecond laser pulses of 6.20 eV photon energy.

[1] O. Jagutzki, A. Cerezo, A. Czasch, et al., IEEE Trans. Nucl. Sci. 49, 2477 (2002).