Nov 6, 2009 - flat crossed wireframe anodes which count incoming particles sub- ..... four pulses on the delay line detector ends for x and y, which are converted into ...... [18] http://www.surface-concept.com/html/electron-detection.html.
Author's personal copy Journal of Electron Spectroscopy and Related Phenomena 178–179 (2010) 317–330
Contents lists available at ScienceDirect
Journal of Electron Spectroscopy and Related Phenomena journal homepage: www.elsevier.com/locate/elspec
Time- and energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations Andreas Oelsner a,∗ , Martin Rohmer b , Christian Schneider b , Daniela Bayer b , Gerd Schönhense c , Martin Aeschlimann b a b c
Surface Concept GmbH, Staudingerweg 7, 55128 Mainz, Germany Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany Johannes Gutenberg Universität Mainz, Institut für Physik, Staudingerweg 7, 55128 Mainz, Germany
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Article history: Available online 6 November 2009 Keywords: Time-resolved photoemission Photoemission electron microscopy Delay line detector Time-of-flight
a b s t r a c t The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for realtime spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump–probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4D imaging (x, y, t, EKin ) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction. By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108 ps absolute and 13.5 ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time-resolved PEEM technique enables to display evolutions of spatially resolved (
