《Vacuum space charge effect in laser-based solid-state photoemission》.pdfVIP

JOURNAL OF APPLIED PHYSICS 107, 014912 2010 Vacuum space charge effect in laser-based solid-state photoemission spectroscopy J. Graf,1,2 S. Hellmann,3 C. Jozwiak,1,2 C. L. Smallwood,2 Z. Hussain,4 R. A. Kaindl,1 L. Kipp,3 K. Rossnagel,3 and A. Lanzara1,2,a 1 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 2 Department of Physics, University of California, Berkeley, California 94720, USA 3 Institute for Experimental and Applied Physics, University of Kiel, D-24098 Kiel, Germany 4 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Received 2 September 2009; accepted 17 November 2009; published online 12 January 2010 We report a systematic measurement of the space charge effect observed in the few-picosecond laser pulse regime in laser-based solid-state photoemission spectroscopy experiments. The broadening and the shift of a gold Fermi edge as a function of spot size, laser power, and emission angle are characterized for pulse lengths of 6 ps and 6 eV photon energy. The results are used as a benchmark for an N-body numerical simulation and are compared to different regimes used in photoemission spectroscopy. These results provide an important reference for the design of time- and angle-resolved photoemission spectroscopy setups and next-generation light sources. © 2010 American Institute of Physics. doi: 10.1063/1.3273487 I. INTRODUCTION regime becomes imperative. A recent study of the space