Journal of large-scale research facilities, 2, A81 (2016) http://dx.doi.org/10.17815/jlsrf-2-87 Published: 02.08.2016 FEMTOSPEX Molecules and Surfaces: Electron spectroscopy setup for time-resolved laser-pump/ X-ray-probe experiments at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientists: - Dr. Florian Sorgenfrei, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062-12924, email: �orian.sorgenfrei@helmholtz-berlin.de Abstract: The �exible end station “FEMTOSPEX Molecules and Surfaces”, which will enable time re- solved photoemission studies in the future at HZB, is presented. 1 Introduction The FEMTOSPEX Molecules and Surfaces end station is designed for time-resolved photoelectron spec- troscopy studies using an optical laser to pump the system under investigation. We are currently explor- ing in in-house projects the possibility to use the PPRE bunch available during normal user operation (Holldack et al., 2014) for time-resolved studies with a temporal resolution of about 60ps as well as using a HHG source for femtosecond time-resolved experiments. The chamber is equipped with a VG Scienta ArTOF (Ovsyannikov et al., 2013) using a lens with an acceptance angle of 60 degrees. A typical spectrum using TaS2 as sample and observing the charge density wave splitting is depicted in Figure 1. Figure 2 shows the setup at the PGM beamline at the slicing facility. *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2016). FEMTOSPEX Molecules and Surfaces: Electron spectroscopy setup for time-resolved laser-pump/ X-ray-probe experiments at BESSY II. Journal of large-scale research facilities, 2, A81. http://dx.doi.org/10.17815/jlsrf-2-87 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-2-87 http://dx.doi.org/10.17815/jlsrf-2-87 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A81 (2016) http://dx.doi.org/10.17815/jlsrf-2-87 Figure 1: Ta 4f lines of TaS2 cooled to ~25 K using 200 eV photons. The spin-orbit split doublet is accompanied by an additional charge density wave (CDW) splitting. Figure 2: On-top view on the FEMTOSPEX Molecules and Surfaces station. 2 http://dx.doi.org/10.17815/jlsrf-2-87 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-2-87 Journal of large-scale research facilities, 2, A81 (2016) 2 Instrument application Typical applications are: • time-resolved PES • angular-resolved PES • XPS • UPS 3 Technical data Monochromator Soft X-ray Experiment in vacuum Yes Detector ARTOF EW 60° lens electron spectrometer Manipulators • VAb Manipulator with two rotation axes in theta-twotheta con�guration • wobble stick for adjusting the phi axis of the samples • APD for de�ning the temporal overlap • Quartz slit for adjusting the halo/slice sep- aration Cryostat Janis ST-400 cryostat typical sample temperature ~25 K Prepration chamber • Sputter gun • Residual gas analyser Table 1: Technical parameters of the FEMTOSPEX Molecules and Surfaces station References Holldack, K., Ovsyannikov, R., Kuske, P., Müller, R., Schälicke, A., Scheer, M., . . . Föhlisch, A. (2014). Single bunch X-ray pulses on demand from a multi-bunch synchrotron radiation source. Nature Communications, 5, 4010. http://dx.doi.org/10.1038/ncomms5010 Ovsyannikov, R., Karlsson, P., Lundqvist, M., Lupulescu, C., Eberhardt, W., Föhlisch, A., . . . Mårtensson, N. (2013). Principles and operation of a new type of electron spectrometer ArTOF. Journal of Electron Spectroscopy and Related Phenomena, 191, 92 - 103. http://dx.doi.org/10.1016/j.elspec.2013.08.005 3 http://dx.doi.org/10.17815/jlsrf-2-87 http://dx.doi.org/10.1038/ncomms5010 http://dx.doi.org/10.1016/j.elspec.2013.08.005 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument application Technical data