Journal of large-scale research facilities, 2, A72 (2016) http://dx.doi.org/10.17815/jlsrf-2-75 Published: 18.05.2016 The plane grating monochromator beamline U49/2 PGM1 at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientists: - Dr. Torsten Kachel, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062-12942, email: torsten.kachel@helmholtz-berlin.de Abstract: U49/2 PGM1 is one of HZB open-port VUV beamlines. Therefore and due to the fact that it delivers highest �ux with very acceptable energy resolution it is the most heavily booked BESSY II beamline. Earlier work has largely focused on surface science and catalysis. After shut down of the former U41 PGM an increasing number of experiments on liquids and solutions are carried out. 1 Introduction The plane grating monochromator U49/2 PGM1 delivers soft X-ray undulator radiation of linear polar- ization between 84 and about 1500 eV. High photon �ux combined with high stability and a compar- atively small spot size allow for "photon hungry" experiments like e.g. coincidence methods, photo- excitation on liquid jets or clusters. Experiments have a strong focus on surface chemistry and surface physics but also serve selected topics in molecular and atomic science. The high demand of these ra- diation properties is visible by the overbooking in beam time requests and the number and quality of high impact publications by external and in-house users. *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2016). The plane grating monochromator beamline U49/2 PGM1 at BESSY II. Journal of large-scale research facilities, 2, A72. http://dx.doi.org/10.17815/jlsrf-2-75 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-2-75 http://dx.doi.org/10.17815/jlsrf-2-75 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A72 (2016) http://dx.doi.org/10.17815/jlsrf-2-75 Figure 1: Top-view of beamline U49/2 PGM1. 2 Instrument application Typical applications are: • Surface science • Catalysis • Photoemission • Liquids • Liquid Solutions 3 Source Type planar hybrid Location H15 Periode length 49.4 mm Periods/Pols 84 Minimal Energy at 1.7 GeV 84.4 eV Minimal Gap 16 mm Polarisation linear horizontal Table 1: Parameters of the undulator U49/2. 2 http://dx.doi.org/10.17815/jlsrf-2-75 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-2-75 Journal of large-scale research facilities, 2, A72 (2016) Figure 2: Photon �ux at beamline U49/2 PGM1. 4 Optical Design The M1 toroidal mirror M1 collimates the radiation horizontally and vertically. The monochromator pre-mirror M2 together with the exchangeable gratings G build up a standard Zeiss P(lane)-G(rating)- M(onochromator) con�guration. The cylindrical mirror M3 focuses the dispersed beam onto the exit slit while it leaves the horizontal component una�ected. The refocusing mirror M4 has an arm length ratio of 3:2 vertically. Horizontally the incoming collimated beam is focused at 1200 mm. Figure 3: Optical layout of beamline U49/2 PGM1. 3 http://dx.doi.org/10.17815/jlsrf-2-75 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A72 (2016) http://dx.doi.org/10.17815/jlsrf-2-75 5 Technical Data Location 16.2 Source U49/2 Monochromator PGM1 Energy range 85 - 1600 eV Energy resolution 25,000 (85 - 500 eV) 15,000 (500 - 1,500 eV) (standard grating) Flux 1013 ph/s (85 - 500 eV) 1012 ph/s (500 - 1500 eV) (standard grating) Polarization Horizontal Divergence horizontal 2 mrad Divergence vertical 2 mrad Focus size (hor. x vert.) 100 µ m x 22 µ m Distance Focus/last valve 959 mm Height Focus/�oor level 1417 mm Free photon beam available Yes Fixed end station No Table 2: Technical parameters of beamline U49/2 PGM1. References Sawhney, K., Senf, F., & Gudat, W. (2001). PGM beamline with constant energy resolution mode for U49-2 undulator at BESSY-II. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 467–468, Part 1, 466 - 469. (7th Int. Conf. on Synchrotron Radiation Instrumentation) http://dx.doi.org/10.1016/S0168-9002(01)00360-6 4 http://dx.doi.org/10.17815/jlsrf-2-75 http://dx.doi.org/10.1016/S0168-9002(01)00360-6 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument application Source Optical Design Technical Data