Journal of large-scale research facilities, 3, A105 (2017) http://dx.doi.org/10.17815/jlsrf-3-142 Published: 14.02.2017 The variable polarization undulator beamline UE52 PGM nanocluster trap at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientists: - Dr. Ruslan Ovsyannikov, Helmholtz-Zentrum Berlin für Materialien und Energie phone: +49 30 8062-17965, email: ovsyannikov@helmholtz-berlin.de - Dr. Tobias Lau, Helmholtz-Zentrum Berlin für Materialien und Energie phone: +49 30 8062-14786, email: tobias.lau@helmholtz-berlin.de Abstract: UE52 PGM nanocluster trap is a soft x-ray beamline at BESSY II that delivers an unfocussed low-divergence beam of variable polarization. Its characteristics are ideally suited for ion trap studies of magnetic properties. 1 Introduction The variable polarization undulator beamline with plane-grating monochromator UE52 PGM nanoclus- ter trap currently hosts the nanocluster trap end station. 2 Instrument application Beamline UE52 PGM is used to investigate magnetic and electronic properties of a large variety of di�erent samples. Because of its beam characteristics, UE52 PGM nanocluster trap currently hosts the nanocluster trap end station, which is set up behind the focal point. *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2017). The variable polariza- tion undulator beamline UE52 PGM nanocluster trap at BESSY II. Journal of large-scale research facilities, 3, A105. http://dx.doi.org/10.17815/jlsrf-3-142 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-3-142 http://dx.doi.org/10.17815/jlsrf-3-142 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 3, A105 (2017) http://dx.doi.org/10.17815/jlsrf-3-142 Figure 1: Top-view of beamline UE52 PGM Nano cluster trap. 2 http://dx.doi.org/10.17815/jlsrf-3-142 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-3-142 Journal of large-scale research facilities, 3, A105 (2017) 3 Source The insertion device is the elliptical undulator UE52 with the following parameters Type APPLE2 Location H09 Periode length 52 mm Periods/Pols 77 n Minimal Energy at 1,7 GeV 72 eV Minimal Gap 16 mm Polarisation linear variable 0° ... +90° elliptical, circular Table 1: Parameters of insertion device UE52. 4 Optical Design UE52 PGM is equipped with an elliptical undulator and plane-grating monochromator with refocusing optics. The energy range of beamline UE52 PGM is similar to most soft x-ray beamlines at BESSY II; it covers 82 eV – 1900 eV in horizontal polarization and 115 eV – 1390 eV in elliptical polarization. Two gratings with 360 l/mm and 1200 l/mm are in principle available in the plane-grating monochro- mator. The standard grating that is utilized by all user groups is the 1200 l/mm grating. This delivers a �ux of 1010 to 1012 photons per second, per 100 mA ring current, and per energy bandwidth at 100 µ m exit slit, depending on the photon energy. Because the focal point of the beamline is occupied by the permanently installed UE52 PGM Co- ESCA end station, UE52 PGM nanocluster trap beamline does not deliver a focused beam, but rather a medium-sized beam pro�le of 0.65 mm × 0.70 mm, with a low divergence of 0.06 mrad in the horizontal and 0.14 mrad in the vertical direction at 700 eV photon energy as shown in Figure 2. The low-divergence beam pro�le makes the UE52 PGM nanocluster trap beamline ideally suited for ion trap studies of atomic, molecular, and cluster physics on dilute samples in the gas-phase, where the overlap of ion cloud and photon beam has to be matched over distances of more than 20 cm. This is the main purpose of the beamline (Egorov et al., 2015; Hirsch et al., 2015; Langenberg et al., 2014; Niemeyer et al., 2012; Zamudio-Bayer, Hirsch, Langenberg, Kossick, et al., 2015; Zamudio-Bayer, Hirsch, Langen- berg, Ławicki, et al., 2015; Zamudio-Bayer et al., n.d., 2013). In this respect, UE52 PGM nanocluster trap beamline is unique at BESSY II, because all other beamlines with elliptical polarization for �exible use at BESSY II feature high divergence beam pro�les with very short distances between the beamline exit port (last valve) due to the installed micrometer focus optics. 3 http://dx.doi.org/10.17815/jlsrf-3-142 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 3, A105 (2017) http://dx.doi.org/10.17815/jlsrf-3-142 Figure 2: Typical beam pro�le (FWHM vs. position) at UE52 PGM. The spot size is ~0.6 × 0.7 mm2 with a low divergence of 0.06 mrad (horizontal) and 0.14 mrad (vertical) at 700 eV and 100 µ m exit slit. 5 Technical Data Location 10.2 Source UE52 Monochromator PGM Energy range 85 - 1600 eV Energy resolution > 10000 at 400 eV Flux 1012 Polarization Variable Divergence horizontal 0.8 mrad Divergence vertical 0.2 mrad Distance Focus/last valve unfocussed low-divergence beam Height Focus/�oor level 1412 mm Free photon beam available No Fixed end station Yes Table 2: Technical data of beamline UE52 nanocluster trap. References Egorov, D., Sadia, B., Hoekstra, R., Ławicki, A., Hirsch, K., Zamudio-Bayer, V., . . . Schlathölter, T. (2015). An intense electrospray ionization source for soft x-ray photoionization of gas phase pro- tein ions. Journal of Physics: Conference Series, 635(11), 112083. http://dx.doi.org/1088/1742- 6596/635/11/112083 4 http://dx.doi.org/10.17815/jlsrf-3-142 http://dx.doi.org/1088/1742-6596/635/11/112083 http://dx.doi.org/1088/1742-6596/635/11/112083 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-3-142 Journal of large-scale research facilities, 3, A105 (2017) Hirsch, K., Zamudio-Bayer, V., Langenberg, A., Niemeyer, M., Langbehn, B., Möller, T., . . . Lau, J. T. (2015). Magnetic moments of chromium-doped gold clusters: The anderson impurity model in �nite systems. Phys. Rev. Lett., 114, 087202. http://dx.doi.org/10.1103/PhysRevLett.114.087202 Langenberg, A., Hirsch, K., Ławicki, A., Zamudio-Bayer, V., Niemeyer, M., Chmiela, P., . . . Lau, J. T. (2014). Spin and orbital magnetic moments of size-selected iron, cobalt, and nickel clusters. Phys. Rev. B, 90, 184420. http://dx.doi.org/10.1103/PhysRevB.90.184420 Niemeyer, M., Hirsch, K., Zamudio-Bayer, V., Langenberg, A., Vogel, M., Kossick, M., . . . Lau, J. T. (2012). Spin coupling and orbital angular momentum quenching in free iron clusters. Phys. Rev. Lett., 108, 057201. http://dx.doi.org/10.1103/PhysRevLett.108.057201 Zamudio-Bayer, V., Hirsch, K., Langenberg, A., Kossick, M., Ławicki, A., Terasaki, A., . . . Lau, J. T. (2015). Direct observation of high-spin states in manganese dimer and trimer cations by x-ray magnetic circular dichroism spectroscopy in an ion trap. The Journal of Chemical Physics, 142(23), 234301. http://dx.doi.org/10.1063/1.4922487 Zamudio-Bayer, V., Hirsch, K., Langenberg, A., Ławicki, A., Terasaki, A., v. Issendor�, B., & Lau, J. T. (2015). Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy. The Journal of Chemical Physics, 143(24), 244318. http://dx.doi.org/10.1063/1.4939078 Zamudio-Bayer, V., Hirsch, K., Langenberg, A., Niemeyer, M., Vogel, M., Ławicki, A., . . . von Issendor�, B. (n.d.). Maximum spin polarization in chromium dimer cations as demonstrated by x-ray mag- netic circular dichroism spectroscopy. Angewandte Chemie International Edition, 54(15), 4498–4501. http://dx.doi.org/10.1002/anie.201411018 Zamudio-Bayer, V., Leppert, L., Hirsch, K., Langenberg, A., Rittmann, J., Kossick, M., . . . Lau, J. T. (2013). Coordination-driven magnetic-to-nonmagnetic transition in manganese-doped silicon clusters. Phys. Rev. B, 88, 115425. http://dx.doi.org/10.1103/PhysRevB.88.115425 5 http://dx.doi.org/10.17815/jlsrf-3-142 http://dx.doi.org/10.1103/PhysRevLett.114.087202 http://dx.doi.org/10.1103/PhysRevB.90.184420 http://dx.doi.org/10.1103/PhysRevLett.108.057201 http://dx.doi.org/10.1063/1.4922487 http://dx.doi.org/10.1063/1.4939078 http://dx.doi.org/10.1002/anie.201411018 http://dx.doi.org/10.1103/PhysRevB.88.115425 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument application Source Optical Design Technical Data