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RGLAB: Russian-German Laboratory at BESSY II

The idea to establish a Russian-German Laboratory at BESSY II, consisting of a beamline and an experimental station, came up in 1994 as the result of the long-standing co-operation between scientists from the physics departments of the Freie Universität Berlin (Prof. G. Kaindl) and Saint Petersburg State University (Prof. V. K. Adamchuk). A scientific case of the installation was worked out in cooperation with specialists of Helmholtz-Zentrum Berlin (Prof. W. Gudat) on the basis of research proposals for tentative experiments collected from more than 40 Russian scientific groups and institutions. Cities of these groups are listed below and their locations are shown on the map of the Russian Federation.

Further discussion and evaluation of the proposal, which took place at the Russian-German Workshops (1995 in Berlin, 1997 in Saint Petersburg), resulted in a conclusion that the experimental equipment should include a high resolution bending-magnet beamline (resolving power up to 25000) operating in the photon-energy range from about 30 to 1500 eV as well as a spectrometer dedicated to photoemission and photoabsorption studies of solids and gases.

The actual construction of a plane-grating-monochromator beamline for the XUV/soft-X-ray region began in 1997, with the Freie Universität Berlin in overall charge. The start of the project was made possible by a substantial donation from the "Stiftung Deutsche Klassenlotterie Berlin" to the Freie Universität Berlin as well as detailed design studies performed by scientists from Saint Petersburg State University in collaboration with staff members of Helmholtz-Zentrum Berlin, which were financially supported by the Bundesministerium für Bildung und Forschung (BMBF). Shortly after, the Ministry of Science and Technology of the Russian Federation agreed also to finance some essential parts of the beamline, which were manufactured by a company in Saint Petersburg. In October 2001 the installation of the beamline was completed and first photoionization spectra of various gases were measured in order to characterize the performance. The official inauguration of the Russian-German Laboratory at BESSY II was celebrated on November 20, 2001, during the "3rd Russian-German Workshop on Synchrotron Radiation Research" (Berlin, November 18-20, 2001). The implementation of an experimental station provided by the Technische Universität Dresden was achieved in January 2002.

A significant upgrade followed in 2011 with implementation of a new experimental end-station for high-resolution photoelectron spectroscopy (RGL-PES) provided by TU Dresden and funded by BMBF. This endstation is fixed at the RGBL-dipole beamline allowing one to address modern problems of condensed matter physics and physical chemistry. Another upgrade yields circularly polarized soft X-rays and is currently in progress.

From 2012 a new undulator beamline was planned and built at the U125-2 undulator under the guidance of Helmholtz-Zentrum Berlin. Funding by BMBF also allowed us to build a new endstation for angle- and spin-resolved photoemission by TU Dresden. To be integrated is also a scanning probe microscope, and Freie Universität Berlin developed and characterized a photoelectron microscope (RGL-PEEM). This significantly broadens the range of experimental capabilities of RGL. Opening of the Undulator Beamline of RGL for the user community was done in 2019 and the inauguration event of this extension of RGL was celebrated on October 28, 2019. This beamline with its unique capabilities opens the doors for cutting-edge research on electronic and spin properties of modern materials, such as topological insulators, graphene, graphene-like structures, and strongly correlated systems.