BL25SU OUTLINE
Inquiry number
INS-0000000337
ABSTRACT
BL25SU is designed for research on electronic structures, magnetic states and surface structures of solids with high energy-resolution circularly-polarized soft x-rays.
Left- and right-handed circularly polarized radiation is obtained along the same optical axis by twin helical undulators. The helicity of the circularly polarized radiation can be periodically switched at 0.1, 1 or 10 Hz by using kicker magnets distributed around the two undulators.
The beamline monochromator is a constant deviation type with varied line-spacing plane gratings covering an energy region of 0.22 ∼ 2 keV. The resolving power of the monochromator is more than 10,000 in the whole energy region.
Four kinds of spectroscopic techniques are available for public use: high energy-resolution photoemission spectroscopy, magnetic circular dichroism of core absorption, two-dimensional angular distributions of photoelectrons, photoelectron emission microscope. Measurements are performed in ultra high vacuum conditions down to 10-8 Pa. RI (radioisotope) elements and activated gases cannot be used in this beamline.
AREA OF RESEARCH
- Observation of electronic structures by photoemission spectroscopy (PES)
- Observation of electronic band structures by angle resolved photoemission spectroscopy (ARPES)
- Magnetic state study by magnetic circular dichroism (MCD) of soft-x-ray absorption
- Element-specific magnetization curve measurements by MCD
- Analysis of atomic arrangements by photoelectron diffraction (PED)
- Observation of Magnetic domains by photoelectron emission microscope (PEEM)
KEYWORDS
- Scientific field
Soft X-ray spectroscopy of solids, Electronic structures, Magnetic states, Magnetic domains, Atomic arrangementsSoft X-ray spectroscopy of solids, Electronic structures, Magnetic states, Magnetic domains, Atomic arrangements - Equipment
Twin helical undulators, Soft x-ray monochromator with varied-line-spacing plane gratings (VLSPGM), Photoelectron analyzer (SES200, Gammadata Scienta AB), Closed-cycle He refrigerator for PES, Electromagnet for MCD, Continuous liq.-He-flow-type cryostat for MCD, Two-dimensional photoelectron analyzer for PED, PEEM (PEEMSPECTOR, ELMITEC GmbH), Ultra high vacuum ,Sample cleavers, Sample annealing systems, Ion guns, Evaporators (E-gun type)
SOURCE AND OPTICS
- Light Source
The light source "Twin Helical Undulators (THU)" is designed for helicity switching of circularly polarized radiation. THU consist of two helical undulators and five kicker magnets which generate a bump electron orbit at each undulator. When the bump orbit is excited at the first undulator (ID1), the radiation of ID1 is deflected to an off-axis direction and that of the second undulator (ID2) exclusively comes to the beamline. The helicity can be switched by switching the position of the bump orbit between ID1 and ID2. Two periodical switching modes at 1 and 10 Hz are currently available. Excitation patterns of the bump orbits are trapezoidal for the 0.1- and 1-Hz modes, and are sine curves for the 10-Hz modes, respectively. The helicity switching is utilized for circular dichroism measurements of core absorption, PED and PEEM.
- References
- "SPring-8 twin helical undulator", T.Hara et al., J. Synchrotron Rad. 5 (1998) 426.
- "Helicity switching of circularly polarized undulator radiation by local orbit bumps", T.Hara et al., Nucl. Instr. and Meth. A 498 (2003) 496.
- "Fast helicity switching of circularly polarized light using twin helical undulators", K.Shirasawa et al., SRI2003 proceedings, AIP conference proceedings 705 (2004) 191.
- "A measurement system for circular dichroism in soft x-ray absorption using helicity switching by twin helical undulators", T.Muro et al., SRI2003 proceedings, AIP conference proceedings 705 (2004) 1051.
- Beamline
The constant-deviation monochromator includes a spherical mirror and a varied-line-spacing plane grating (VLSPG) between entrance and exit slits. Energy scan is performed by a single rotation of the VLSPG, which allows simple mechanical control and high energy tunability. The deviation angle of the VLSPG can be chosen from two discrete angles of 174° and 176° corresponding to the lower and higher energy sides. VLSPGs with two different central groove densities of 600 and 1,000 lines/mm are also selectable. An energy range from 0.22 to 2 keV is covered by changing combinations of the deviation angles and VLSPGs.
- References
- "Twin helical undulator beamline for soft x-ray spectroscopy at SPring-8", Y.Saitoh et al., J. Synchrotron Rad. 5 (1998) 542.
- "Performance of a very high resolution soft x-ray beamline BL25SU with a twin-helical undulator at SPring-8", Y.Saitoh et al., Rev. Sci. Instrum. 71 (2000) 3254.
- "Soft x-ray beamline for spectroscopy of solids at SPring-8", Y.Saitoh et al. Nucl. Instr. and Meth. A 467-468 (2001) 553.
- X-rays at Sample
Energy resolution E/ΔE > 10000 Photon flux > 1011 ph/s/0.02%b.w. Beam size < 0.4 mmφ
EXPERIMENTAL STATIONS
PUBLICATION SEARCH
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CONTACT INFORMATION
Please note that each e-mail address is followed by "@spring8.or.jp."
Tetsuya NAKAMURA
SPring-8 / JASRI
1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198
Phone : +81-(0)791-58-0832
Fax : +81-(0)791-58-0830
e-mail : naka
Takayuki MURO
SPring-8 / JASRI
1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198
Phone : +81-(0)791-58-0832
Fax : +81-(0)791-58-0830
e-mail : muro
Takuo OHUKOCHI
SPring-8 / JASRI
1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198
Phone : +81-(0)791-58-0832
Fax : +81-(0)791-58-0830
e-mail : o-taku