Inquiry number

INS-0000000312

ABSTRACT

  The BL39XU beamline is capable of performing X-ray spectroscopy experiments in the hard X-ray region. The target materials are samples containing 3d transition metal elements, rare earth elements, and 5d transition metal elements. The main measurement techniques are X-ray absorption spectroscopy (XAFS), X-ray magnetic circular dichroism (XMCD) spectroscopy, and X-ray emission spectroscopy (XES). The main advantage of this beamline is the availability of X-rays in various polarization states. By using a diamond X-ray phase retarder, polarized X-rays can be easily switched between left- and right-circular polarization, horizontal and vertical linear polarization, and arbitrary elliptical polarization. The experimental station is equipped with a cryostat (helium-flowing and pulsed-tube type) and a magnetic field apparatus (electromagnet and superconducting magnet). The sample temperature can be varied between 11 and 500 K for the helium-flowing type cryostat and between 3 and 300 K for the pulsed-tube type cryostat, and magnetic fields up to 3.5 T at room temperature and 1.5 T at low temperature can be applied to the sample. For experiments requiring higher fields and/or lower temperatures, a superconducting magnet with a maximum field of 7 T and a minimum temperature of 2 K is available. This method allows us to obtain XMCD data with very high signal-to-noise ratio in a very short time. For XES measurements, spherically-bent analyzer crystals can be used to monochromatize fluorescence X-rays with high energy resolution (0.5∼2 eV), which can be used for high-energy-resolution fluorescence detection (HERFD) XAFS measurements.
  In addition, a microbeam of 1 µm (vertical: V) and 10 µm (horizontal: H) can be obtained in experimental hutch 1 and a nanobeam of 100 nm (V) and 100 nm (H) can be obtained in experimental hutch 3 by using KB focusing mirror system. These beams can be used for scanning XMCD imaging and measurement of element-specific magnetization curves in small areas. In addition, XAFS and XMCD experiments can be performed under high pressure (ambient pressure - about 180 GPa at room temperature and ambient pressure - about 40 GPa at low temperatures) using a diamond anvil high pressure cell (DAC).

AREA OF RESEARCH

• X-ray magnetic circular dichroism (XMCD) spectroscopy
• Element-specific magnetometry (ESM)
• X-ray emission spectroscopy (XES) and high-energy-resolution fluorescence detection (HERFD) XAFS
• XAFS, XRF, and XMCD imaging using micro/nanobeam, and XAFS, XMCD and ESM measurements in micro-region and tiny samples, with a 100-300 nm spatial resolution
• XAFS and XMCD at high pressure
• X-ray spectroscopy using variable X-ray polarization

KEYWORDS

• Scientific field
  XAFS, X-ray magnetic circular dichroism, Element-specific magnetometry, Magnetic EXAFS, X-ray emission spectroscopy, High-energy-resolution XAFS, Polarization XAFS, microbeam, magnetic imaging, high pressure
• Equipment
  X-ray phase plate, Electromagnet, Superconducting magnet, Cryostat, KB focusing mirrors, diamond anvil high pressure cell (DAC)

SOURCE AND OPTICS

  The X-ray source of the beamline is an in-vacuum undulator. A liquid nitrogen cooled silicon double crystal monochromator is employed to provide monochromatized X-rays. The available X-ray energy range is from 5 to 37 keV (Si 111 or Si 220). Synchronized control of the undulator and monochromator allows maximum intensity X-rays to be used at any energy. Ru-coated mirrors are used to remove higher harmonics. This mirror is of the triple-reflection type, which means that the optical axis does not change with changes in glancing angle, allowing removal of higher harmonics over a wide energy range of 4.92 to 30 keV, while maintaining the focusing size and position by the focusing mirror installed downstream.

• Beamline layout
  

  An X-ray phase retarder made of diamond crystals is permanently installed downstream of the double crystal monochromator and the higher-harmonics cut mirror. In XMCD experiments, this phase retarder acts as an efficient λ/4 plate. Five different crystal thicknesses (0.10, 0.31, 0.45, 0.73, and 1.4 mm) are used, depending on the X-ray energy. By selecting the appropriate crystals, circularly polarized X-rays with high circular polarization (> 90%) are available in the range of 4.92 ∼ 16 keV. Vertical linear polarization is also available by using a phase retarder with a λ/2 plate. The polarization of perpendicular linear polarization is 40 ∼ 90%.

• X-rays at Sample

   

  Energy range	5 ∼ 37 keV (Si 111 or Si 220)
  Resolution ΔE/E	2 × 10-4 (Si 111),  1 × 10-4 (Si 220)
  Flux at sample	5.3 × 1013 photons/s (Si 111),  2.4 × 1013 photons/s (Si 220) @ 10 keV
  Beam size at sample (FWHM)	0.6 (V) × 0.6 (H) mm2
  Higher harmonic content	< 1 × 10-4
  Linear polarization rate	99.9 %
  Circular polarization rate	> 90 %

   

EXPERIMENTAL STATIONS

• X-ray emission spectrometer
• Electromagnet and closed-cycle helium refrigerator
• 7 T superconducting magnet (Temperature: 2 K)
• Helicity-modulation XMCD
• Examples of experimental data
• Facilities and Accessories

PUBLICATION SEARCH

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BL39XU PUBLICATION SEARCH

CONTACT INFORMATION

Please note that each e-mail address is followed by "@spring8.or.jp."

Naomi KAWAMURA
SPring-8 / JASRI
1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198
Phone : +81-(0)791-58-0833
Fax : +81-(0)791-58-0830
e-mail : naochan

Kotaro HIGASHI
SPring-8 / JASRI
1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198
Phone : +81-(0)791-58-0833
Fax : +81-(0)791-58-0830
e-mail : higashi