BL-11A Soft X-Ray Grazing Incidence Monochromator Station
Spokesperson :Yoshinori KITAJIMA
5645(PHS:4279)
yoshinori.kitajima@kek.jp
BL-11A will be shut down until the end of March, 2023, because the PF has decided to construct a new R&D beamline at the area of BL-11. Present activities at BL-11A will be performed at a relocated beamline of BL-12A and other PF beamlines. BL-12A will be available after the autmun of 2023.
1. Outline
BL-11A provides soft X rays in the energy range between 70 eV and 1900 eV with a grazing-incidence monochromator from a bending-magnet source. As there are several stations available at the Photon Factory which cover similar energy ranges with undulator sources, such as BL-13A and BL-16A, the optics of BL-11A has been designed especially under consideration of the availability for wider energy range so that EXAFS spectra for light elements such as C, N, O, F, Na, Mg, and Al can be measured. BL-7A is another soft X-ray station which covers similar energy range.
Fig. 1: Layout of BL-11A
Synchrotron radiation from the bending magnet B11 (maximum horizontal acceptance of 3.5 mrad) is reflected by two cylindrical mirrors, M0 and M0', monochromated and focused by a grazing-incidence monochromator consist of spherical mirror, M2, and varied-line-spacing plane grating, G, between entrance and exit slits, S1 and S2, finaly refocused by a toroidal mirror, Mf, to the sample position. A double-mirror system Mw can be inserted between S2 and Mf to eliminate higher-order reflection.
The monochromator is equipped with mechanisms to exchange two gratings with different groove densities, 600 l/mm and 1200 l/mm, according to the appropriate energy ranges, which enables us to use a wide energy range of 70 - 1900 eV without breaking vacuum. Energy scan is achieved by the rotaion of the grating only with a sine-arm mechanism, ensuring high stability and reliability for XAFS measurements. Control system is also simple.
2. Performance
| Optics | Pre-Focusing Mirrors/Varied-Line-Spacing Plane Grating Monochromator/Refocusing Mirror |
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| Energy Range | 70 eV - 1900 eV |
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| Resolving Power | E/dE = 500 ~ 4000 |
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| Spot Size | ~ 2 mm (H) x 0.5 mm (V) |
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| Photon Flux | maximum ~1012 photons/s |
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Fig. 4: Available flux distribution. Note the resolving powers are not constant because the slit opening is fixed in these measurements.
Figure 4 shows flux distribution spectra. Highly pure soft X rays up to 1900 eV are available with the holographically recorded gratings.
3. Equippments
- Personal computer for monochromator control [PC (Windows)]
- Software for monochromator control and XAFS measurements
- Photon intensity monitor system (mesh and pico-Ammeter)
- Stage for vacuum chambers (1.6 m x 2.0 m)
4. Remarks
- BL-11A does not have own vacuum chambers so that users should bring one. Many of experimental apparatuses of PF can be connected. Please contact the spokesperson for each apparatus.
- Sample chamber should be evacuated to < 10-6 hPa.
- Beam is ~1.38 m above the floor level but ~1.2 m from the above-mentioned stage at sample position. It comes 8 mm up when double mirror is inserted.
5. Publications
List of publications those registered to PF publication database is available.
Last modified: April 1, 2022.