Beam line 11-2 is a high-flux XAS station dedicated to molecular biogeochemical and interface sciences. It is optimized for challenging XAS measurements on dilute or radioactive samples and interfaces. To support these experiments, BL11-2 is equipped with collimating and focusing optics, a "double double" Si(220) LN2-cooled monochromator, and a 100-pixel monolithic solid state Ge detector array. Additional instrumentation includes LHe and LN2 cryostats, a grazing incidence XAS spectrometer, and HEPA-filtered controlled exhaust systems that are continuously monitored to detect the presence of air-born radioactivity. It has an adjacent sample preparation room for handling and temporary storage of radioactive samples. BL11-2 can accommodate samples containing uranium and other radionuclides, depending upon their radiotoxicity level, activity, shielding requirements, and complexity of the experimental requirements. See additional information below under Sample Environment.
| Status | Open |
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| Supported Techniques | X-ray Absorption Spectroscopy Grazing incidence x-ray absorption spectroscopy |
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| Main Scientific Disciplines | Catalysis Environmental Sciences Geochemistry |
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| Beam Line Specifications | |||||||||||||||||||||
Source26-pole, 2.0-Tesla Wiggler, ≤1.5 mrad variable acceptance
OpticsM0 mirror: vertically collimating, flat, bent, 1 m, Si, Rh-coated M1 mirror: Bent cylindrical, 1 m, Si, Rh-coated, ~1:1 focusing In-hutch harmonic rejection capability using a 370 mm Rh coated flat mirror Monochromator: LN2 cooled, Si(220), ϕ = 0o & 90o. double-crystal, variable-exit geometry Monochromator Crystal Glitch Library Crystal changes need to be scheduled and coordinated in advance with BL support staff. AbsorptionN/A |
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| Instrumentation | Detectors: Ionization chambers, Lytle-type fluorescence-yield ion chamber detector, Canberra 100-pixel Ge solid-state monolith, Vortex SiLi solid state detector for special detection geometry requirements. Cryostat: Oxford LHe, LN2 cryostat for magazine capability and radioactive samples Other: Soller slits and scatter-guards, Goniometers for grazing-incidence XAS
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| Sample Environment | Ambient pressure experiments Sample temperature: 10-200 K (cryostats) Sample size: 3 x 20 x 1 mm (standard powder cell), flat wafers up to 2.5 cm diam Minimum Sample Requirement: 500 μM, 100 μl solutions; 20 ppm, 10 mg solids Radioactive Samples: Users interested in running such samples should refer to the SSRL safety radioactive sample safety page http://www-ssrl.slac.stanford.edu/content/safety/radioactive-materials-ssrl). For more information, please contact Matt Padilla (x3861). Radioactive materials (RAM) users should be aware of the following important points (that often trip up first-time users): * Advanced notifications of your intent to ship RAM are required 30-, 7-, and 1-days in advance * Only approved holders listed in the SSRL radioactive sample holder catalog may be used * Shipping containers and practices must conform closely to the instructions provided to users following submission of you 7-day notifications * ALL samples containing radioisotopes are considered to be RAM by DOE, and we are required to control their movement on site. This requirement would include, for example, natural samples containing only 20 ppm of natural U. For this reason, ALL RAM samples require advanced notification and approval prior to shipment. Please help us to comply with these requirements by providing full information regarding the isotope compositions and activities of your samples when you request beam time and submit your notifications. |
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| Data Acquisition and Analysis | XASSERV, EXAFSPAK, SixPAK, µscan GUI |
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| Beam Line Phone | 650-926-8650. On-site Users: Contact the Duty Operator at 9-926-4040 |
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