BM31 is specialized X-ray Absorption Spectroscopy (XAS) and High Resolution Powder
Diffraction (HRPD) beamline.
The beamline is designed in a flexible way to measure XAS and HRPD or even combination
of both techniques on the samples under different experimental conditions
(heating, cooling, in situ catalytic conditions etc).
X-ray Absorption Spectroscopy (XAS) is a powerful structural technique to investigate the short-range
environment around selected atomic species in condensed matter. XAS is applicable for the
fundamental studies of structural properties in materials like:
- poly- and single-crystalline materials;
- amorphous and highly disordered solids;
- liquids, molecular solutions, liquid crystals;
- molecules and macromolecules containing metallic atoms or partially substituted with heavy
Schematic layout of the Swiss-Norwegian beamline BM31
BM301 is designed to perform experiments, which require the capabilities of most second-generation
synchrotron sources. The main characteristics are the following:
- Incident energy range with the reasonable flux from 4.9 to 70 keV.
- 13 element Ge detector with fast digital multi channel analyser electronics.
- Step-by-step data collection with the reasonable acquisition time of 1s for optimised samples.
- Quick monochromator scans with 'on-the-fly' date collection for fast XANES measurements
- Feedback on the second crystal of the monochromator to minimize the glitches
- Fast switching between 111 and 311 (~ several minutes)
|Monochromator||Water-cooled double-crystal monochromator with piezo for second crystal|
|Monochromator crystals||Flat Si pair and Flat Si pair|
|Spectral range||4 - 70 keV|
|Intrinsic resolution (DE/E)||Si: 1.4 x 10-4 Si: 0.3 x 10-4|
|Mirrors||Two flat mirrors with Cr and Au surfaces for harmonic rejection|
|Spot size||up to 10 mm horizontal x 0.6 mm vertical|
Flux factor of 3 less for Si  compared to Si 
The following options are available:
- Three ionisation chambers, 30 cm long for transmission experiments
- 13-element Germanium Detector for XAS measurements at low concentrations.
We use standard ESRF spec software and have full support of BLISS group.
- Low temperature measurements down to 5K can be performed using specially designed cryostat
with the sample in He atmosphere. Kapton windows allow measuring the samples in transmission
and fluorescence modes. Several samples can be mounted simultaneously on the sample holder
and measured one after the other using linear translation stage.
- Gas blower to heat the samples inside the capillary up to 750 C
- Some cells for catalysis experiments are available
Recommendations to Users
When submitting beam time proposals, please be as clear and accurate as possible in terms of the
concentration of the absorber in your sample. This determines the type of detection system to be
used and permits a much better estimation of the necessary number of shifts to perform the experiment.
The information about the sample environment (temperature, gases etc) is also very important
to plan the experiment in advance.
A robust 2-circle diffractometer is available for High Resolution Powder Diffraction measurements.
Each circle has a high precision encoder mounted directly on the rotary axis.
The diffractometer is currently equipped with 6 counting chains, meaning that 6 complete patterns
are collected simultaneously, with an offset in 2-theta. The angular offset between the detectors has
been kept to very small (~1.1 deg) in order to keep the total data collection time to a minimum.
An Si-111 analyser crystal is mounted in front of each detector (Na-I scintillation counter), resulting
in an intrinsic resolution (FWHM) of approx. 0.01 deg at a wavelength of 1 A. The available wavelength
range for the instrument is 0.4 to 1.2 A.
Transmission (capillary) measurements can be perfomed between 5 and 1023 K. A flat plate sample
spinner as well as a texture attachment can be mounted. Avalable on the beamline are thus a cryostat
for temperatures between 4 and 298 K.
The environment in the furnace can be controlled with both oxidizing and inert atmospheres.