FAME A New Beamline for XRay Absorption Investigations of VeryDiluted Systems of Environmental, Material and Biological Interests

TLDR

FAME is a French ESRF beamline for material and environmental X‑ray absorption spectroscopy, operational since September 2002. The beamline uses a 0.85 T bending‑magnet source and a two‑crystal Si(111)/Si(220) monochromator, with the first crystal liquid‑nitrogen cooled and the second dynamically bent to focus horizontally, while bendable mirrors before and after the monochromator collimate and vertically focus the beam, maintaining a constant 150 × 200 µm² spot during scans. The high flux and 30‑element fluorescence detector reduce the detection limit to about 10 ppm (≈ a monolayer) and enable quick‑EXAFS acquisition in as little as 30 s.

Abstract

FAME is the French Absorption spectroscopy beamline in Material and Environmental sciences at the ESRF (France), operational since September 2002. Technically speaking, the source is a 0.85 T bending magnet and the main optical element is a two-crystals monochromator using either Si(111) or Si(220) monocrystals so that the available energy ranges from 4 to 40 keV. The first crystal is liquid nitrogen cooled in order to avoid a thermal bump and thus preserve the energy resolution. The second crystal is dynamically bent during the energy scan in order to focus the beam in the horizontal plane. Two bendable mirrors are located before and after the monochromator, for beam-collimation (to optimize the energy resolution) and vertical focalization, respectively. During scans, the beam on the sample is kept constant in position and size (around 150 × 200 μm2, V × H). The high flux on the sample combined with the sensitivity of our 30-elements fluorescence detector allow to decrease the detection limit down to 10 ppm or around less than a monolayer. Moreover, quick-EXAFS acquisition is operational: the acquisition time may be reduced down to 30s.