Published online by Cambridge University Press: 27 October 2010
An instrument for X-ray emission spectroscopy (XES) based on perfect crystal Bragg optics was recently commissioned at beam line ID26 of the ESRF (European Synchrotron Radiation Facility). The spectrometer is used to record high-energy resolution fluorescence-detected X-ray absorption spectra with sub-lifetime resolution and to perform resonant and non-resonant XES. The hard X-ray probe is material bulk sensitive and allows demanding sample environments (in situ chemistry, high pressure, etc.). Spectrometers for XES are being installed or designed at almost all upcoming synchrotron radiation sources worldwide. The particularity of the ID26 spectrometer is to accommodate five analyser crystals with exact Rowland tracking in the vertical plane and with crystals radii between 0.5 and 2 m.The main upgrade of the new version of this large instrument (3 tonnes, overall size 2.5 m and height 3 m) is to allow the change of the scattering angle over the range 0–180°. This involves rotating the entire spectrometer around a vertical axis that passes through the sample. In order to optimize the vibration stability of the spectrometer's structure, we chose to support the structure in multiple points and not only on three (kinematic mount) like it is specified to do with air pads. According to this choice, we have developed special foot holders for air pads.The calculations during the design phase have shown that we can obtain a first modal frequency of the spectrometer's structure at more than 30 Hz. To confirm our predictive calculations, we have performed some vibration measurements.