The AERHA spectrometer (the acronym stands for "adjustable energy resolution high acceptance") is a permanent end-station on the SEXTANTS beamline and provides a state-of-the-art instrument for high-resolution RIXS studies with high angular acceptance.
The target design of RIXS spectrometers is primarily focused on energy resolution, that is to say the power to resolve close-lying spectral lines. However, the intensity of the inelastically scattered photons is extremely low so the quest for high-resolution leads inevitably to very low counting rates. A team of scientists and engineers at Laboratoire de Chimie Physique - Matière et Rayonnement (Univ. Pierre et Marie Curie) developed, in collaboration with colleagues at SOLEIL, an instrument with outstanding trade-off between resolution and instrumental transmission.
The AERHA spectrometer features high energy resolution, yet provides sufficient throughput to enable RIXS studies on small concentrations of matter as encountered in thin films or buried interfaces. An innovative optical scheme, based on a combination of elliptical mirror and plane varied-line-spacing diffraction gratings, is used to enable AERHA to cover a broad energy range with two gratings only. The instrument is unique worldwide in its ability to operate at variable diffraction grating included-angle independently of photon energy. It is therefore possible to "zoom out" to perform a broad scan with highest available transmission or "zoom in" when exploring a narrow energy band with best possible energy resolution.
The instrument is open to French and worldwide users through beamtime proposals submitted at Synchrotron SOLEIL.
Related publications:
Design and performance of AERHA, a high acceptance high resolution soft x-ray spectrometer
Sorin G. Chiuzbăian, Coryn F. Hague, Antoine Avila, Renaud Delaunay, Nicolas Jaouen, Maurizio Sacchi, François Polack, Muriel Thomasset, Bruno Lagarde, Alessandro Nicolaou, Stefania Brignolo, Cédric Baumier, Jan Lüning, and Jean-Michel Mariot
Review of Scientific Instruments 85, 043108 (2014) (view online)
High acceptance high resolution soft X-ray grating spectrometer: Choice of optical design
S.G. Chiuzbaian and C.F. Hague
Journal of Electron Spectroscopy and Related Phenomena 108, 121-126 (2013) (view online)