High pressure experiments at the XAFS Beamline, INDUS-2

Abstract

The dispersive XAFS beamline BL-08 at the INDUS-2 synchrotron radiation source, RRCAT, Indore uses a bent Si (111) crystal as dispersive-cum-focusing element and a position sensitive CCD detector to enable instantaneous measurement of the whole XAFS spectrum around the absorption edge of interest. This beamline is ideal for characterisation of materials under high pressure using Diamond Anvil Cell with ∼50 μm spot size. For this setup, the theoretically determined spot size (Horizontal × Vertical) varies between 17 × 137 μm and 37 × 142 μm for the x-ray energy range 5 keV-20 keV. To reduce the vertical spot size to <50 μm, we have designed an additional focusing mirror between the polychromator and sample position. The mirror, procured from SESO (France), will be installed shortly. Meanwhile, we have developed a dummy mirror bender setup at CDM (B ARC) and have carried out feasibility tests to confirm reduction in spot size using the same. We have also conducted preliminary XAFS experiments (at BL-08) on SrRuO3 at ∼16 keV, under ambient conditions and inside diamond anvil cell, in order to assess the signal intensity and quality. We have obtained reasonably good signal.