Nano X-ray Tomography at the CARNAÚBA Beamline (SIRIUS-LNLS) in diamond mineral inclusions

Abstract The CARNAÚBA beamline is an X-ray nanoprobe that enables nanoscale tomography by scanning a beam smaller than 500 nm. It features a high flux (10 9 to 10 10 ph/s/100 mA at 12 keV) and simultaneous acquisition of transmission and fluorescence data, through a photodiode and two fluorescence detectors, respectively, allowing the mapping of various elements and facilitating 3D images with multiple contrasts. This technique was applied to analyze two distinct minerals trapped in a diamond. Tomography measurements required precise alignment of the inclusions at different rotation angles, conducted at 12 keV over a scanned area of 100x100 µm 2 . The experiment itself involved 7 hours of data acquisition over a scanned area of 80x80 µm 2 , resulting in voxel sizes of 0.8x0.8x0.8 µm 3 . Data reconstruction was performed using a modified version of Chang’s method for fluorescence data, incorporating µ-Tomography reconstruction to address diamond-related self-absorption effects. This technique allowed us to identify different types of geological features. We present here the case of two mineral inclusions in the same diamond.