Welcome to I14

A collection of dried coccolithophore microalgae, as seen by combined XRF and DPC imaging.

Image courtesy of Dr. D. Chevrier (Faivre Group/BIAM), CEA Cadarache, France in collaboration with Dr. A. Scheffel, MPI Molecular Plant Physiology

2D elemental mapping at 50 nm spatial resolution provides information on the chemical composition and elemental distribution in the sample. Additional information can be obtained by simultaneously acquiring imaging data. 

9-Energy X-ray fluorescence microscopy of ZnO nanorods after in-situ 1-hour incubation in a simulated sludge (humic acid 10 mg L-1)

Fluorescence map acquired at the maximum of Zn K-edge XANES spectrum (Emax=9669 eV).
Cluster analisys revealing three main regions according to their Zn K-edge XANES spectra.
Speciation maps of the expected Zn-species: ZnO, ZnS, Zn3(PO4)2 and Zn adsorbed to Fe-oxyhydroxides (Zn-Fe(ox)) (from left to right),
where the red colour equals a 100% compound contribution and the blue colour corresponds to 0%
The numbering on the scale bars on the fluorescence map represent fluorescence intensity (arbitrary units). Scale bars equal to 750 nm in all cases.

DOI: 10.1021/acsnano.9b02866

Spatially-resolved X-ray Absorption Near-Edge Structure provides information on the chemical speciation of the element of choice.

Multivariate cluster anaylsis revealing statistically-similar regions acording to their XANES spectra, can be performed by the cross-platform python package - Mantis.

Speciation maps can be calculated through fitting the absorption data from each pixel to the linear combination of the standard spectra, representing the ratio between the expected species (Gomez-Gonzalez et al. 2019 - ACS Nano, 2019, 13, 11049–11061).

X-ray diffraction (XRD) can be used to spatially map changes in crystallographic direction, d-spacing or strain across a sample. A 2D XRD pattern is collected per pixel, in concert with the XRF signal. Processing in 1D or 2D is later achieved through DAWN.

At I14, XRD mapping is available in both wide- and small- angle scattering geometry. The q range available is ~1-3 A for WAXS.

Reconstruction of ptychographic data, recorded with monochromatic beam using the i14-MERLIN detector:

(a) Probe modulus. Reconstructed probe size = 1.845 µm at 7.308 keV (800µm defocus)
(b) Object phase of a corroded Fe nanometric thin-film deposited onto a silicon nitride window. The reconstructed pixel size is 45 nm and the field of view is 16 × 16 µm2 at 7.308 keV.
(c) Object phase of a siemens star test sample, with radial markers representing ~100 nm line spacings.The reconstructed pixel size is 27 nm and the field of view is 18.3 × 18.3 µm2. Reconstructed probe size = 1.62 µm at 12 keV (800µm defocus).

X-ray ptychography imaging, which is a scanning coherent diffractive imaging technique, is now available at i14.

PtyREX, the reconstruction package for electrons and X-rays, was used for the processing and analysis of the ptychographic data. Each channel from the MERLIN detector was processed individually through 100 iterations of ePIE, with position correction and up-sampling.