Fig. 3: Presence of tetrapyrrole moieties highlighted by XANES analyses on intracellular inclusions.
From: Intracellular bound chlorophyll residues identify 1 Gyr-old fossils as eukaryotic algae
a Microphotograph of the studied specimens. b, c Fe and Ni SR-μXRF maps obtained at SLS (pixel: 1.5 μm, 200 ms/px) showing the enrichment in Ni and Fe of the intracellular inclusions (ICI). Color scales correspond to normalized counts. d XANES spectra at the Ni K-edge of 4 ICIs performed in zones with low Fe content (gray circles) and their linear combination fitting (red lines) and XANES spectra of two Ni-porphyrin (NiTPP: Ni(II)-tetraphenylporphine, NiOEP: Ni(II)-octaethylporphine)43, asphaltene44, and NiO standards. The shoulder and the spectral line shape are typical of Ni in coordination (IV) in bound Ni-porphyrinic species. Differences between the fitted spectra and the data come from the molecular heterogeneities between the standards used for the fitting and the incorporated tetrapyrroles moieties in the kerogen.
