First, it is important to remind that NEXAFS probes unoccupied states via electronic transitions from core levels. DFT allows calculating the contribution to the density of states (DOS) of each orbital per atom of the unit cell. To compare DFT calculations with NEXAFS experimental data, Figure shows the summed contributions of the Ti 3d orbitals for ilmenite (red) and pseudo-brookite (blue), respectively. The t2g level (lower binding energy) is composed from 𝑑 𝑥𝑦 , 𝑑 𝑥𝑧 and 𝑑 𝑦𝑧 orbitals, while e g (higher binding energy) gathers 𝑑 𝑥 2 -𝑦 2 and 𝑑 𝑧 2 ones. We performed the synchrotron X-rays measurements using circular polarization to remove any contributions arising from charge anisotropies in the sample. Thus, if the pseudo-brookite clusters are isotropically oriented, summing over all orbital orientation is valid for a qualitative comparison with the experimental data. Calculated DOS reproduce the experimental NEXAFS spectra features. First, pseudo-brookite exhibits an energy shift toward higher energies. The calculated shift value (~ 1 eV) is much larger compared to the experimental measured value (0.1 eV). This is probably related to the approximation made here, i.e. considering ilmenite structure to model the Ti-doped hematite. Indeed, the estimated Ti substitution level for our samples is less than 10 %, while ilmenite structure can be assimilated to 50 % Ti doping. Second, the experimental variation of the branching ratio A:B (Figure ) is reproduced by the calculated DOS. Thus, the pseudo-brookite has increased A:B ratio compared to ilmenite. In addition, pseudo-brookite DOS presents two distinct features at +4 eV and +5 eV relative to the Femi level, that can be associated to the asymmetry of the eg measured by NEXAFS (B peak in Figure ). Structural analysis performed by resolution STEM (Figure ) consolidates the spectro-microscopy results. Figure shows the detail of a Ti-doped hematite nanoparticle with pseudo-brookite surface clusters. The size of these clusters, of few tens of nanometers, fits well the average size determined from spectro-ptychography. We observe two types of morphology for the pseudo-brookite clusters: one with pronounced 3D character (columnar-like) (Figure -ROI1), with long chains composed of few clusters and where the interface between hematite nanoparticles and pseudo-brookite clusters is quite small (see also Figure ). The second one is characterized by clusters lying on the surface of the hematite nanoparticles (Figure -ROI2). Both morphologies can be recognized in Figure obtained by spectro-ptychography, where we can identify isolated and elongated "blue" spots exhibiting pseudo-brookite spectral features.