  This paper introduces Spectral Incoherent Diffractive Imaging (SIDI) as a
novel method for achieving dark-field imaging of nanostructures with
heterogeneous oxidation states. With SIDI, shifts in photoemission profiles can
be spatially resolved, enabling the independent imaging of the underlying
emitter distributions contributing to each spectral line. In the X-ray domain,
this approach offers unique insights beyond the conventional combination of
diffraction and X-ray Emission Spectroscopy (XES). When applied at X-ray
Free-Electron Lasers (XFELs), SIDI promises to be a versatile tool for
investigating a broad range of systems, offering unprecedented opportunities
for detailed characterization of heterogeneous nanostructures for catalysis and
energy storage, including of their ultrafast dynamics.
