@article{Harouna-MayerKlemeyerZitoetal.2026,
  author    = {Harouna-Mayer, Sani Y. and Klemeyer, Lars and Zito, Cecilia A. and Bielecki, Johan and Cheng, Xuemei and Derelli, Davide and Estillore, Armando D. and Gröne, Tjark L. R. and Haas, Lukas V. and Letrun, Romain and Kim, Chan and Koliyadu, Jayanath C. P. and Mall, Abhishek and Mazumder, Parichita and Melo, Diogo V. M. and Round, Adam R. and Samanta, Amit K. and Sarma, Abhisakh and Shen, Zhou and Sun, Xiao and Vagovic, Patrik and Wollweber, Tamme and Bean, Richard and K{\"u}pper, Jochen and Chapman, Henry N. and Koziej, Dorota and Ayyer, Kartik},
  title     = {Single-Particle X‑ray Scattering Reveals a High Local Supersaturation of Precursors as the Origin of CoO Assembly Formation},
  journal   = {The Journal of Physical Chemistry Letters},
  volume    = {17},
  number    = {23},
  publisher = {American Chemical Society},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.6c00191},
  url       = {https://nbn-resolving.org/urn:nbn:de:hbz:kob7-26672},
  pages     = {6418 -- 6424},
  year      = {2026},
  abstract  = {Single-particle small-angle X-ray scattering (SP-SAXS) at X-ray free electron lasers (XFELs) enables quantitative analysis of morphological heterogeneity that is fundamentally inaccessible to ensemble-averaged in situ techniques. By recording diffraction snapshots from isolated particles, SP-SAXS resolves low-contrast, less abundant, or transient species within heterogeneous particle populations that would otherwise remain hidden to conventional X-ray techniques. We demonstrate this unique capability by investigating the solvothermal formation of CoO nanocrystal assemblies from a Co­(acac)3 precursor in benzyl alcohol. The single-particle data revealed amorphous, uniform-density Co­(acac)2 spheres as transient intermediates that directly crystallize into cavernous CoO nanocrystal assemblies, explaining why CoO forms as hierarchical aggregates rather than as isolated nanocrystals. These results establish SP-SAXS as a uniquely powerful framework for uncovering nonclassical nanoparticle formation pathways hidden in ensemble measurements.},
  language  = {en}
}