COMPLEX SYSTEMS AND BIOMEDICAL SCIENCES

74 ESRF

Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays, G. Smolentsev (a), C.J. Milne (a), A. Guda (b), K. Haldrup (c), J. Szlachetko (d), N. Azzaroli (a), C. Cirelli (a), G. Knopp (a), R. Bohinc (a), S. Menzi (a), G. Pamfilidis (a), D. Gashi (a), M. Beck (a), A. Mozzanica (a), D. James (a), C. Bacellar (a,e), G.F. Mancini (a,e), A. Tereshchenko (b), V. Shapovalov (b), W.M. Kwiatek (d), J. Czapla-Masztafiak (d), A. Cannizzo (f),

M. Gazzetto (f), M. Sander (g), M. Levantino (g), V. Kabanova (g), E. Rychagova (h), S. Ketkov (h), M. Olaru (i), J. Beckmann (i) and M. Vogt (i), Nat. Commun. 11, 2131 (2020); https://doi. org/10.1038/s41467-020-15998-z. (a) Paul Scherrer Institute, Villigen (Switzerland) (b) Southern Federal University, Rostov-on- Don (Russia) (c) Technical University of Denmark, Kongens Lyngby (Denmark)

(d) Institute of Nuclear Physics, Polish Academy of Sciences, Kraków (Poland) (e) École Polytechnique Fédérale de Lausanne (Switzerland) (f) University of Bern (Switzerland) (g) ESRF (h) G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Nizhny Novgorod (Russia) (i) University of Bremen (Germany)

HIGH-SPATIAL-RESOLUTION 3D IMAGING OF HUMAN SPINAL CORD AND COLUMN ANATOMY

Modern high-spatial-resolution radiologic methods are enabling increasingly detailed volumetric post-mortem investigations of human neuroanatomy for diagnostic, research and educational purposes. X-ray phase-contrast micro-CT uniquely renders both hard-tissue vertebral bone structure and soft-tissue spinal cord neuroanatomy in 3D, including deep microscale cellular and vascular features, without contrast-agent use.

PRINCIPAL PUBLICATION AND AUTHORS

details of the occurring structural changes. For a given model of structural rearrangements, these signals can be calculated and then compared with the experimental ones, taking into account other contributions (namely the solvent response) to the experimental signal. This allows to reveal how Cu atoms and electron-rich ligands move relative to each other.

Complementary methods to X-ray scattering including pump-probe X-ray absorption measured at the SLS synchrotron and pump- probe X-ray emission measured at SwissFEL were also used in order to probe how charge redistributes between Cu and P atoms. The data

indicate that the structural rearrangements that accompany the transition from the ground to the triplet excited state are small: Cu atoms do not have the possibility to significantly rearrange their coordination environment. That is the property required to minimise non- radiative losses and it is the reason why CuPCP is a good candidate for OLEDs. The obtained experimental information makes it possible to validate theoretical methods based on DFT and to compare approaches used for the prediction of excited-state properties. This is relevant to predict which new OLED materials will be efficient, thus speeding up the discovery of new materials for cheap and efficient OLEDs.

Detailed visualisation of human neuroanatomy is paramount to a better understanding of the structure, function, and diseases of the human central nervous system, and advancements in both in-vivo and post-mortem neuroimaging have had a wide impact on modern medicine, from diagnostics and public health management to the assessment of disease etiology and educational purposes [1]. Emerging technologies for dissection-free post-mortem microscale 3D analysis of fixed soft-tissue human central nervous system specimens include high-field- strength post-mortem MRI (Magnetic Resonance Imaging) [2] and tabletop absorption-based micro- to nano-CT systems [3].

Complementary to MRI microscopy, and more sensitive and efficient than absorption-based micro-CT, synchrotron-based X-ray phase- contrast micro-CT is a tissue-conserving, contrast-agent-free technique, which provides

wide fields of view, time-efficient measurements and high soft-tissue sensitivity for microscale 3D imaging of large fixed human organ specimens, including human breast samples [4], human carotid artery specimens [5] and human knee joints [6]. At the price of reduced fields of view, cutting-edge synchrotron setups can also reach submicron spatial resolutions, and this methodology can be applied to diverse animal model neuroimaging work [7-9]. Here, the 3D anatomy of the human spine, a challenging organ to image owing to the thick and complex bone structures surrounding the spinal cord environment, was studied at high spatial resolution using synchrotron-based phase- contrast micro-CT at beamline ID17.

Several multi-vertebral human spinal column samples, unilaterally perfused with an iodinated vascular contrast agent, were harvested from Thiel-embalmed human cadavers. Thiel