Unique thermal properties of metal clusters are believed to originate from the hierarchy of the bonding. However, an atomic-level understanding of how the bond stiffnesses are affected by the atomic packing of a metal cluster and the interfacial structure with the surrounding environment has not been attained to date. Here we elucidate the hierarchy in the bond stiffness in thiolate-protected, icosahedral-based gold clusters Au25(SC2H4Ph)18, Au38(SC2H4Ph)24 and Au144(SC2H4Ph)60 by analysing Au L3-edge extended X-ray absorption fine structure data. The Au–Au bonds have different stiffnesses depending on their lengths. The long Au–Au bonds, which are more flexible than those in the bulk metal, are located at the icosahedral-based gold core surface. The short Au–Au bonds, which are stiffer than those in the bulk metal, are mainly distributed along the radial direction and form a cyclic structural backbone with the rigid Au–SR oligomers.

Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed seventeen Ryugu samples measuring 1-8 mm. CO 2 -bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and Ca, Al-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed by aqueous alteration reactions at low temperature, high pH, and water/rock ratios < 1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate Ryugu’s parent body formed ~ 2 million years after the beginning of Solar System formation.

The structural kinetics of surface events on a Pt 3 Co/C cathode catalyst in a polymer electrolyte fuel cell (PEFC) was investigated by operando time-resolved X-ray absorption fine structure (XAFS) with a time resolution of 500 ms. The rate constants of electrochemical reactions, the changes in charge density on Pt, and the changes in the local coordination structures of the Pt 3 Co alloy catalyst in the PEFC were successfully evaluated during fuel-cell voltage-operating processes. Significant time lags were observed between the electrochemical reactions and the structural changes in the Pt 3 Co alloy catalyst. The rate constants of all the surface events on the Pt 3 Co/C catalyst were significantly higher than those on the Pt/ C catalyst, suggesting the advantageous behaviors (cell performance and catalyst durability) on the Pt 3 Co alloy cathode catalyst.

The fluxional nature of small gold clusters has been exemplified by reversible isomerization between [Au(PPh)] with a crown motif (Au(C)) and that with a butterfly motif (Au(B)) induced by association and dissociation with compact counteranions (NO, Cl). However, structural isomerization was suppressed by substitution of the central Au atom of the Au core in [Au(PPh)] with a Pd atom: [PdAu(PPh)] with a crown motif (PdAu(C)) did not isomerize to that with a butterfly motif (PdAu(B)) upon association with the counteranions. Density functional theory calculation showed that the energy difference between PdAu(C) and PdAu(B) is comparable to that between Au(C) and Au(B), indicating that the relative stabilities of the isomers are not a direct cause for the suppression of isomerization. Temperature dependence of Debye-Waller factors obtained by X-ray absorption fine-structure analysis revealed that the intracluster bonds of PdAu(C) were stiffer than the corresponding bonds in Au(C). Natural bond orbital analysis suggested that the radial Pd-Au and lateral Au-Au bonds in PdAu(C) are stiffened due to the increase in the ionic nature and decrease in electrostatic repulsion between the surface Au atoms, respectively. We conclude that the formation of stiffer metal-metal bonds by Pd atom doping inhibits the isomerization from PdAu(C) to PdAu(B).