Interplay between transition-metal K-edge XMCD, slight structural distortions and magnetism in a series of trimetallic (CoNi)[Fe(CN)] Prussian blue analogues.

The magnetic properties of a series of trimetallic (Co,Ni)Fe Prussian blue analogues (PBAs) were investigated by SQUID magnetometry and X-ray magnetic circular dichroism (XMCD) at the three transition metal (TM) K-edges. In turn, the PBA trimetallic series was used as a tool in order to better understand the information contained in TM K-edge XMCD and particularly the chemical nature of the probed species (extended sub-lattice or localized entities). The results show that the magnetic behavior of the compounds is dictated by competing exchange interactions between the Co-Fe and Ni-Fe pairs, without spin frustration.

Evidence of the Anomalous Fluctuating Magnetic State by Pressure-Driven 4f Valence Change in EuNiGe.

In rare-earth compounds with valence fluctuation, the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration and the magnetic moment. Here, we provide direct experimental evidence for an induced magnetic polarization of the Eu atomic shell with = 0, due to intra-atomic exchange and spin-orbital coupling interactions with the Eu atomic shell. By applying external pressure, a transition from antiferromagnetic to a fluctuating behavior in EuNiGe single crystals is probed.

Interplay between Transition-Metal K-edge XMCD and Magnetism in Prussian Blue Analogs.

To disentangle the information contained in transition-metal K-edge X-ray magnetic circular dichroism (XMCD), two series of Prussian blue analogs (PBAs) were investigated as model compounds. The number of 3d electrons and the magnetic orbitals have been varied on both sites of the bimetallic cyanide polymer by combining with the hexacyanoferrate or the hexacyanochromate entities' various divalent metal ions A (Mn, Fe, Co, Ni, and Cu). These PBA were studied by Fe and Cr X-ray absorption spectroscopy and XMCD.

Deciphering Photochemical Reaction Pathways of Aqueous Tetrachloroauric Acid by X-ray Transient Absorption Spectroscopy.

Photolysis reaction pathways of [Au(III)Cl] in aqueous solution have been investigated by time-resolved X-ray absorption spectroscopy. Ultraviolet excitation directly breaks the Au-Cl bond in [Au(III)Cl] to form [Au(II)Cl] that becomes highly reactive within 79 ps. Disproportionation of [Au(II)Cl] generates [Au(I)Cl], which is stable for ≤10 μs.

Toward Quantitative Magnetic Information from Transition Metal K-Edge XMCD of Prussian Blue Analogs.

Two series of Prussian blue analogs (PBA) were used as model compounds in order to disentangle the information contained in X-ray magnetic circular dichroism (XMCD) at the K-edges of transition metals. The number of 3d electrons on one site of the bimetallic cyanide polymer has been varied by associating to the [Fe(CN)] or the [Cr(CN)] precursors various divalent metal ions A (Mn, Fe, Co, Ni, and Cu). The compounds were studied by X-ray diffraction and SQUID magnetometry, as well as by X-ray absorption spectroscopy and XMCD at the K-edges of the A transition metal ion.