Investigation of the Photoinduced Magnetization of Copper Octacyanomolybdates Nanoparticles by X-ray Magnetic Circular Dichroism

Through an extensive set of SQUID magnetic measurements, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism, we have determined the nature of the metastable photomagnetic phase in the cyano-bridged 3D network Cs₂Cu₇[Mo(CN)₈]₄. The photomagnetic effect is induced by the photoconversion of Mo(IV) ions in low spin (LS) configuration (<i>S</i> = 0) into Mo(IV) ions in high spin (HS) configuration (<i>S</i> = 1). The magnetic and spectroscopic measurements fully support the LS to HS conversion, whereas the previously invoked charge transfer mechanism Mo(IV) + Cu(II) ⇒ Mo(V) + Cu(I) can be completely ruled out