Spin Transition of [Fe(btr)_3](ClO_4)_2 Studied by X-ray Absorption Spectroscopy

摘要

Complex [Fe(btr)_3](ClO_4)_2 (where btr = 4,4'-bis-1,2,4-triazole) exhibits an unusual two-step spin transition at 188 K and 225 K, respectively. The corresponding three-dimensional framework structure at each step was characterized by X-ray diffraction. X-ray absorption spectroscopy (XAS) at both the Fe K-edge and the Fe L-edge is performed to probe the exact electronic configuration at various temperatures. The two-step behavior observed in the magnetic measurement is well reproduced by XAS. Two types of spin transitions: one abrupt and the other gradual are also observed precisely. The proper technique on monitoring the spin transition by taking advantage of synchrotron radiation is therefore established.