Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5404204 | Journal of Luminescence | 2006 | 9 Pages |
Abstract
In situ X-ray absorption spectroscopy (XAS) using synchrotron radiation was used to probe the local structure of photo-induced phase transition of Fe (II) spin-crossover complex. We demonstrate that the local structure of spin-converted metastable phase can be probed by XAS using a novel pixel array detector using less than 1Â mg of specimen. We find that the arrangement of nearest neighbors, i.e., the FeN6 cluster does not change its symmetry upon the diamagnetic (S=0) âparamagnetic (S=2) transformation under laser light (532Â nm) excitation below 50Â K. The intermediate-range structure (next-nearest neighbor correlation) shows that ligand molecules in the photo-induced high spin phase is distorted. The results suggest that the essential difference between the photo-induced and thermally induced high spin phases is the absence of intermediate-range order in the former. We propose that quenched disorder (inhomogeneity) in the intermediate-range structure is the microscopic origin of nonlinear nature of photo-induced phase transition (crippled cooperativity). It is demonstrated that in situ XAS using synchrotron radiation and state-of-the-art X-ray detector can provide detailed information on the local structure of metastable states trapped at low temperature.
Related Topics
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Authors
H. Oyanagi, T. Tayagaki, K. Tanaka,