Nonexponential Relaxation of the Metastable State of the Spin-Crossover System [Fe(L)2](ClO4)2·H2O [L = 2,6-Bis(pyrazol-1-ylmethyl)pyridine]

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• 作者：Cristian Enachescu ; Jorge Linares ; Franç ; ois Varret ; Kamel Boukheddaden ; Epiphane Codjovi ; Sunita Gawali Salunke ; and Rabindranath Mukherjee
• 刊名：Inorganic Chemistry
• 出版年：2004
• 出版时间：August 9, 2004
• 年：2004
• 卷：43
• 期：16
• 页码：4880 - 4888
• 全文大小：159K
• 年卷期：v.43,no.16(August 9, 2004)
• ISSN：1520-510X

文摘

The relaxation of the metastable state of the spin-crossover compound [Fe(L)₂](ClO₄)₂·H₂O, with L = 2,6-bis(pyrazol-1-ylmethyl)pyridine, populated by the LIESST (light induced excited spin state trapping) effect, has beeninvestigated by magnetic measurements. The time dependence of the relaxation curve at several temperatures,starting from different initial states, is in the shape of stretched exponentials, and the thermal variation of thephotostationary state under constant photoexcitation is progressive and reversible. These features are satisfactorilymodeled by considering noninteracting two-level systems with a distribution of activation energies. A suggestedorigin for the distribution is the conformational flexibility of the nonplanar heterocyclic ligands. The effect of theintensity distribution during the LIESST process is also accounted for in a simple way.