Wavelength selective light-induced magnetic effects in the binuclear spin crossover compound {[Fe (bt ) (NCS )2]2 (bpym )}
Wavelength selective light-induced magnetic effects in the binuclear spin crossover compound {[Fe (bt ) (NCS )2]2 (bpym )}
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DOI：
10.1103/physrevb.75.054101
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发表时间：
2007-02
影响因子：
3.7
通讯作者：
N. O. Moussa;E. Trzop;S. Mouri;S. Zein;G. Molnár;A. Gaspar;E. Collet;M. B. Cointe;J. Real
中科院分区：
文献类型：
--
作者：
N. O. Moussa;E. Trzop;S. Mouri;S. Zein;G. Molnár;A. Gaspar;E. Collet;M. B. Cointe;J. Real
利用傅里叶变换红外光谱、X射线衍射和光照射下的磁化率测量，对双核自旋交叉化合物{[Fe（bt）（NCS）2]2bpym}中的选择性光诱导自旋激发态俘获（LIESST）和可逆LIESST效应进行了深入的研究.在该系统中，每个磁位点可以从低自旋（LS）切换到高自旋（HS），从而存在三种状态，即LS-LS、HS-LS和HS-HS。所有这些技术都为该系统的高光调谐性提供了新的视角。除了从LS-LS到HS-LS或到HS-HS状态的直接光开关之外，在这里，我们表明激发光诱导状态之间的光诱导开关可以以可逆的方式触发：从HS-LS到HS-HS（照射约800 nm），或从HS-HS到HS-LS的反向（照射约1300 nm）。通过比较光谱测量和结构分析，讨论了热诱导和光诱导自旋态变化过程中中间态HS-LS的性质。在HS-LS分子态中，两个磁性Fe位点不再相等，反转对称性的损失并不伴随着晶体中非中心对称分子的任何长程有序。因此，连续的两步旋转转换对应于双交叉。
Using Fourier transform infrared spectroscopy, x-ray diffraction, and magnetic susceptibility measurements under light irradiation, the selective light-induced excited spin state trapping (LIESST) and the reversible-LIESST effect have been evidenced and studied in depth in the binuclear spin crossover compound {[Fe(bt)(NCS)2]2bpym}. In this system, each magnetic site can switch from low spin (LS) to high spin (HS), so that three states exist, namely, the LS-LS, HS-LS, and HS-HS. All these techniques shine a new light on the high phototunability of this system. In addition to the direct photoswitching from the LS-LS to the HS-LS or to the HS-HS state, here we show that photoinduced switching between the excited photoinduced states can be triggered in a reversible way: from HS-LS to HS-HS (irradiation around 800 nm), or reverse from HS-HS to HS-LS (irradiation around 1300 nm). The nature of the intermediate HS-LS state during the thermal and light-induced spin state changes is also discussed by comparing the spectroscopic measurements and the structural analysis. The loss of inversion symmetry in the HS-LS molecular state, where the two magnetic Fe sites are no more equivalent, is not accompanied by any long-range ordering of the noncentrosymmetric molecules in the crystal. Therefore the continuous double-step spin conversion corresponds to a double crossover.