Thermo-chromism and photo-chromism in a Prussian blue analogue
Thermo-chromism and photo-chromism in a Prussian blue analogue
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普鲁士蓝类似物的热致变色和光致变色
DOI：
10.1016/s0277-5387(01)00616-7
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发表时间：
2001
期刊：
影响因子：
2.6
通讯作者：
M. Verdaguer
中科院分区：
文献类型：
--
作者：
A. Goujon;F. Varret;V. Escax;A. Bleuzen;M. Verdaguer
报道了光磁性普鲁士蓝类似物系列CsxCo[Fe(CN)6]y(Cs-PBA)。根据已经为K-∼和RB-PBA系列建立的方程：FeII+CoIII(LS)→FeIII+CoII(HS)，它们在高温(PBA 250K)下都经历了价互变异构化，在低温下又经历了光激发。通过热淬火可以捕获高温态。由于光体吸收的强烈影响，没有对光磁数据进行定量分析。然而，定量研究可以通过漫反射来完成，漫反射只探测样品的顶层(=光激发)。因此，我们观察到：(I)由于红光和近红外中电荷转移带的减弱，光过程的漂白效应；(Ii)与自发互变异构化相比，光转化的完整特征；(Iii)从吸收光谱和弛豫动力学的比较得出，光激发态和高温态之间的相似性。我们重点研究了Cs0.175Co[Fe(CN)6]y的“优化”组成，并说明了光致磁结构的一般特征(如磁亚稳性)。一个有希望的特征是电子激发态的寿命，它在∼130K仍然足够长，足以在相当长的时间尺度上进行大规模的光激发实验。这是在未来应用到光信息存储的道路上有希望的一步。
We report on the photo-magnetic Prussian blue analogue series CsxCo[Fe(CN)6]y(Cs-PBA). They undergo both a valence tautomeric conversion at high temperature (∼250 K) and a photo-excitation at low temperature, according to the equation already established for K-PBA and Rb-PBA series: FeII+CoIII(LS)→FeIII+CoII(HS). The high-temperature state can be trapped by thermal quenching. The photo-magnetic data are not analysed quantitatively because of the strong effects of bulk absorption of light. However, the quantitative investigation could be completed by diffuse reflectivity, which only probes the top (=photo-excited) layers of the sample. We thus observed: (i) the bleaching effect of the photo-process, due to the weakening of the charge-transfer band in the red and near IR; (ii) the complete character of the photo-transformation, compared to the spontaneous tautomeric conversion; (iii) the similitude between the photo-excited and the high-temperature states, deduced from the comparison of absorption spectra and relaxation kinetics. We have focussed on the “optimised” composition Cs0.175Co[Fe(CN)6]y. Generic features of photo-induced magnetic structures (e.g. magnetic metastability) are also illustrated. A promising feature is the lifetime of the electronic excited state, which up to ∼130 K remains long enough to allow sizeable photo-excitation experiments on a rather long time scale. This is a promising step on the route of futuristic applications to optical information storage.