Study on the local structural change associated with the photo-induced phase transition in single crystals of quasi-one dimensional charge-transfer complex TTF-CA.

准一维电荷转移复合物TTF-CA单晶中与光致相变相关的局部结构变化的研究。

基本信息

批准号：
13440096
负责人：
ITOH Chihiro
金额：
$ 8.51万
依托单位：
Wakayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Crystals of quasi one-dimensional charge-transfer complex TTF-CA show structural phase transition between quasi-neutral phase, in which the donors (TTFs) and the acceptors (CAs) are almost neutral, and quasi-ionic phases, in which the partially ionized TTFs and CAs form heterodimers. Since the discovery of the photo-induced phase transition (PIPT) of the ionic phase of the TTF-CA crystal, many efforts have been made for revealing the PIPT's dynamics. However, identification and characterization of the photo-induced phase (PIP) has not been made yet. In the present study, we carried out electron-spin echo detection of electron spin resonance (ESE-ESR) and Fourier-transformation infrared (FT-IR) measurement for characterizing the PIP of TTF-CA crystal. For proving the local structure of the ionic phase and the PIP, we utilized spin solitons formed between two degenerated structures of the ionic phase as a spin probe. The symmetry and the local structural information of the spin soliton a … More t 4 K was obtained by measuring angular dependence of the ESE-ESR spectra at 4 K, and by using electron-spin echo envelope modulation (ESEEM) technique. The results suggest that the spin soliton has the configuration of unpaired ionized molecule. When the crystal was excited continuously by the 523-nm laser beam having the E vector perpendicular to the stacking axis, the ESE-ESR signal arising from the spin solitons was reduced largely. On the other hand, the excitation with E vector parallel to the stacking axis gave small change. By time-resolved ESE-ESR measurements, the ESR signal due to the spin solitons was largely affected in the μs region even by the excitation with the E vector parallel to the stacking axis. The result suggests that the laser excitation leads to temporal change in the configuration of the spin solitons even when the excitation is insufficient for inducing the phase transition. By FT-IR measurements under weak excitation, we have revealed that the charge-transfer absorption of the crystal was largely affected. The result suggests that the donor-acceptor pairs are partially dissociated. Less

准一维电荷转移复合物TTF-CA的晶体显示出准中性相之间的结构相变，其中供体（TTFS）和受体（CAS）几乎是中性的，而准离子相几乎是中性的，其中部分离子化的TTFS和CAS形成了CAS形成杂物。自从发现TTF-CA晶体的离子阶段的光诱导相变（PIPT）以来，已经为揭示PIPT的动力学做出了许多努力。但是，尚未进行光诱导相（PIP）的识别和表征。在本研究中，我们对电子自旋共振（ESE-ESR）和傅立叶变换红外（FT-IR）测量进行了电子旋转回声检测，以表征TTF-CA晶体的PIP。为了证明离子相和PIP的局部结构，我们利用了在离子相的两个退化结构之间形成的自旋固体作为自旋探针。通过测量ESE-ESR光谱在4 K处的角度依赖性以及使用电子旋转回声ECHO ECHO INVELOPE调制（ESEEM）技术，获得了自旋soliton A的对称性和局部结构信息。结果表明，自旋孤子具有未配对的离子分子的构型。当晶体非常令人兴奋时，通过具有垂直于堆叠轴的e射器的523 nm激光束连续连续，由旋转固体产生的ESE-ESR信号大大降低。另一方面，与堆叠轴平行的E向量的兴奋给出了很小的变化。通过时间分辨的ESE-ESR测量值，即使通过与堆叠轴平行的E矢量兴奋，由于旋转固体引起的ESR信号在μS区域也受到了很大的影响。结果表明，即使兴奋不足以诱导相变，激光兴奋也会导致自旋孤子的构型暂时变化。通过在弱兴奋下的FT-IR测量值，我们透露，晶体的电荷转移受苦很大程度上受到影响。结果表明，供应者对部分分解了。较少的