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PHOTOINDUCED PHASE TRANSITION IN QUASI ONE-DIMENSIONAL ORGANIC CRYSTALS BY MEANS OF THE-RESOLVED RAMAN SCATTERING SPECTROSCOPY

利用分辨拉曼散射光谱研究准一维有机晶体中的光致相变

基本信息

批准号：
15340097
负责人：
TANIMURA Katsumi
金额：
$ 10.5万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

The purpose of this research project was to establish general understanding of the mechanism of photoinduced structural transformation in quasi one-dimensional organic crystals, based on the dynamics in ultra short temporal domain and on the direct information on structural properties. For this, femtosecond time-resolved optical methods and time-resolved Raman spectroscopic methods were extensively used.For a charge-transfer organic crystal of tetrathiafulvalen-p-chloranil (TTF-CA), we could resolve completely the three consecutive primary steps involved in the transition ; the precursor-forming step, local proliferation, and N-phase order formation. The microscopic understanding in each step has been obtained by the results of multi-wavelength reflection measurements. For a process of forming a quasi one-dimensional conjugated it-bond order in diacetylene crystals, dynamics in forming the key entity of di-radical intermediatd in the polymerization reactions has been elucidated in 5,7-dodecadiyne-1,12-diol bis[phenyl carbamate] (TCDU) crystals : triplet-exciton fusion generates dimer diradicals. By applying Raman spectroscopy, we could obtain precise structural knowledge on each step of polymerization from diradicals to dicarben, origornaers and finally it-bond chains. The polydiacetylene crystals thus formed show both A and B phases, and relaxation dynamics in each phase have been studied by ferntosecond time-resolved reflection spectroscopy. Although photoinduced phase transition has not been induced in this poly TCDU, important process of forming intrinsic meta-stable states has been discovered.The results obtained in the present project have provided the important basis on which we can construct the mechanism of photoinudced phase transition based on microscopic understanding of structural knowledge in each step involved in the process.

本研究项目的目的是建立在超短时间域的动力学和结构特性的直接信息的基础上，在准一维有机晶体的光致结构转变的机制的一般理解。飞秒时间分辨光学方法和时间分辨拉曼光谱方法被广泛应用，对于四硫富瓦仑-对氯醌（TTF-CA）电荷转移有机晶体，我们可以完全解析跃迁过程中的三个主要步骤：电子转移形成步骤、局域扩散步骤和N相有序形成步骤.通过多波长反射测量的结果，获得了对每一步的微观理解。对于丁二炔晶体中形成准一维共轭π键序的过程，在5，7-十二碳二炔-1，12-二醇双[苯基氨基甲酸酯]（TCDU）晶体中，阐明了聚合反应中形成双自由基中间体的动力学过程：三重态激子融合生成二聚体双自由基。通过应用拉曼光谱，我们可以获得精确的结构知识的每一个步骤的聚合反应，从双自由基到二卡宾，origornaers，最后it键链。由此形成的聚丁二炔晶体显示A和B相，并在每个阶段的弛豫动力学已被研究的飞秒时间分辨反射光谱。虽然在该聚TCDU中没有诱导出光致相变，但发现了形成本征亚稳态的重要过程，本课题的研究结果为我们从微观上理解光致相变过程中各步骤的结构知识，构建光致相变的机理提供了重要依据。