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Infrared-based and Raman-based Observation of Molecular Vibrations towards Physicochemical Analysis of Ionic Liquids

基于红外和拉曼的分子振动观察对离子液体的物理化学分析

基本信息

批准号：
14340190
负责人：
ONISHI Hiroshi
金额：
$ 6.53万
依托单位：
Kanagawa Academy of Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Two non-linear, time-domain Raman methods have been developed towards physicochemical analysis of ionic liquids.(1)Interface-specific observation of molecular vibrations was achieved with visible light by a fourth-order optical process. An aqueous solution of oxazine dye interfaced with air was irradiated with 16-fs pluses at 600 nm. A pump pulse excited Raman-active nuclear motions of the dye. A probe pulse interacted with the excited molecules to generate second harmonic light, the intensity of which was oscillated as a function of the pump-probe delay. Fourier-transformation of the oscillation provided a vibrational spectrum of 0 - 1000 cm^<-1> for the dye located at the air-solution interface.(2)Femtosecond time-resolved photoinduced reflectivity change was measured for the first time on a spincoated dye (cresyl violet) of submonolayer coverage on a fused silica substrate. We found that the sensitivity of the reflection measurement was much higher than that of the absorption measurement for thin monolayers of dye. A prominent beating structure due to vibrational coherence of the dye was observed on the time-resolved reflection signal. A vibrational spectrum of the dye at submonolayer coverage, which corresponded its resonance Raman spectrum, was obtained in the range of 0-800 cm^<-1> by a Fourier transform analysis of the reflection signal.

两种非线性、时域拉曼光谱方法已发展用于离子液体的物理化学分析。（1）通过四阶光学过程，在可见光下实现了分子振动的界面特异性观察。用600 nm的16-fs脉冲照射与空气接触的恶嗪染料的水溶液。泵浦脉冲激发染料的拉曼活性核运动。探测脉冲与激发分子相互作用产生二次谐波光，其强度作为泵浦-探测延迟的函数振荡。振动的傅立叶变换为位于空气-溶液界面处的染料提供了0 - 1000 cm-2的振动光谱<-1>。（2）首次在熔融石英基底上的亚单层覆盖的旋涂染料（甲酚紫）上测量了飞秒时间分辨的光致反射率变化。我们发现对于薄染料单层，反射测量的灵敏度远高于吸收测量的灵敏度。由于染料的振动相干性，在时间分辨反射信号上观察到突出的拍频结构。通过对反射信号的傅里叶变换分析，在0-800 cm-1范围内获得了染料在亚单层覆盖下的振动光谱，其对应于其共振拉曼光谱<-1>。