TWO-DIMENSIONAL INFRARED-SPECTROSCOPY
TWO-DIMENSIONAL INFRARED-SPECTROSCOPY
复制标题
DOI：
10.1021/ja00203a008
复制
发表时间：
1989-10-11
影响因子：
15
通讯作者：
NODA, I
中科院分区：
文献类型：
--
作者：
NODA, I
摘要二维红外光谱是一种基于时间分辨红外光谱的新技术。在二维红外光谱中，系统受到外界扰动的激发，引起红外光谱的动态起伏。相关分析应用于时间依赖的IR信号，以产生由两个独立的波数定义的光谱。通过在第二维上扩展IR峰，可以基本上简化由重叠峰组成的复杂光谱，并且提高光谱分辨率。位于2D光谱平面上的峰提供了与IR带相关的官能团之间的连接性和相互作用的信息。二维红外光谱的无规聚苯乙烯（PS）和低密度聚乙烯（PE）的混合物组成的系统来说明这些功能。光谱证据清楚地表明，PS和PE在共混物中是在分子水平上分离的，允许组分相互独立地响应施加的外部扰动。一种物质！在PS的主链和侧基官能度的局部移动性中观察到差异。在此基础上，将中心位于1454 cm-1附近的1459-cirf 12峰归属于PS分子中的CH 2骨架形变。在2D IR中，光谱作为两个独立波数轴的函数获得，并且位于光谱平面上的峰用于研究官能团之间的分子内和分子间相互作用。2D IR的基本概念有点类似于NMR中广泛使用的2D相关技术。然而，由于振动弛豫速率比自旋弛豫快许多数量级，因此基于多脉冲激发为2D NMR开发的双傅立叶变换技术不容易适用于IR。相反，提出了不同的实验程序来产生2D IR相关光谱。
Abstract Two-dimensional infrared (2DIR) spectroscopy, a novel technique based on time-resolved IR spectroscopy, is introduced. In 2D IR, a system is excited by an external perturbation, which induces a dynamic fluctuation of the IR spectrum. A correlation analysis is applied to the time-dependent IR signals to yield a spectrum defined by two independent wavenumbers. By spreading IR peaks over the second dimension, a complex spectrum consisting of overlapped peaks can be substantially simplified, and spectral resolution is enhanced. Peaks located on a 2D spectral plane provide information on connectivity and interactions among functional groups associated with the IR bands. 2D IR spectra are presented for a system consisting of a mixture of atactic polystyrene (PS) and low-density polyethylene (PE) to illustrate these features. The spectroscopic evidence clearly shows PS and PE in a blend are segregated at the molecular level, allowing the components to respond to an applied external perturbation independently of each other. A substantia! difference is observed in the local mobility of the backbone and side-group functionalities of PS. On the basis of this observation, it is possible to assign the 1459-cirf1 2component of the broad IR band centered around 1454 cm'1 to the backbone CH2 deformation in PS.A novel analytical concept in vibrational spectroscopy called two-dimensional infrared (2D IR) spectroscopy is introduced. In 2D IR, a spectrum is obtained as a function of two independent wavenumber axes, and peaks located on the spectral plane are used to study intra-and intermolecular interactions among functional groups. The basic concept of 2D IR is somewhat analogous to the 2D correlation technique used extensively in NMR. 1'3 However, since vibrational relaxation rates are many orders of magnitude faster than spin relaxations, the double Fourier transform technique developed for 2D NMR based on multi-ple-pulse excitations is not readily applicable to IR. Instead, a different experimental procedure is proposed to generate 2D IR correlation spectra.