Near-Field Optical Studies of Thin-Film Mesostructured Organic Materials
Near-Field Optical Studies of Thin-Film Mesostructured Organic Materials
复制标题
薄膜介观结构有机材料的近场光学研究
DOI：
10.1021/ar960274k
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发表时间：
1997
影响因子：
18.3
通讯作者：
P. Barbara
中科院分区：
文献类型：
--
作者：
D. Vandenbout;J. Kerimo;D. Higgins;P. Barbara
用于薄膜分析的光学显微镜技术正在经历一场革命，以满足分析复杂薄膜的挑战。这些薄膜的范围从生物例子，包括细胞膜，到现代合成材料，如有机发光二极管（LED）中的发射层，以及高度组织的多层组件。这些材料在原子、分子、纳米、介观，甚至宏观等多个尺度上都具有同时存在的独特的组织结构。近场扫描光学显微镜（NSOM）是薄膜分析中最强大的新兴技术之一。NSOM是一种扫描探针光学显微镜，突破了普通显微镜的衍射极限（λ/2）。这是通过NSOM探针的亚波长孔径照明（或从样品收集光）来实现的。回顾了20世纪80年代和90年代初NSOM的巨大发展。1-5最常见的NSOM探头是一种锥形的、镀铝的单模光纤，其一端的孔径为几十纳米。这些探针的光学分辨率小至12纳米。2在NSOM中，样品在XY平面上的横向位置被光栅扫描，而样品/探针的分离保持固定（图1）。NSOM尖端/样品距离调节机制与NSOM图像同时提供扫描力显微镜（SFM）地形图像（类似于AFM图像）。这导致样品的光学性质与其地形的信息相关。两种最常见的NSOM图像类型是透射型NSOM和荧光型NSOM，它们的不同取决于是收集了针尖/样品区域发出的所有光，还是只收集了激发的荧光。使用NSOM探针的光谱学非常简单，既可以在NSOM图像中进行化学对比，也可以在局部区域研究样品的光物理/光化学。特别是，荧光NSOM非常敏感，可以进行亚单层观察甚至单分子检测和光谱分析。6-11本报告回顾了NSOM最近对荧光功能有机薄膜材料的研究。本文着重研究了材料的介观结构如何调节其光谱学和光物理特性。我们强调实验室的结果。NSOM的许多关键优势和基本原则
Techniques in optical microscopy for thin-film analysis are undergoing a revolution to meet the challenges of analyzing complex thin films. These films range from biological examples, including cell membranes, to modern synthetic materials such as emitting layers in organic lightemitting diodes (LED), and highly organized, multilayer assemblies. All of these materials posses simultaneous and distinct organization on multiple distance scales, ie, atomic, molecular, nanoscopic, mesoscopic, and in some cases even macroscopic. Among the most powerful emerging techniques for thin-film analyses is near-field scanning optical microscopy (NSOM). NSOM is a scanning probe optical microscopy that breaks the diffraction limit (λ/2) to the resolution of ordinary microscopy. This is achieved by illuminating (or collecting light from the sample) through a subwavelength aperture in a NSOM probe. The dramatic developments of NSOM in the 1980s and early 1990s have been reviewed. 1-5 The most common NSOM probe is a tapered, aluminum-coated, single-mode optical fiber which has an aperture of a few tens of nanometers at one end. These probes offer optical resolution as small as 12 nm. 2 In NSOM the sample’s lateral position in the XY plane is raster scanned while the sample/probe separation remains fixed (Figure 1). The NSOM tip/sample distance regulation mechanism provides a simultaneous scanning force microscopy (SFM) topographic image (similar to an AFM image) with the NSOM image. This leads to an informative correlation of the samples optical properties with its topography. The two most common types of NSOM images are transmission NSOM and fluorescence NSOM, which differ depending on whether all the light emanating from the tip/sample region, or only the excited fluorescence light, is collected. Spectroscopy with the NSOM probe is straightforward, allowing for both chemical contrast in the NSOM images and the study of the photophysics/photochemistry of the sample in localized regions. In particular, fluorescence NSOM is extraordinarily sensitive, leading to submonolayer observations and even single-molecule detection and spectroscopy. 6-11 This Account reviews recent NSOM studies of functional organic thin-film materials that fluoresce. The paper focuses on how the mesostructure of a material modulates its spectroscopy and photophysics. We emphasize results from our laboratory. Many of the key advantages and fundamental principles of the NSOM