Development of Scanning Nano-Raman Spectroscopy with Apertureless Near-Field Optics

继续在纳米科学和纳米技术的最新进展，需要与纳米级的横向分辨率的化学，构象和应力分析方法的发展。该奖项的目的是开发一种扫描拉曼光谱仪，其空间分辨率为10-50 nm，具有强烈增强的光学信号。所提出的工作的中心特征是使用无孔径近场光学器件来提供拉曼信号的强度的至少10exp.10的增益，该增益超过了基于由光纤产生的孔径受限光学器件的当前可用的商业仪器可以实现的增益。这种方法将提供精致的空间分辨率和使用扫描金属尖端的拉曼信号的大的局部增强。增强对于测量来自小体积的信号是绝对必要的。这项工作的一个长期目标是开发一种能够进行单分子检测的拉曼光谱仪。为实现工作的总体目标，将实现以下具体目标：（1）开发用于产生金属尖端的技术，该金属尖端提供拉曼信号的强局部增强;（2）优化用于提供入射光和收集特定实验任务的拉曼信号的不同光学方案;（3）纳米级空间分辨率扫描拉曼光谱仪样机的研制。在磁共振成像方案下支持的扫描纳米拉曼光谱仪的开发将适用于若干科学活动。在研究人血蛋白吸附到明确的表面，SNRS将提供横向解决的信息，在吸附后的蛋白质的构象变化。来自嵌段共聚物的生物材料中表面纳米域的分布、胶原纤维的组装和纤维蛋白的形成是SNRS仪器将提供独特信息的进一步生物材料问题。在粘合剂共混物表面的化学组成的横向变化也可以映射与SNRS和相关的表面机械性能的变化。在长支链和直链的共混物中，SNRS将提供一种横向分辨的替代非破坏性方法来研究同位素标记的共混物中的近表面组成。它还将提供一种无需标记就可研究近表面成分的方法。其他研究活动包括研究聚合物刷和树枝状聚合物的混合纳米结构，以及绘制各种薄膜的表面功能，包括具有混合功能的自组装单层。扫描纳米拉曼光谱仪的发展将对国家的学术研究基础设施产生重大影响，不仅是聚合物材料，而且是半导体技术，生物技术和生物学。它提供的前所未有的测量将促进更好地理解纳米尺度上材料的结构/性能关系。

Continuing the recent progress in nanoscience and nanotechnologies requires the development of methods of chemical, conformational, and stress analysis with nanoscale lateral resolution. The objective of this award from the MRI Program is to develop a scanning Raman spectrometer with spatial resolution of the order of 10-50 nm with a strongly enhanced optical signal. A central feature of the proposed work is the use of apertureless near- field optics to provide a gain of at least 10 exp.10 in intensity of the Raman signal over what may be achieved with currently available commercial instruments based on aperture-limited optics created with fibers. This approach will provide both exquisite spatial resolution and large local enhancement of the Raman signal using a scanning metallic tip. The enhancement is absolutely essential for measurement of the signal from small volumes. A long-term goal of the work is development of a Raman spectrometer capable of single molecule detection. The following specific objectives will be met in achieving the overall goal of the work: (1) Development of the technology for the creation of a metallic tip providing strong local enhancement of the Raman signal; (2) Optimization of different optical schemes for providing the incident light and collecting the Raman signal for particular experimental tasks; and (3) Construction of the scanning Raman spectrometer prototype with nanometer scale spatial resolution. Development of a scanning nano-Raman spectrometer (SNRS) supported under the MRI Program will be applicable to several scientific activities. In the study of adsorption of human blood proteins to well-defined surfaces, SNRS will provide laterally resolved information on conformational changes in the protein upon adsorption. The distribution of surface nano-domains in biomaterials from block copolymers, assembly of collagen fibrils, and fibrin formation are further biomaterials problems for which the SNRS instrument will provide unique information. Lateral variations in chemical composition at the surface of adhesive blends can also be mapped with SNRS and correlated with variations in surface mechanical properties. In blends of long-branched and linear chains SNRS will provide a laterally resolved alternative non-destructive method to study near surface composition in blends with isotopic labeling. It will also offer a means to study near surface composition without labeling. Additional research activities include the study of hybrid nanostructures from polymer brushes and dendrimers and mapping of surface functionality in ultrathin films of various sorts, including self-assembled monolayers with mixed functionalities. Development of the scanning nano-Raman spectrometer will have a significant impact on the Nation's academic research infrastructure not only polymeric materials, but also semiconductor technology, biotechnology and biology. The unprecedented measurements it will provide will promote better understanding of structure/property relationships in materials on the nanometer scale.