水膜限制增强拉曼散射效应及其应用初探

Present technology on Raman enhancement have remained a challenge in characterization of the molecules of weak interaction with substrate, due to the substrate hard to capture or adsorb probe molecules and thus unable to recognize the enhanced Raman scattering signal. This project presents a water-film confined enhanced Raman scattering effect and its characterization method. Namely, the water thin film induced confinement can make the probe molecules restricted in the effective region of substrates with local field enhancement, and further realize its Raman enhanced characterization. The key of this project is need to control the evaporation process of the probe aqueous solution on the enhanced substrates in order to gain an appropriate thin water-film state in the Raman characterization and promote the characterization stability. The research included: exploring the noble metal micro/nanostructured array substrates with high local field enhancement and their construction methods, investigating the surface wettability of the enhanced substrates and its impacts on Raman enhancement, further through the controlling and optimizing the local field enhancement effect, surface wettability and the process of Raman characterization, to promote the stability of water-film confined Raman scattering characterization method, prolong the characterization duration, and develop the application studies. Our project provides a new method for enhanced Raman scattering characterization, and a possibility for the enhanced Raman based characterization and detection on molecules of weak interaction with substrate.

现有拉曼增强技术在表征与基底弱相互作用分子时遇到挑战，即基底难以捕捉或吸附探测分子而无法获取其增强拉曼散射信号。本项目提出水膜限制增强拉曼散射效应及其表征方法，即利用水薄膜对探测分子的限制作用，促使分子被限制在基底局域场增强区域内，进而实现其拉曼增强表征。项目关键需要控制探测分子水溶液在增强基底上的蒸发过程，捕获适宜拉曼表征的水薄膜态，提高表征稳定性。研究包括：探索具有高局域场增强的贵金属微/纳结构阵列基底及其构筑方法；研究增强基底的表面润湿性及其对拉曼增强的影响；进而通过基底局域场增强效应、表面润湿性、以及拉曼表征过程的控制和优化，提高水膜限制增强拉曼散射表征方法的稳定性、延长适合表征的窗口，开展应用初探研究。项目提供了一种新的增强拉曼散射表征方法，为与基底弱相互作用分子的拉曼表征或检测提供了可能性。

基于表面增强拉曼散射（SERS）效应的检测，由于其指纹识别、高灵敏度、快速响应等优点，是实现弱极性有害分子快速、痕量探测的有效途径。然而，如何获得高活性SERS基底，并且具有良好的结构稳定性和制备的可重复性，以及如何有效捕捉和富集弱极性有害分子，是实现其基于SERS效应检测的两大关键问题。本项目以基于SERS效应的弱极性有害分子（如沙林模拟剂等）快速、痕量检测为目标牵引，针对其关键问题，以贵金属微/纳结构阵列为SERS基底，发展阵列构筑的新方法，研究阵列的SERS活性、表面浸润性及其结构、成分相关性，探索弱极性有害分子的有效捕捉方法，进而发展新的检测技术等。已取得如下一些结果：发展了基于模板的微/纳结构阵列的构筑新方法，这些方法，原理简单、操作便捷，具有较好的普适性，为高质量SERS基底的按需构筑提供了有效的实现途径；设计制备出系列新型微/纳结构阵列，实现了金、银微/纳有序阵列的结构、形态与成分的调控和优化，揭示了阵列SERS效应的结构相关性，为高活性SERS基底的设计提供了依据与思路；发现了微/纳结构阵列表面浸润性的结构相关性，凹形和凸形球面阵列表面展示出截然不同的动态润湿行为，进而，通过调控结构实现了浸润性的控制，为高浓缩系数的SERS基底以及可控粘附力提供了结构设计思路；提出了水薄膜限制与蒸发浓缩增强拉曼的新思路，实现了基底对弱极性有害分子（沙林模拟剂等）的有效捕捉，建立并证实了蒸发浓缩与拉曼信号间的定量关系，发展了相关的测量技术，实现了弱极性有害分子的高灵敏度探测，为这类分子的基于SERS效应检测提供了新的有效方法。