Fiber optic raman spectrometer with in situ probing capabilities for characterization of metal nanoparticles and metallodielectric composite materials

纳米科学和纳米技术在我们的生活中发挥着越来越重要的作用。几个世纪以来，金属纳米颗粒和纳米复合材料一直被人类称为红宝石金玻璃。如今，由于等离子体和光子学的技术应用，人们对金属纳米颗粒的显著光学性质进行了广泛的研究，成为纳米科学的主要课题之一。与通常使用的红外光谱相比，拉曼光谱具有更强的区分性，在表征有机分子方面具有很大的优势。然而，拉曼散射通常具有很弱的信号强度，这阻碍了它的广泛应用，即使在强大的激光出现的情况下也是如此。这就是金，特别是银纳米粒子提供巨大好处的地方，它可以将金属表面附近的微弱拉曼信号增强到十个数量级。拉曼光谱将在两个主要方向应用于我们的研究。首先是对纳米颗粒合成的优化和对合成机理的理解。在很大程度上，纳米尺度的原位监测相当复杂，阻碍了机制的阐明。然而，光纤拉曼仪器的最新进展带来了强大的研究工具，可以很容易地用于现场监测。原位监测将使我们能够更好地了解纳米粒子的形成，对于我们研究手性纳米构建块将是非常有利的。第二个方向是设计银纳米颗粒和纳米复合材料，优化增强拉曼信号，已被证明具有最终的单分子检测能力。能够制备具有高度重复性的这种复合材料将对分析检测具有巨大的价值，例如生物诊断。总而言之，最近的技术发展带来了非常实惠的仪器，而不会影响质量和性能，这使得拟议的拉曼装置成为我们正在进行的金属纳米颗粒和纳米复合材料研究中非常经济、高效和不可或缺的表征工具。

Nanoscience and nanotechnology play an increasingly important role in our life.  Metal nanoparticles and nanocomposites have been known to mankind for centuries as a ruby gold glass. Nowadays, extensive studies of the prominent optical properties of metal nanoparticles responsible for glass colouration are driven by technological applications of plasmonics and photonics and became one of the major subjects of nanoscience. Raman spectroscopy, being more discriminatory compared to commonly used IR spectroscopy, offers great advantages in characterization of organic molecules. However, Raman scattering typically has very weak signal intensity, which prevented its wide-spread application even with the advent of powerful lasers. That is where gold and especially silver nanoparticles offer tremendous benefits of boosting a weak Raman signal in the vicinity of the metal surface up to ten orders of magnitude.  The Raman spectroscopy will be applied in our research in two major directions. First is optimization of the nanoparticle synthesis and understanding synthetic mechanisms. For the most part, mechanism elucidation has been hampered by considerable complexity of in-situ monitoring on a nanoscale. However, recent advances in fiber optic Raman instrumentation brought powerful research tools that can be readily used for in situ monitoring. In situ monitoring will allow us to gain better understanding of the nanoparticle formation and will be highly advantageous for our research in chiral nano-building blocks. Second direction will be design of silver nanoparticles and nanocomposites with optimized enhancement of the Raman signal that has been shown to have an ultimate capability of single-molecule detection. Ability to prepare such composite materials with highly-reproducible properties will be of tremendous value for analytical detection, e.g. biodiagnostics.   In summary, recent technological developments brought very affordable instruments without compromising quality and capabilities that makes the proposed Raman setup a very cost-effective, efficient and indispensable characterization tool for our ongoing research in metal nanoparticles and nanocomposites.