Enabling Ultrasensitive Optical Measurements with Plasmonics

金属纳米结构已经在各种应用中实现了关键的进步，从执行逻辑功能的光子器件，医学研究到更好地靶向肿瘤以进行进一步的局部光热治疗，太阳能电池技术到高灵敏度光学传感器。限制在单个银或金纳米颗粒或相互作用颗粒的集合附近的电磁场（例如激光）显示取决于纳米结构的光学几何性质的共振。在适当的实验条件下，这种局部共振的激发可以产生几个数量级的电磁场的增强，这可以被利用为光谱灵敏度。它在材料科学和生物材料中的应用是巨大的，提供了更高的空间分辨率和灵敏度，可以检测到单个分子。该研究计划旨在提供解决方案，使光学光谱学中的拉曼灵敏度测量，并阐明沿着四个主要目标：*（i）使用尖端增强拉曼光谱的生物材料的高空间分辨率振动光谱将进行。我们将专注于DNA链，并制定一项策略，以更好地评估DNA链中的病变。我们的设置提供了10 nm范围内的分辨率，允许人们探测和操纵组成DNA的几个碱基的序列。(ii)等离子体介导的检测神经元细胞之间的生物分子交换将使用表面增强效应。我们将结合联合收割机表面图案化，以引导细胞在等离子体传感器上生长，从而能够探测细胞膜附近发生的化学和生物化学交换。荧光和拉曼增强将用于探测化学交换。(iii)我们将制定策略来设计和优化中红外等离子体平台。 为了在中红外的宽光谱域上产生大的增强，我们将开发分形等离子体结构。由于等离子体平台的小尺寸（通常为100 × 100微米平方），使用明亮的红外源（例如在加拿大光源处可访问的红外源）对于这些平台的研究将具有很大的价值。(iv)最后，将进行等离子体激元结构中产生的非线性光学效应。非中心对称的几何形状将导致大的光学非线性将探测二次谐波产生显微镜。最终，等离子体结构的手性也将是一个参数，将被重视手性传感使用非线性效应在光学biosensing.This计划的各种应用，旨在提供纳米成像的尖端方法，以探测最基本的细胞过程中所涉及的化学和生物化学过程的亲密性质。**

Metallic nanostructures have enabled critical advances in a variety of applications ranging from photonic devices that perform a logical function, medical research to better target tumors for further localized photothermal treatment, solar cells technology to high sensitivity optical sensors. An electromagnetic field such as a laser light confined in the vicinity of a single silver or gold nanoparticle or an ensemble of interacting particles, displays resonances that are dependent on the opto-geometric properties of the nanostructure. Under the right experimental conditions, the excitation of such local resonance can yield enhancement of the electromagnetic field by several orders of magnitude which can be exploited for ultrahigh sensitivity optical spectroscopy. Its application in materials science and biomaterial is tremendous offering improved spatial resolution and sensitivity at a level down to the detection of a single molecule. This research program aims at providing solutions to enable ultrahigh sensitivity measurements in optical spectroscopy and is articulated along four principal objectives:****(i) High spatial resolution vibrational spectroscopy of biomaterials using tip-enhanced Raman spectroscopy will be conducted. We will focus on DNA strands and develop a strategy to better evaluate lesions in DNA strands. Our setup offers a resolution in the 10 nm range allowing one to probe and manipulate a sequence of a few bases that compose the DNA. (ii) Plasmon mediated detection of biomolecular exchanges between neuronal cells will be developed using surface-enhanced effects. We will combine surface patterning to direct cell growth over plasmonic sensor enabling to probe chemical and biochemical exchanges occurring in the vicinity of the cell membrane. Fluorescence and Raman enhancements will be used to probe chemical exchanges. (iii) We will develop strategies to design and optimize mid-infrared plasmonics platforms. To yield a large enhancement over a wide spectral domain in the mid-IR we will develop fractal plasmonic structures. Because of the small size (typically 100x100 micron square) of the plasmonic platform, the use of a bright infrared source such as the one accessible at the Canadian Light Source will be of great value for the study of these platforms. (iv) Finally, nonlinear optical effects generated in plasmonic structures will be conducted. Non-centrosymmetric geometries should lead to large optical nonlinearities will be probed by second-harmonic generation microscopy. Ultimately the chirality of the plasmonic structure will also be a parameter that will be valued for chiral sensing using nonlinear effects opening a variety of applications in optical biosensing.This program aims at providing cutting-edge approaches in nanoscale imaging to probe the intimate nature of chemical and biochemical processes involved in the most basic cellular processes. **