Surface-enhanced linear and nonlinear vibrational spectroscopy from first-principles

来自宾夕法尼亚州立大学的Lasse詹森获得了化学理论、模型和计算方法项目的一项奖项的支持，该项目旨在开发新的理论工具，用于分析和预测纳米颗粒或具有表面等离子体的纳米结构界面附近的分子光谱。例如，这些可能是几纳米（十亿分之一米）大小的金颗粒。表面等离子体激元是强烈吸收和散射特定颜色范围的入射光的集体电子运动。该项目旨在开发和分发计算工具，以分析和理解分子和光在这种情况下如何相互作用。特别注意的是，光散射是由两个入射光子的光，而不是通常的情况下，一个入射光子触发的独特情况。由此产生的计算工具将是重要的许多应用在催化的化学反应，光转换为能量，和生物成像。将通过将其纳入现有的化学计算软件包，向广大科学界传播这些数据。一个互动的纳米光学模拟器可视化模块将被整合到高中生的夏季研究经验，并通过纳米科学的中央门户网站nanoHub提供给更多的观众。本科生通过参与这项研究接受尖端科学培训。研究生通过参与研究和教育活动获得研究专业知识，指导经验和协作技能。了解纳米界面的多光子特性对于全光开关，能量上转换，多相催化和生物成像的应用非常重要。表面增强拉曼散射（Sers）及其非线性模拟表面增强超拉曼散射（SEHRS）可用于提供分子激发态性质的详细信息，可精确到单分子水平。这项研究解决了理解Sers和SEHRS的主要挑战，通过开发准确有效的方法来直接从第一原理模拟光谱。这些方法被用于1）理解增强机制，2）建立对可能增强的限制，以及3）设计针对SEHRS应用的等离子体基片。计划通过纳入ADF和NWChem等软件包进行传播。 最终，这项研究的目的是在分子水平上详细了解新材料的非线性光学性质。

Lasse Jensen from the Pennsylvania State University is supported by an award from the Chemical Theory, Models and Computational Methods program to develop new theoretical tools for analyzing and predicting spectroscopy of molecules near nanoparticles or nanostructured interfaces with surface plasmons. These may be, for example, particles of gold that are several nanometers (billionths of a meter) in size. Surface plasmons are collective electronic motions that strongly absorb and scatter incoming light of particular color ranges. This project aims at developing and distributing computational tools to analyze and understand exactly how molecules and light interact in such circumstances. Particular attention is paid to the unique situation that light scattering is triggered by two incoming photons of light instead of the usual circumstance of a single incoming photon. The resulting computational tools will be important for many applications in catalysis of chemical reactions, conversion of light to energy, and biological imaging. They will be disseminated to a broad scientific community through incorporation into available chemical compuational software packages. An interactive Nano-Optics Simulator visualization module will be integrated into summer research experiences for high school students and made available to a larger audience through the nanoHub, a central web portal for nanoscience. Undergraduate students are trained in cutting-edge science by participating in this research. Graduate students gain research expertise, mentoring experiences, and collaborative skills through their participation in both research and educational activities.Understanding multi-photon properties at nano-interfaces is of great importance for applications in all-optical switching, energy-up conversion, heterogeneous catalysis and biological imaging. Surface-enhanced Raman scattering (SERS) and its nonlinear analogue surface-enhanced hyper-Raman scattering (SEHRS) can be used to provide detailed information about molecular excited state properties down to the single-molecule level. This research addresses the main challenges in understanding SERS and SEHRS by developing accurate and efficient methods to directly simulate the spectra from first principles. These methods are being used to 1) understand the enhancement mechanisms, 2) establish limits on the possible enhancements, and 3) design plasmonic substrates that are targeted for SEHRS applications. Dissemination is planned through incorporation into sofware packages such as ADF and NWChem. Ultimately, this research is aimed at a detailed molecular level understanding of nonlinear optical properties in novel materials.