Femtosecond IR Probe of Ultrafast Dynamics of Molecular Adsorbates on Nanoparticles: Solvation and Electron Transfer

埃默里大学的连天全博士的飞秒红外探针对纳米颗粒分子吸附的超快动力学的研究获得了化学学部物理化学项目的资助。他将进一步发展和测试溶剂化诱导的振动峰移理论，并利用这种新方法研究纳米颗粒/液体界面上分子的溶剂化动力学。对于偶极矩在基态和激发态之间变化较大的分子，飞秒激发使激发态分子处于非平衡溶剂构型。随后的溶剂化对溶质振动谱的影响尚不清楚，不像对溶质电子谱的影响研究得很好。他正在发展一种基于Onsager介质-溶质相互作用的连续介质模型的溶剂诱导溶质动态振动峰移理论。在不同溶剂中测量Re(dcbpy)(CO)3Cl及相关分子的动态峰移。CO拉伸峰移的幅度和动态将用于与理论模型进行比较和严格测试。他还将使用振动峰移作为研究固液界面溶剂化动力学的新方法。红外探针和纳米晶薄膜的结合将允许在广泛的溶剂中研究溶剂化动力学。这种方法是对现有技术（如荧光斯托克斯位移和光学克尔效应）的补充，并且可能在微散射介质（如纳米晶体薄膜）中具有独特的应用，这些介质很难使用现有技术进行研究。拟议的研究是Lian博士在理解纳米颗粒分子吸附的超快动力学方面的研究努力的延续。半导体和金属纳米粒子有许多潜在的应用，从纳米电子学、太阳能转换到生物医学成像。大多数纳米粒子是用附着的分子合成或修饰的，如钝化、结构连接、增敏或分子传感基团。这些分子在这些系统中的电荷和能量的转移、输运和耗散中起着至关重要的作用。所提出的工作将导致对纳米颗粒表面分子动力学的基本理解，例如溶剂化和能量松弛。这些知识对于开发基于纳米颗粒的更有效的设备至关重要。拟议的研究还将允许在纳米科学和纳米技术领域培训博士后、研究生和本科生，为未来的劳动力提供教育。

Dr. Tianquan Lian of Emory University is funded for his research on femtosecond IR probe of ultrafast dynamics of molecular adsorbates on nanoparticles - solvation by a grant in the Physical Chemistry program of the Chemistry Division. He will further develop and test the theory of solvation-induced vibrational peak shift and use this novel approach to study solvation dynamics of molecules at nanoparticle/liquid interfaces. For molecules with large dipole moment changes between ground and excited states, femtosecond excitation prepares the excited molecule in a non-equilibrium solvent configuration. The effect of the subsequent solvation on solute vibrational spectra is not yet understood, unlike the well-studied effect on solute electronic spectra. He is developing a theory of solvation-induced solute dynamic vibrational peak shift based on the Onsager dielectric continuum model of solvent-solute interaction. Dynamic peak shifts will be measured in Re(dcbpy)(CO)3Cl and related molecules in different solvents. The magnitude and dynamics of the CO stretching peak shifts will be used to compare with and critically test the theoretical model. He also will use vibrational peak shift as a new method to study solvation dynamics at solid-liquid interfaces. The combination of IR probe and nanocrystalline films will allow the study of solvation dynamics in a wide range of solvents. This approach is complementary to existing techniques such as fluorescence Stokes shift and the optical Kerr effect, and may have unique applications in slightly scattering media such as nanocrystalline thin films, that are difficult to study using these extant techniques. The proposed research is a continuation of Dr. Lian's research effort in understanding ultrafast dynamics of molecular adsorbates on nanoparticles. Semiconductor and metal nanoparticles have many potential applications ranging from nanoelectronics, solar energy conversion, to biomedical-imaging. Most nanoparticles are synthesized or modified with attached molecules as passivating, structural linkage, sensitizing, or molecular sensing groups. These molecules play essential roles in transfer, transport and dissipation of charge and energy in these systems. The proposed work will lead to a fundamental understanding of the dynamics of molecules on the nanoparticle surface, such as solvation and energy relaxation. This knowledge is essential to developing more efficient devices based on nanoparticles. The proposed research will also allow the training of postdoctoral fellows, graduate students and undergraduate students in the area of nanoscience and nanotechnology, educating the workforce of the future.