Single Nanoparticle Trapping Studies of Size Dependent Chemistry and Optical Properties

在这个由化学系的大分子、超分子和纳米化学项目资助的项目中，犹他州大学的斯科特安德森教授将开发研究单个孤立纳米颗粒的新技术。 该方法将测量捕获的纳米颗粒的光学特性和表面化学反应，同时允许通过测量陷阱中的颗粒运动频率以百万分之一的精度测量颗粒质荷比。 还通过确定绝对电荷状态，将测量绝对质量。 这些新功能将首次允许高精度地研究颗粒大小，电荷状态以及光学和化学性质之间的相关性。 这些技术最初将应用于半导体量子点，允许测量光谱特性，包括荧光寿命，与颗粒大小，成分，电荷状态和带电物质的性质相关。 还将进行旨在扩展该技术以研究非荧光纳米颗粒的表面化学的实验。 在这些实验中，两个粒子被同时捕获，并且非荧光粒子的质荷比通过其对共同捕获的荧光粒子的运动的影响来推断。 1-10纳米直径范围内的纳米颗粒具有强烈依赖于尺寸的电子性质。 这种颗粒广泛用于从生物传感的荧光标签到非均相催化剂到纳米材料的应用中，并且在每种应用中，电子性质对光学或化学性质的影响都是至关重要的。 由于纳米颗粒通常以显著的尺寸分布产生，因此很难在任何细节上解开尺寸-性质关系。 安德森教授，沿着一名研究生和一名本科生，将开发一种单一的纳米粒子捕获方法来研究半导体纳米粒子（量子点）的光学性质，同时进行高精度质量测量。 这些技术将扩展到金属和其他纳米粒子。 安德森教授将继续努力招收少数族裔学生，并将继续接待高中和本科生进行研究，使他们接触复杂的物理和数学概念。

In this project, funded by the Macromolecular, Supramolecular, and Nanochemistry Program of the Division of Chemistry, Professor Scott Anderson of the University of Utah will develop new techniques for studying single, isolated nanoparticles. The approach will measure the optical properties and surface chemical reactions of trapped nanoparticles while simultaneously allowing the particle mass-to-charge ratio to be measured with precision of one part per million, via measurement of the particle motional frequency in the trap. By also determining the absolute charge state, the absolute mass will be measured. These new capabilities will allow, for the first time, correlations between particle size, charge state, and optical and chemical properties to be studied with high precision. The techniques will initially be applied to semiconductor quantum dots, allowing measurements of spectral properties, including fluorescence lifetimes, to be correlated with particle size, composition, charge state, and the nature of the charging species. Experiments directed at extending the technique to study surface chemistry of non-fluorescent nanoparticles will also be carried out. In these experiments, two particles are trapped simultaneously, and the mass/charge ratio of the non-fluorescent particle is inferred by its effects on the motion of a co-trapped fluorescent particle. Nanoparticles in the 1-10 nanometer diameter range have electronic properties that depend strongly on size. Such particles are used extensively in applications ranging from fluorescent tags for biosensing, to heterogeneous catalysts, to nanomaterials, and in each application, the effects of electronic properties on optical or chemical properties is critical. Because nanoparticles generally are produced with significant size distributions, it is difficult to unravel size-property relationships in any detail. Professor Anderson, along with a graduate student and undergraduate student, will develop a single nanoparticle trapping approach to studying optical properties of semiconductor nanoparticles (quantum dots), with simultaneous high precision mass measurement. The techniques will be extended to metal and other nanoparticles. Prof. Anderson will continue his efforts at recruiting minority students, and will continue to host high school and undergraduate students for research that expose them to sophisticated physical and mathematical concepts.