Single Nanoparticle Trapping Studies of Size Dependent Chemistry and Optical Properties

在这个由化学学部大分子、超分子和纳米化学项目资助的项目中，犹他大学的斯科特·安德森教授将开发研究单个、分离纳米颗粒的新技术。该方法将测量捕获的纳米粒子的光学特性和表面化学反应，同时通过测量捕获中的粒子运动频率，以百万分之一的精度测量粒子的质量电荷比。通过确定绝对电荷状态，就可以测量出绝对质量。这些新功能将首次允许对颗粒大小、电荷状态、光学和化学性质之间的相关性进行高精度研究。该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、组成、电荷状态和充电物质的性质相关。还将进行旨在将该技术扩展到研究非荧光纳米颗粒表面化学的实验。在这些实验中，两个粒子同时被捕获，非荧光粒子的质量/电荷比是通过其对共捕获荧光粒子运动的影响来推断的。在1-10纳米直径范围内的纳米粒子具有强烈依赖于尺寸的电子特性。这些粒子广泛应用于各种应用，从生物传感的荧光标签，到异相催化剂，再到纳米材料，在每种应用中，电子特性对光学或化学特性的影响都是至关重要的。由于纳米颗粒通常具有显著的尺寸分布，因此很难在任何细节上解开尺寸-性质关系。安德森教授将与一名研究生和一名本科生一起，开发一种单纳米粒子捕获方法，用于研究半导体纳米粒子（量子点）的光学特性，同时进行高精度质量测量。该技术将扩展到金属和其他纳米颗粒。安德森教授将继续努力招收少数族裔学生，并将继续接待高中生和本科生进行研究，使他们接触到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.