Laser-Based Metrology for Engineered Aerosolized Nanoparticles

纳米粒子在材料科学的前沿领域非常突出，对加拿大的制造业至关重要。它们独特的机械、化学和电磁特性被用来增强各种材料，是令人兴奋的新技术的基础。然而，由于它们的功能强烈依赖于它们的大小，加拿大工业迫切需要一种诊断方法，能够对工程纳米颗粒的气溶胶进行时间和空间分辨率的尺寸测量，以充分实现它们的商业潜力。这项拟议研究的目标是将目前用于测量烟尘的燃烧诊断技术--时间分辨激光诱导白炽灯(Tour-LII)转变为一种新的工具，用于测量合成气雾化纳米颗粒的大小。Tour-LII使用激光脉冲为纳米颗粒样本提供能量，当它们与周围气体重新平衡时，它们的光谱白炽度被记录下来。由于较大的纳米颗粒的冷却速度比较小的纳米颗粒慢，因此可以从LII信号的衰减来推断纳米颗粒的尺寸分布。将轮胎LII扩展到新的气雾剂有两个挑战：第一，解释轮胎LII数据需要一个激光激励的纳米颗粒和周围气体之间的热传递的准确模型；第二，从轮胎LII数据推断颗粒尺寸是复杂的，因为LII信号是由一系列颗粒尺寸的发射引起的，所以从这个数据推断颗粒尺寸分布在数学上是不合适的。这项研究将通过实验分析和数值模拟来表征纳米尺度下的热传递物理，并开发一种恢复纳米颗粒尺寸分布的数学算法来应对这些挑战。通过这项研究获得的知识将为加拿大新兴的纳米制造行业带来一个强有力的新工具。这项研究还将培养6名研究生和3名本科生在纳米技术方面的实验和分析技能，为他们在工业和学术界的职业生涯做好准备。这些高素质的人才对于加拿大保持纳米技术的领先地位至关重要。

Nanoparticles are prominent at the frontiers of material science, and are critical to Canada's manufacturing sector. Their unique mechanical, chemical, and electromagnetic properties are used to enhance a wide range of materials, and are the basis of exciting new technologies. Since their functionality depends strongly on their size, however, Canadian industry urgently needs a diagnostic that can make temporally- and spatially-resolved size measurements on aerosols of engineered nanoparticles to fully realize their commercial potential. The goal of the proposed research is to transform time-resolved laser-induced incandescence (TiRe-LII), a combustion diagnostic presently used to measure soot, into a new tool for sizing synthetic aerosolized nanoparticles. TiRe-LII uses a laser pulse to energize a sample of nanoparticles, and their spectral incandescence is recorded as they re-equilibrate with the surrounding gas. Since larger nanoparticles cool more slowly than smaller ones, the nanoparticle size distribution can be inferred from the LII signal decay. There are two challenges in extending TiRe-LII to new aerosols: first, interpreting TiRe-LII data requires an accurate model of the heat transfer between the laser-energized nanoparticles and surrounding gas; and second, inferring particle sizes from the TiRe-LII data is complicated by the fact that the LII signal is due to emission from a range of particle sizes, so inferring the particle size distribution from this data is mathematically ill-posed. The research will address these challenges by characterizing the nanoscale physics underlying heat transfer through experimental analysis and numerical simulation, and developing a mathematical algorithm for recovering nanoparticle size distributions. Knowledge gained through this research will lead to a potent new tool for Canada's nascent nanofabrication industry. This research will also train six graduate and three undergraduate students with experimental and analytical skills in nanotechnology, equipping them for careers in both industry and academe. These highly-qualified personnel are essential for Canada to remain at the forefront in nanotechnology.