Abstract Aerosol nanoclusters (AN), defined here as molecular aggregates suspended in a gas with dimensions between 2 and 10 nm, are the link between substances that we think of as molecules, or the “gas phase,” and those that we consider as particles, or the “condensed phase.” The ability to measure and model the physical and chemical properties of size-resolved AN, which at present is rudimentary at best, is crucial for understanding how particles form and evolve in a number of environments that are natural or influenced by human activities. This review describes the current state-of-the-art for measuring and modeling the size-resolved composition of atmospheric AN. We focus specifically on instruments, many relying on mass spectrometry, that show promise for closing the measurement gap under atmospherically relevant conditions by increasing the size of measurable gas-phase clusters (bottom-up approaches) and by decreasing the size of measurable nanoparticles (top-down approaches). Theoretical methods for predicting AN composition have similarly relied on bottom-up approaches that extend the accuracy of quantum chemistry calculations to larger molecular systems, as well as top-down approaches that correct bulk composition aerosol models for size-dependent properties such as viscosity and volatility. Current measurement and modeling challenges that must be overcome in order to close the gap are discussed.

中文翻译：

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大气团簇到纳米粒子：弥合化学成分差距的最新进展和挑战

摘要 气溶胶纳米团簇 (AN)，这里定义为悬浮在气体中的分子聚集体，尺寸在 2 到 10 nm 之间，是我们认为是分子或“气相”的物质与我们认为是粒子的物质之间的联系。 ，或“凝聚相”。测量和模拟尺寸分辨 AN 的物理和化学特性的能力，目前充其量只是初步的，对于了解粒子如何在自然或受人类活动影响的许多环境中形成和演化至关重要。这篇综述描述了当前用于测量和建模大气 AN 的尺寸分辨成分的最新技术。我们特别关注仪器，其中许多依赖于质谱，通过增加可测量的气相团簇的尺寸（自下而上的方法）和减小可测量的纳米粒子的尺寸（自上而下的方法），有望在大气相关条件下缩小测量差距。预测 AN 成分的理论方法同样依赖于自下而上的方法，将量子化学计算的准确性扩展到更大的分子系统，以及自上而下的方法，用于校正体积成分气溶胶模型的尺寸相关特性，例如粘度和挥发性. 讨论了为缩小差距必须克服的当前测量和建模挑战。预测 AN 成分的理论方法同样依赖于自下而上的方法，将量子化学计算的准确性扩展到更大的分子系统，以及自上而下的方法，用于校正体积成分气溶胶模型的尺寸相关特性，例如粘度和挥发性. 讨论了为缩小差距必须克服的当前测量和建模挑战。预测 AN 成分的理论方法同样依赖于自下而上的方法，将量子化学计算的准确性扩展到更大的分子系统，以及自上而下的方法，用于校正体积成分气溶胶模型的尺寸相关特性，例如粘度和挥发性. 讨论了为缩小差距必须克服的当前测量和建模挑战。