Abstract Electrical Mobility is arguably the property upon which some of the most successful classification criteria are based for aerosol particles and ions in the gas phase. Once the value of mobility is empirically obtained, it can be related to a geometrical descriptor of the charged entity through a size-mobility relationship. Given the multiscale range of sizes in the aerosol field, approaches that can provide accurate transformations from mobility to size are not straightforward, and many times rely on experimentally derived parameters. The most well-known size-mobility analytical expression covering the whole Knudsen range for spherical particles is the semi-empirical Stokes-Millikan correlation. This expression matches Stokes' drag friction coefficient in the continuum regime and the friction factor for a predominantly diffuse reemission of the gas molecule in the free molecular regime, as theorized by Epstein, with empirical slip coefficients chosen to agree with Millikan's oil drop experiments. Despite its success, the Stokes-Millikan correlation has its shortcomings. For example, it needs to be modified to predict the mobility of non-spherical entities and needs correction terms when potential interactions or reduced mass effects are non-negligible. The Stokes-Millikan asymptotic behavior also fails to predict the gradual transition from diffuse to specular reemission behavior that is observed for increasingly smaller ions within the free molecular regime. Here we make an attempt at providing a comprehensive account of the existing mass-mobility relations in the continuum, transition and free molecular regimes for both spherical and non-spherical particles. Epstein's diffuse interaction is critically explored experimentally and numerically for different gases in the free molecular regime with the observation that, as the size of the particle increases, a progression from specular to diffuse reemission occurs for all gases studied. The rate at which this variation happens seems to differ from gas to gas and to be related to the conditions for which diffuse reemission effects stem from a combination of scattering and potential interactions.

中文翻译：

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离子、气溶胶和其他带电粒子物质的尺寸-迁移率关系。

摘要 电迁移性可以说是一些最成功的分类标准所基于的属性，用于气相中的气溶胶颗粒和离子。一旦根据经验获得迁移率的值，就可以通过大小-迁移率关系将其与带电实体的几何描述符相关联。鉴于气溶胶领域的多尺度尺寸范围，可以提供从流动性到尺寸的准确转换的方法并不简单，而且很多时候依赖于实验得出的参数。涵盖球形颗粒的整个 Knudsen 范围的最著名的尺寸迁移率分析表达式是半经验 Stokes-Millikan 相关性。这个表达式匹配斯托克斯的 连续体区域中的阻力摩擦系数和自由分子区域中气体分子主要弥散再发射的摩擦系数，如爱泼斯坦所推论的，选择的经验滑移系数与密立根的油滴实验一致。尽管取得了成功，Stokes-Millikan 相关性也有其缺点。例如，需要修改它以预测非球形实体的移动性，并且当潜在的相互作用或减少的质量效应不可忽略时需要修正项。Stokes-Millikan 渐近行为也无法预测从漫反射到镜面反射再发射行为的逐渐转变，这是在自由分子范围内观察到的越来越小的离子。在这里，我们试图全面说明球形和非球形粒子在连续、过渡和自由分子状态中的现有质量-迁移率关系。爱泼斯坦的扩散相互作用在自由分子状态下的不同气体中进行了严格的实验和数值研究，观察到随着粒子尺寸的增加，所有研究的气体都会发生从镜面反射到扩散再发射的过程。这种变化发生的速率似乎因气体而异，并且与散射和潜在相互作用的组合产生的漫反射再发射效应的条件有关。对自由分子区域中不同气体的扩散相互作用进行了严格的实验和数值研究，观察到随着粒子尺寸的增加，所有研究的气体都会发生从镜面反射到扩散再发射的过程。这种变化发生的速率似乎因气体而异，并且与散射和潜在相互作用的组合产生的漫反射再发射效应的条件有关。对自由分子区域中不同气体的扩散相互作用进行了严格的实验和数值研究，观察到随着粒子尺寸的增加，所有研究的气体都会发生从镜面反射到扩散再发射的过程。这种变化发生的速率似乎因气体而异，并且与散射和潜在相互作用的组合产生的漫反射再发射效应的条件有关。