Viehland Larry A, Ducasse Emerson, Cordier Michelle, Trout Aaron, Dashdorj Jamiyanaa
Department of Chemistry, Chatham University, Pittsburgh, Pennsylvania 15232, USA.
Department of Mathematics, Chatham University, Pittsburgh, Pennsylvania 15232, USA.
J Chem Phys. 2021 Nov 28;155(20):204301. doi: 10.1063/5.0065616.
Mobility and diffusion coefficients are generally extracted from experimental measurements of ion arrival time distributions using tensors of ranks one and two, i.e., in terms of the diffusion equation that is equivalent to Fick's second law. The theory is extended here to tensors of rank three. It is shown that under customary circumstances, the generalized diffusion equation only contains a single third-order transport coefficient. This equation is used to generate synthetic data for ions moving through a pure gas. The mobility and diffusion coefficients and third-order transport coefficients inferred from these data are compared with values used to simulate the arrival time distribution. Finally, an existing computer program has been modified in order to compute one component of the third-order transport coefficient, and this program has been applied to Li in He.
迁移率和扩散系数通常从离子到达时间分布的实验测量中提取，使用一阶和二阶张量，即根据与菲克第二定律等效的扩散方程。这里将该理论扩展到三阶张量。结果表明，在通常情况下，广义扩散方程仅包含一个单一的三阶输运系数。该方程用于生成离子在纯气体中移动的合成数据。从这些数据推断出的迁移率、扩散系数和三阶输运系数与用于模拟到达时间分布的值进行了比较。最后，对现有的计算机程序进行了修改，以计算三阶输运系数的一个分量，并将该程序应用于氦气中的锂。
