Theoretical Calculation of the Low-Density Transport Properties of Monatomic Silver Vapor

Abstract

Calculations of low-density transport property collision integrals are used to obtain the high-temperature transport properties of silver atoms as a function of temperature. The collision integrals depend on the two-body interaction potentials between silver atoms in various electronic states. Contributions are included from the ground $X^{1}\Sigma_{\rm g}^{+}$ and excited $^{3}\Sigma _{\rm u}^{+}$ molecular electronic states of the silver dimer that dissociate to two ground-state silver atoms and from the excited $A^{1}\Sigma_{\rm u}^{+}$ molecular state that dissociates to a ground state and an excited state silver atom. Spectroscopic constants are available for these three electronic states, and these spectroscopic constants have been used to determine the Hulburt–Hirschfelder (HH) potentials for these three states. The HH potential is perhaps the best general-purpose potential for representing atom–atom interactions. This potential depends only on the spectroscopic constants, and can be used to calculate the viscosity and diffusion collision integrals for the three molecular electronic states. The collision integrals are then degeneracy averaged over the three states. The heat capacity of silver atoms is also calculated at high temperatures. These results provide the information required to obtain the thermal conductivity, viscosity, and self-diffusion coefficients of silver atoms over a wide temperature range from the boiling point of silver to temperatures at which ionization becomes important.