The coefficient of viscosity of atomic hydrogen from 25 to 300 °K

Abstract

The elastic scattering of two H atoms in the singlet ground state has been investigated on the basis of a deep square-well potential, bounded by the long-range van der Waals attraction. Phase shifts with their appropriate multiples of $\pi$ are presented for L = 0(1)29. Some phase shifts exhibit a step-like gain of $\pi$ with increasing wave number. This phenomenon is illustrated by wave function graphs and is discussed. Viscosity cross-sections are given. For scattering in the triplet ground state a Buckingham-Corner form of potential has been used and previously calculated cross-sections have been extrapolated and applied. Effective rigid-sphere diameters have been estimated by the empirical method of Hirschfelder & Eliason, both for the approximate and accurate potentials. Two curves are given for the temperature dependence of the coefficient of viscosity, one calculated, the other estimated, and the true curve should lie nearer the latter.