Theory of the Low-Temperature Chromatographic Separation of the Hydrogen Isotopes

Abstract

A new electrostatic theory is presented which quantitatively explains the chromatographic separation of the hydrogen isotopes on an alumina column at low temperatures. The theory is based on the interaction of the surface electric fields of the alumina with the polarizable hydrogen isotopes. By calculating the electric fields over an adopted Al2O3 surface, it is found that there are two active adsorption sites at 77.4°K, one over a vacancy in the Al2O3 structure, and the other over an Al3+. The total interaction potential over either site is a function of the polarizabilities of the adsorbed molecules and the distance the molecules are from the surface. A 5–9 potential over a vacancy site gives results which favorably agree with experimental values. The rotational barrier, necessary to explain the separation of the ortho and para species, is shown to arise from the difference in the parallel and perpendicular components of the molecular polarizability of the hydrogen molecule.