Extrinsic field conversion of parahydrogen over the rare earths

Abstract

Parahydrogen conversion rates have been measured at room temperature over most of the rare earths as catalysts. With the catalyst in zero extrinsic magnetic field the conversion rates are, within experimental error, proportional to the square of the magnetic moment of the paramagnetic species. With the catalyst in an extrinsic field of 18 kOe, large increases in conversion rates are observed for all rare earths. These increases bear no relation to the number of f electrons, or to the presence of even or odd numbers of unpaired electrons in the paramagnetic ions. It appears, therefore, that the electron-spin relaxation time cannot be rate-determining for either the zero field effect or the extrinsic field acceleration, over these catalysts.