Hydrogen adsorption on Ni (100)

The adsorption of hydrogen on the (100) plane of nickel at room temperature has been investigated using the technique of flash desorption spectroscopy. It is shown that no variation in the adsorption enthalpy of 23.1 kcal/mole occurs during the chemical cleaning of the surface by repeated oxidation and reduction. The number of adsorption sites does however increase to 3.3×10¹⁴/cm² during this process. Determination of the partition functions of the adsorbed species and of the activated complex indicates that the hydrogen atoms are localised on specific adsorption sites but that greater liberty exists in the activated complex. Finally the experimental desorption spectra may be described using a model with a repulsive interaction of 400 cal/mole between nearest neighbours.