Kinetics of hydrogen absorption in transition metals and subsurface bonding

We have modified the kinetic equations for the absorption of hydrogen in transition metals to include the effects of strong subsurface bonding. The new equations show that the subsurface, self-trapped hydrogen acts as a valve for the admission of hydrogen into the bulk. The explanation for a number of experimental facts, not well understood before, neatly follows. Discrepancies between theory and experiments found earlier are explained by the inclusion of the subsurface term into the kinetic equation.