For chemistry sets that involve electrons and ions, some special formulations of surface reactions are available. These formulations allow modification of the ion flux as well as the ion impact energy for ion-surface collisions.

Ion fluxes are often not determined by a "thermal" collision frequency (as used in our sticking-coefficient formulations). Instead, ion fluxes are often limited by transport from the plasma to the edge of the plasma sheath, which an electric field that exists near surfaces adjacent to a plasma gas. For non-thermal plasmas, the limiting flux is then defined by the Bohm criterion, [29] which depends on the ion mass and the electron temperature. Ansys Chemkin Surface Kinetics allows a user to indicate that certain reactions are governed by the Bohm flux.

In addition, there are many examples in materials processing, where ions interact with surfaces to alter the morphology, sputter material, or enhance heterogeneous chemical reactions. Ions are often accelerated through a plasma sheath to grounded or electrically biased materials. In this way, the directed energy of ions encountering a surface may be significantly greater than that represented by the ion temperature in the plasma gas. Surface Kinetics therefore makes the provision for a reaction-rate constant to depend upon the energy of a positive ionic reactant species, .

Details of the ion flux and ion-energy options are described in this section.