Activated Chemisorption: Internal Degrees of Freedom and Measured Activation Energies

In activated chemisorption occurring both by direct impact from the gas and by conversion from a precursor on the surface, the measured activation energy can provide information about the mechanism of activation. If translational motion is dominant in promoting passage over the adsorption barrier, a single activation energy describes the reaction whether gas and surface are isothermal or hot gas strikes a cold surface. When internal degrees of freedom must be excited for chemisorption to occur, different activation energies characterize these two regimes of measurement.