Gaseous species translational energy

For a species having n degrees of translational freedom, the translational energy is equal to nkBT/2. Since the activated complex has two degrees of translational freedom, and gaseous A has three, we write... 

Thus, if a gaseous species has nx translational degrees of freedom, n2 rotational degrees of freedom and n3 vibrational degrees of freedom, then the total energy of the species is given by n3 (kT/2) + n2 (kT/2) + n3 (kT). 

A certain fraction of the incident gas atoms are trapped in the attractive potential well, and once trapped they can move along the surface by diffusion. The adsorbed species may desorb from the surface if sufficient energy is imparted to it at a given surface site to overcome the attractive surface forces. The types of interactions that take place between a gas atom or molecule and the surface depend on the energy of the gaseous species (kinetic or translational energy, internal energy, rotation, vibration, or electronic excitation when appropriate), the temperature, and the atomic structure of the solid surface. 

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