Gaseous species internal energy

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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