Kinetics latent period

If a gas molecule strikes an empty space on the elementary crystalline space lattice it condenses and is held for a period of time (t) on the surface before it evaporates. This period of time between condensation and evaporation or the mean life of the molecule on the surface may vary from a small fraction of a second to an almost indefinite period. In those cases where the strength of union between adsorbate and adsorbing agent is weak and where the adsorbed molecule readily receives sufficient kinetic energy from shocks, provided by bombarding gas molecules and pulses from the solid adsorbate, to equal the latent heat of evaporation. 

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