Translational energy accommodation coefficient

For an incident atom, = 0 if the kinetic energies of the incident and scattered atoms are the same incident = scauered- Conversely, = 1 if the kinetic energy of the scattered species is equal to the kinetic energy expected for desorbing from a surface of thermal energy kgT urface> since, in this circumstance, scattered = surface-For a scattered atom, the energy accommodation coefficient becomes the translational-energy accommodation coefficient. 

Figure 4.8. Translational, vibrational, and rotational energy accommodation coefficients for NO scattered from Pt(l 11) as a function of crystal temperature [93J.

In the case of polyatomic molecules, one may consider separately the accommodation coefficients for translational and for vibrational energy. Values of the latter, civ, are discussed by Nilsson and Rabinovitch [7]. 

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