Breakdown of Kinetic Compensation Effect in Physical Desorption

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College of Natual Science and Mathematics, Physics and Astronomy


Kinetic theory, Interface & surface thermodynamics, Statistical Physics


The kinetic compensation effect, observed in many fields of science, is the systematic variation in the apparent magnitudes of the Arrhenius parameters, the activation energy Ea, and the preexponential factor ν as a response to perturbations. If, in a series of closely related activated processes, these parameters exhibit a strong linear correlation, then it is expected that an isokinetic relation will occur, and the rates assume a common value at the compensation temperature Tc. The reality of these two phenomena continues to be debated as they have not been explicitly demonstrated and their physical origins remain poorly understood. Using kinetic Monte Carlo simulations on a model interface, we explore how site and adsorbate interactions influence the Arrhenius parameters during a typical desorption process. We find that their transient variations result only in a partial compensation as the variations in the prefactor are not large enough to completely offset those in Ea. In addition, the observed isokinetic relation arises as a result of a transition to a noninteracting regime and not due to compensation between Ea and lnν. These results provide a deeper insight into the microscopic events from which compensation effects and isokinetic relations originate in this system, suggesting that similar mechanisms may be at play in other systems where compensation effects have been reported.

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