Effect of surface morphology on kinetic compensation effect

TL;DR

This study uses kinetic Monte Carlo simulations to explore how substrate surface morphology influences the kinetic compensation effect during thermal desorption, revealing topology-dependent variations in activation energy and preexponential factors.

Contribution

It demonstrates that surface topology affects the relationship between activation energy and preexponential factor, challenging the assumption of their full correlation in kinetic models.

Findings

Compensation effect persists on disordered surfaces.

Surface topology introduces independent variations in preexponential factors.

Parameters cannot be fully characterized as functions of each other.

Abstract

As part of a systematic study on the kinetic compensation effect, we use kinetic Monte Carlo simulations to observe the effects of substrate topology on the transient variations in the Arrhenius parameters - effective activation energy $E_{a}$, and preexponential factor $\nu$ - during thermal desorption, with a particular focus on differences between ordered and disordered surfaces at a fixed global coordination number. The rates of desorption depend on surface configuration due to the inherent differences in the local environments of adsorbing sites in the two cases. While the compensation effect persists for the disordered substrate, the change in topology introduces an element that produces variations in $\nu$ that are independent of variations in $E_{a}$, which implies that the parameters cannot be fully characterized as functions of each other. We expect our results to provide a deeper insight into the microscopic events that originate compensation effects in our system of study but also in other fields where these effects have been reported.