Localized Probing of Gas Molecule Adsorption Energies
and Desorption Attempt Frequencies
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Abstract
Gas-mediated
electron beam induced etching (EBIE) and deposition
(EBID) can be used to measure activation energies that are interpreted
as the adsorption energies of surface-adsorbed precursor molecules.
However, the measured quantities often disagree with adsorption energies
measured by conventional analysis techniques such as thermally programmed
desorption and have anomalous dependencies on parameters such as the
electron beam current used to perform EBID. Here, we use the theory
of EBIE and EBID rate kinetics to explain this behavior and identify
conditions under which the activation energies and the associated
pre-exponential factors correspond to gas molecule adsorption energies
and desorption attempt frequencies, respectively. Under these conditions,
EBIE and EBID can be used as robust, nanoscale techniques for the
analysis of adsorbates