Fundamental Energy Transfer Mechanisms in High Temperature Phonon-Mediated Gas-Surface Interactions
Abstract
The desorption of O/CO from graphitic carbon surfaces is investigated using a one-dimensional model describing the adsorbate interactions with the surface phonon bath. The kinetics of desorption are described through the solution of a master equation for the time-dependent population of the adsorbate in an oscillator state, which is modified through thermal fluctuations at the surface. The interaction of the adsorbate with the surface phonons is explicitly captured by using the computed phonon density of states (PDOS) of the surface. The coupling of the adsorbate with the phonon bath results in the transition of the adsorbate up and down a vibrational ladder. The adsorbate-surface interaction is represented in the model using a Morse potential, which allows for the desorption process to be directly modeled as a transition from bound to free (continuum) state. PDOS is an important input within the phonon-induced desorption (PID) model, which is a property of the material and the lattice and is highly sensitive to the presence of defects. The effect of random surface defects, etch pits, and adsorbates on the PDOS is considered in the present work. The presence of defects systematically shifts the phonons to lower frequencies and broadens the distribution which changes the phonon frequency modes available for adsorbate coupling at the surface.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 03, 2022
- Accession Number
- AD1231100
Entities
People
- Kelly Stephani
Organizations
- University of Illinois Urbana–Champaign