Long-Time Non-Debye Kinetics of Molecular Desorption from Substrates with Frozen Disorder

Area of Science:

• Physical Chemistry
• Surface Science
• Materials Science

Background:

• Molecular desorption kinetics from disordered adsorbents often deviate from simple Debye theory.
• Previous explanations involving second-order effects do not fully account for observed non-Debye behavior at long times.

Purpose of the Study:

• To develop a theoretical framework explaining the non-Debye kinetics of molecular desorption from disordered adsorbents.
• To provide a quantitative interpretation of experimental desorption data.

Main Methods:

• Theoretical modeling of desorption kinetics.
• Analysis of experimental data on hydrogen desorption from crystalline and amorphous adsorbents.

Main Results:

• Demonstrated that frozen fluctuations in activation energy are crucial for non-Debye desorption kinetics.
• Derived a closed-form expression for desorption rate with clear physical interpretation.
• Showed that second-order effects become dominant at significantly longer times than where non-Debye behavior is observed.

Conclusions:

• The proposed theory, incorporating frozen activation energy fluctuations, successfully explains non-Debye desorption kinetics.
• The model provides a quantitative interpretation for desorption from both crystalline and amorphous adsorbents.
• Further theoretical development and experimental validation are suggested.