Related Experiment Videos
Influence of surface morphology on D2 desorption kinetics from amorphous solid water.
L Hornekaer1, A Baurichter, V V Petrunin
1Department of Physics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. liv@phys.au.dk
The Journal of Chemical Physics
|April 20, 2005
Summary
Surface structure affects how D2 desorbs from amorphous solid water (ASW). Porosity and annealing reduce desorption rates by altering binding sites and pore structure, crucial for understanding interstellar dust.
Area of Science:
- Materials Science
- Physical Chemistry
- Astrochemistry
Background:
- Surface morphology and porosity significantly influence desorption kinetics.
- Understanding desorption is vital for modeling processes on interstellar dust grains.
Purpose of the Study:
- Investigate the impact of surface morphology and porosity on D2 desorption from amorphous solid water (ASW).
- Correlate experimental desorption data with theoretical calculations.
- Analyze the effects of thermal annealing on ASW structure and D2 desorption.
Main Methods:
- Low-temperature vapor deposition of ASW films with varying conditions and thermal histories.
- Experimental measurement of D2 desorption kinetics and binding energies.
- Theoretical calculations to correlate adsorption site characteristics with binding energies.
- Investigation of D2 desorption on thermally annealed ASW films.
Main Results:
- A broad distribution of D2 binding energies was observed on both nonporous and porous ASW.
- Porosity reduced desorption rates and altered peak shapes, explained by diffusion into pores and changing binding statistics.
- Thermal annealing reduced porosity and highly coordinated binding sites due to ASW restructuring and pore collapse.
Conclusions:
- Surface features like valleys and peaks on nanoscale rough films dictate D2 binding energies.
- Porous ASW exhibits reduced desorption rates and altered kinetics due to diffusion and surface area effects.
- ASW restructuring via annealing significantly impacts D2 desorption by modifying porosity and binding sites, relevant to interstellar medium processes.