AVS 52nd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM7
The Effect of Incident Collision Energy on the Phase, Crystallization Kinetics, and Porosity of Vapor Deposited Amorphous Solid Water Films

Thursday, November 3, 2005, 10:20 am, Room 200

Session: Water-Surface Interactions
Presenter: T. Zubkov, Pacific Northwest National Laboratory
Authors: T. Zubkov, Pacific Northwest National Laboratory
R.S. Smith, Pacific Northwest National Laboratory
Z. Dohnálek, Pacific Northwest National Laboratory
B.D. Kay, Pacific Northwest National Laboratory
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Molecular beam techniques that allow for the precise control of the impingement flux, deposition angle, and incident collision energy are used to grow nanoscale films of amorphous solid water (ASW). The phase (amorphous or crystalline), porosity, and subsequent crystallization kinetics of the ASW films are probed using temperature programmed desorption, inert gas physisoption, and infrared spectroscopy. We find that for films grown at 20 K and normal incidence, the incident collision energy (up to 2 eV) has no effect on the phase of the deposited film or the subsequent crystallization kinetics. On the other hand, the incident beam energy does affect the porosity of the deposited films. At low beam energy (0.05 eV), the porosity of the vapor deposited film depends strongly on the incident growth angle. Films with structures from non-porous to highly porous can be grown by increasing the angle of incidence of the impinging molecules. The porosity of the ASW films decrease with increasing beam energy. The results of these experiments and their implications for the physical properties of ASW are presented and discussed. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.