Control of amorphous solid water morphology using molecular beams. II. Ballistic deposition simulations

Ballistic deposition simulations of thin film growth were performed. The re sults of the simulations are compared to experiments of N-2 adsorption by p orous amorphous solid water thin films. The simulations are in qualitative agreement with the experimental observations: The porosity of the thin film s is controlled by using a collimated beam to vapor deposit the films. Film s with normal or near normal growth angles (theta similar to0 degrees) are relatively dense and smooth. Films with larger growth angles are highly por ous and the average pore size increases as the growth angle increases. The simulations indicate that for growth angles greater than similar to 70 degr ees, adsorption into the largest pores is not possible leading to the exper imentally observed maximum in N-2 adsorption by porous amorphous solid wate r at theta = 70 degrees. (C) 2001 American Institute of Physics.