Amorphous solid water (ASW), a metastable phase of water occurring when water is deposited on a substrate cooled below 140K, is of fundamental interest for an array of applications including but not limited to desorption from interstellar ices and investigation of diffusion and solvation processes. When deposited over an immiscible substance, such as CCl4, the underlayer desorption is dictated by the morphology of the ASW overlayer. This desorption process culminates in the rapid release of the underlayer commensurate with the development of crystallization induced cracks through the ASW. This episodic release is termed the “molecular volcano”. Thus, the desorption event reports on changes in the structure of the ASW overlayer. Infrared spectroscopy combined with programmed desorption elucidates the complex interplay between the dewetting and crystallization processes which dominate the eruption event. The effects of the ASW deposition temperature and overlayer thickness on the CCl4 desorption process will be presented and discussed.

 

This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The research was performed using EMSL, a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory, which is operated by Battelle, operated for the U.S. DOE under Contract DE-AC05-76RL01830.