Probing the interaction of amorphous solid water on a hydrophobic surface: dewetting and crystallization kinetics of ASW on carbon tetrachloride

Abstract

Desorption of carbon tetrachloride from beneath an amorphous solid water (ASW) overlayer is explored utilizing a combination of temperature programmed desorption and infrared spectroscopy. Otherwise inaccessible information about the dewetting and crystallization of ASW is revealed by monitoring desorption of the CCl₄ underlayer. The desorption maximum of CCl₄ on graphene occurs at ∼140 K. When ASW wets the CCl₄ no desorption below 140 K is observed. However, the mobility of the water molecules increases with ASW deposition temperature, leading to a thermodynamically driven dewetting of water from the hydrophobic CCl₄ surface. This dewetting exposes some CCl₄ to the ambient environment, allowing unhindered desorption of CCl₄ below 140 K. When ASW completely covers the underlayer, desorption of CCl₄ is delayed until crystallization induced cracking of the ASW overlayer opens an escape path to the surface. The subsequent rapid episodic release of CCl₄ is termed a “molecular volcano”. Reflection absorption infrared spectroscopy (RAIRS) measurements indicate that the onset and duration of the molecular volcano is directly controlled by the ASW crystallization kinetics.