Lateral growth of xenon hydrate films on mica

Abstract

<abstract> <p>In this paper, we report an <italic>in situ</italic> optical microscopy study of lateral growth of xenon (Xe) hydrate thin films on mica at sub-zero temperatures. The interactions between a solid surface and water molecules can strongly affect the alignment of water molecules and induce ice-like ordered structures within the water layer at the water-surface interface. Mica was chosen as a model surface to study the surface effect of hydrophilic sheet silicates on the lateral growth of Xe hydrate films. Under the experimental conditions, the lateral growth of Xe hydrate films was measured to be at an average rapid rate of ~200 μm/s and 400 μm/s under two different pressures of Xe. Mass transfer estimation of the Xe-water system revealed that the increasing trend of lateral film growth rates followed the increase in the net mass flux and aqueous solubility of Xe. However, as the supercooling temperature increased, the trend of lateral film growth rates attained a plateau region where little change in the rate was observed. This unique feature in the lateral film growth trend, the fast lateral growth kinetics, and the short induction time for hydrate film growth hinted at the assistance of the mica surface to aid the lateral growth process of Xe hydrate films at low Xe mass flux and at a low degree of subcooling. A mechanism based on the reported structured water layer at the interface on mica was proposed to rationalize a postulated surface-promotional effect of mica on the nucleation and lateral growth kinetics of Xe hydrate films.</p> </abstract>