Ice Nucleation on a Corrugated Surface

Abstract

Heterogeneous ice nucleation is a key process in many environmental and technical fields and is of particular importance in modeling atmospheric behavior and the Earth’s climate. Despite an improved understanding of how water binds at solid surfaces, no clear picture has emerged to describe how 3D ice grows from the first water layer, nor what makes a particular surface efficient at nucleating bulk ice. This study reports how water at a corrugated, hydrophilic/hydrophobic surface restructures from a complex 2D network, optimized to match the solid surface, to grow into a continuous ice film. Unlike the water networks formed on plane surfaces, the corrugated Cu(511) surface stabilizes a buckled hexagonal wetting layer containing both hydrogen acceptor and donor sites. First layer water is able to relax into an “icelike” arrangement as further water is deposited, creating an array of donor and acceptor sites with the correct spacing and corrugation to stabilize second layer ice and allow continued commensurate multilayer ice growth. Comparison to previous studies of flat surfaces indicates nanoscale corrugation strongly favors ice nucleation, implying surface corrugation will be an important aspect of the surface morphology on other natural or engineered surfaces.

Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene

“…For example, on graphene, water has previously only been visualised when subsurface, due to its dynamic nature 61,62 . Compared with other techniques, He atom scattering has the advantage of being the most delicate surface-probing technique and is sensitive to H atoms in the top layer [63][64][65][66] . All measurements have therefore been performed using the Cambridge helium-3 spin-echo facility (HeSE) 27,67,68 .…”

Material properties particularly suited to be measured with helium scattering: selected examples from 2D materials, van der Waals heterostructures, glassy materials, catalytic substrates, topological insulators and superconducting radio frequency materials

“…Due to the large cross section of HAS to isolated adsorbates (including hydrogen as described in Section 3.5), the position and structure of hydrogen atoms and adsorbed water layers can be readily determined. [103][104][105] These include also the hydrogenation of a graphene surface 106 while H-positions are hard to determine with other methods (e.g., hydrogen is a weak scatterer for electrons) which also present a severe risk of damaging the H-layer. 107 In a study of highly proton-ordered water structures on oxygen pre-covered Ru(0001) it could be shown that the atomic oxygen and the oxygen from water form a (2 Â 2) surface reconstruction, which however, is broken by the hydrogen to give a (2 Â 4) surface reconstruction: while LEED measured a (2 Â 2), HAS measured a (2 Â 4) superstructure.…”

Nanoscopic diffusion of water on a topological insulator

“…However, to make these fast diffusive motions accessible to microscopy studies, the process typically needs to be considerably slowed down. At the same time an intrinsic problem of scanning probe microscopy is that the probes inevitably induce perturbation to the fragile water structure, due to the excitation of tunnelling electrons and the tip-water interaction forces 10,14 .…”