The ice–vapour interface during growth and sublimation

Abstract

Abstract. We employed environmental scanning electron microscopy (ESEM) in low-humidity atmosphere to study the ice growth, coalescence of crystallites, polycrystalline film morphology, and sublimation, in the temperature range of −10 to −20 ∘C. First, individual ice crystals grow in the shape of micron-sized hexagonal columns with stable basal faces. Their coalescence during further growth results in substantial surface defects and forms thick polycrystalline films, consisting of large grains separated by grain boundaries. The latter are composed of 1 to 3 µm wide pores, which are attributed to the coalescence of defective crystallite surfaces. Sublimation of isolated crystals and of films is defect-driven, and grain boundaries play a decisive role. A scallop-like concave structure forms, limited by sharp ridges, which are terminated by nanoscale asperities. The motivation for this work is also to evaluate ESEM's ability to provide a clean and reproducible environment for future study of nucleation and growth on atmospherically relevant nucleators such as materials of biological origin and inorganic materials. Hence, extensive information regarding potential ESEM beam damage and effect of impurities are discussed.

Microanalysis Techniques to Study Atmospheric Ice Nucleation and Ice Crystal Growth

“…Pedersen et al [2011] observed that when ice crystals grow in contact, they form an ice grain boundary that induces a surface transition on the facets in contact and does not propagate across the facet edges. A similar study by Cascajo-Castresana et al [2021] observed the same phenomenon as shown in Fig. 19.…”

“…Grain boundaries represent the interface between individual ice crystals. These grain boundaries change when ice crystals grow, melt, or sublimate [Cascajo-Castresana et al, 2021;Pedersen et al, 2011;Pfalzgraff et al, 2010]. These processes, in turn, influence ice crystal shape, its interaction with adsorbing and reactive gas species (e.g., heterogeneous reactions), and distribution of species expelled during ice growth [Bogdan, 2018;Bogdan and Molina, 2017;Zobrist et al, 2008].…”

“…ESEM has allowed the detailed study of ice crystal shapes under growth and sublimation conditions and when ice crystals contact each other [Cascajo-Castresana et al, 2021;Chen et al, 2017;Magee et al, 2021;Magee et al, 2014;Nair et al, 2018;Pach and Verdaguer, 2022;Pedersen et al, 2011;Pfalzgraff et al, 2010].…”

Studying Ice with Environmental Scanning Electron Microscopy

“…Very recently, the complete process of ice growth and sublimation on surfaces was followed by in situ ESEM, from the initial ice growth through the coalescence of the crystals and formation of polycrystalline film to the sublimation of ice on an oxidized Si wafer [ 90 ]. The final surface of ice, after the merging of individual crystallites into a polycrystalline film, was dominated by grain boundaries and defects (pores), which were pointed out as areas where the sublimation of ice originates.…”

Kinetics formulation for Two-Dimensional Growth Behavior of Water/Ice Interface on Si Substrate

“…Regarding the Si substrate, previous studies have primarily focused on the effects of the surface conditions on water droplet nucleation time − and the influence of the pattern of the substrate form on the coagulation or freezing time of water droplets. , Cascajo-Castresana et al observed ice crystal growth on Si substrates via environmental scanning electron microscopy; however, this ice formation was owing to the condensation of water vapor onto the substrate and not the freezing behavior of the water film. These studies, although insightful, have left a gap in our understanding of the behavior of liquid films that span the entire substrate surface.…”