Direct observation of ice nucleation events on individual atmospheric particles

Abstract

The work presents microscopic observations of heterogeneous ice nucleation from experiments conducted inside an environmental scanning electron microscope. Observations of ice formation on kaolinite particles demonstrate that ice preferentially nucleates at the edges of the stacked platelets, rather than on the basal planes. This platform is applied for directly detecting and tracking ice nucleating particles in ambient aerosol samples and is complemented by micro-spectroscopic chemical imaging. This technique opens a path to new physical chemistry studies of ice formation in atmospheric science, cryobiology, and material science.www.rsc.org/pccp Heterogeneous ice nucleation is a physical chemistry process of critical relevance to a range of topics in the fundamental and applied sciences and technologies. Heterogeneous ice nucleation remains insufficiently understood, partially due to the lack of experimental methods capable of obtaining in situ microscopic details of ice formation over nucleating substrates or particles. We present microscopic observations of ice nucleation events on kaolinite particles at the nanoscale and demonstrate the capability of direct tracking and micro-spectroscopic characterization of individual ice nucleating particles (INPs) in an authentic atmospheric sample. This approach utilizes a custom-built ice nucleation cell, interfaced with an Environmental Scanning Electron Microscope (IN-ESEM platform) operated at temperatures and relative humidities relevant for heterogeneous ice nucleation. The IN-ESEM platform allows dynamic observations of individual ice formation events over particles in isobaric and isothermal experiments. Isothermal experiments on individual kaolinite particles demonstrate that ice crystals preferably nucleate at the edges of the stacked kaolinite platelets, rather than on their basal planes.These experimental observations of the location of ice nucleation provide direct information for further theoretical chemistry predictions of ice formation on kaolinite.

Observing the formation of ice and organic crystals in active sites

“…However, the correlation between lattice match and nucleation is in general not strong (29), and there is a wide scatter in the reported nucleating abilities of atmospheric aerosols (30). The mechanism of ice nucleation in capillary-condensed water that was proposed 50 y ago by Fukuta has only recently been revisited (31,32), but it has already been suggested that it contributes to the ice nucleation capacity of kaolinite (33,34) and leads to enhanced ice nucleation by porous aerosol particles (35,36). It is also noteworthy that alkali feldspars, which have been shown to be particularly efficient ice h is the predicted size of a liquid condensate at saturation with respect to a solid.…”

Cloud history can change water–ice–surface interactions of oxide mineral aerosols: a case study on silica

“…For example, the ice nucleation ability of an ice-nucleating particle may be influenced by the change in surface properties due to aging (Coluzza et al, 2017) or other secondary ice processes (Zipori et al, 2018). Solutes are able to affect freezing (Zobrist et al, 2008), even at low concentrations (Whale et al, 2018). Depending on the atmospheric conditions, water molecules may heterogeneously crystallize next to an icenucleating particle surface, forming various ice polymorphs with different physical and/or surface properties (Parambil et al, 2014).…”

Applications of ESEM on Materials Science: Recent Updates and a Look Forward

“…Apparently, the configuration of ESEM makes it feasible to design in situ experiments of phase transitions of water, in case of the rational controlling over the chamber temperature and pressure. For example, the icing process of water and the melting process of ice, which can provide the fundamentals for phase transitions of water, are frequently observed and examined by in situ ESEM experiments in terms of structural and morphological changes . Kiselev et al investigated the nucleation and growth of aligned ice crystals from water vapor on feldspar (an atmospherically important component of mineral dust) under ESEM to clarify the dominate reason in regulating the ice‐nucleation properties on specific substrates.…”

“…For example, the icing process of water and the melting process of ice, which can provide the fundamentals for phase transitions of water, are frequently observed and examined by in situ ESEM experiments in terms of structural and morphological changes. [9,[104][105][106] Kiselev et al investigated the nucleation and growth of aligned ice crystals from water vapor on feldspar (an atmospherically important component of mineral dust) under ESEM to clarify the dominate reason in regulating the ice-nucleation properties on specific substrates. The observation was conducted in an ESEM with a double-stage Peltier element, with its low temperature limit down to 213 K. The results gave a direct experimental evidence to indicate that the active sites for ice-nucleation on the surface of feldspar are the surface patches with (100) crystallographic orientation.…”