Vertical diffusion of water molecules near the surface of ice

Jung, Kwang-Hwan; Park, Seong-Chan; Kim, Junghwan; Kang, Heon

doi:10.1063/1.1770518

Cited by 45 publications

(47 citation statements)

References 33 publications

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“…At higher temperatures, diffusional mixing is easier to perform due to molecular motion and self-diffusion. The activation energy of diffusion measured at the surface was E a surface = 14 ± 2 kJ mol −1 , whereas in the bulk it was E a bulk = 71 ± 4 kJ mol −1 (110,111). Thus, diffusion at the surface is more significant than in bulk at 100-140 K. This finding indicates higher mobility on the surfaces and demonstrates that reaction preferentially occurs on ice surfaces, rather than in the bulk, at low temperatures.…”

Section: Molecular Diffusion/intermixingsupporting

confidence: 48%

“…At low temperatures, ice surfaces provide a reaction environment that is unique in comparison with that of the liquid state. Diffusional mixing of H 2 O and D 2 O has been investigated with LEIS (110). In this study, the authors deposited amorphous H 2 O onto a ruthenium substrate and performed fractional deposition of D 2 O onto the H 2 O surfaces in the temperature range between 100 and 140 K, followed by time-dependent reactive ion scattering.…”

Section: Molecular Diffusion/intermixingmentioning

confidence: 99%

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Probing Molecular Solids with Low-Energy Ions

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Bhuin

Natarajan

et al. 2013

Annual Rev. Anal. Chem.

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Ion/surface collisions in the ultralow-to low-energy (1-100-eV) window represent an excellent technique for investigation of the properties of condensed molecular solids at low temperatures. For example, this technique has revealed the unique physical and chemical processes that occur on the surface of ice, versus the liquid and vapor phases of water. Such instrumentdependent research, which is usually performed with spectroscopy and mass spectrometry, has led to new directions in studies of molecular materials. In this review, we discuss some interesting results and highlight recent developments in the area. We hope that access to the study of molecular solids with extreme surface specificity, as described here, will encourage investigators to explore new areas of research, some of which are outlined in this review.

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Section: Molecular Diffusion/intermixingsupporting

confidence: 48%

Section: Molecular Diffusion/intermixingmentioning

confidence: 99%

Probing Molecular Solids with Low-Energy Ions

Bag

Bhuin

Natarajan

et al. 2013

Annual Rev. Anal. Chem.

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“…For experimental studies of surface diffusivities at temperatures well below 200 K other techniques have been developed and were reviewed more recently . There is evidence that a translational surface mobility in the outer ice layers is preserved down to temperatures of 100 K (Verdaguer et al, 2006;Lee et al, 2007;Jung et al, 2004).…”

Section: Diffusion Of Water At the Ice Surfacementioning

confidence: 99%

A review of air–ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow

et al. 2014

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Abstract. Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air–ice interface, often termed quasi-liquid layer, and a liquid phase are highlighted. The reactivity in these different compartments of surface snow is discussed using many experimental studies, simulations, and selected snow models from the molecular to the macro-scale. Although new experimental techniques have extended our knowledge of the surface properties of ice and their impact on some single reactions and processes, others occurring on, at or within snow grains remain unquantified. The presence of liquid or liquid-like compartments either due to the formation of brine or disorder at surfaces of snow crystals below the freezing point may strongly modify reaction rates. Therefore, future experiments should include a detailed characterisation of the surface properties of the ice matrices. A further point that remains largely unresolved is the distribution of impurities between the different domains of the condensed phase inside the snowpack, i.e. in the bulk solid, in liquid at the surface or trapped in confined pockets within or between grains, or at the surface. While surface-sensitive laboratory techniques may in the future help to resolve this point for equilibrium conditions, additional uncertainty for the environmental snowpack may be caused by the highly dynamic nature of the snowpack due to the fast metamorphism occurring under certain environmental conditions. Due to these gaps in knowledge the first snow chemistry models have attempted to reproduce certain processes like the long-term incorporation of volatile compounds in snow and firn or the release of reactive species from the snowpack. Although so far none of the models offers a coupled approach of physical and chemical processes or a detailed representation of the different compartments, they have successfully been used to reproduce some field experiments. A fully coupled snow chemistry and physics model remains to be developed.

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“…At low temperature (−50 • C), by analogy with ceramic sintering, lattice diffusion from the surface of the grains and/or boundary diffusion from grain boundaries should be favoured (Ashby, 1974). The activation energy for surface diffusion is estimated to be in the range of 14-38 kJ mol −1 (Jung et al, 2004;Nie et al, 2009).…”

Section: Revised Temperature Sensitivity Of the Firn Densification Ratementioning

confidence: 99%

“…On the contrary, the slightly lower creep parameter at low temperature leads to a worse agreement between model and data for the Dome C deglaciation than when using the new model. Test C has been designed so that the activation energy at low temperature corresponds to estimates of activation energy for ice surface diffusion (Jung et al, 2004;Nie et al, 2009), a mechanism that is expected to be important at low temperature (Ashby, 1974). Using such a parameterization leads to a fair agreement between the modelled and the measured δ 15 N change over the last deglaciation for the different sites.…”

Section: Testmentioning

confidence: 99%

Modelling firn thickness evolution during the last deglaciation: constraints on sensitivity to temperature and impurities

et al. 2017

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Abstract. The transformation of snow into ice is a complex phenomenon that is difficult to model. Depending on surface temperature and accumulation rate, it may take several decades to millennia for air to be entrapped in ice. The air is thus always younger than the surrounding ice. The resulting gas-ice age difference is essential to documenting the phasing between CO 2 and temperature changes, especially during deglaciations. The air trapping depth can be inferred in the past using a firn densification model, or using δ 15 N of air measured in ice cores.All firn densification models applied to deglaciations show a large disagreement with δ 15 N measurements at several sites in East Antarctica, predicting larger firn thickness during the Last Glacial Maximum, whereas δ 15 N suggests a reduced firn thickness compared to the Holocene. Here we present modifications of the LGGE firn densification model, which significantly reduce the model-data mismatch for the gas trapping depth evolution over the last deglaciation at the coldest sites in East Antarctica (Vostok, Dome C), while preserving the good agreement between measured and modelled modern firn density profiles. In particular, we introduce a dependency of the creep factor on temperature and impurities in the firn densification rate calculation. The temperature influence intends to reflect the dominance of different mechanisms for firn compaction at different temperatures. We show that both the new temperature parameterization and the influence of impurities contribute to the increased agreement between modelled and measured δ 15 N evolution during the last deglaciation at sites with low temperature and low accumulation rate, such as Dome C or Vostok. We find that a very low sensitivity of the densification rate to temperature has to be used in the coldest conditions. The inclusion of impurity effects improves the agreement between modelled and measured δ 15 N at cold East Antarctic sites during the last deglaciation, but deteriorates the agreement between modelled and measured δ 15 N evolution at Greenland and Antarctic sites with high accumulation unless threshold effects are taken into account. We thus do not provide a definite solution to the firnification at very cold Antarctic sites but propose potential pathways for future studies.

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Vertical diffusion of water molecules near the surface of ice

Cited by 45 publications

References 33 publications

Probing Molecular Solids with Low-Energy Ions

Probing Molecular Solids with Low-Energy Ions

A review of air–ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow

Modelling firn thickness evolution during the last deglaciation: constraints on sensitivity to temperature and impurities

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