Diffusion von18O in Eis-Einkristallen

Delibaltas, P.; Dengel, O.; Helmreich, D.; Riehl, Ν.; Simon, Helmut

doi:10.1007/bf02422709

Cited by 21 publications

(29 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…is consistent with the rate of self-diffusion even in single crystal ice ͑D c =10 −6 m 2 /ms͒. [44][45][46][47][48][49][50] Although the H 2 O+D 2 O reaction is nearly complete on the time scale of a millisecond in experiments with ultrathin D 2 O layers, this is not the case with thicker deuterium oxide films. As shown in Fig.…”

Section: A Fast Thermal Desorption Spectra Of D 2 O and Hdosupporting

confidence: 58%

“…59 Extrapolating this result to the temperatures near ice melting point, we obtain a value of 10 −4 m 2 / ms for the estimate of the upper limit of water diffusivity in our nanocrystallites. The lower limit for the diffusion coefficient in microscopic crystallites at −2°C is given by the value of water selfdiffusion coefficient in defect-free bulk ice single crystals that is on the order of 10 −6 m 2 / ms. [45][46][47][48][49][50] In summary, we assume the following values for the properties of the microscopic grains in our polycrystalline ice samples:…”

Section: A Crystallite Dimensions and Transport Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Fast thermal desorption spectroscopy study of H∕D isotopic exchange reaction in polycrystalline ice near its melting point

McCartney

Sadtchenko

2007

The Journal of Chemical Physics

View full text Add to dashboard Cite

Using fast thermal desorption spectroscopy, a novel technique developed in our laboratory, we investigated the kinetics of HD isotopic exchange in 3 microm thick polycrystalline H2O ice films containing D2O layers at thicknesses ranging from 10 to 300 nm at a temperature of -2.0+/-1.5 degrees C. According to our results over the duration of a typical fast thermal desorption experiment (3-4 ms), the isotopic exchange is confined to a 50+/-10 nm wide reaction zone located at the boundary between polycrystalline H2O and D2O ice. Combining these data with a theoretical analysis of the diffusion in polycrystalline medium, we establish the range of possible values for water self-diffusion coefficients and the grain boundary widths characteristic of our ice samples. Our analysis shows that for the grain boundary width on the order of a few nanometers, the diffusivity of D2O along the grain boundaries must be at least two orders of magnitude lower than that in bulk water at the same temperature. Based on these results, we argue that, in the limit of low concentrations of impurities, polycrystalline ice does not undergo grain boundary premelting at temperatures up to -2 degrees C.

show abstract

Section: A Fast Thermal Desorption Spectra Of D 2 O and Hdosupporting

confidence: 58%

Section: A Crystallite Dimensions and Transport Propertiesmentioning

confidence: 99%

Fast thermal desorption spectroscopy study of H∕D isotopic exchange reaction in polycrystalline ice near its melting point

McCartney

Sadtchenko

2007

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…An interstitial mechanism for water self-diffusion is also strongly supported by the observation of moving dislocations (Goto et al, 1986). The water molecules' diffusion coefficients, summarised in Petrenko and Whitworth (1999), decrease from ≈ 2 to 0.22 × 10 −15 m 2 s −1 between 263 K and 233 K, in good agreement with tracer diffusion work (Blicks et al, 1966;Delibaltas et al, 1966;Ramseier, 1967) and direct observations by synchrotron X-ray tomography (Ramseier, 1967). Whether water molecules migrate in the bulk below 230 K preferentially via a vacancy mechanism as suggested by Livingston and George (2002) remains an open question; very little indeed is known about vacancies in hexagonal ice (Petrenko and Whitworth, 1999).…”

Section: Diffusion Of Water In the Ice Crystalsupporting

confidence: 56%

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

et al. 2014

View full text Add to dashboard Cite

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.

show abstract

“…With the presence of open pore space, water occurs as solid, liquid and vapor phases at subfreezing temperatures and transport will proceed in all three of its states but at different speeds. For example, diffusion coefficients of water molecules in ice crystals are of the order of 10 À14 -10 À17 m 2 s À1 for temperature range of À20 to À31°C (Dengel and Riehl, 1963;Itagaki, 1964;Delibaltas et al, 1966;Ramseier, 1967;Livingston et al, 1997) while the molecular diffusivity of water in liquid water at 31°C is on the order of 10 À10 m 2 s À1 (Gillen et al, 1972) and in vapor on the order of $10 À5 m 2 s À1 (Jean-Baptiste et al, 1998). Equilibration between mobile (vapor and liquid) and immobile (ice) phases will be determined by the slowest diffusion coefficient in ice.…”

Section: Characterization Of Transport Processesmentioning

confidence: 99%

Ground ice recharge via brine transport in frozen soils of Victoria Valley, Antarctica: Insights from modeling δ18O and δD profiles

Hagedorn

Sletten

Hallet

et al. 2010

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

Diffusion von18O in Eis-Einkristallen

Cited by 21 publications

References 9 publications

Fast thermal desorption spectroscopy study of H∕D isotopic exchange reaction in polycrystalline ice near its melting point

Fast thermal desorption spectroscopy study of H∕D isotopic exchange reaction in polycrystalline ice near its melting point

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

Ground ice recharge via brine transport in frozen soils of Victoria Valley, Antarctica: Insights from modeling δ18O and δD profiles

Contact Info

Product

Resources

About