A Fully Size-Resolved Perspective on the Crystallization of Water Clusters

Pradzynski, Christoph C.; Forck, Richard M.; Zeuch, Thomas; Slavı́ček, Petr; Buck, U.

doi:10.1126/science.1225468

Cited by 181 publications

(281 citation statements)

References 41 publications

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“…For narrower pores, subcritical ice clusters may be produced at a high rate, but cannot grow to the critical size due to the confinement. This view is supported by experimental Pradzynski et al, 2012) and modeling studies (Moore et al, 2012;Li et al, 2011;Reinhardt and Doye, 2012), which estimate that critical ice clusters consist of 70 to 275 molecules in the temperature range from 195 to 231 K corresponding to r c = 1.2-1.8 nm if one assumes a spherical shape of the critical clusters. Also for larger pores and at higher temperatures, the radius of a critical cluster with spherical shape seems to determine the melting and freezing temperatures in pores.…”

Section: Marcolli: Deposition Nucleation 2075supporting

confidence: 56%

Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

2014

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Abstract. Heterogeneous ice nucleation is an important mechanism for the glaciation of mixed phase clouds and may also be relevant for cloud formation and dehydration at the cirrus cloud level. It is thought to proceed through different mechanisms, namely contact, condensation, immersion and deposition nucleation. Conceptually, deposition nucleation is the only pathway that does not involve liquid water, but occurs by direct water vapor deposition onto a surface. This study challenges this classical view by putting forward the hypothesis that what is called deposition nucleation is in fact pore condensation and freezing (PCF) occurring in voids and cavities that may form between aggregated primary particles and host water at relative humidity RH w < 100 % because of the inverse Kelvin effect. Homogeneous ice nucleation is expected to occur below 235 K when at least one pore is filled with water. Ice nucleation in pores may also happen in immersion mode but with a lower probability because it requires at least one active site in a water filled pore. Therefore a significant enhancement in ice nucleation efficiency is expected when temperature falls below 235 K. For a deposition nucleation process from water vapor no discontinuous change in ice nucleation efficiency should occur at T = 235 K because no liquid water is involved in this process. Studies on freezing in confinement carried out on mesoporous silica materials such as SBA-15, SBA-16, MCM-41, zeolites and KIT have shown that homogeneous ice nucleation occurs abruptly at T = 230-235 K in pores with diameters (D) of 3.5-4 nm or larger but only gradually at T = 210-230 K in pores with D = 2.5-3.5 nm. Pore analysis of clay minerals shows that kaolinites exhibit pore structures with pore diameters (D p ) of 20-50 nm. The mesoporosity of illites and montmorillonites is characterized by pores with D p = 2-5 nm. The number and size of pores is distinctly increased in acid treated montmorillonites like K10. Water adsorption isotherms of MCM-41 show that pores with D p = 3.5-4 nm fill with water at RH w = 56-60 % in accordance with an inverse Kelvin effect. Water in such pores should freeze homogeneously for T < 235 K even before relative humidity with respect to ice (RH i ) reaches ice saturation. Ice crystal growth by water vapor deposition from the gas phase is therefore expected to set in as soon as RH i > 100 %. Pores with D > 7.5 nm fill with water at RH i > 100 % for T < 235 K and are likely to freeze homogeneously as soon as they are filled with water. Given the pore structure of clay minerals, PCF should be highly efficient for T < 235 K and may occur at T > 235 K in particles that exhibit active sites for immersion freezing within pores. Most ice nucleation studies on clay minerals and mineral dusts indeed show a strong increase in ice nucleation efficiency when temperature is decreased below 235 K in accordance with PCF and are not explicable by the classical view of deposition nucleation. PCF is probably also the prevailing ice nucleation mechanism below...

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Section: Marcolli: Deposition Nucleation 2075supporting

confidence: 56%

Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

2014

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“…Electron diffraction experiments performed in the 1980's suggested that water clusters become crystalline in the size range 200-1000 molecules [12]. This result was confirmed by vibrational IR spectroscopy experiments on pure water and Na-doped clusters [10,13], which suggest an onset of crystallization at about 275 water molecules [13]. Computer simulations support the assumption of amorphous-tocrystalline transition occurring above 200 molecules [14].…”

Section: Introductionmentioning

confidence: 59%

Experimental nanocalorimetry of protonated and deprotonated water clusters

Boulon

Braud

Zamith

et al. 2014

The Journal of Chemical Physics

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An experimental nanocalorimetric study of mass selected protonated (H 2 O) n H + and deprotonated (H 2 O) n-1 OH -water clusters is reported in the size range n=20-118. Water cluster's heat capacity exhibit a change of slope at size dependent temperatures varying from 90 to 140 K, which is ascribed to phase or structural transition. For both anionic and cationic species, these transition temperatures strongly vary at small sizes, with higher amplitude for protonated than for deprotonated clusters, and change more smoothly above roughly n35. There is a correlation between bonding energies and transition temperatures, which is split in two components for protonated clusters while only one component is observed for deprotonated clusters. These features are tentatively interpreted in terms of structural properties of water clusters.

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“…The cluster sizes we probe here (see below) are smaller than the onset of crystallization in water clusters. 10 We therefore assume that solid state band structure effects, e.g., band dispersion, do not play a role in our sample. It seems nevertheless plausible that aggregation will have some influence on the β parameter.…”

Section: Introductionmentioning

confidence: 99%

The photoelectron angular distribution of water clusters

Zhang

Andersson

Förstel

et al. 2013

The Journal of Chemical Physics

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The angular distribution of photoelectrons emitted from water clusters has been measured by linearly polarized synchrotron radiation of 40 and 60 eV photon energy. Results are given for the three outermost valence orbitals. The emission patterns are found more isotropic than for isolated molecules. While a simple scattering model is able to explain most of the deviation from molecular behavior, some of our data also suggest an intrinsic change of the angular distribution parameter. The angular distribution function was mapped by rotating the axis of linear polarization of the synchrotron radiation. [http://dx

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A Fully Size-Resolved Perspective on the Crystallization of Water Clusters

Cited by 181 publications

References 41 publications

Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

Experimental nanocalorimetry of protonated and deprotonated water clusters

The photoelectron angular distribution of water clusters

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