the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Deposition freezing, pore condensation freezing and adsorption: three processes one description?
Maria Lbadaoui-Darvas
Athanasios Nenes
Abstract. Heterogeneous ice nucleation impacts the hydrological cycle and climate through affecting cloud microphyiscal state and radiative properties. Despite decades of research, a quantitative description and understanding of heterogeneous ice nucleation remains elusive. Parameterizations are either fully empirical or heavily rely on classical nucleation theory (CNT), which does not consider molecular level properties of the ice nucleating particles - which can alter ice nucleation rates by orders of magnitude through impacting pre-critical stages of ice nucleation. The Adsorption Nucleation Theory (ANT) of heterogeneous droplet nucleation has the potential to remedy this caveat and provide quantitative expressions in particular for heterogeneous freezing in the deposition mode (the existence of which has even been questioned recently). In this paper we use molecular simulations to understand the mechanism of deposition freezing and compare it with pore condensation freezing and adsorption. We put forward the plausibility of extending the ANT framework to ice nucleation (using black carbon as a case study) based on the following findings: i) The quasi-liquid layer at the free surface of the adsorbed droplet remains practically intact throughout the entire adsorption and freezing process, therefore the attachment of further water vapor to the growing ice particles occurs through a disordered phase, similar to liquid water adsorption. ii) The interaction energies that determine the input parameters of ANT (the parameters of the adsorption isotherm) are not strongly impacted by the phase state of the adsorbed phase. Thus, not only the extension of ANT to the treatment of ice nucleation is possible, but the input parameters are also potentially transferable across phase states of the nucleating phase.
Maria Lbadaoui-Darvas et al.
Status: final response (author comments only)
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RC1: 'Comment on egusphere-2023-644', Anonymous Referee #1, 05 May 2023
This is the review of the manuscript entitled “Deposition freezing, pore condensation freezing and adsorption: three processes one description?” by Mária Lbadaoui-Darvas, Ari Laaksonen, and Athanasios Nenes. This study aims to gain a deeper understanding of deposition ice nucleation by means of molecular simulations. Deposition ice nucleation is mechanistically compared to the recently suggested pore condensation freezing (PCF) and how it is related to adsorption. The results of this study support the application of the so-called adsorption nucleation theory (ANT) to describe deposition ice nucleation in place of classical nucleation theory (CNT), PCF, and other parameterizations. A black carbon substrate, with and without pores, serves as a surrogate of an ice nucleating substrate. The simulations show that a quasi-liquid layer remains on the water cluster on the surface, i.e., adsorption and ice nucleation occur in a disordered phase. Also, the input parameters for ANT that describe the interaction between water or ice and black carbon are very similar suggesting that an ANT description might hold for the water nucleation (adsorption) as well as for deposition ice nucleation.
Further fundamental understanding of ice nucleation is crucial, and this study nicely fills this gap. Hence, in terms of topic and theme it fits in the scope of the journal Atmospheric Chemistry and Physics. In general, I am in support of publishing this study. However, I have a couple of revision requests the authors should address.
I think it should be stressed that the terminology/definition of deposition ice nucleation is historically macroscopically defined (before the application of in situ microscopy and MD simulations). For many current experimental techniques, this still has validity. Though on a molecular level this may not be true. Following the conventional definition, it is “deposition ice nucleation” and not “deposition freezing”. Liquid (macroscopic) water freezes, but deposition ice nucleation does not involve (following convention) bulk liquid water. If the authors by purpose mix these two definitions and generate a novel terminology, since they observe deposition ice nucleation to originate from a liquid-like water cluster, then this has to be discussed. However, this seems not to be the case since this term is readily used. Also, I would not challenge the conventional definition based on one simulation study only. Hence, “deposition freezing” should be exchanged for deposition ice nucleation throughout the manuscript.
The other issue regarding terminology is to call the water clusters “droplets”, “dropletwise”, etc. I see that the authors struggle with this issue as well, trying also “nanodroplets” or “nanophase”. In this community droplets are usually defined to be 10s of micron in size. The “nanodroplets” forming inside the pore are about 2 nm or smaller. Typically, we call those entities clusters. It may not even be clear if this cluster size possesses bulk-liquid water properties (surface tension, etc.)? I am also not entirely sure how to name those condensed nanometer-sized islands of water but naming those “droplets” is unfortunate and ambiguous. Liquid-like or ice-like water clusters may be an idea. Maybe “nanodroplets” works to convey the idea but I feel this is not ideal either.
From the abstract and introduction, one would expect some analysis using ANT, i.e., deriving ice nucleation rates, etc. However, this study makes the case that ANT can be applied to deposition ice nucleation based on the simulation results. As written, this fact may not be so clear, and the overall confidence is only supported by this study looking at one idealized substrate. Maybe in some instances the text could convey a more exploratory study. I do not disagree with the authors; I suggest being a bit more conservative. Especially when reading the model methods. Many caveats are discussed (which I appreciate, and this does not minimize the impact of the study) but it feels a bit counter (i.e., weaker) to the introduction. This is maybe something the authors could consider.
Specific comments:
Line 22: The authors could cite here the recent review by (Knopf and Alpert, 2023).
Line 30: I doubt that (DeMott et al., 2010) discuss in detail nucleation theory and rates relevant for this paper and they do not discuss specifically deposition ice nucleation. Other literature would be needed in this place.
Line 37: “…adsorbed water can exist….”
Line 40: At this point it is not clear what you mean by “whereas other locations that collect pre-critical clusters might have an opposite effect.” Why do they have an opposing effect?
Line 47: Here it suddenly switches to immersion freezing. I recommend keeping the focus on deposition ice nucleation throughout the introduction. Also, I am not sure if I agree with this statement. When CNT is expressed in terms of water activity, intrinsic parameters like contact angle, interfaces, etc. are considered. See, e.g., the work by Knopf and Barahona groups. In fact (Knopf and Alpert, 2023) show that deposition ice nucleation may be well described using water activity as for the case of homogeneous ice nucleation and immersion freezing.
Line 55-57: Missing words, empty brackets?
Line 73-75: As mentioned above, considering water activity in CNT descriptions might account for these issues (Knopf and Alpert, 2023; Koop et al., 2000; Barahona, 2015, 2014; Knopf and Alpert, 2013).
Line 81: Period missing?
Line 81-86: A long sentence, maybe too long. Also, this statement is too general. Careful literature review will show that there are several studies (some employ nanoscale resolution) which do not corroborate PCF occurring in observed deposition ice nucleation experiments, e.g. (Wang et al., 2016). I would avoid “in reality” and write “…’freezing’ could be pore condensation…”.
Line 112: It is crucial to conduct atomistic and coarse-grained molecular simulations as discussed in (Knopf and Alpert, 2023) and shown in (Roudsari et al., 2022). They can yield different results while atomistic simulations are likely the preferred method, if feasible.
Line 127: What do you mean by energetic background? This is not a thermodynamic expression. Maybe just state the parameters you assess?
Line 146-147: Could you please elaborate here. The target vapor pressure corresponds to the adsorption layer structure”? At such high vapor pressure, one would have multiple layers of water? I assume, this is what you want?
Line 159: What do you mean by “deterministic dynamics”?
Line 168: Figure 1 instead 4?
Line 170-175: Long sentence with a lot of information. Again, a rather strong caveat. Maybe split up this information.
Line 194: sigma parameter has no units?
Line 242: What is “dropletwise phase”? Does this expression exist? See also general comment.
Line 247: You discuss Fig. 5 before Fig. 4?
Figure 3: Panel (b) is missing?
Line 277: Does this statement depend on pore size? Is it correct to generalize this?
Line 281: Maybe semicolon after “point I.” to make this easier to follow?
Line 287: “In neither case is complete pore filling required for freezing.” I think this is a very interesting and important finding of this study. It challenges the PCF mechanism. I am wondering why this is not mentioned in the abstract.
Figure caption 4: I am not sure what is the difference between freezing onset and initial stage. Onset is an “initial’ condition in a way. Not sure how to better (unambiguously) define this. Panel (b) is not described? And panel indicator “(b)” in caption text should be “(c)”?
Line 319-320: Several MD studies suggest that the critical nucleus forms in second water layer, e.g., (Cox et al., 2013). I assume the nucleus attaches after it forms?
Line 324-327: This sentence could be split in two to make understanding easier. From where comes the insight that layer-by-layer ice growth (is it growth or nucleation?) represents barrierless freezing? Please add references. Though if it is growth, then we talk about other energies than that needed for nucleation?
Line 327: What do you mean with “it shifted to the left”?
Line 360: What is meant by (kal)?
Line 361 -362: The A-values have no units?
Line 458: Clearly these 2 nm clusters are not supercooled droplets in the conventional application of terminology.
Line 479: empty citation?
Line 489: Was ITIM defined previously?
Line 493: (kal)?
Technical corrections:
Line 18: omit first “of”
Line 39: superfluous space
Line 55: “…implemented in regional…”
Line 102: solid-vapor phase? I suggest to use hyphens for expressing interfaces.
Line 117: Omit “even”.
Line 195: superfluous space
Line 205: space missing
Figure caption 2: Shaded areas not visible in my pdf file.
Line 231: double citation.
Line 282: superfluous space
Line 318: “dropletwise”?
Line 325: reach
Line 393: space needed before “for”
Line 442: adsorption
Line 444: …superior compared to that on…
Line 470: proven
Line 480: superfluous space
Line 480: molecules, respectively,
References
Barahona, D.: Analysis of the effect of water activity on ice formation using a new thermodynamic framework, Atmos. Chem. Phys., 14, 7665-7680, 10.5194/acp-14-7665-2014, 2014.
Barahona, D.: Thermodynamic derivation of the activation energy for ice nucleation, Atmos. Chem. Phys., 15, 13819-13831, 10.5194/acp-15-13819-2015, 2015.
Cox, S. J., Raza, Z., Kathmann, S. M., Slater, B., and Michaelides, A.: The microscopic features of heterogeneous ice nucleation may affect the macroscopic morphology of atmospheric ice crystals, Faraday Discuss., 167, 389-403, 10.1039/c3fd00059a, 2013.
DeMott, P. J., Prenni, A. J., Liu, X., Kreidenweis, S. M., Petters, M. D., Twohy, C. H., Richardson, M. S., Eidhammer, T., and Rogers, D. C.: Predicting global atmospheric ice nuclei distributions and their impacts on climate, Proc. Natl. Acad. Sci. U. S. A., 107, 11217-11222, 10.1073/pnas.0910818107, 2010.
Knopf, D. A. and Alpert, P. A.: A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets, Faraday Discuss., 165, 513-534, 10.1039/C3FD00035D, 2013.
Knopf, D. A. and Alpert, P. A.: Atmospheric ice nucleation, Nat. Rev. Phys., 10.1038/s42254-023-00570-7, 2023.
Koop, T., Luo, B. P., Tsias, A., and Peter, T.: Water activity as the determinant for homogeneous ice nucleation in aqueous solutions, Nature, 406, 611-614, 10.1038/35020537 2000.
Roudsari, G., Pakarinen, O. H., Reischl, B., and Vehkamaki, H.: Atomistic and coarse-grained simulations reveal increased ice nucleation activity on silver iodide surfaces in slit and wedge geometries, Atmos. Chem. Phys., 22, 10099-10114, 10.5194/acp-22-10099-2022, 2022.
Wang, B., Knopf, D. A., China, S., Arey, B. W., Harder, T. H., Gilles, M. K., and Laskin, A.: Direct observation of ice nucleation events on individual atmospheric particles, Phys. Chem. Chem. Phys., 18, 29721-29731, 10.1039/C6CP05253C, 2016.
Citation: https://doi.org/10.5194/egusphere-2023-644-RC1 -
RC2: 'Comment on egusphere-2023-644', Anonymous Referee #2, 18 May 2023
Review of “Deposition freezing, pore condensation freezing and adsorption: three processes one description?” by M. Lbadaoui-Darvas, A. Laaksonen, and A. Nenes, submitted to Atmos. Chem. Phys.
General comments and assessment:
The authors present atomistic and coarse-grained molecular dynamics and grand canonical monte carlo simulations of deposition freezing on graphitic surfaces that are either flat or contain a pore. The main result is that water molecules from the gas phase first form supercooled liquid-like “droplets” when adsorbing to the surface, before a critical ice nucleus forms heterogeneously. Based on these observations, the authors conclude that deposition freezing could be described by the adsorption nucleation theory (ANT).
The study is scientifically relevant and of high quality; it represents an important contribution to understanding atmospheric ice nucleation on the atomistic level. The manuscript is overall well written and the results are mostly presented in a clear way. However, there are quite many technical issues in the text and the figures, listed below, that the authors need to address. I therefore recommend the Editors accept the manuscript after the necessary revisions.
Specific comments:
The atomistic simulations of the graphite/water interface, used to determine the FHH parameters employ the TIP5P water potential. While TIP5P overall predicts structural and thermodynamic properties of water and ice quite well, it does underestimate the density difference between water and ice Ih [see e.g. Vega et al., J. Phys.: Cond. Matter 7, S3283–S3288 (2005)]. Do you believe that using a water model yielding more realistic differences in density between liquid and ice phases, in conjunction with the fixed definition of the layer thickness, could lead to systematic differences in the average interaction energies obtained, in addition to possible differences in interaction energies resulting from the different water model?
I would encourage the authors to review their variable names and formulae. Throughout the manuscript, sub- or superscripts in variables that do not denote indices are set in italics (e.g. A_{FHH}, k_B, \sigma_{OC}, V_{filled}, N_{ice}, etc.). These sub- and superscripts should be changed to roman font. In addition, several variable names appear unnecessarily long or convoluted to me (e.g., in eq. 2, the number of carbon atoms “NC” could be “N_\mathrm{C}” and the number of water molecules in i-th adsorbed layer, “NW_{Li}” could simply be “N_i“, so that the mean interaction energy per unit area in the i-th adsorbed layer could simply be denoted “E_i”.
Technical corrections:
l.14: not only the extension … is possible -> not only is the extension … possible
l. 39: clusters , -> clusters,
l.55: implemented regional -> implemented into regional
l.57: two broken references
l.69: …with direct links to the molecular-scale interactions…
l.139: …a graphite slab with a hemispherical or cylindrical pore consisting…
l.164: numercially->numerically
l.171: remove comma after carbon
l.176: remove spurious “because”
l.178: any estimating -> estimating any
l.194: units missing for \sigma_OC^LJ (I assume nm)
l.206: space missing before reference.
Figure 2 caption: describe arrows and label water and graphite in panel (a). Shaded areas mentioned in the caption not visible in panel (b).
l.230: increase of adsorbed water molecules
l.231: re-format reference
Figure 3: “b)” is missing in the figure. A period is missing at the end of the first sentence in the caption. Carbon atoms are not mentioned in the caption.
l.299: steepness -> slope?
Figure 4: “teal” and “blue” curves are very hard to distinguish; please change one of the two colors! “gray” curve appears black to me, especially as the graph has a gray background. Period at the end of the first sentence of the caption is missing. “adsobing” -> adsorbing. “out-of-pore nucleation” -> ice growing out of the pore?
Figure 5: panels (a) and (b) in the actual figure are not references in the caption. Instead, the caption references a “top” and “bottom” panel, which are both part of panel (a) in the actual figure. The content of panel (b) is not explained at all in the figure caption, but it is referenced in the main text…
l.327: shifted towards the left -> shifted to smaller time values?
l.345 remove “makes”
l.355 “and a A_{FHH}” -> and A_{FHH}
l.360 broken reference
l.381: missing math environment 3k_{B}T/2
l.385/Fig 6: in the text, E_i has the unit of energy (kJ/mol), in the figure the unit of energy/area (kJ/mol/nm^2). Please fix this.
l.386: missing math environment k_{B}T
Figure 6: caption: add explanation that “LnS” denotes the interation between the surface and the n-th adsorbed layer in the graphs. add information that the means and standard deviations(?) (in parantheses) of the distributions are also shown as insets on the graphs of the distributions. Check whether the unit of energy/surface area is the correct one for E_i (see l.385 in the main text)
l.393: missing space after 30º
l.399: ice made up TIP5P water molecules -> the ice phases of the TIP5P water model?
l.401: box plots obtained from the time series… -> box plots of the distribution…
Figure 7: caption: box plots of the time series… -> box plots of the distribution…
l.425: “the potential that deposition freezing can be described” -> “that deposition freezing can/could be described”Citation: https://doi.org/10.5194/egusphere-2023-644-RC2 -
CC1: 'Comment on Lbadaoui-Darvas et al.', Claudia Marcolli, 23 May 2023
We appreciate the authors' efforts putting this manuscript together, which proposes Adsorption Nucleation Theory (ANT) as a unifying theory of pore condensation and freezing (PCF), adsorption, and deposition nucleation. However, we want to point out that in certain portions of the manuscript, PCF is misrepresented.
On lines 76–86, PCF is correctly summarized as involving pore filling followed by immersion or homogeneous freezing of the pore water and ice growth out of the pores. But on the next lines (86–91), it insinuates that the foundation of this framework is based on molecular simulations in David et al. (2019), which is not the case. Instead, PCF describes pore filling with the Kelvin equation, ice nucleation with classical nucleation theory (CNT) parameterizations based on experimentally determined homogeneous ice nucleation rates, and ice growth again based on the Kelvin equation (Marcolli, 2014; 2020; David et al., 2019; 2020; Marcolli et al., 2021). In David et al. (2019), molecular simulations are used to show that (i) ice does not nucleate on the substrate, which was tailored to mimic the silica surface, (ii) ice also does not grow out of a single ice-filled pore with a diameter of 3 nm, but (iii) that ice is growing out of closely-spaced 3 nm pores.
As in PCF ice nucleation occurs in pores, it is very different from deposition nucleation and ANT, which both rely on an ice-nucleating surface as the location of ice nucleation. Therefore, the claim to unify PCF and deposition nucleation under a theory based on ANT cannot be kept unless PCF is strongly distorted. For PCF in its right description, the question posed in the title has therefore to be answered with “no”. We think a title change is appropriate to reflect this.
Moreover, it is incorrect that in David et al. (2019) droplet emulsion experiments were used to show that ice nucleation rates are high enough to occur in the small volumes of pore water (as stated on line 85). Instead, we use slurry experiments (and not emulsion freezing experiments) in David et al. (2020) to show that the pores in the mesoporous silica particles are wide enough to hold ice. Marcolli (2020) discusses in more detail the role of homogeneous nucleation rates. There, it is also shown that the water volume just needs to be large enough to hold the critical ice embryo for water to freeze when temperatures fall below about 230 K.
On lines 420–422, the authors write that PCF involves pore filling as a prerequisite for ice nucleation. This statement might be a misinterpretation of David et al. (2019), where ice nucleation in the cylindrical pores of mesoporous silica particles is investigated. The filling of cylindrical pores is occurring almost instantaneously when RH is above a threshold value. Therefore, these pores are either completely filled or empty. Yet, pores with other shapes like conical pores and wedges fill gradually as discussed in Marcolli (2020). For such pores, ice nucleation occurs when the water volume is large enough to hold a critical ice embryo. Moreover, it occurs irrespective of whether the surface is ice nucleating when temperatures are below about 230 K.
PCF was introduced to explain measured ice nucleation data as e.g. in Marcolli (2014) and in Marcolli et al. (2021). In the latter, the requirements for ice nucleation on soot particles were established taking the primary particle size, overlap, soot contact angle, and soot aggregate size into account. This soot PCF framework can explain why some types of soot nucleate ice while others do not. Specifically, it predicts that soot particles with a contact angle of 90° do not nucleate ice below water saturation because, according to the Kelvin equation, there is no capillary condensation in pores for contact angles of 90° or higher. Conversely, the graphitic surface in the present study shows an unrealistically high water adsorption of several monolayers for RHw < 100 % despite its contact angle of 90°. A reason for this strong water adsorption might be that the simulation was carried out at a supersaturation of 300 % RHi or Si = 300 % (lines 145–146). A high saturation ratio of 250 % RHi was also used for the simulation with mW water shown in Fig. 3 of David et al. (2019) to speed up the simulation. Nevertheless, the simulation in David et al. does not indicate significant water adsorption on the flat silica surface although its contact angle of 64° is clearly below the one of the graphitic surface and the simulation time was much longer (300 ns compared to 10 ns in the present study). Moreover, experiments with the non-porous particles do not show any deposition nucleation (David et al., 2019). The question therefore arises why the water adsorption is so high in the simulations with a graphite slab (non-porous) and monatomic water despite the high contact angle of 90°.
Another point that sheds doubt on the meaning and relevance of the simulation results shown in Lbadaoui-Darvas et al. is that the graphitic surface proved to be an efficient ice-nucleating agent in immersion mode in molecular simulations with mW water (Lupi and Molinero, 2014; Lupi et al., 2014). Yet, experiments have shown that soot is a poor INP in immersion mode or even ice nucleation inactive (Hoose and Möhler, 2012; Kanji et al. 2020). We wonder why the authors chose a graphitic surface for their study, although the mW water model is known to overpredict the ice nucleation activity of the graphitic surface in immersion mode (Qiu et al., 2018). The high water adsorption together with the false prediction of IN activity may explain the ability of the mW water to nucleate ice on a flat graphitic surface. Yet, these simulations do not represent real physical processes occurring in or on soot particles.
Zamin A. Kanji, Robert O. David, Claudia Marcolli
References:
David, R. O., Marcolli, C., Fahrni, J., Qiu, Y. Q., Sirkin, Y. A. P., Molinero, V., Mahrt, F., Bruhwiler, D., Lohmann, U., and Kanji, Z. A.: Pore condensation and freezing is responsible for ice formation below water saturation for porous particles, P. Natl. Acad. Sci. USA, 116, 8184–8189, https://doi.org/10.1073/pnas.1813647116, 2019.
David, R. O., Fahrni, J., Marcolli, C., Mahrt, F., Brühwiler, D., and Kanji, Z. A.: The role of contact angle and pore width on pore condensation and freezing, Atmos. Chem. Phys., 20, 9419–9440, https://doi.org/10.5194/acp-20-9419-2020, 2020.
Hoose, C. and Möhler, O.: Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments, Atmos. Chem. Phys., 12, 9817–9854, https://doi.org/10.5194/acp-12-9817-2012, 2012.
Kanji, Z. A., Welti, A., Corbin, J. C., and Mensah, A. A.: Black carbon particles do not matter for immersion mode ice nucleation, Geophys. Res. Lett., 47, e2019GL086764, https://doi.org/10.1029/2019GL086764, 2020.
Lupi, L. and Molinero, V.: Does hydrophilicity of carbon particles improve their ice nucleation ability? J. Phys. Chem. A, 118, 7330–7337, https://doi.org/ 10.1021/jp4118375, 2014.
Lupi, L., Hudait, A., and Molinero, V.: Heterogeneous nucleation of ice on carbon surfaces, J. Am. Chem. Soc.,136, 3156–3164, https://doi.org/10.1021/ja411507a, 2014.
Mahrt, F., Marcolli, C., David, R. O., Grönquist, P., Barthazy Meier, E. J., Lohmann, U., and Kanji, Z. A.: Ice nucleation abilities of soot particles determined with the Horizontal Ice Nucleation Chamber, Atmos. Chem. Phys., 18, 13363–13392, https://doi.org/10.5194/acp-18-13363-2018, 2018.
Marcolli, C.: Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities, Atmos. Chem. Phys., 14, 2071–2104, https://doi.org/10.5194/acp-14-2071-2014, 2014.
Marcolli, C.: Technical note: Fundamental aspects of ice nucleation via pore condensation and freezing including Laplace pressure and growth into macroscopic ice, Atmos. Chem. Phys., 20, 3209– 3230, https://doi.org/10.5194/acp-20-3209-2020, 2020.
Marcolli, C., Mahrt, F., and Kärcher, B.: Soot PCF: pore condensation and freezing framework for soot aggregates, Atmos. Chem. Phys., 21, 7791–7843, https://doi.org/10.5194/acp-21- 7791-2021, 2021.
Qiu, Y., Lupi, L., and Molinero, V.: Is water at the graphite interface vapor-like or ice-like?, J. Phys. Chem. B, 122, 3626–3634, https://doi.org/10.1021/acs.jpcb.7b11476, 2018.
Citation: https://doi.org/10.5194/egusphere-2023-644-CC1
Maria Lbadaoui-Darvas et al.
Maria Lbadaoui-Darvas et al.
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