@article {35953,
	title = {The effects of aminium and ammonium cations on the ice nucleation activity of K-feldspar},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
	volume = {128},
	year = {2023},
	month = {DEC 2023},
	pages = {e2023JD039971},
	abstract = {<p>Mineral dust is one of the most abundant types of ice nucleating particles in the atmosphere. During atmospheric transport, mineral dust particles can become coated with inorganic and organic solutes, which can impact their ice nucleation activity. Aminium cations formed from amines are one type of organic solute that can coat mineral dust particles in the atmosphere, but their effects on the ice nucleation activity of mineral dust have not been studied. We investigated the effects of primary, secondary, and tertiary aminium cations with methyl and ethyl groups, as well as ammonium cations, on the ice nucleation activity of K-feldspar, an important type of mineral dust, in the immersion freezing mode at low cation concentrations (0.2\&ndash;20\&nbsp;mM) using a droplet-freezing apparatus. Ammonium cations substantially increased the ice nucleation activity of K-feldspar, consistent with previous studies. In contrast, primary aminium cations significantly reduced K-feldspar ice nucleation activity, and secondary and tertiary aminium cations had no significant effect (the effect was less than the uncertainty of our measurements). Our combined results are consistent with the following mechanisms: ammonium cations undergo ion exchange with K-feldspar, providing exposed N\&ndash;H groups for hydrogen bonding with ice; primary aminium cations undergo ion exchange with K-feldspar, exposing a hydrophobic tail that is not effective at nucleating ice; secondary and tertiary aminium cations do not undergo ion exchange with K-feldspar due to steric effects caused by the multiple hydrophobic groups on the cation.</p>},
	keywords = {aminium, ammonium, ice nucleation, Ion exchange, MINERAL DUST},
	doi = {10.1029/2023JD039971},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023JD039971},
	author = {Chen, L. and Worthy, S. E. and Gu, W. and Bertram, A. K. and Tang, M.}
}
@article {2405,
	title = {Effects of sulfuric acid and ammonium sulfate coatings on the ice nucleation properties of kaolinite particles},
	journal = {Geophysical Research Letters},
	volume = {36},
	year = {2009},
	note = {ISI Document Delivery No.: 401YZTimes Cited: 17Cited Reference Count: 28Eastwood, Michael L. Cremel, Sebastien Wheeler, Michael Murray, Benjamin J. Girard, Eric Bertram, Allan K.},
	month = {Jan},
	pages = {5},
	type = {Article},
	abstract = {The onset conditions for ice nucleation on H2SO4 coated, (NH4)(2)SO4 coated, and uncoated kaolinite particles at temperatures ranging from 233 to 246 K were studied. We define the onset conditions as the relative humidity and temperature at which the first ice nucleation event was observed. Uncoated particles were excellent ice nuclei; the onset relative humidity with respect to ice (RHi) was below 110\% at all temperatures studied, consistent with previous measurements. H2SO4 coatings, however, drastically altered the ice nucleating ability of kaolinite particles, increasing the RHi required for ice nucleation by approximately 30\%, similar to the recent measurements by Mohler et al. [2008b]. (NH4)(2)SO4 coated particles were poor ice nuclei at 245 K, but effective ice nuclei at 236 K. The differences between H2SO4 and (NH4)(2)SO4 coatings may be explained by the deliquescence and efflorescence properties of (NH4)(2)SO4. These results support the idea that emissions of SO2 and NH3 may influence the ice nucleating properties of mineral dust particles. Citation: Eastwood, M. L., S. Cremel, M. Wheeler, B. J. Murray, E. Girard, and A. K. Bertram (2009), Effects of sulfuric acid and ammonium sulfate coatings on the ice nucleation properties of kaolinite particles, Geophys. Res. Lett., 36, L02811, doi: 10.1029/2008GL035997.},
	keywords = {AEROSOLS, AQUEOUS-SOLUTIONS, crystallization, GOETHITE, MINERAL DUST, NUCLEI, TEMPERATURES},
	isbn = {0094-8276},
	url = {<Go to ISI>://000262981800002},
	author = {Eastwood, M. L. and Cremel, S. and Wheeler, M. and Murray, B. J. and Girard, E. and Bertram, A. K.}
}
@article {2397,
	title = {Simulation of Water Adsorption on Kaolinite under Atmospheric Conditions},
	journal = {Journal of Physical Chemistry A},
	volume = {113},
	number = {27},
	year = {2009},
	note = {ISI Document Delivery No.: 466WNTimes Cited: 5Cited Reference Count: 61Croteau, T. Bertram, A. K. Patey, G. N.},
	month = {Jul},
	pages = {7826-7833},
	type = {Article},
	abstract = {Grand canonical Monte Carlo calculations are employed to investigate water adsorption on kaolinite at 298 and 235 K. Both basal planes (the Al and Si surfaces) as well as two edge-like surfaces are considered. The general force field CLAYFF is used together with the SPCIE and TIP5P-E models for water. Problems that occur in single slab simulations due to arbitrary truncation of the point charge lattice are identified, and a working remedy is discussed. The edges and the Al surface adsorb water at subsaturation in the atmospherically relevant pressure range. The Si surface remains dry up to saturation. Both edges have a very strong affinity for water and adsorb continuously up to monolayer coverage. The Al surface has a weaker affinity for water but forms a subsaturation monolayer. On the Al surface, the monolayer is formed in an essentially sharp transition, and strong hysteresis is observed upon desorption. This indicates collective behavior among the water molecules which is not present for the edges. Binding energies of singly adsorbed water molecules at 10 K were determined to understand the differences in water uptake by the four kaolinite surfaces. Binding energies (SPC/E) of -21.6, -46.4, -73.5, and -94.1 kJ/mol, were determined for the Si surface, Al surface, unprotonated edge, and protonated edge, respectively. The water monolayer on the Al surface, particularly at 235 K, exhibits hexagonal patterns. However, the associated lattice parameters are not compatible with ice 1h. Water density and hydrogen bonding in the monolayers at both 298 and 235 K were also determined to better understand the structure of the adsorbed water.},
	keywords = {ADSORBED, CLAY-MINERALS, COMPUTER-SIMULATION, DYNAMICS, HYDROGEN-BOND, ICE FORMATION, INITIO MOLECULAR-DYNAMICS, LIQUID WATER, MINERAL DUST, MONTE-CARLO SIMULATIONS, NITRIC-ACID, WATER},
	isbn = {1089-5639},
	url = {<Go to ISI>://000267694800018},
	author = {Croteau, T. and Bertram, A. K. and Patey, G. N.}
}
@article {1516,
	title = {Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: Crystallization relative humidities and nucleation rates},
	journal = {Journal of Physical Chemistry A},
	volume = {110},
	number = {28},
	year = {2006},
	note = {ISI Document Delivery No.: 063EXTimes Cited: 12Cited Reference Count: 70Pant, Atul Parsons, Matthew T. Bertram, Allan K.},
	month = {Jul},
	pages = {8701-8709},
	type = {Article},
	abstract = {Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10\%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 ( the relative humidity at which 50\% of the droplets crystallize) ranges from about 41 to 51\% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 mu m. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 Am diameter) free of solid material is approximately 34.3\% RH under atmospheric conditions.},
	keywords = {AEROSOL-PARTICLES, ATMOSPHERIC AEROSOL, deliquescence, HETEROGENEOUS NUCLEATION, HYGROSCOPIC GROWTH, MINERAL DUST, ORGANIC-COMPOUNDS, PHASE-TRANSITIONS, TROPOSPHERIC AEROSOLS, WATER-UPTAKE},
	isbn = {1089-5639},
	url = {<Go to ISI>://000239001600013},
	author = {Pant, A. and Parsons, M. T. and Bertram, A. K.}
}
