Phase transformations in sulfuric acid aerosols: Implications for stratospheric ozone depletion

Imre, Dan G.; Xu, Jiele; Tridico, Anthony C.

doi:10.1029/96gl03291

Cited by 30 publications

(24 citation statements)

References 35 publications

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“…A number of investigators have attempted to determine the freezing temperatures of H 2 SO 4 /H 2 O aerosols using flowing aerosol or single particle experiments [10][11][12]14,15,17,18 while others studied aerosols deposited on a surface. 13,16 However, results have been mixed.…”

Section: Comparison With Aerosol Experimentsmentioning

confidence: 99%

“…They detected formation of SAT by observing the sulfate peak at 1060 cm -1 ; however, SAO and SAH also have this peak in their respective spectra. Imre et al 15 and Clapp et al 14 reported evidence for SAO formation in laboratory aerosol particles based on vapor pressure measurements of a single particle and IR spectra measurements of flow tube aerosols, respectively. Anthony et al 10 could not rule out the crystallization of H 2 SO 4 hydrates in small amounts; however, they had no indication of homogeneous freezing or heterogeneous freezing on ice at temperatures down to 193 K. Prenni et al 18 did not have temperatures below the SAO or SAT melting points in this region, thus they only detected ice in coexistence with H 2 SO 4 liquid.…”

Section: Comparison With Aerosol Experimentsmentioning

confidence: 99%

“…Clapp et al 14 reported a similar IR spectrum for aerosols. Imre et al 15 generated aerosols that transformed into solids with a vapor pressure consistent with the octahydrate, but others have not seen evidence of freezing to the octahydrate in their aerosol experiments, though not all investigators analyzed for the presence of SAO. [10][11][12][13][16][17][18] In the experiments described here, we have reinvestigated the H 2 SO 4 /H 2 O solid/liquid phase diagram over the entire range of compositions, but we focused mainly on the region from ice to SAT.…”

Section: Introductionmentioning

confidence: 96%

“…[1][2][3][4][5][6][7][8][9] Nucleation in H 2 SO 4 /H 2 O aerosols has also been studied with respect to the formation of ice or other hydrates in laboratory studies. [10][11][12][13][14][15][16][17][18] When stratospheric and upper tropospheric sulfate aerosols cool, solids may nucleate in the droplets. This can have an impact on heterogeneous chemistry under various conditions in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

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The Search for Sulfuric Acid Octahydrate: Experimental Evidence

2003

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We have investigated the H 2 SO 4 /H 2 O binary liquid/solid phase diagram using a highly sensitive differential scanning calorimeter (DSC) and infrared spectroscopy of thin films. In particular we have sought to investigate the region from pure ice to sulfuric acid tetrahydrate (SAT), including a detailed look at the sulfuric acid octahydrate (SAO). Our studies have found that there is a unique, repeatable IR spectrum for SAO. Our spectrum is not merely a combination of spectra of ice and sulfuric acid tetrahydrate (SAT), as has been previously suggested could be the case by Zhang et al. (Zhang, R.; Wooldridge, P. J.; Abbatt, J. P. D.; Molina, M. J. J. Phys. Chem. 1993, 97, 7351). From our thermal analysis experiments, we have identified the melting transition of SAO. We report for the first time in the literature the enthalpy of fusion of SAO. We have also determined from our studies using the energies of fusion of ice and the various hydrates of H 2 SO 4 that SAO is a major component of H 2 SO 4 solutions in the range 20-40 wt % when they freeze. Our results indicate that SAO could be present in solid or partially frozen polar stratospheric and upper tropospheric cloud particles. Finally, we make a comment based on our results regarding the stoichiometric composition of SAO.

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Section: Comparison With Aerosol Experimentsmentioning

confidence: 99%

Section: Comparison With Aerosol Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Search for Sulfuric Acid Octahydrate: Experimental Evidence

2003

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“…Thus the current laboratory data on ice nucleation in supercooled water are not suited to adequately address how cirrus clouds may form in the upper troposphere. Currently, only a few laboratory groups have measured critical ice nucleation parameters in aqueous H2SO4 acid droplets [Bertram et al, 1996;Imre et al, 1997]. Here we use classical nucleation theory along with the laboratory data of Bertram et al [1996] to parameterize an algorithm for ice nucleation from an aqueous H2SO4 acid solution droplet.…”

Section: Introductionmentioning

confidence: 99%

A model description for cirrus cloud nucleation from homogeneous freezing of sulfate aerosols

Tabazadeh¹,

Jensen²,

Toon³

1997

J. Geophys. Res.

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Abstract. Classical nucleation theory for homogeneous freezing as well as recent laboratory data are used to formulate an algorithm for ice nucleation from an aqueous sulfuric acid solution droplet. A new pammeterized function is derived from re•nt thermodynamic data to express the variation of stflfiafc acid solution composition with temperature and relative humidity. This function is then used to derive critical ice nucleation parameters from recent laboratory data. The critical nucleation parameters are used in a classical nucleation theory to derive the diffusion activation energy of water molecules in a sulfuric acid solution from the measurements. The derived diffusion activation energy of water molecules in a sulfuric acid solution does not agree with the diffusion activation energy calculated from a viscous flow formulation that is commonly used in classical nucleation rate calculations. Our restfits show that ice nucleation in a stdfate droplet occurs when the interface energy of ice against the stdfate solution is approximately 17 dyn cm 4. We calculate that a supersaturation ratio of about 1.3 to 1.5 is required to nucleate ice from an aqueous stdfuric acid solution droplet in the temperature range of about 185 to 240 K. This supersaturation corresponds to a supercooling of a stdfate solution to about 2 to 3 K below the equilibrium condensation point of ice. Simple functions are given for estimating the nucleation point of ice in the upper troposphere. The differences between previous parameterizations and this work are discussect

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Quantum chemical study of atmospheric aggregates: HCl•HNO3•H2SO4

Verdes

Paniagua

2014

J Mol Model

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HCl, HNO3 and H2SO4 are implicated in atmospheric processes in areas such as polar stratospheric clouds in the stratosphere. Ternary complexes of HCl, HNO3 and H2SO4 were investigated by ab initio calculations at B3LYP level of theory with aug-cc-pVTZ and aug-cc-pVQZ basis sets, taking into account basis set superposition error (BSSE). The results were assessed in terms of structures (five hexagonal cyclic structures and two quasi-pentagonal cyclic structures), inter-monomeric parameters (all ternary complexes built three hydrogen bonds), energetics (seven minima obtained), infrared harmonic vibrational frequencies (red shifting of complexes from monomers), and relative stability of complexes, which were favorable when the temperature decreases under stratospheric conditions, from 298 K to 188 K, and in concrete, at 210 K, 195 K and 188 K.

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Phase transformations in sulfuric acid aerosols: Implications for stratospheric ozone depletion

Abstract: Upon fi'eezing, we observe H2SO4.SH20, not the generally invoked H2SO4.4H20. We suggest that the water-rich octahydrate phase is likely to be one of the high relative humidity forms which is efficient in chlorine activation.

Cited by 30 publications

References 35 publications

The Search for Sulfuric Acid Octahydrate: Experimental Evidence

The Search for Sulfuric Acid Octahydrate: Experimental Evidence

A model description for cirrus cloud nucleation from homogeneous freezing of sulfate aerosols

Quantum chemical study of atmospheric aggregates: HCl•HNO3•H2SO4

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