Sulfuric acid-water nucleation

Kulmala, M., A. Laaksonen, and L. Pirjola, Parameterizations for Sulfuric Acid Water Nucleation Rates, J. Geophys. Res., 103, 8301-8307 (1998). 

Another application of quantum chemical methods is the investigation of the fundamental chemical behaviour of molecular systems potentially relevant to nu-cleation. Within the field of tropospheric nucleation mechanisms, two questions which have merited considerable study under the last decade are the modeling of the hydration of sulfuric acid, and the role of ammonia in sulfuric acid-water nucleation. 

Kulrnala M, Kerminen VM, Laaksonen A (1995) Simrrlatiorts on the effect of sulphuric acid formation on atmospheric aerosol concentrations. Atmos Environ 29 377-382 Kulmala M, Laaksonen A, Piijola L (1998a) Parameterizatiorts for sulfuric acid/water nucleation rates. 

The few observations of nucleation in the free troposphere are consistent with binary sulfuric acid-water nucleation. In the boundary layer a third nucleating component or a totally different nucleation mechanism is clearly needed. Gaydos et al. (2005) showed that ternary sulfuric acid-ammonia-water nucleation can explain the new particle formation events in the northeastern United States through the year. These authors were able to reproduce the presence or lack of nucleation in practically all the days both during summer and winter that they examined (Figure 11.16). Ion-induced nucleation is expected to make a small contribution to the major nucleation events in the boundary layer because it is probably limited by the availability of ions (Laakso et al. 2002). Homogeneous nucleation of iodine oxide is the most likely explanation for the rapid formation of particles in coastal areas (Hoffmann et al. 2001). It appears that different nucleation processes are responsible for new particle formation in different parts of the atmosphere. Sulfuric acid is a major component of the nucleation growth process in most cases. 

Noppel, M., Vehkamaki, H., and Kulmala, M. (2002) An improved model for hydrate formation in sulfuric acid-water nucleation, J. Chem. Phys. 116, 218-228. 

Sulfuric acid-water nucleation falls into the category where component B (H2SO4) is present at a very small concentration relative to that of A (H2O), yet the critical cluster is not dilute with respect to H2SO4. Thus the preexponential factor (10.94) applies. The rate... 

Kreidenweis, S. M., and J. H. Seinfeld, Nucleation of Sulfuric Acid-Water and Methanesulfonic Acid-Water Solution Particles Implications for the Atmospheric Chemistry of Organosulfur Species, Atmos. Environ., 22, 283-296 (1988a). 

Jaecker-Voirol, A., and P. Mirabel, Heteroniolecular Nucleation in the Sulfuric Acid-Water System," Atmos. Environ., 23, 2053-2057 (1989). 

Wyslouzil, B. E., J. H. Seinfeld, R. C. Flagan, and K. Okuyama, Binary Nucleation in Acid-Water Systems. II. Sulfuric Acid-Water and a Comparison with Methanesulfonic Acid-Water, J. Chem. Phys., 94, 6842-6850 (1991). 

Kusaka I, Wang ZG, Seirrfeld JH (1998a) Direct evalrration of the equilibrium distribution of physical clusters by a grand canonical Monte Carlo simrrlation. J Chem Phys 108 3416-3423 Kusaka I, Wang ZG, Seinfeld JH (1998b) Binary nucleation of sulfuric acid-water Monte Carlo simulation. J Chem Phys 108 6829-6848... 

Thermochemical data from either measurements or computations on organic compounds, including vapor pressures and solubility in organic and aqueous salt solutions. Data on cluster properties of organics and the sulfuric acid-water-ammonia system are necesary for understanding nucleation. 

Doyle, G. J. (1961). Self-nucleation in the sulfuric acid water system. J. Chem. Phys. 35,795-799. Drapcho, D. L., D. Sisterson, and R. Kumar (1983). Nitrogen fixation by lightning activity in a thunderstorm. Atmos. Environ. 17, 729-734. 

FIGURE 11.12 Composition of the critical H2S04-H20 nucleus, calculated for / = 1 cm-3 s, as a function of RH. The different curves correspond to the temperatures shown. (Reprinted from Atmos. Environ. 23, Jaecker-Voirol, A. and Mirabel, P., Heteromolecular nucleation in the sulfuric acid-water system, p. 2053, 1989, with kind permission from Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington OX5 1 GB, UK.)... 

Sulfuric acid-water binary nucleation (Kulmala and Laaksonen 1990)... 

Doyle, G. J. (1961) Self-nucleation in the sulfuric acid-water system, J. Chem. Phys. 35, 795-799. 

Wyslouzil, B. E., Seinfeld, J. H., Flagan, R. C., and Okuyama, K. (1991b) Binary nucleation in acid-water systems. II. Sulfuric acid-water and a comparison with methanesulfonic acid-water,... 

As mentioned in Section IX-2A, binary systems are more complicated since the composition of the nuclei differ from that of the bulk. In the case of sulfuric acid and water vapor mixtures only some 10 ° molecules of sulfuric acid are needed for water oplet nucleation that may occur at less than 100% relative humidity [38]. A rather different effect is that of passivation of water nuclei by long-chain alcohols [66] (which would inhibit condensation note Section IV-6). A recent theoretical treatment by Bar-Ziv and Safran [67] of the effect of surface active monolayers, such as alcohols, on surface nucleation of ice shows the link between the inhibition of subcooling (enhanced nucleation) and the strength of the interaction between the monolayer and water. 

The vapor pressure of H2S04 above solutions with water depends on the solution composition and the temperature. For example, the vapor pressure at 25°C varies from 2.6 X 10-9 Pa for a 54.1 wt% H2S04-H20 solution to 5.9 X 10 6 Pa for a 76.0 wt% solution (Marti et al., 1997). The vapor pressures above solutions partially neutralized with ammonia are also reported by Marti et al. (1997) as discussed in Chapter 9.B.1, the vapor pressures of the partially neutralized solutions are orders of magnitude smaller than those of the acid. As a result, ammonia may play an important role in nucleation of gaseous sulfuric acid in the atmosphere to form new particles. 

The term binary homogeneous nucleation is used to describe the formation of particles from two different gas-phase compounds such as sulfuric acid and water such nucleation can occur when their individual concentrations are significantly smaller than the saturation concentrations needed for nucleation of the pure compounds. It is believed that in the atmosphere, formation of particles from low-volatility gases occurs not by condensation of a single species but rather by the formation and growth of molecular clusters involving at least two, and as described shortly, probably three or more different species. 

As discussed in detail by Pandis et al. (1995), nucleation theory shows there is a critical sulfuric acid concentration above which binary nucleation of sulfuric acid and water should occur. Based on the work of Jaecker-Voirol and Mirabel (1989), they parameterize the theoretical dependence of this critical concentration needed to generate nuclei at a rate of 1 cm 3 s 1 on the relative humidity (RH, expressed in this case as a fraction, i.e., between 0 and 1) and temperature, T (in K) ... 

These sulfuric acid particles become less concentrated as the temperature decreases or the water vapour increases. Under very cold stratospheric conditions, these liquid aerosols may take up water and HNO, forming ternary solutions H,S0/HN0,/H,0, which eventually freeze [19,24,26], Below 192 K, HNO, becomes the dominant condensed acid, and H,S04 drops to below 3 wt %. The thermodynamics and freezing nucleation of ice and H,S04 or HNO, hydrates from such solutions are however not well understood [27,28]. Other types of solid particles, such as the less stable nitric acid dihydrate (NAD, HN0,.2H,0) [29], sulfriric acid tetrahydrate (SAT, H S04.4H,0) [18,30], sulphuric acid hemihexahydrate (SAH, H2S04.6.5H20) [18], nitric acid penta-hydrate (NAP, HN03.5H,0) [31] and more complex sulfuric acid/nitric acid mixed hydrates [32] may also be a key to understanding Type IPSC nucleation and evolution [28],... 

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