Ternary homogeneous nucleation

Phase 3. High precursor supersaturation triggers homogeneous nucleation, either binary or ternary, possibly in regions of high humidity creates ultrafine particle abundances reaching 100,000 s/cm3 [31,32],... 

The extension of the CNT to homogeneous nucleation in atmospheric, essentially multicomponent, systems have faced significant problems due to difficulties in determining the activity coefficients, surface tension and density of binary and ternary solutions. The BHN and THN theories have been experiences a number of modifications and updates. At the present time, the updated quasi-steady state BHN model [16] and kinetic quasi-imary nucleation theory [24,66], and classical THN theory [25,33] and kinetic THN model constrained by the experimental data... 

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. 

A microemulsion is a thermodynamically stable, optically clear dispersion of two immiscible liquids such as water and oil, stabilized by the presence of a surfactant and, in some cases, a co-surfac-tant.i i7i,265-267 synthesis of nanoparticles by microemulsions has two main advantages. On the one hand, particle size can be controlled by adjusting the size of the micelle containing the metal precursors. Therefore, thermal treatments for particle size control can be avoided. On the other hand, since the micelles have the same composition, i.e. metal precursors are distributed homogeneously the nucleation of metallic particles renders particles of the same composition. This latter feature is very important for the synthesis of bimetallic (or ternary) catalysts. The main drawback of the microemulsion, or any other approach using surfactants, is surfactant removal. Severe thermal treatments are required in order to achieve complete removal of the surfactant which may result in particle aggregation and/or surface enrichment, or complete phase segregation of the components of the bimetallic samples. ... 

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