Surfactant Effects and an Order-Disorder Transition in Binary Gas-Liquid Nucleation

Napari, Ismo; Laaksonen, A.

doi:10.1103/physrevlett.84.2184

Cited by 16 publications

(9 citation statements)

References 16 publications

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“…34 In particular, the energy parameters for the partially miscible system are ⑀ϭ⑀ 00 ϭ1.0, ⑀ 11 /⑀ 00 ϭ⑀ 22 /⑀ 00 ϭ0.6, k 01 ϭϪ0.7, k 02 ϭ0.8, and k 12 ϭ0.0 ͑hereafter this system is called the NL system͒. For the reference ''ideal'' binary mixture system, 12,29 we set the energy parameters for unlike atoms to be ⑀ 01 ϭ(⑀ 00 ϩ⑀ 11 )/2 and ⑀ 02 ϭ(⑀ 00 ϩ⑀ 22 )/2.…”

Section: Resultsmentioning

confidence: 99%

“…In their theoretical work, however, Napari and Laaksonen found that the mutual enhancement of nucleation occurred only in monomer-rich vapors. 34 They attributed the mutual enhancement of nucleation to the reduction of the surface tension of the critical cluster. This reduction stems from the appearance of orientational surface order for the dimers at the surface of clusters.…”

Section: Resultsmentioning

confidence: 99%

“…Clearly, simple fluid models cannot account for the apparent mutual enhancement of nucleation behavior in water/alcohol systems. Recently Napari and Laaksonen 34 de-vised a model system to mimic binary nucleation in water/ alcohol systems. This model system consists of monomers ͑as water͒ and dimer molecules ͑as higher alcohols͒.…”

Section: Introductionmentioning

confidence: 99%

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Monte Carlo simulation of homogeneous binary vapor–liquid nucleation: Mutual enhancement of nucleation in a partially miscible system

Yoo

Zeng

2001

The Journal of Chemical Physics

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A small-system ensemble Monte Carlo simulation of supersaturated vapor: Evaluation of barrier to nucleation A molecular theory of the homogeneous nucleation rate. II. Application to argon vapor By means of a constrained canonical-ensemble Monte Carlo technique the equilibrium physical cluster distribution ͕n i j ͖ in a supersaturated vapor mixture is computed. From this the intensive Gibbs free energy of ij-cluster formation ⌬G i j is obtained via the relation n i j ϭNe Ϫ⌬G i j /k B T , where N is the number of molecules in the system, T is temperature, and k B is the Boltzmann constant. The saddle point on the free energy surface ⌬G i j versus i and j provides a measure of the activation barrier to nucleation ⌬G*. A statistical mechanical formula of ⌬G i j is derived based on the physical-cluster theory of nucleation, and from which a molecular interpretation of ⌬G i j is given. We applied the Monte Carlo method to investigate the mutual enhancement of nucleation in a binary model system which is composed of spherical Lennard-Jones monomers and rigid Lennard-Jones dimers consisting of a monophilic atom and a monophobic atom. This model system bears some qualitative similarity to the partially miscible water/higher alcohol systems in which the mutual enhancement of nucleation has been observed experimentally. The simulation confirms the existence of mutual enhancement of nucleation in monomer-rich vapors, as originally predicted by Napari and Laaksonen from a density-functional theory ͓Napari and Laaksonen, Phys. Rev. Lett. 84, 2184 ͑2000͔͒. The nucleation enhancement is also seen in dimer-rich vapors at high supersaturations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Monte Carlo simulation of homogeneous binary vapor–liquid nucleation: Mutual enhancement of nucleation in a partially miscible system

Yoo

Zeng

2001

The Journal of Chemical Physics

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“…The latter has been a focus of intensive research at the University of Helsinki where continuous observations of nucleation events (Mäkelä et al, 1997(Mäkelä et al, , 2000 and theoretical work addressing new particle formation (e.g. Laaksonen and Oxtoby, 1995;Korhonen et al, 1999;Napari and Laaksonen, 2000;Vehkamäki and Ford, 2000) have been linked with the help of multicomponent microphysical models AEROFOR2 (Pirjola and Kulmala, 2000a) and MONO32 (Pirjola and Kulmala, 2000b;Pirjola et al, 2003), applying sectional and multimodal monodisperse particle descriptions, respectively. While these models have succeeded in reproducing the qualitative features of observed phenomena, recent improvements in understanding the inital steps of particle formation and growth as well as advancements in the numerical description of particle size distribution necessitate updating of modelling tools.…”

Section: Introductionmentioning

confidence: 99%

Multicomponent aerosol dynamics model UHMA: model development and validation

2004

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Abstract. A size-segregated aerosol dynamics model UHMA (University of Helsinki Multicomponent Aerosol model) was developed for studies of multicomponent tropospheric aerosol particles. The model includes major aerosol microphysical processes in the atmosphere with a focus on new particle formation and growth; thus it incorporates particle coagulation and multicomponent condensation, applying a revised treatment of condensation flux onto free molecular regime particles and the activation of nanosized clusters by organic vapours (Nano-Köhler theory), as well as recent parameterizations for binary H2SO4-H2O and ternary H2SO4-NH3-H2O homogeneous nucleation and dry deposition. The representation of particle size distribution can be chosen from three sectional methods: the hybrid method, the moving center method, and the retracking method in which moving sections are retracked to a fixed grid after a certain time interval. All these methods can treat particle emissions and atmospheric transport consistently, and are therefore suitable for use in large scale atmospheric models. In a test simulation against an accurate high resolution solution, all the methods showed reasonable treatment of new particle formation with 20 size sections although the hybrid and the retracking methods suffered from artificial widening of the distribution. The moving center approach, on the other hand, showed extra dents in the particle size distribution and failed to predict the onset of detectable particle formation. In a separate test simulation of an observed nucleation event, the model captured the key qualitative behaviour of the system well. Furthermore, its prediction of the organic volume fraction in newly formed particles, suggesting values as high as 0.5 for 3–4 nm particles and approximately 0.8 for 10 nm particles, agrees with recent indirect composition measurements.

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Section: Introductionmentioning

confidence: 99%

Multicomponent aerosol dynamics model UHMA: model development and validation

Korhonen¹,

Lehtinen²,

Kulmala³

2004

Preprint

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Abstract. A size-segregated aerosol dynamics model UHMA (University of Helsinki Multicomponent Aerosol model) was developed for studies of multicomponent tropospheric aerosol particles. The model includes major aerosol microphysical processes in the atmosphere with a focus on new particle formation and growth; thus it incorporates particle coagulation and multicomponent condensation, applying a revised treatment of condensation flux onto free molecular regime particles and the activation of nanosized clusters by organic vapours (Nano-Köhler theory), as well as recent parameterizations for binary H2SO4–H2O and ternary H2SO4–NH3-H2O homogeneous nucleation and dry deposition. The representation of particle size distribution can be chosen from three sectional methods: the hybrid method, the moving center method, and the retracking method in which moving sections are retracked to a fixed grid after a certain time interval. All these methods can treat particle emissions and transport consistently, and are therefore suitable for use in large scale atmospheric models. In a test simulation against an accurate high resolution solution, all the methods showed reasonable treatment of new particle formation with 20 size sections although the hybrid and the retracking methods suffered from artificial widening of the distribution. The moving center approach, on the other hand, showed extra dents in the particle size distribution and failed to predict the onset of detectable particle formation. In a separate test simulation of an observed nucleation event, the model captured the key qualitative behaviour of the system well. Furthermore, its prediction of the organic volume fraction in newly formed particles, suggesting values as high as 0.5 for 3–4 nm particles and approximately 0.8 for 10 nm particles, agrees with recent indirect composition measurements.

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Surfactant Effects and an Order-Disorder Transition in Binary Gas-Liquid Nucleation

Cited by 16 publications

References 16 publications

Monte Carlo simulation of homogeneous binary vapor–liquid nucleation: Mutual enhancement of nucleation in a partially miscible system

Monte Carlo simulation of homogeneous binary vapor–liquid nucleation: Mutual enhancement of nucleation in a partially miscible system

Multicomponent aerosol dynamics model UHMA: model development and validation

Multicomponent aerosol dynamics model UHMA: model development and validation

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