Nucleation: Measurements, Theory, and Atmospheric Applications

Abstract

New experiments have succeeded in measuring actual rates of nucleation and are revealing the shortcomings of classical nucleation theory, which assumes that the molecular-scale regions of the new phase may be treated using bulk thermodynamics and planar surface free energies. In response to these developments, new theories have been developed that incorporate information about molecular interactions in a more realistic fashion. This article reviews recent experimental and theoretical advances in the study of nucleation of liquids from the vapor and of crystals from the melt, with particular emphasis on phenomena that relate to particle formation in the atmosphere.

Formation free energy of clusters in vapor-liquid nucleation: A Monte Carlo simulation study

“…The classical nucleation theory has been widely used to correlate experimental measurements. 4,5 It has been shown that the theory generally predicts the supersaturation dependence of the nucleation rate quite well but not the temperature dependence. To develop a better theory, either phenomenological or molecular, of nucleation, it would be desirable to obtain the formation free energy ͑i.e., barrier of nucleation͒ for a commonly studied model system, such as the Lennard-Jones ͑12,6͒ fluid, from first principles.…”

Numerical study of gas–liquid nucleation in partially miscible binary mixtures

“…From the nucleation theorem 9 it would then follow that one of the two components has a negative concentration in the critical nucleus. Laaksonen and Oxtoby, who used density functional theory to study nucleation in a mixture, 10,11 argue that the failure of CNT can be traced back to the fact that this theory does not predict the composition of the critical nucleus correctly.…”

Atmospheric Ions and Aerosol Formation

“…As the parameter a increases, the MOFA of positive and negative ions approach each other. Note that neutral A a W w clusters which are also important in theories of homogeneous bi-molecular nucleation have so far not been measured (Laaksonen et al 1995;Kulmala et al 2004). Therefore the cluster ion measurements also help to constrain theories on homogeneous nucleation.…”