HR: 14:55h
AN: A43E-06    [Abstracts]
TI: Multivariate analysis of homogeneous nucleation measurements: Application to the p-toluic acid/sulfuric acid/water system
AU: * McGraw, R L
EM: rlm@bnl.gov
AF: Brookhaven National Laboratory, Atmospheric Sciences Division Bldg. 815E, Upton, NY 11973, United States
AU: Zhang, R
EM: zhang@ariel.met.tamu.edu
AF: Texas A&M University, Department of Atmospheric Sciences 3150 TAMU, College Station, TX 77843, United States
AB: Recent kinetic extensions of the nucleation theorem (KNT) suggest that the logarithm of the steady-state nucleation rate has strong multi-linear dependence on the log concentrations of condensable species present in the vapor phase. A further remarkable result is that the coefficients of this linear dependency provide a direct determination of the molecular content of the critical nucleus itself. Building on these results, the powerful utility of multivariate statistical methods is demonstrated here for physically-based parameterization and interpretation of nucleation rate measurements. The new approach is applied to recent measurements by Zhang and co- workers on the p-toluic acid/ sulfuric acid/water ternary vapor system. A parameterization for nucleation rate dependence on vapor composition, accurate over the range of the measurements, is obtained and estimates of critical nucleus molecular composition are presented. We show that a single molecule of p-toluic acid present in the critical nucleus is sufficient to trigger a ternary nucleation event. Efforts underway to apply the new methods to analysis of new particle formation in the atmosphere are described.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0365 Troposphere: composition and chemistry
DE: 3311 Clouds and aerosols
DE: 4465 Phase transitions
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting