Lifshitz--van der Waals forces in aerosol particle collisions. I. Introduction: Water droplets

Journal Article · Mon Dec 15 04:00:00 EST 1980 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.440127· OSTI ID:7093622

Marlow, W H

Collision rates among water droplets are computed by the application of results of a current paper which gives a rigorous expression for free-molecular collisions between aerosol particles with a singular, attractive contact potential and the extension of that expression throughout the transition regime via Fuchs' interpolation method. An expression for the Lifshitz--van der Waals attractive potential recently derived by Kiefer et al. is modified to include a physically motivated, frequency-dependent retardation factor and is used with experimental data for water's frequency-dependent dielectric susceptibility. This expression is employed in the computation of the ratio of the collision rate incorporating the interaction potential to the collision rate omitting the potential for various pairs of water particles of 1, 10, 100, and 1000 nm radii at 0.1, 1.0, and 10.0 atm. pressures. A graph of this ratio for a pair of 200 nm radius particles as a function of pressure is given and shown to display similar pressure-dependent behavior to recent experimental results by Wagner and Kerker on the coagulation rates of DEHS particles of the same size. This appears to be the first explanation of the systematic deviations near to and beyond experimental error of their experimental data from the predictions of Fuchs' unmodified formula. The ratio is also calculated by dividing the integral over the electromagnetic frequency spectrum in the van der Waals energy into long and short wavelength parts. This is used to estimate the relative importance of these components upon aerosol particle collision rates. By inference they suggest broader patterns of behavior for other particles.

• Research Organization: Environmental Chemistry Division, Department of Energy and Environment, Brookhaven National Laboratory, Upton, New York 11973
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7093622
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 73:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AEROSOLS
COLLISIONS
COLLOIDS
DISPERSIONS
DROPLETS
HYDROGEN COMPOUNDS
KINETICS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
OXYGEN COMPOUNDS
PARTICLES
SOLS
VAN DER WAALS FORCES
WATER