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Measurement of droplet interfacial phenomena by light‐scattering techniques
Author(s) -
Taflin Daniel C.,
Zhang S. H.,
Allen Theresa,
James Davis E.
Publication year - 1988
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690340809
Subject(s) - evaporation , light scattering , rayleigh scattering , refractive index , scattering , mie scattering , fourier transform , optics , phase (matter) , chemistry , materials science , monolayer , analytical chemistry (journal) , thermodynamics , nanotechnology , physics , chromatography , organic chemistry , quantum mechanics
Two light‐scattering techniques have been applied to study the kinetics of droplet evaporation and attendant interfacial phenomena. The first technique, which is particularly useful for noisy data, utilizes the fast Fourier transform of phase function data (intensity vs. scattering angle) to obtain the size by comparing the phase function with Lorenz‐Mie theory. The second method applies optical resonance measurements to obtain very precise measurements of size and/or refractive index as functions of time. The techniques have been used to measure the slow evaporation of multicomponent and single‐component organic microdroplets, rapid evaporation of water droplets, and rapid evaporation of droplets of aqueous solutions and surfactant solutions. The experiments were performed in an electrodynamic balance, which was used to suspend single microdroplets in a polarized laser beam. Rapid evaporation rate data yield information on the surface temperature, and data for surfactant solution evaporation show that insoluble monolayer formation at the microdroplet surface reduces the evaporation rate by a factor of 200. In addition, it is shown that droplet explosion due to surface charge effects can occur well below the Rayleigh limit of charge.