Observation of the Binary Coalescence and Equilibration of Micrometer-Sized Droplets of Aqueous Aerosol in a Single-Beam Gradient-Force Optical Trap

R. Power, J. P. Reid, S. Anand, D. McGloin, A. Almohamedi, N. S. Mistry, A. J. Hudson

Research output: Contribution to journalArticle (Academic Journal)peer-review

15 Citations (Scopus)


The binary coalescence of aqueous droplets has been observed in a single-beam gradient-force optical trap. By measuring the time-dependent intensity for elastic scattering of light from the trapping laser, the dynamics of binary coalescence have been examined and the time scale for equilibration of a composite droplet to ambient conditions has been determined. These data are required for modeling the agglomeration of aqueous droplets in dense sprays and atmospheric aerosol. Elastic-light scattering from optically trapped particles has not been used previously to study the time-resolved dynamics of mixing. It is shown to offer a unique opportunity to characterize the binary coalescence of aqueous droplets with radii from 1 to 6 mu m. The study of this size regime, which cannot be achieved by conventional imaging methods, is critical for understanding the interactions of droplets in the environment of dense sprays.

Original languageEnglish
Pages (from-to)8873-8884
Number of pages12
JournalJournal of Physical Chemistry A
Issue number35
Publication statusPublished - 6 Sep 2012

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