title: Monitoring Gold Nanoparticle Growth in Situ via the Acoustic Vibrations Probed by Four-Wave Mixing.
abstract: We monitor in situ gold nanoparticle growth in aqueous solution by probing the acoustic vibrations with four-wave mixing. We observe two acoustic vibrational modes of gold nanoparticles from the nonlinear optical response: an extensional mode with longitudinal expansion and transverse contraction and a breathing mode with radial expansion and contraction. The mode frequencies, which show an inverse dependence on the nanoparticle diameter, allow one to monitor the nanoparticle size and size distribution during synthesis. The information about the nanoparticle size and size distribution calculated on the basis of the mode frequencies agrees well with the results obtained from the electron microscopy analysis, validating the four-wave mixing technique as an accurate and effective tool for in situ monitoring of colloidal growth.
authors.affiliation: Department of Electrical and Computer Engineering, University of Victoria , Victoria, British Columbia V8P 5C2, Canada.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Electrical and Computer Engineering, University of Victoria , Victoria, British Columbia V8P 5C2, Canada.
authors.forename: Dao
authors.initials: D
authors.lastname: Xiang
authors.affiliation: Department of Electrical and Computer Engineering, University of Victoria , Victoria, British Columbia V8P 5C2, Canada.
authors.forename: Reuven
authors.identifier: 0000-0002-1485-6067
authors.initials: R
authors.lastname: Gordon