In-situ Monitoring and Active Controls of Individual Nucleation and Crystal Growth through Nanoscale Mass Transport

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This project is funded by the Chemical Measurement and Imaging program of Chemistry Division at the National Science Foundation. Professor Gangli Wang and his group members at Georgia State University develop new analytical methods providing knowledge of early-stage nucleation and subsequent crystal growth at greater time and spatial resolutions than is otherwise possible. High quality single crystals display chemical, physical, and mechanical properties, and have superb performance in practical applications in chemical, pharmaceutical and materials industries. Lack of capable methods to measure and to actively control the crystallization process has been a limit on the advance of fundamental research as well as practical applications. The capability to measure the dynamic process in-situ and thus to actively control crystal formation is expected to establish much-needed high throughput and high efficiency crystallization technology. The broader impacts are demonstrated in that the proposed aims advance the paradigm of crystallization. Students from underrepresented groups and from disadvantageous backgrounds in metro Atlanta gain first-hand knowledge and experiences through the grant activities. The overarching goal of this proposal is to establish an electroanalytical methodology combined with optical imaging that enables in-situ monitoring and active controls of single nucleus formation and single crystal growth. Analytical platforms are being developed with optimized nanostructures and surface functionalities to spatially confine the formation and growth of a single nucleus at the earliest stage (molecular assembly) one at a time. The kinetics of a single crystal nucleus formation and growth, governed by local transport of the target molecules around the nucleus, are controlled externally via a programmed potential waveform. Active control of mass transport is another superior advantage over the passive diffusion mechanism adopted in conventional crystallization methods. Because the transport and assembly processes are associated with changes in ionic current signals as well as optical properties, in-situ monitoring and adjustments are performed to tailor the nucleation and growth kinetics of individual events.