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Abstract: Electron beams present a new platform for manipulating colloidal particles with localized nanoscale control. Leveraging the high spatial and temporal resolution of scanning electron microscopy, we investigate the driven response of dispersed silica particles pinned to the interface of an ionic liquid droplet. By tuning the beam voltage, we precisely adjust both the strength and polarity of the interaction, sweeping between repulsive and attractive regimes. With this improved control, we demonstrate the capability of directed particle transport for writing colloidal patterns at the droplet surface. We additionally use this platform to explore particle-particle interactions in dense monolayers of bidisperse size mixtures. We find that the interaction is inherently non-additive, as determined by the confined packing geometry. Adjusting the particle size ratio modulates this geometric non-additivity, providing a unique platform for systematically investigating its structural and dynamic consequences.
Speaker Bio: Jonathan Raybin is a postdoctoral researcher at UC Berkeley working with Prof. Naomi Ginsberg. His research focuses on imaging the environmental response of soft materials outside of equilibrium, exploring a range of phenomena including fluctuations, transport, and phase transformations. He earned his PhD from the University of Chicago, studying block copolymer self-assembly under the supervision of Prof. Steven Sibener. Jonathan is the recipient of the Charles H. Viol Fellowship and an NRC Postdoctoral Fellowship.