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(363e) Self-Assembly of Plasmonic Chiral Superstructures on Substrate By Circularly Polarized Light

McGlothin, C., University of Michigan
Turali-Emre, E. S., University of Michigan
Kotov, N., University of Michigan
Self-assembly of geometrically complex structures have been accomplished in dispersions but not on the surfaces, which is needed for further studies and applications of their intriguing electromagnetic/optical properties. Their successful assembly can be accomplished using intrinsic chirality of the nanostructure and/or exerting local chiral bias. That could be translated to a variety of technologies, from medicinal chemistry to advanced manufacturing. Here, we show that strong optical activity of plasmonic materials under circularly polarized light (CPL) afford photon to matter chirality transfer, fabricating centimeter scale chiral 3D superstructures. Illuminating CPL on substrate immersed in metal precursor solutions induces the formation of nanoparticles (NPs) with 15–20 nm in diameter and subsequent asymmetric deposition/assembly were formed to construct chiral superstructures on the substrate. Circular dichroism (CD) spectra of resulted superstructure vividly showed opposite polarity after exposure to photons with left- and right circular polarization. Electron microscopy images for its intermediate growth stages showed vivid handedness of the rotational assemblies of NPs. The experimental evolution of CD peaks in different growth stages correlated well with those calculated for assembled nanostructure models with complex geometry, as established by prediction of deposition/assembly pattern by electromagnetic simulations. The chiral patterns were fabricated on polydimethylsiloxane (PMMA) stamp by CPL exposure time to demonstrate the simplicity and universality of this photosynthetic routes to direct construction of metallic 3D chiral metamaterials on arbitrary substrates with controlled chirality. These simple and versatile architected metamaterials can be used for extensive applications, including but not limited to photonic, optoelectronic, and electromechanical devices as well as enantioselective catalytic and sensing systems.