Interferometric lithography of self-assembled monolayers provides a fast, inexpensive, simple route to the fabrication of metal nanostructures over square cm areas. Single exposures of self-assembled monolayers (SAMs) of alkylthiolates on gold in a Lloyd's mirror inteferometer, by irradiation at 244 nm, followed by etching in ethanolic mercaptoethylamine, yields gold wires, while double exposure yields nanostructures of varying dimensions and aspect ratios, in a variety of arrangements (square lattice, hexagonal, rows) depending on (i) the angle of rotation of the sample between exposures and (ii) the angle between the sample and the mirror in the interferometer. Structures may be fabricated with high reproducibility and structure-property relationships explored in a combinatorial fashion. For example, their optical properties depend on their dimensions (length, width, height) and packing arrangements (type of periodicity, spacing between structures). Annealing yields nanostructures with a high degree of crystallinity that exhibit strong plasmon bands. Strong coupling is observed to biomolecules, leading to highly sensitive detection, and strong enhancements are observed for Raman-active adsorbates. Exposure of SAMs of alkylphosphonates on titania cuases photocatalytic degradation, yielding nanopatterned monolayer resists that enable the fabrication of Ti nanostructures on silica with dimensions (full width at half maximum height) as small as 24 nm. These are suitable for use as re-usable for protein nanopatterning, by passivating the silica with a protein-resistant silane and by utilizing the photiocatalytic properties of the native oxide of the titania nanostructures to regenerate the surface after protein adsorption.

Fabrication of metal nanostructures over macroscopic areas by interferometric lithography of self-assembled monolayers

247th National Meeting (2014)

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