Light-matter interactions can be controlled by manipulating the photonic environment. We uncovered an optical topological transition in strongly anisotropic metamaterials that results in a dramatic increase in the photon density of states-an effect that can be used to engineer this interaction. We describe a transition in the topology of the iso-frequency surface from a closed ellipsoid to an open hyperboloid by use of artificially nanostructured metamaterials. We show that this topological transition manifests itself in increased rates of spontaneous emission of emitters positioned near the metamaterial. Altering the topology of the iso-frequency surface by using metamaterials provides a fundamentally new route to manipulating light-matter interactions.

Inelastic electron tunneling spectroscopy (IETS) of an alkanedithiol self-assembled monolayer (SAM) is investigated using a nanometer-scale device. The IETS spectrum of the octanedithiol device clearly shows vibrational signatures of an octanedithiolate, −SC 8 H 16 S−, bonded to gold electrodes. The pronounced IETS peaks correspond to vibrational modes perpendicular to the junction interface, which include the stretching modes of Au−S (at 33 mV) and C−C (at 133 mV) and the wagging mode of CH 2 (at 158 mV). The observed peak intensities and peak widths are in good agreement with theoretical predictions.

The site‐specific engineering of colloidal surfaces has provided a powerful approach to pushing the boundaries of today's materials research. The resulting surface‐anisotropic and patchy particles have become the center of vital research areas, ranging from the need for large‐scale fabrication techniques to exploring new applications of these materials. This Review summarizes patchy particle fabrication techniques, including but not limited to particle and nanosphere lithography and glancing‐angle deposition. The variety of existing patchy particle fabrication techniques is revealed and the need for a scalable approach to high‐volume patchy particle production is identified. Ongoing modeling efforts describing patchy particle interactions and properties are reviewed as potential predictive tools. Research endeavors that deal with the directed assembly of patchy particles in electric and magnetic fields, as well as with supraparticular assembly through chemical interactions, are discussed. The Review is concluded with a note on the future application of patchy particles as phoretic motors.magnified image

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The application of glancing angle deposition (GLAD) as a means to produce patchy particles is reported. Shadow effects are caused by neighboring particles within the particle monolayer. The patch geometry is determined by the angle of incidence of the vapor rays and the monolayer orientation. A mathematical model is used to study the patch geometry and to calculate the area of the patch. The smallest patch produced with GLAD is 3.7% of the particle surface.