Abstract
Throughout the 19th and 20th century, chirality has mostly been associated with chemistry. However, while chirality can be very useful for understanding molecules, molecules are not well suited for understanding chirality. Indeed, the size of atoms, the length of molecular bonds and the orientations of orbitals cannot be varied at will. It is therefore difficult to study the emergence and evolution of chirality in molecules, as a function of geometrical parameters. By contrast, chiral metal nanostructures offer an unprecedented flexibility of design. Modern nanofabrication allows chiral metal nanoparticles to tune the geometric and optical chirality parameters, which are key for properties such as negative refractive index and superchiral light. Chiral meta/nano‐materials are promising for numerous technological applications, such as chiral molecular sensing, separation and synthesis, super‐resolution imaging, nanorobotics, and ultra‐thin broadband optical components for chiral light. This review covers some of the fundamentals and highlights recent trends. We begin by discussing linear chiroptical effects. We then survey the design of modern chiral materials. Next, the emergence and use of chirality parameters are summarized. In the following part, we cover the properties of nonlinear chiroptical materials. Finally, in the conclusion section, we point out current limitations and future directions of development.
Highlights
Throughout the 19th and 20th century, chirality has mostly been associated the shape of galaxies all the way down to sub-atomic particles
We present an overview of several linear chiroptical effects, such as optical rotation, circular dichroism, Raman optical activity and vibrational optical activity
In the general case both the extinction coefficient and refractive index would be different for left circularly polarized (LCP) and RCP light, which leads to the simultaneous occurrence of Optical rotation (OR) and CD
Summary
Whereas OR is sensitive to the geometric arrangement of the electromagnetic field, on the molecular or nanostructure level, CD is sensitive to chirality in energy transitions. The two effects are complementary.[49] In the case of OR spectra, the refractive index affects the phase velocity of LCP (σ−) and RCP (σ+) light differently, while the extinction coefficient is the same for both. In the general case both the extinction coefficient and refractive index would be different for LCP and RCP light, which leads to the simultaneous occurrence of OR and CD. The resonance condition is clearly seen in the polarizability of the nanoparticle at a given wavelength: α This polarizability is an expression of the idea that the surface electrons are driven by the electric field of light. For a spherical chiral plasmonic nanoparticle the extinction coefficient becomes :[65]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
