Geometric modulation of induced plasmonic circular dichroism in nanoparticle assemblies based on backaction and field enhancement

Abstract

The interplay between local field enhancement and backaction determines plasmonic chiral responses and leads to widely tunable geometry-dependent optical activities.

Chirality Transfer from Sub‐Nanometer Biochemical Molecules to Sub‐Micrometer Plasmonic Metastructures: Physiochemical Mechanisms, Biosensing, and Bioimaging Opportunities

“…However, how to model chiral molecules has been a great challenge in many theoretical studies, among which two approaches are found to show good agreement with experimental observations. [44][45][46][47]60] The first approach was proposed by Govorov based on the density-matrix formalism, where a chiral molecule is treated as a two-level system with nonorthogonal magnetic and electric dipole moments and subsequently the CD spectrum of the hybrid molecule-NC complex can be rigorously calculated as the total contribution from the molecule and the NC. [44,45] In the second approach, Zhang and co-workers simply considered the plasmonic absorption as the dominant contribution to the overall CD of the hybrid system, where the chiral molecule is regarded as an electric dipole with different effective polarizabilities for LCP and RCP excitation.…”

“…[44,45] In the second approach, Zhang and co-workers simply considered the plasmonic absorption as the dominant contribution to the overall CD of the hybrid system, where the chiral molecule is regarded as an electric dipole with different effective polarizabilities for LCP and RCP excitation. [46,47] As discussed below, this method represents a classical point of view of isotropic chiral medium, and can be derived from Govorov's quantum treatment by considering Fedorov [61] and Rosenfeld's equations. [62]…”

“…Since the intrinsic CD of the chiral molecule is relative weak at the plasmonic band (which is equivalent to the density-matrix formalism in which CD molecule ≪ CD NC ), only dominant CD contribution from the NC's differential absorption is considered. The CD NC can be written as [46,69]…”

“…A primary driving force behind this development is the breakthrough in design and fabrication of artificial metallic nanostructures, ranging from top-down techniques such as focused ion beam milling, [40] electron-beam lithography [41] and direct laser writing, [42] to bottom-up methods like chemical synthesis and self-assembly. [39,43] Together with theories that can elegantly describe the interaction between chiral molecules and plasmonic nanostructures, [44][45][46][47] the study of chirality has entered a fast development path. There have been several reviews focusing on various aspects of this field, including fabrication, [39,43,48,49] theories, [50][51][52] and applications.…”

Circular Polarized Light Activated Chiral Satellite Nanoprobes for the Imaging and Analysis of Multiple Metal Ions in Living Cells

“…Recently,c hiral assemblies,p articularly chiroplasmonic assemblies,h ave been shown to display the unique activity of strong polarization rotation, which makes them ar emarkable new class of chiroptical materials. [20][21][22][23] Circular dichroism (CD) peaks in the visible/near-infrared window were found to change from negative to positive in the process of uptake due to as pontaneous twisting motion around the bridged DNAwhen the nanoparticle dimers move from the interstitial fluid to the cytosol. [24,25] This interesting property could enable chiroplasmonic assemblies to be used as intra/ extracellular biosensors for the detection of multiple metal ions using handedness-dependent CPL.…”