Chiral Plasmonic Pinwheels Exhibit Orientation-Independent Linear Differential Scattering under Asymmetric Illumination  

作　　者：Lauren A.McCarthy Ojasvi Verma Gopal Narmada Naidu Luca Bursi Alessandro Alabastri Peter Nordlander Stephan Link 

机构地区：[1]Department of Chemistry,Rice University,Houston,Texas 77005,United States [2]Department of Chemistry,University of Michigan,930 N.University Ave.,Ann Arbor,MI 48109 [3]Department of Physics and Astronomy,Rice University,Houston,Texas 77005,United States [4]Dipartimento di Fisica,Informatica e Matematica-FIM,Universitàdi Modena e Reggio Emilia,and Istituto Nanoscienze,Consiglio Nazionale delle Ricerche CNR-NANO-S3,I-41125 Modena,Italy [5]Department of Electrical and Computer Engineering,Rice University,Houston,Texas 77005,United States [6]Department of Physics and Astronomy and Department of Electrical and Computer Engineering,Rice University,Houston,Texas 77005,United States

出　　处：《Chemical & Biomedical Imaging》2023年第1期30-39,共10页化学与生物医学影像（英文）

基　　金：the National Science Foundation(CHE1903980);thanks the Robert A.Welch Foundation for support through the Charles W.Duncan,Jr.−Welch Chair in Chemistry(C-0002);P.N.and N.N.G.were supported by the Robert A.Welch Foundation(C-1222);L.A.M.acknowledges the National Science Foundation Graduate Research Fellowship Program(1842494)for support.We thank the Rice Shared Equipment Authority and Electron Microscopy Center for instrument use.

摘　　要：Plasmonic nanoantennas have considerably stronger polarization-dependent optical properties than their molecular counterparts,inspiring photonic platforms for enhancing molecular dichroism and providing fundamental insight into light-matter interactions.One such insight is that even achiral nanoparticles can yield strong optical activity when they are asymmetrically illuminated from a single oblique angle instead of evenly illuminated.This effect,called extrinsic chirality,results from the overall chirality of the experimental geometry and strongly depends on the orientation of the incident light.Although extrinsic chirality has been well-characterized,an analogous effect involving linear polarization sensitivity has not yet been discussed.In this study,we investigate the differential scattering of rotationally symmetric chiral plasmonic pinwheels when asymmetrically irradiated with linearly polarized light.Despite their high rotational symmetry,we observe substantial linear differential scattering that is maintained over all pinwheel orientations.We demonstrate that this orientation-independent linear differential scattering arises from the broken mirror and rotational symmetries of our overall experimental geometry.Our results underscore the necessity of considering both the rotational symmetry of the nanoantenna and the experimental setup,including illumination direction and angle,when performing plasmonenhanced chiroptical characterizations.Our results demonstrate spectroscopic signatures of an effect analogous to extrinsic chirality for linear polarizations.

关 键 词：linear dichroism phase retardation single-particle scattering spectroscopy chiral nanoantennas extrinsic chirality 

分 类 号：O62[理学—有机化学]