Metasurface-enhanced Momentum-resolved Circular Dichroism Spectroscopy

Le résumé fourni par la source

Nanophotonic resonators can amplify weak molecular circular dichroism (CD) signals, but the structural chirality from angle-dependent photoexcitation or collection may mask intrinsic, molecular chiroptical features. Here, we develop an achiral nanodisk array and angle-resolved spectral measurement approach which deconvolves chiral molecular and substrate signals and enables artifact-free chiral-optical enhancement. Circular polarization-resolved momentum-space spectroscopy maps chiroptical response across wavelength and collection angle in a single measurement, simultaneously reporting intrinsic, molecularly-linked CD and extrinsic, nanostructure-induced signals in distinct optical channels. As a model system, we design silicon nitride nanodisks that overlap spectrally with thiocamphor’s CD features with a simulated ~150 fold, uniform-sign enhancement in the volume-averaged density of optical chirality within the analyte-accessible region. We validate the enhancement of otherwise weak CD signals with the predicted spectral and angular sensitivity in a thiocamphor solution and measure its enantiomeric excesses. Thiocamphor concentrations down to 0.1 mM are detected with robust quantification established at 1 mM, supporting at least one order of magnitude limit of detection improvement relative to a conventional measurement at comparable path length. Additionally, this enhanced CD response demonstrates a monotonically increasing dose–response behavior across enantiomeric excesses ranging from 1% to 25%, consistent with a linear trend across the measured range. Our approach demonstrates momentum-resolved, metasurface-enhanced CD spectroscopy as a promising path to reliable and sensitive detection of molecular chirality and enantiomeric purity.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.