Enhancement of deep ultraviolet chiral molecular sensing performance by collective lattice resonances of diamond nanostructure arrays

Abstract

Detecting the circular dichroism (CD) spectra of chiral molecules in the deep ultraviolet (DUV) region is of significant research importance in the biomedical field, as it can reflect not only enantiomer concentration but also molecular structural information. Although low-loss dielectric materials in the ultraviolet region can avoid the photothermal effects of traditional plasmonic materials, their poor electromagnetic field localization limits their application in molecular signal enhancement. Here, we designed a diamond nanostructure array. By exciting the collective lattice resonance (CLR) modes with non-local field distribution characteristics and introducing the coupling between the electric and magnetic CLRs, the optical chirality enhancement in the gap region between the diamond nanostructures is increased to a maximum of more than 150, with an average of over 52 at DUV wavelengths. Such characteristics allow the largely enhanced spatial superposition between the superchiral near field and the target chiral analytes. Moreover, simulation results demonstrate a 22-fold enhancement in the DUV CD signals of chiral molecules, with the enhanced CD intensity exhibiting a linear dependence on molecular concentration. Our results could be potentially used for ultrasensitive detection of chiral biomolecules, which is of interest in biopharmaceutical research applications such as rapid detection of chiral drug molecules at ultra-low concentrations.