Circular dichroism analysis of half-roll plasmonic chiral nanostructures

Surface-plasmon-enhanced circular dichroism (CD) spectroscopy is a powerful analytical technique used for detecting chiral molecules, with great potential in biomedical diagnosis and pathogen detection. This work focuses on understanding the physical mechanisms of CD production and developing high-sensitivity CD detection substrates. Numerical simulation of the finite difference time domain (FDTD) method is utilized to design and study half-roll plasmonic nanostructures. The scattering spectra of the structure and the corresponding CD spectra show two resonance peaks, λ₁ = 691 nm and λ₂ = 903 nm, where the charge distribution of the upper surface and the lower surface shows a quadrupole distribution and a dipole distribution, and both of them are in antibonding mode. The structure’s sensitivity is demonstrated by varying the structure parameters and surrounding medium environment, which provides valuable insights for designing optical devices.