Elucidating the contribution of dipole resonance mode to polarization-dependent optical properties in single triangular gold nanoplates

Highlight• We characterized optical properties of single triangular gold nanoplate under DF microscopy. • The optical properties are mainly dominated by the dipole resonance in single Au nanoplate with aspect ratio of 5. • We observed the polarization-dependent, periodic DF defocused images and intensities of single Au nanoplates. We synthesized triangular gold nanoplates (AuNPs) through a one-pot seedless growth method and characterized their optical properties under dark-field (DF) microscopy at the single particle level. We experimentally demonstrated that the dipole resonance is not completely separated from the quadrupole resonance for single AuNPs with an aspect ratio of ∼5. We further used a defocused orientation and position imaging technique to visualize the spatial scattering field distributions from dipole and quadrupole modes. Their optical properties were mainly dominated by the dipole resonance, which resulted in the polarization-dependent, periodic DF defocused images and intensities of single AuNPs.