This paper presents experimental evidence of sharp spectral features in the optical response of 2D arrays of gold nanorods. The authors use a coupled dipole model to describe the observed spectral line shape, which involves the interplay between the excitation of localized surface plasmons (LSPRs) on the particles and diffraction from the periodic arrangement of these particles. By varying the particle size, aspect ratio, and interparticle spacing, they investigate the effects on the position, width, and intensity of the sharp spectral feature. The study confirms the existence of these sharp diffractive features in the optical response of metallic nanoparticle arrays, providing a clear understanding of the underlying physics. The results are supported by detailed measurements and simulations, demonstrating the role of array period, particle size, and shape on the spectral line shape.This paper presents experimental evidence of sharp spectral features in the optical response of 2D arrays of gold nanorods. The authors use a coupled dipole model to describe the observed spectral line shape, which involves the interplay between the excitation of localized surface plasmons (LSPRs) on the particles and diffraction from the periodic arrangement of these particles. By varying the particle size, aspect ratio, and interparticle spacing, they investigate the effects on the position, width, and intensity of the sharp spectral feature. The study confirms the existence of these sharp diffractive features in the optical response of metallic nanoparticle arrays, providing a clear understanding of the underlying physics. The results are supported by detailed measurements and simulations, demonstrating the role of array period, particle size, and shape on the spectral line shape.