  The optical response of metallic nanoparticle arrays is dominated by
localized surface plasmon excitations and is the sum of individual particle
contributions modified by inter-particle coupling depending on specific array
geometry. Here we scrutinize how experimentally measured properties of large
scale (30 mm$^{2}$) amorphous Au nanodisk arrays stem from single particle
properties and their interaction. They give rise to a distinct oscillatory
behavior of the plasmon peak position, full-width at half-maximum, and
extinction efficiency which depends on the minimum particle center-to-center
(CC) distance.
