as a function of dimensionless frequency ω/ω * p . In terms of these units, the optical calculations apply to a range of materials, with different colloid compositions and background media encoded through specific choices of ω * p and ε m . For example, typical values for colloidal tindoped indium oxide (ITO) nanoparticles are ε m = 2ε 0 , ω * p = 10 000 cm -1 , γ = 500 cm -1 , and