Fig. 3.

Behavior of the film-coupled nanosphere, assuming a local model and the nonlocal model with various values of β, as a function of gap distance. Calculations refer to a gold nanosphere of radius r = 30nm on a 300 nm thick film. (A) Position of the peak scattering intensity as a function of gap distance. (B) The corresponding field enhancement ratio. Note that in the absence of nonlocal effects, the peak scattering wavelength is extreme and the field enhancement grows to enormous values; nonlocality places a limit on the ultimate enhancement.