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. Author manuscript; available in PMC: 2010 May 4.
Published in final edited form as: Nano Lett. 2008 Jul 1;8(8):2245–2252. doi: 10.1021/nl080872f

Figure 3.

Figure 3

Layer-by-layer polyelectrolyte (PE) assembly on gold film with no nanoparticles present. (A) Alternating PE layers always terminated in a positively charged top surface to enable chemisorption of gold NPs. (B) Ellipsometric measurement suggest a ∼4 nm bilayer thickness. (C) Experimental configuration for exciting and measuring the surface plasmon polariton (SPP) of the gold film with TIR evanescent white light at 45° incidence. (D) Measurement of SPP extinction from the gold films exhibits the expected red shift as the dielectric thickness increases, which is also summarized in (B), where the SPP extinction minimum is plotted versus the number of deposited PE layers. Note that by changing the angle of illumination, the wavelength of the SPP mode would shift so it was kept at 45° throughout all “in-air” measurements presented in this article.