Combined Electrostatic-Covalent Building of Au NPs Multilayers and Their Size-Enhanced Cohesive and SERS Properties

Table 1

Evaluation of the complex refractive index (𝑛, 𝑘) of NPs multilayer structure and a thermally evaporated Au film by ellipsometry.

	Refractive index 𝑛	Extinction coefficient 𝑘
Au evaporated film 30 nm	0.488	−2.4
5 nm Au colloidal 1 layer equivalent to 5 nm	3.814	−0.896
5 nm Au colloidal 4 layers equivalent to 20 nm	3.014	−1.664
15 nm Au colloidal 4 layers equivalent to 60 nm	3.045	−1.522