The surface-enhanced Raman scattering properties of films consisting of gold nanoparticles with two different diameters are evaluated. The enhancement of Raman scattering in these gold nanoparticle films is not proportional to the mixing ratios of differently sized gold nanoparticles.

Densely-packed thin films of plasmonic nanoparticles enhance Raman scattering. The effect of size uniformity of plasmonic nanoparticles in such thin films contributes to the development of highly sensitive Raman scattering spectroscopy for practical use. In this research, densely-packed thin films containing a mixture of gold nanoparticles with two different sizes are fabricated and evaluated about their surface-enhanced Raman scattering properties. The enhancement efficiency of gold nanoparticle films with different sizes is lower than that of single-sized gold nanoparticle films. This tendency suggests a relationship between Raman scattering enhancement efficiency and the electric field generated by localized surface plasmon resonance among gold nanoparticles of different sizes.