Determining the Local Refractive Index of Single Particles by Optical Imaging Technique

The refractive index points to the interplay between light and objects, which is rarely studied down to micronano scale. Herein, we demonstrated a conventional bright-field imaging technique to determine the local refractive index of single particles combined with a series of refractive index standard solutions. This intrinsic optical property is independent with the particle size and surface roughness with a single chemical component. Furthermore, we accurately tuned refractive index of homemade core-shell nanoparticles by adjusting the ratio of core-to-shell geometry. This simple and effective strategy reveals extensive applications in exploring, designing and optimizing the physical and optical characterizations of composite photonic crystals with high precision. It also indicates potentials in the field of reflective displays, optical identification, and encryption.

Automated summary

In this study, a conventional bright-field imaging technique combined with a series of refractive index standard solutions was used to determine the local refractive index of single particles. The refractive index was found to be independent of particle size, surface roughness, and chemical composition. Additionally, the refractive index of homemade core-shell nanoparticles was accurately tuned by adjusting the ratio of core-to-shell geometry. This simple and effective strategy has extensive applications and potentials in the exploration, design, and optimization of composite photonic crystals, as well as in the fields of reflective displays, optical identification, and encryption.