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

Abstract

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.

Characterization of Optical, Thermal, and Viscoelastic Properties of Pollenkitt in Angiosperm Pollen Using In-Line Digital Holographic Microscopy

“…The refractive index (RI) is a valuable property to monitor, as it provides information on the interactions between light and matter, which can be further attributed to the size, shape, chemical composition, and mass density of the sample (including heterogeneous mixtures). − Several techniques exist to measure the average RI in bulk, such as standard refractometry, , laser diffractometry, index matching techniques, , and Mie resonance spectroscopy. , When RI is measured locally or for single particles, optical techniques − outweigh other methods in both ease of implementation and precision. For materials that are hard to prepare in bulk, such as pollenkitt, a single-particle method is preferred over bulk methods.…”