A Method for Measuring the Refractive Index of Molecular Layer

Abstract

The invention provides a method for measuring the refractive index of a molecular layer. The method comprises the following steps that firstly, metal nanometer cores are prepared, molecules to be measured are adsorbed to the surfaces of the metal nanometer cores, a molecular layer with molecules to be measured is formed, and meanwhile the absorption spectrum deflection generated before and after the molecules to be measured are adsorbed to the metal nanometer cores is measured; secondly, the outer surface of the molecular layer is wrapped with a metal shell layer, metal nanometer particles of a core-shell structure with embedded molecules to be measured are obtained, the dimension of the core-shell gap is measured with a transmission electron microscope, and the thickness of the molecular layer is obtained; thirdly, according to the measured thickness data of the molecular layer, a relation model of absorption spectra and refractive indexes of molecular layers is established; fourthly, a plurality of refractive indexes of the molecular layer are assumed, multiple simulative spectrum deflections are worked out with the relation model, and finally the effective refractive index of the molecular layer to be measured is obtained. By means of the method, the refractive index of the surface molecular layer of nanometer particles can be effectively measured.

Description

technical field [0001] The invention belongs to the field of nanometer material optics, in particular to a method for measuring the effective refractive index of a subnanometer-thick molecular layer. Background technique [0002] Thin film materials are currently a research hotspot in optical engineering and other fields. The determination of the refractive index of thin films can provide assistance for optical experiments, material performance research, and derivation of material physical parameters. In the field of bio-nanosensing, accurate determination of the refractive index of the molecular layer is also of great significance. For example, the sensing technology based on surface plasmon resonance has the advantages of high sensitivity and label-free. It mainly relies on the shift of the plasmon resonance peak of the nanostructure after the molecules to be measured form a thin molecular layer on the surface of the nanometal structure. The application of this technolo...

AI Technical Summary

Problems solved by technology

But both have certain defects: the ellipsometry cannot directly measure the thickness of the molecular layer, and can only use the computer to calculate the relationship chart between the refraction angle and the thickness and the refractive index, and then according to the measured refraction angle, fit the corresponding Refractive index

However, if the molecular layer to be measured is wrapped on the surface of the nanoparticle, there are few effective methods to measure the refractive index of the molecular layer

[0005] To sum up, the measurement of the effective refractive index of the molecular layer plays an extremely important role in the research of the field of bio-nanosensing, but the existing measurement methods can neither accurately measure the extremely thin molecular layer at the sub-nanometer scale, nor can it measure the molecular layer wrapped in the nanometer The effective refractive index of the molecular layer on the particle surface

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