Method for exciting surface-enhanced Raman spectroscopy (SERS) through long range surface plasmon

A surface plasmon and surface-enhanced Raman technology, applied in the field of spectral analysis and detection, can solve the problems of weak electric field strength on the metal surface and unsatisfactory SERS signal effect, and achieve economical and practical enhancement, lower requirements, and increased electromagnetic field strength. Effect

Inactive Publication Date: 2012-11-21
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The electric field strength on the metal surface is relatively weak, and the effect of obtaining SERS signals is not ideal.

Method used

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  • Method for exciting surface-enhanced Raman spectroscopy (SERS) through long range surface plasmon
  • Method for exciting surface-enhanced Raman spectroscopy (SERS) through long range surface plasmon
  • Method for exciting surface-enhanced Raman spectroscopy (SERS) through long range surface plasmon

Examples

Experimental program
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Effect test

Embodiment 1

[0025] According to the Fresnel equation and multilayer film theory (S.Ekgasit, C.Thammacharoen, and W.Knoll, Anal.Chem., 2004, 76, 561), the electric field distribution and reflection on the surface of the metal film under the SPR device can be simulated rate formula. The basic principle is described as follows:

[0026] For a multilayer film system composed of prisms and multilayer dielectric substances, the medium between the high refractive index cylindrical mirror and the semi-infinite dielectric substrate can be treated as a multilayer medium. The dielectric constants of the cylindrical mirror and the semi-infinite dielectric substrate are respectively ε p and ε s To represent. The dielectric constant of the jth layer medium is ε j , with thickness d j . When a beam of plane light waves is incident on the interface between the cylindrical mirror and the multilayer medium through the cylindrical prism at an incident angle θ, the incident light 1 is decomposed into ref...

Embodiment 2

[0048] The distribution of the electric field in each layer under the traditional SPR structure constructed by the semi-cylindrical cylindrical mirror / silver film / water three-layer mold is simulated by using the formula (7) in Example 1 and the relevant formula of electromagnetic field propagation in the medium. The material of the semi-cylindrical cylindrical mirror is K9 glass, the refractive index is 1.53, and the thickness of the silver film is 45nm. Simulation results such as Figure 4 Shown in the middle left figure. The penetration depth of the electric field is 510nm. The electric field under the long-range SPR structure constructed of semi-cylindrical cylindrical mirror / lithium fluoride layer / silver film / water is simulated at each layer. The material of the semi-cylindrical cylindrical mirror is K9 glass, the thickness of the lithium fluoride layer is 680nm, the refractive index is 1.39, and the thickness of the silver film is 20nm. Simulation results such as Fig...

Embodiment 3

[0050] like Figure 5 As shown, component 4 is a base prism for constructing a long-range SPR chip (the prism is a semi-cylindrical cylindrical mirror with a radius of 18cm and a height of 30cm), and the material is K9 optical glass with a refractive index of 1.53 for coupling surface plasmon waves with the incident light wave. 12 is a laser light source for exciting surface plasmon (Changchun New Industry Optoelectronics Technology Co., Ltd. MXL-III-532 laser), the wavelength is 532nm, and the power is adjustable from 0 to 500mW. 13 is a reflected light detector (such as a photodiode), which is used to detect the intensity signal of the reflected light 2 . 5 is a buffer layer on the bottom surface of the prism, which is made of lithium fluoride with a refractive index of 1.39 and a thickness of 680 nm. 6 is a metal layer on the buffer layer, which is made of noble metal silver and has a thickness of 20nm. Both the buffer layer and the metal layer are prepared by vacuum eva...

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Abstract

The invention relates to a spectral method capable of exciting surface-enhanced Raman spectroscopy (SERS) in a long range surface plasmon mode. The method comprises the following steps of: constructing a buffer layer, a metal layer and a protective layer on the bottom surface of a prism to form a long range surface plasmon resonance (LRSPR) device; placing the LRSPR device with multilayer structure under the irradiation of a laser source, and adjusting the incident angle of the laser source to an LRSPR angle; and in a specific incident direction, generating the LRSPR, so that the electric magnetic field on the surface of a metal is enhanced, and the excitation process of the surface-enhanced Raman spectroscopy of a detected object of a deeper area in a sample layer is completed. Because the long range effect has deeper penetrating effect, the construction of the protective layer on the surface of the metal layer becomes possible. The transduction membrane made of chemically inert goldor platinum is changed into a silver membrane with lower cost, oxidation resistance and better enhancing effect. The LRSPR-mechanism-based SERS detection method has great significance.

Description

technical field [0001] The invention belongs to the technical field of spectral analysis and detection, and specifically relates to a spectral technology capable of stimulating surface-enhanced Raman scattering through long-range surface plasmon, which is used to improve the spectral quality of surface-enhanced Raman scattering signals and improve the sensitivity of analysis and detection. Background technique [0002] Surface-enhanced Raman spectroscopy (SERS) refers to the enhancement of metal nanomaterials and structures up to 10 4 -10 10 Raman signal. At present, it is generally believed that the physical enhancement of SERS mainly comes from surface-plasmon resonance (SPR). Surface plasmon (Surface Plasmon, SP) is essentially a light wave that is trapped on the surface by interacting with free electrons on the surface of a conductor. The incident light forces the free electrons on the surface of the conductor to form a collective vibration, and when the collective vi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/65
Inventor 徐蔚青刘钰徐抒平赵冰周向华
Owner JILIN UNIV
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