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: 2011-09-14
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The electric field strength on the metal surface is relativel

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

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Experimental program
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Effect test

Embodiment 1

[0025] According to 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 media, 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 cylindrical mirrors and semi-infinite dielectric substrates are respectively ε p And ε s To represent. The dielectric constant of the j-th layer is ε j , The thickness is d j . When a plane light wave is incident on the interface between the cylindrical mirror and the multilayer medium at the incident angle θ through the cylindrical prism, the incident light 1 is decomposed into the reflected light beam 2 and the transmi...

Embodiment 2

[0048] The electric field distribution in each layer under the traditional SPR structure constructed by the semi-cylindrical cylindrical mirror / silver film / water three-layer model is simulated using the formula (7) in Example 1 and the related 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. The simulation results are as Figure 4 As shown in the left picture. The penetration depth of the electric field is 510 nm. The electric field under the long-range SPR structure constructed by the semi-cylindrical cylindrical mirror / lithium fluoride layer / silver film / water four layers is simulated in each layer. The material of the semi-cylindrical cylindrical mirror is K9 glass, the thickness of the lithium fluoride layer is 680 nm, the refractive index is 1.39, and the thickness of the silver film is 20 nm. The simulation results ar...

Embodiment 3

[0050] Such as 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), the material is K9 optical glass, and the refractive index is 1.53, which is used to couple surface plasma waves With incident light waves. 12 is a laser light source (Changchun New Industry Optoelectronics Technology Co., Ltd. MXL-III-532 laser) that excites surface plasmons, with a wavelength of 532nm and an adjustable power of 0-500mW. 13 is a reflected light detector (such as a photodiode) for detecting the intensity signal of the reflected light 2. 5 is the buffer layer on the bottom surface of the prism, the material is lithium fluoride, the refractive index is 1.39, and the thickness is 680 nm. 6 is the metal layer on the buffer layer, the material is precious metal silver, and the thickness is 20 nm. Both the buffer layer and the metal layer are prepared by a vacuum evapor...

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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 gold or 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 spectroscopy technique capable of exciting surface enhanced Raman scattering through a long-range surface plasma mode, which is used to improve the spectral quality of the surface enhanced Raman scattering signal 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 by up to 10 4 -10 10 Raman signal. At present, it is generally believed that the physical enhancement of SERS is mainly derived from surface-plasmon resonance (SPR). Surface Plasmon (SP) is essentially a light wave that interacts with free electrons on the surface of a conductor and is captured on the surface. The incident light forces free electrons on the surface of the conductor to form a collective vibration. When the frequency of the collective ...

Claims

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Application Information

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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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