CN100498299C

CN100498299C - Surface plasma resonance and surface reinforced Raman combined spectral investigator

Info

Publication number: CN100498299C
Application number: CNB2005100166224A
Authority: CN
Inventors: 徐蔚青; 赵冰; 徐抒平; 卜凤泉; 徐翔
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2005-03-11
Filing date: 2005-03-11
Publication date: 2009-06-10
Anticipated expiration: 2025-03-11
Also published as: CN1657914A

Abstract

The invention is a surface plasma syntonizing and surface enhanced Raman spectrum measure apparatus. Its main structure consists of laser source 21, angular instrument of initiate angle and polarize status adjustable together with polarize fins forms the light source system; sample table consists of edge glass of semi-circular or right angle or hemisphere and a basal chip with SERS activity. SERS signal detecting system made up of spectrograph and CCD detector. SPR signal detector is installed on one side of the edge glass while the light source system on the other side. The invention is adopted with the SPR detecting method of variable angle internal reflection, initiating the sample in the elapse field to obtain the SERS spectrum, and synchronizingly obtaining the SPR spectrum and the further enhanced SERS spectrum under syntonizing enhancing angle. Higher detecting sensitivity and s/n ratio can be obtained when measuring the SERS signal under dim background.

Description

Surface plasma body resonant vibration and surface reinforced Raman combined spectral investigator

Technical field

The invention belongs to the experimental facilities field of analyzing.Be particularly related to the device of a kind of laser Raman spectroscopy and surface plasma resonance absorption spectrum synchronous detection.

Background technology

Finding that Surface enhanced raman spectroscopy (is called for short: SERS) in 30 years after the effect, although (be called for short: SPR) with SERS contact is closely arranged on the electromagnetism enhanced mechanism, few people are their simultaneous determinations and analyze its mutual relationship for the surface plasma resonance optical spectrum that various SERS active group basal surfaces or nano particle produce.Over the past two years, along with the fast development of these two technology, particularly people to the deepening continuously of the special size effect understanding of nanoparticle and film, this problem just begins to cause concern.The development of SPR-SERS spectrometer will provide important experimental basis for the research of SERS mechanism, also will become the important technical of further investigation surface and interface, nanostructured and characteristic.

The prior art close with the present invention is that the SPR-SERS of the Japanese Northwest Ozaki of university of institute (yukihiro Ozaki) group design detects spectrometer.The visible Fig. 1 of its primary structure, light-source system 1 are two light sources, and 11 is white light source, and 12 is LASER Light Source; 2 is sample stage, and 3 is silver particles or silver-colored single aggregation, is the silver-colored particle that has adsorbed the SERS bioactive molecule; 4 is microscopic system, and wherein 13 is object lens, and 14 is wave filter, and 15 is polarizer, and 16 is lens, and 17 is catoptron, and 18 is diaphragm, and 19 is eyepiece; 5 is signal detection system, comprises polychromator+CCD detecting device.Ozaki (yukihiro Ozaki) group considers that the electric field level that is positioned at the nano particle junction is relevant with the polarization of incident light situation, adopt the dark field microscope experimental provision, the SPR that laser excitation SERS composes and white light excites that has made respectively under the different polarization angle at the same position on the silver-colored aggregation that has adsorbed the SERS bioactive molecule composes, result of study finds that SPR and SERS increase simultaneously or reduce along with the polarization angle difference.They had both observed when the peak position of SPR band and had moved to higher-energy on same device, and observing SERS intensity again increases.

The SPR-SERS that the design of 0zaki group is built detects different test purpose of the two and the differences on the method for being with maximum of the present invention of spectrometer, the physical significance difference that information reflected of the two detection just.It is the SPR absorption characteristic and the relation that is adsorbed on SERS (perhaps SERRS) effect of the probe molecule on this particle that is used to discuss single aggregation or particle that the SPR-SERS of 0zaki group detects spectrometer; And the present invention is used for detecting simultaneously the angle of nano metal film material to a certain wavelength excitation light generation SPR resonance absorption, and the SERS effect that this material and absorbing molecules effect produce under SPR resonance absorption angle.

Summary of the invention

The technical problem to be solved in the present invention is: design special apparatus structure, make it can detect detected sample on the absorption nano metal film material simultaneously to the angle of a certain wavelength excitation light generation SPR resonance absorption, and the SERS effect of this material and absorbing molecules effect generation under SPR resonance absorption angle.

The angle of exciting light and sample can have configurations such as 90 degree and 180 degree backward scatterings in common SERS technology, does not consider the angular relationship of SERS enhancer and SPR resonance absorption.The present invention adopts angle internal reflection spectroscopy mode to detect SPR, in evanescent field sample excitation is obtained the SERS spectrum simultaneously.Owing under SPR resonance absorption angle, can obtain bigger SERS enhancer; This apparatus structure can synchronization gain SPR and the further SERS spectrum that strengthens.Because employing internal reflection spectroscopy mode to sample excitation, is measured the SERS signal under dark background in evanescent field, make non-SERS signal be suppressed, and can obtain higher SERS detection sensitivity and signal to noise ratio (S/N ratio).

The concrete structure of surface plasma body resonant vibration and surface reinforced Raman combined spectral investigator is: light-source system, comprise LASER Light Source, can adjust the optical facilities that excite angle and polarization state---angular instrument and polaroid, sample stage is the semicircle or hemispheric prism of square, the compound substrate of modifying with silver or gold with SERS activity on the bottom surface of prism.The spr signal detecting device, the SERS signal detection system of forming by spectroscope and CCD detecting device.Spr signal detecting device installation site and light-source system separation prism both sides; The SERS signal detection system places prism bottom surface faces sample, receives the SERS signal that sample produces at the LASER Light Source opposite side.

Be that variable detects the SPR spectrum with the laser incident angle during a whole set of instrument work, detect Raman spectrum at the details in a play not acted out on stage, but told through dialogues observation angle.

Angular instrument in the light-source system can adopt θ-2 θ goniometer configuration or the synchronous goniometer configuration of dicyclo; The SERS signal detection system is the polychromator+CCD detecting device of mid-focal length, also can adopt monochromator and single photon counting system.The collection of SERS signal can be adopted Lens Coupling/fibre-optical probe or microscope imaging device.

Test sample of the present invention needs pre-service, and detected sample is at first placed (perhaps by physics chemical action absorption) and on the substrate of modifying with silver or gold with SERS activity, this substrate is fixed on a square or the hemispheric prism then;

Prism had both carried sample substrate, was again coupling exciting light and SPR and two kinds of media that spectrum takes place simultaneously of SERS.Because prism adopts square or semisphere, guarantee the invariant position of the incident light excited sample of any angle.

Device of the present invention can also comprise employing fluid sampling system, thereby can realize that fluid detects in real time.

The preparation of substrate need be satisfied the requirement that SPR and SERS detect two aspects.The substrate that adopts methods such as vacuum coating, nanometer assembling will be generally used for the SPR test is modified into the substrate with SERS activity, makes it not only be suitable for the SPR test but also be fit to the Surface enhanced raman spectroscopy test.Study the architectural feature at the bottom of the high SERS active group, the decorative layer that preparation has higher SERS activity makes it obtain to use in interface and surface, nanostructured analysis and chip analysis chemical research.Preparation with the concrete grammar of the substrate with SERS activity that silver or gold are modified is:

1. vacuum evaporation metal film method: clean quartz or glass substrate are placed vacuum coater, and under the certain vacuum condition, with the metal melting gasification, evaporation forms metal level at substrate surface.

2. the method for making of supermolecule static assembling is specific as follows: 1, glass or quartz substrate are put into concentrated sulphuric acid hydrogen peroxide solution (volume ratio is 31) boil to there not being bubble to produce, this moment the optical fiber inside surface be hydroxyl (-OH) change the surface of processing; 2, the polymkeric substance of enrichment positive charge (is fixed on the surface as Poly (dially-dimethylammonium chloride is called for short PDDA) by the effect with hydroxyl; 3, aurosol that the surface is electronegative or silver sol by and polymkeric substance between electrostatic interaction be deposited in the substrate, 4, by reduction silver (gold) method on the throne---with reductive agents such as sodium borohydride, sodium citrate, p-dihydroxy-benzene, azanol reduction silver nitrate (gold chloride), make the sol particles thickening of growing up, until being fit to the thickness that SERS detects; Or the sol particles of the suitable yardstick of direct growth.

3. the method for chemical reaction assembling decorative layer is as follows: it is identical to handle 1,2 step of assembling with the static assemble method, then substrate is put into silver nitrate and IodineSodium Solution, generate silver iodide colloidal sol, this colloidal sol surface is a negative charge, is adsorbed on the PDDA, forms and decides the silver iodide colloidal sol of degree of roughness.Use reductive agent (as enumerating in the static assemble method 3) that silver iodide colloidal sol is reduced into silver particles at last, thereby finish modification substrate surface.

The experimental provision of the present invention's design has some different with independent SPR spectrometer and the Raman spectroscopy instrument that background technology relates to:

(1) with traditional independently SPR spectrometer device and independently the Raman spectrometer compare, the present invention has adopted compound apparatus structure, except possessing two quasi-instruments basic function separately, also have the synchronous detection function, its unique distinction is can strengthen under the angle in resonance sample excitation is obtained SERS spectrum.

(2) with background technology in the experimental provision of the zaki group described compare different test purpose of the two and the differences on the method for being with maximum of the present invention, the physical significance difference that information reflected of the two detection just.The SPR spectrum that SPR-SERS in the background technology detects in the spectrometer is at single particle or aggregation, employing be that white light source irradiation, absorption spectra mode detect, SERS spectrum is laser direct irradiation sample excitation SERS signal.And SPR spectrum of the present invention is at the superficial film material, the reflectance spectrum under the specific absorption angle of a certain wavelength (use be laser), and SERS spectrum is the SERS signal by the evanescent field excited sample.SPR-SERS in the background technology detects SPR spectral investigation purpose reflection that spectrometer detects by the relation between single particle or single aggregation SPR absorption characteristic (this characteristic is to be caused by nano-scale) and particle surperficial enhanced propertied.And the present invention is used for detecting simultaneously the angle of nano metal film material to a certain wavelength excitation light generation SPR resonance absorption, and the SERS effect that this material and absorbing molecules effect produce under SPR resonance absorption angle.

(3) front surface that the angle of exciting light and sample is generally configurations such as 0-90 degree in the background technology excites, the present invention adopt the internal reflection spectroscopy mode in evanescent field to sample excitation, under dark background, measure the SERS signal, make non-SERS signal be suppressed, can obtain higher SERS detection sensitivity and signal to noise ratio (S/N ratio).

Description of drawings

Fig. 1 is that the SPR-SERS of background technology detects spectrometer

Fig. 2 is the structure principle chart of surface plasma body resonant vibration of the present invention and surface reinforced Raman combined spectral investigator.

Embodiment

Below in conjunction with accompanying drawing SPR-SERS joint test instrument apparatus of the present invention is further specified.

Embodiment 1

See Fig. 1,1 is light-source system, constitute by LASER Light Source 21, and be thereafter to adjust the optical facilities that excite angle and polarization state, comprise angular instrument (not drawing among Fig. 1) and polaroid 22, angular instrument can adopt θ-2 θ goniometer configuration or the synchronous goniometer configuration of dicyclo.2 is sample stage, sample stage 2 adopts the semicircle or hemispheric prism 23 of square, the compound substrate of modifying with silver or gold with SERS activity 24 on the bottom surface of prism, 25 is the modified membrane of silver or gold copper-base alloy, sample 26 is placed on the

substrate

24,27 expression evanescent waves, 28 presentation surface plasma waves.4 is microscopic system, and wherein 13 is object lens, and 14 is wave filter, and 15 is polarizer, and 16 is lens, and 17 is that catoptron 18 is diaphragm, and 19 is eyepiece; 5 is the SERS signal detection system, and signal detection system comprises polychromator+CCD detecting device, adopts fibre-optical probe or microscopie unit to collect the SERS signal.6 is the spr signal detecting device.

When surface plasma body resonant vibration of the present invention and surface reinforced Raman combined spectral investigator work, the monochromatic light that LASER Light Source 21 is sent incides the bottom surface of prism 23 through polaroid 22 vertical prisms 23 surfaces, the vertical prism of reflected light 23 symmetrical surfaces arrive spr signal detecting device 6, obtain the surface plasma resonance optical spectrum figure of sample.Monochromatic light incides the SERS signal that the transmitted light behind prism 23 bottom surfaces obtains through sample 26, is accepted by SERS signal detection system 5 through microscopic system 4, thereby obtains the Surface enhanced raman spectroscopy of sample 26.The present invention excites angle by the angular instrument change, detects SERS spectrum at SPR maximum resonance absorption point place, is maximal value in this angle SERS enhancer, promptly can the strongest SPR and the SERS spectrum of synchronization gain.

Embodiment 2

The fluid sampling system can be made of the devices such as sample cell, sample recovery pond and liquid-transport pipe-line that comprise stepper motor, be placed on prism 23 bottom surfaces.

Claims

1, a kind of surface plasma body resonant vibration and surface reinforced Raman combined spectral investigator, structure have light-source system (1), sample stage (2), microscopic system (4), SERS signal detection system (5); Object lens (13), wave filter (14), polarizer (15), lens (16), catoptron (17), diaphragm (18) and eyepiece (19) are wherein arranged in the microscopic system (4); SERS signal detection system (5) comprises polychromator and CCD detecting device; It is characterized in that light-source system (1) is single LASER Light Source (21), is thereafter to adjust the optical facilities that excite angle and polarization state, comprises angular instrument and polaroid (22); Sample stage (2) is the semicircle or hemispheric prism of square (23), the compound substrate of modifying with silver or gold with SERS activity (24) on the bottom surface of prism (23), and sample (26) is placed on the substrate (24); The installation site of spr signal detecting device (6) and light-source system (1) separation prism (23) both sides; SERS signal detection system (5) places prism (23) bottom surface faces sample (26), receives the SERS signal that sample (26) produces at LASER Light Source (21) opposite side.

According to described surface plasma body resonant vibration of claim 1 and surface reinforced Raman combined spectral investigator, it is characterized in that 2, said angular instrument adopts θ-2 θ goniometer configuration or the synchronous goniometer configuration of dicyclo; Said SERS signal detection system (5) is the monochromator and the photomultiplier single photon counting system of 320mm focal length, adopts fibre-optical probe or microscopie unit to collect the SERS signal.