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Enhanced Raman Scattering of amorphous matrices for Fiber Optics Sensor
M Amraoui, M Fombonne, Marie Adier, A-M Jurdyc, F. Bessueille, Bernard Champagnon, J. Margueritat, L. Bois, Bernard Dussardier, Dominique
Vouagner
To cite this version:
M Amraoui, M Fombonne, Marie Adier, A-M Jurdyc, F. Bessueille, et al.. Enhanced Raman Scattering of amorphous matrices for Fiber Optics Sensor. 3rd International Workshop on Metallic Nano-Objects (MNO 2016), Nov 2016, Lyon, France. �hal-02332400�
M.Amraoui
1, M.Fombonne
1, M.Adier
1, A-M.Jurdyc
1, F.Bessueille
2, B.Champagnon
1, J.Margueritat
1, L.Bois
3, B,Dussardier
4, D.Vouagner
11
Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex, France
2Institut des Sciences Analytiques, UMR5280 UCB Lyon 1-CNRS, Université de Lyon, 69100 Villeurbanne Cedex, France
3
Laboratoire des Multimatériaux et Interfaces, UMR5615, UCB Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex, France
4LPMC, CNRS, UMR 7336, Université Nice Sophia Antipolis, Parc Valrose 06108 NICE CEDEX 2, France
Enhanced Raman Scattering of amorphous
matrices for Fiber Optics Sensor
Extinction spectroscopy: LSPR and transmission window (absence of LSPR) Enhanced Raman spectra of SiO2 (200nm)
with both gold structure (HP and LP) on glass slide (baseline removed) AFM images (after removing the sol gel layer
of SiO2) Application to a silica fiber (25nm Au (HP) + 200nm sol gel)
Experimental results
Introduction and objectives
Discussion and conclusion
Surface-Enhanced Raman Scattering (SERS)
2. Chemical effect :
Charge transfer between metal and adsorbed molecules inducing an increase of dielectric polarizability α.
1. Electromagnetic effect :
Surface plasmon resonance increases local electric field Elloc intensity experienced by Raman probed materials:
- Localized surface plasmon resonance (LSPR)
- Propagative surface plasmon (SPP)
𝐼
𝑅𝑎𝑚𝑎𝑛∝ 𝛼²𝐸
𝑙𝑜𝑐²λexc= 780 nm, Pinc= 14 mW, tintegration= 1 min, ObjX20 (NA=0,40) • Most of Surface Enhanced Raman Scattering Sensors (SERS) is applied
to detection of molecules in solution
• Development of a Fiber Optic Sensor (FOS) allowing the detection of liquid and solid analytes
• SERS at the interface between Raman probed materials and a noble metal with a negative real part dielectric constant ε(ω)<0 (Au, Ag…)
• Two mechanisms are responsible for SERS
Raman shift (cm-¹) In te ns ity (c ou nt s) 500 1 000 1 500 0 100 200 300 400 500 600 700 Spectrum : 1020pbRS 1020pbRS 8025hpref1 26 4. 27 38 4. 15 49 0. 47 61 7. 13 79 3. 57 992. 62 Raman shift (cm-¹) In te ns ity (c ou nt s) 400 600 800 1.0 1.5 2.0 2.5 3.0 Spectrum : 1020pbRS 64 1.5 7 1020pbRS 8025hpRS ref abs 61 9.0 7 Wavelenght (nm) Ex tinction (D,O) LP « heaps » structure Particle size 128±15nm RMS : 1,52 HP « granular » structure Particle size 72±12nm RMS : 3,17 nm 10 mA 20nm LP 80 mA 25nm HP ref1 300 400 500 600 700 800 1,0 1,5 2,0 2,5 3,0 3,5 4,0 Ex tinc tion (D .O) Wavelength (nm) 10 mA 20nm LP 80 mA 25nm HP ref1 Non exalting « granular » structure Particle size 202±32nm 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 20 40 60 80 100 120 140 160 180 0 200 400 600 800 1000 1200 1400 1600 1800 2000 10 20 30 40 50 60 70 80 In te n sity (cou n ts) Raman Shift (cm-1) Fiber + Au + Si 0 200 400 600 800 1000120014001600 18002000 2 4 6 8 10 12 14 16 18 20 In te n si ty (co u n ts) Raman Shift (cm-1 ) Fiber + Au 265 497 392 Raman Shift (cm-1) Fiber + Au + Ti 639
• Application to sol gel amorphous matrices (TiO2, SiO2) covering a nanostructured gold layer deposited on glass substrate and pieces of stripped optical fibers (model samples)
laser @ 780nm To Raman spectrometer Enhanced backscattered signal Microscope objective
Raman experimental setup
Sputtering Intensity (mA) Sputtering pressure (mbar) Gold structure 80 0,1 HP 10 0,05 LP
Tested samples
Sol gel layer (200nm)
Gold nanostructured film (25nm)
Glass slide /optical fiber substrate
Sol gel layer (analyte)
Gold nanostructured film
Glass substrate
• In the case of solid analytes: surface (SERS) or volume (VERS*) effect? * Volume Enhanced Raman Scattering?
• Similar Raman exaltation with 2 different nanostructured gold layer HP, LP (nanostructures size and roughness)
laser @ 780nm To Raman spectrometer Enhanced Backscattered signal Microscope objective Analyte Nanostructured metallic film Incident light Lens
Stripped optical fiber
Metallized silica fiber covered by sol gel Step 4 : Annealing (solvent removing ) 250°C 30 min
Model samples elaboration
Step 2 : Sol elaboration
- SiO2 precursors: TEOS + Ethanol + Chlorhydric
acid
- TiO2 precursors: Titanium isopropoxyde + Methanol + acetic acid
Step 3 : Dip-coating of amorphous gel layer Step 1 : Gold sputtering
B e- e- Ar Path of : Argon atoms Argon Ions
Atoms from the cathode Electrons Substrate Anode Cathode Magnet Ar+ Ar+ Ar+
- Raman bands exaltation of amorphous matrices (TiO2 and SiO2) obtained after metallization (nanostructured gold layer) of model samples (glass slide and pieces of stripped optical fibers). No Raman signal is obtained without this underlying gold layer.
- Amorphous SiO2 identified Raman bands : D0 band at 490 cm-1 => O
3Si-OH symmetric stretch
D2 band at 617 cm-1 => ring breathing of three-membered siloxane
Band at 793 cm-1 => bond-bending vibration of Si-O-Si
Band at 992 cm-1 => symmetric stretch vibrations of silanol ≡Si-OH
Strong band at 264 cm-1 => unidentified, might be due to phase transformations. - Amorphous TiO2 identified Raman bands :
Band at 639 cm-1 => Ti-O stretching vibration
- Lowering the pressure during the sputtering allow to get two different nanostructures (gold
nanostructures size and roughness) but both Enhanced Raman spectra are almost identical: the
number of interstices between gold grains, where hot spots take place, and where sol can penetrate during the dip coating process, could be an important factor for this enhancement effect.
- The next step will be to test Raman Enhancement by guided optics allowing a coupling between the optical mode of the fiber and the gold plasmon wave.
Beam splitter
• Raman signal exaltation of amorphous matrices (TiO2 and SiO2) obtained after metallization of the stripped fiber pieces
