FEM And Near-field Simulations: A Vital Mechanistic Tool for Studying Silver-based Plasmonic Systems Ramesh Asapu 1 , Sammy Verbruggen 1,2 , Nathalie Claes 3 , Sara Bals 3 , Siegfried Denys 1 and Silvia Leanerts 1 1 Department of Bioscience Engineering, DuEL, University of Antwerp, Belgium 2 Centre for Surface Chemistry and Catalysis, COK, KU Leuven, Belgium 3 Department of Physics, EMAT, University of Antwerp, Belgium
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FEM And Near-field Simulations: A Vital Mechanistic Toolfor Studying Silver-based Plasmonic Systems
Ramesh Asapu1, Sammy Verbruggen1,2, Nathalie Claes3, Sara Bals3, Siegfried Denys1 and Silvia Leanerts1
1Department of Bioscience Engineering, DuEL, University of Antwerp, Belgium2Centre for Surface Chemistry and Catalysis, COK, KU Leuven, Belgium3Department of Physics, EMAT, University of Antwerp, Belgium
Silver Plasmonic Systems: What and Where?
Surface Plasmon Resonance:
Collective oscillation of conduction electrons at the dielectric-metal interface of a nanoparticle stimulated by incident light of matching wavelength.
Highest near field enhancement by silver among the plasmonic noble metals like Au, Ag, Pt, Cu etc.
Size tuneable plasmonic properties β FEM vital tool for analysis
Ag silver nanoparticles exhibit high near field enhancement
Prone to oxidation forming a diffuse Ag2O layer effecting the near field enhancement significantly.
Not suitable for applications over long period of time or oxidative conditions.
Ξ»Inc = 355 nm
E
k5 nm
Ag2O shell 2 nm
Ξ»Inc = 355 nm
E
k5 nm
a) b)
E-Field enhancement contour of Ag nanoparticle
Ξ»Inc = 355 nm
E
k5 nm
Ag2O shell 2 nm
Ξ»Inc = 355 nm
E
k5 nm
a) b)
E-Field enhancement contour of Ag@Ag2O nanoparticle
Silver colloidal nanoparticles stability test in air
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Ultrastable Ag nanoparticles:
Encapsulation of Ag NPs with ultrathin protective polymer shell using LbL method.
4 layers Ag/(PAH/PAA)2
shell 1.4 nm
8 layers Ag/(PAH/PAA)4
Shell 2.4 nm
Bare Ag nanoparticle dia~18nm
Effect of polymer shell on the field enhancement of core-shell nanoparticles.
polymer shell thickness (nm)
0 2 4 6 8 10
Ma
xim
um
en
ha
nce
me
nt fa
cto
r |E
/E0|2
0
100
200
300
400
500
TEM Characterization
Centrifuge to remove excess
polymer
Ag NP
Polyelectrolyte
Ag NPOne cycle
each of
polycationand polyanion= One Bilayer
20 min stirring under dark
Centrifuge Final washing step
Redispersed in Milli-Q water
Validation of models:
Parametric sweep of incident wavelength to generate extincion plots (Mie solution implementation in COMSOL in water and npolymershell = 1.48
Experimental absorption spectra compared with COMSOL model and Mie analytical solution using Bohren and Huffmanβs BHCOAT (implemented in MATLAB) for coated nanoparticles. Data from J&C β Jhonson and Christy
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4.34.8
5.4
400.9
386.9 386.7
405.2
391.7 392.1
365
370
375
380
385
390
395
400
405
410
415
0
2
4
6
8
10
12
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Experimental Mie Analytical J&C Comsol J&C
Surface P
lasmo
n R
eson
ance Ξ»
SPR
max
Red
sh
ift
in S
urf
ace
Pla
smo
n R
eso
on
ance
(n
m)
SPR Red shift SPR-Layer 0 SPR-Layer 4
8 layers Ag/(PAH/PAA)4 2.4 nm shell
4 layers Ag/(PAH/PAA)2 1.4 nm shell
Bare Ag anoparticle 18 nm
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Ultrastable Ag plasmonic nanoarrays for multi-domain applications:
Ag nanoparticle arrays generate hot spots SERS : EF4 ~ 108-1011
Engineering of Nano arrays based on the feedback from E-field simulations. Mesh convergence study for core-shell nanoparticle dimers
Mesh Density Number of Elements Computation time [s] Max point of (Norm. E-field)2
Normal 10374 9 3.13E+05
Fine 16588 11 4.64E+05
Finer 42048 24 4.21E+05
Extra fine 135833 85 3.50E+05
Extremely fine 647861 609 3.45E+05
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Ag plasmon enhanced TiO2 gas phase photocatalysis
Application of silver nanoparticles for long-term stable plasmonenhanced gas phase photocatalysis.
Acetaldehyde as a model pollutant in gas phase photocatalysis
FEM numerical simulations to corroborate experimental evidence to identify the major mechanism responsible for plasmonic enhancement.
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18.6
25.2
21.0
17.0
19.821.3
18.216.8
22.0
0
5
10
15
20
25
30
P25 P25_Ag P25_Ag_L4
% A
ceta
ldeh
yde
deg
rad
atio
n
Long term stability study of Ag-TiO2 photocatalytic system using 4 layered Ag core-shell nanoparticles