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Volume 5, Issue 3 (Suppl)
Mod Chem Appl, an open access journal
ISSN: 2329-6798
Global Chemistry 2017
September 04-06, 2017
September 04-06, 2017 | London, UK
5
th
Global Chemistry Congress
Mod Chem Appl 2017, 5:3(Suppl)
DOI: 10.4172/2329-6798-C1-006
Single particle spectroscopic studies on two-photon photoluminescence of plasmon coupled gold nano
triangle dimers
Monalisa Garai
and
Qing-Hua Xu
NUS, Singapore
S
urface plasmon resonance (SPR) coupling between adjacent metal nanoparticles in aggregated nanoclusters results in
significant enhancements in many optical responses, such as fluorescence, surface enhanced Raman scattering (SERS) and
two-photon photoluminescence (2PPL). Here, 2PPL properties of gold nanotriangle (Au NT) dimers with different spatial
arrangements have been investigated on single particle level to understand their different plasmon coupling effects on 2PPL
enhancement mechanism and explore the limit of maximum achievable enhancement factor.
Compared to NT monomer, scattering spectra of both side-by-side and tip-to-tip coupled NT dimers are red-shifted by 101
nm and 175 nm respectively with strong polarization dependence along their assembly axis, which can be understood in terms
of plasmon hybridization theory. A close resemblance between scattering spectra and 2PPL spectra indicated SPR is the origin
of observed 2PPL signal. 2PPL intensities of side-by-side and tip-to-tip dimers are enhanced by 1.0×10
3
fold and 2.6×10
4
fold
respectively, compared to the NT monomer. Such a huge enhancement in tip-to-tip dimer is a combined effect of plasmon-
coupling-induced red-shifted SPR band which has better overlap with the excitation wavelength and giant local electric field
amplification due to the presence of sharp tips in interparticle gap. The influence of sharp tips has been further demonstrated
by comparing Au NT monomer and dimers with Au nanosphere (NS) monomer and dimer of similar dimensions. The 2PPL
intensity of Au NT monomer is 20 times stronger compared to Au NS monomer, where as that of Au NT tip-to-tip dimer
is 93.5 times stronger compared to Au NS dimer. All our experimental results show excellent agreement with numerically
calculated integrated |E/E0|4 results. These findings offer a deeper insight in fundamental understanding of plasmon coupling
enhanced 2PPL properties and provide a platform for various sensing and imaging applications.
a0107206@u.nus.edu