Confined plasmons in nanofabricated single silver particle pairs:: Experimental observations of strong interparticle interactions

被引:472
作者
Gunnarsson, L
Rindzevicius, T
Prikulis, J
Kasemo, B
Käll, M
Zou, SL
Schatz, GC
机构
[1] Chalmers Univ Technol, Dept Appl Phys, SE-41296 Gothenburg, Sweden
[2] Northwestern Univ, Dept Chem, Evanston, IL 60208 USA
关键词
D O I
10.1021/jp049084e
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We report on the optical properties of single isolated silver nanodisks and pairs of disks fabricated by electron beam lithography. By systematically varying the disk size and surface separation and recording elastic scattering spectra in different polarization configurations, we found evidence for extremely strong interparticle interactions. The dipolar surface plasmon resonance for polarization parallel to the dimer axis exhibited a red shift as the interdimer separation was decreased; as expected from previous work, an extremely strong shift was observed. The scattering spectra of single particles and pairs separated by more than one particle radius can be well described by the coupled dipole approximation (CDA), where the particles are approximated as point dipoles using a modified dipole polarizability for oblate spheroids. For smaller particle separations (d < 20 nm), the simple dipole model severely underestimates the particle interaction. indicating the importance of multipolar fields and finite-size effects. The discrete dipole approximation (DDA), which is a finite-element method. describes the experimental results well even at d < 20 nm. including particles that have metallic bridges.
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页码:1079 / 1087
页数:9
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