Abstract:
Interparticle dipolar coupling leads to a shift in plasmon absorption maxima as particles are brought from infinite distance to the proximity of each other. The distance between the particles can thus be related to the shift in the plasmon band3-5. Sonnichsen et al.4 and Reinhard et al.5 designed a plasmon ruler equation based on this principle. Using an appropriate biomolecular binding scheme they achieved coupling of gold nanoparticles and measured nanoscale distances in biological systeM.S. based on the observed shift in the plasmon band. Few quantitative studies have been carried out on the distance dependence of dipolar plasmon coupling in systeM.S. in which metal particles are separated by a dielectric gap and a universal scaling behavior has been predicted.6-9 Such studies include lithographically fabricated Au nanodiscs in polymers,6,7,10, dielectric core-Au nanoshells,8,11 head-to-tail dimers of elongated particles of different aspect ratios and curvatures and a trimer of nanospheres9. We considered it to be of interest to examine whether the same scaling law extends to a 3-dimensional assembly of metal particles e.g. those frozen in polymer matrices.
