Pairs of silver nanoparticles with diameters of 41.0 � 4.6 nm, so called silver plasmon rulers, were synthesized using a rational DNA programmed self-assembly procedure. The relationship of plasmon resonance energy (Eres) versus interparticle distance was calibrated for these dimers in the 1-25 nm range by correlating single dimer Rayleigh scattering spectra with structural information obtained through transmission electron microscopy. The performed calibration reveals two different plasmon coupling regimes . For dimers with large separation, Eres red-shifts continuously with decreasing center-to-center distance (L) until the L to diameter (D) ratio reaches a value of L/D ~ 1.05. For nearly touching dimers with L/D <1.05, Eres does not further decrease, instead the slope of Eres(L/D) levels off. Overall, the spectral response of nearly touching dimers indicates a reduced plasmon coupling in nearly touching noble metal nanoparticles which has important implications for the design of noble metal nanostructures with maximized E-field enhancement.

Calibration of the distance dependent plasmon coupling in dimers of DNA tethered silver nanoparticles: Experimental evidence of distinct plasmon coupling regimes

239th National Meeting (2010)

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