Resonance energy transfer near metal nanostructures mediated by surface plasmons

We develop a unified theory of plasmon-assisted resonance energy transfer (RET) between molecules near a metal nanostructure that maintains energy balance between transfer, dissipation, and radiation. We show that in a wide range of parameters, including in the near field, RET is dominated by plasmon-enhanced radiative transfer (PERT) rather than by a nonradiative transfer mechanism. Our numerical calculations performed for molecules near the Ag nanoparticle indicate that RET magnitude is highly sensitive to molecules’ positions.

Figure 1

RET vs distance for $R=30$ nm Ag NP is shown at $\theta =\pi /3$ with (a) $d_a=d_d=d$ and (b) $d_a=20$ nm, $d_d=d$ using the full Eq. (2), the nonradiative (NR) channel only, Förster’s transfer Eq. (1), and the Gersten-Nitzan (GN) model.[30, 31]

Figure 2

(a) Spectral function Eq. (16) and molecules’ optical bands relative to SP band ${\alpha }_1/R^3$ (inset) are shown together with (b) quenching factor ${\gamma }_d^r/{\Gamma }_d$ and coupling $\left|D_{\mathrm{ad}}\right|{}^2$ (inset) using full and nonradiative (NR) models.

Figure 3

RET vs distance for $R=20$ nm Ag NP is shown (a) at $\theta =\pi /3$ with $d_a=d_d$ and $d_a=2$ nm (inset) and (b) with $d_a=10$ nm at $\theta =\pi /3$ and $\theta =\pi$ (inset) using full, nonradiative (NR), and Förster models.