(a) Distribution of particle radii determined from AFM counted in 3 nm bins and resulting fit of data by a Gaussian distribution with a mean radius and a standard deviation σ; (b) AFM image of vacuum dried NP with mean radius of 28 nm on glass. Regions of non-aggregated NPs were used for determining size distribution.
Normalized optical absorbance (solid) and emission (dashed) spectra of Methylene Blue, Cresyl Violet, and MEH-PPV nanoparticles (exc: 500 nm). There is significant spectral overlap between MEH-PPV NP emission and the absorption spectra of dyes.
Emission spectra (exc: 500 nm) and Stern-Volmer plots for quenching experiments conducted using MEH-PPV NPs. Extrapolated lines are used to estimate Γ when the NP surface is saturated with quencher dyes.
Lifetime measurement of MEH-PPV NPs from time-correlated single-photon counting transients with various Methylene Blue concentrations. Measurement error is smaller than the displayed markers. MEH-PPV lifetime is reduced by addition of quencher dye on a similar scale as the reduction of integrated emission in steady-state photoluminescence measurements.
Plots of normalized exciton density ( ) from Eq. (15) with L, R, and r scaled by 1/R at constant L = 0.3R for various quenching efficiencies.
Plots of normalized exciton density ( ) from Eq. (15) with L, R, and r scaled by 1/R for various L at 100% quenching efficiency (a) and 50% quenching efficiency (b).
(a) Contour plot of simulated quenching from numerical integration of Eq. (15) in Eq. (16) for a Gaussian distribution of NP radii, showing the dependence of the L on the efficiency of quenching efficiency [color online]; (b) Model given by Eqs. (15) and (16) with numerical integration over for both the fitted Gaussian function and the measured distribution of nanoparticle sizes. The simulated lines were further compared with the one obtained from approximate solution (Eq. (20) ) using = 28 nm and σ = 5 nm.
Article metrics loading...
Full text loading...