Silver nanowires as receiving-radiating nanoantennas in plasmon-enhanced up-conversion processes

Abstract

We demonstrate efficient coupling between plasmons in a single silver nanowire and nanocrystals doped with rare earth ions, α-NaYF4:Er(3+)/Yb(3+). Plasmonic interaction results in a sevenfold increase of the up-converted emission of nanocrystals located in the vicinity of the nanowires as well as much faster luminescence decays. The enhancement of the emission can be precisely controlled by the polarization of the excitation laser and is significantly stronger for polarization parallel to the nanowire antennas. Imaging of angular-resolved emission patterns in the Fourier plane reveals plasmon-mediated luminescence, where the up-converted radiation is emitted via the nanowire antennas as leakage radiation.

Spectral Selectivity of Plasmonic Interactions between Individual Up-Converting Nanocrystals and Spherical Gold Nanoparticles

“…As the interactions with plasmon excitations in metallic nanoparticles frequently yield strong modifications of the radiative properties of nearby emitters, in order to quantify the observed effects, it is necessary to measure—in addition to PL intensity—also the PL dynamics, especially the FLIM (Fluorescence-lifetime Imaging Microscopy) maps. Thus, we have carried out spatially-resolved PL lifetime imaging experiment with microsecond temporal resolution [ 19 , 20 ]. Briefly, we raster scanned the sample and measured the luminescence transient for each position on the piezo stage for both emissions.…”

“…Briefly, we raster scanned the sample and measured the luminescence transient for each position on the piezo stage for both emissions. Subsequently, we estimated the intensity-weighted average lifetime and assigned the obtained value to each pixel on the map [ 19 ]. The resulting spatial distributions of the PL decay time obtained for the same regions as shown in Figure 2 a,b, are displayed in Figure 2 d,e.…”

Photochemical Printing of Plasmonically Active Silver Nanostructures

“…of erbium and is presented in Figure 3. Nanocrystals excited at 980 nm show visible up-conversion emission lines, centered at 550 and 660 nm, assigned to the 2 H11/2+ 4 S3/2→ 4 I15/2 and 4 F9/2→ 4 I15/2 electricdipole transitions in Er 3+ ions, respectively (Figure 4a) [25]. Typical photoluminescence transient acquired at 660 nm for a single NC on glass is presented in Figure 4b.…”

“…Erbium-ytterbium doped NaYF 4 nanocrystals were synthesized by wet chemistry, as described elsewhere [24]. They exhibit efficient anti-Stokes luminescence, commonly referred to as energy transfer up-conversion emission [25]. In this system, Yb 3+ plays the role of a donor, whereas Er 3+ is the acceptor of the energy.…”

“…Typical photoluminescence transient acquired at 660 nm for a single NC on glass is presented in Figure 4b. The transient has a biexponential character, and can be globally described by the averaged time constant of about 120 μs [25]. Nanocrystals, with an average diameter of about 30 nm, were dispersed in chloroform, where they form an optically stable colloid.…”