Gap-Plasmon Enhanced Gold
Nanoparticle Photoluminescence
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Abstract
Gap-plasmon-enhanced
gold nanoparticle photoluminescence is studied
experimentally at the single-particle level. The photoluminescence
spectra of gold nanoparticles on an Al<sub>2</sub>O<sub>3</sub>-coated
gold film under both 532 and 633 nm excitation show a clear peak near
the measured gap-plasmon resonance wavelength. Comparing the collected
emission spectrum with that from a gold reference film under 633 nm
excitation, a peak photoluminescence enhancement factor of 28β000
is observed. The spectral shape and absolute magnitude of the enhancement
factors for both excitation wavelengths are reproduced using numerical
calculations without the use of any free parameters. The photoluminescence
enhancement is explained in terms of a gap-mode-enhanced e<i>β</i>h pair generation rate and a wavelength-dependent
enhancement of the emission efficiency