Photoluminescence from nanosize gold clusters

Abstract

We have observed visible light emission from nanosize gold clusters. Liquid chromatographic analysis of the metal clusters shows that relatively intense photoluminescence occurs only when the size of the metal nanocluster is sufficiently small (<5 nm). The emission is strongly Stokes shifted and is assigned to radiative recombination of Fermi level electrons and sp- or d-band holes. The electron and/or hole states are perturbed by surface states, as indicated by the dependence of the emission spectrum on the nature of the cluster surface. Finally, we found that large, nonemitting gold clusters can also be made luminescent by partial dissolution using KCN.

Blue luminescence of Au nanoclusters embedded in silica matrix

“…Broad blue bands at ~3.1 eV and ~3.4 eV match closely with those reported for ~5 nm Au colloidal solution. 5 A prominent peak at 3.1 eV is also reported for supported Au nanoislands with relatively larger size ( ≥10 nm). 4 A small blueshift (~0.1 eV) along with increase in the intensity is observed for peak position at 3.4 eV with decreasing fluence, i.e., decreasing nanoparticle size.…”

“…3 Radiative decay of collective plasmon states of the nanoislands is thought to be responsible for the observed PL. Blue luminescence from both the supported Au nanoislands ( ≥ 10 nm) 4 and Au colloidal suspension (~5 nm) 5 have also been reported. The origin of PL is primarily assigned to the radiative recombination of Fermi level electrons and d-band holes.…”

“…The origin of PL is primarily assigned to the radiative recombination of Fermi level electrons and d-band holes. 4,5 Moreover, recent studies on lifetime of hot electrons (electrons above Fermi level) in noble metals, namely, Au and Cu have shown interesting results with increased decay time considering electron-electron ( e-e) scattering involved in the relaxation process. 6,7 With several advantages of embedded nanoclusters, e.g., its chemical stability and capability of use in practical nonlinear device applications, PL study of these structures is of high importance.…”

Photothermal Methods for Single Nonluminescent Nano-Objects

“…Because the luminescence yield of these particles is extremely weak, almost all of the absorbed energy is converted into heat (8). The increase in temperature induced by this absorption gives rise to a local variation of the refractive index.…”

Fine structure of gold nanoparticles stabilized by buthyldithiol: Species identified by Mössbauer spectroscopy

“…Small particles with diameters below 2 nm exhibit intense photoluminescence [8,12,13], e.g. cytotoxic singlet oxygen can be generated on them by using appropriate photosensitisers [14].…”