Tunneling-Electron-Induced Light Emission from Single Gold Nanoclusters (original) (raw)
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Journal of Nano- and Electronic Physics, 2016
The light emission spectra of individual Au nanoparticles induced by a scanning tunneling microscope (STM) have been investigated. Two-dimensional ensembles of tunnel-coupled Au particles were prepared by thermal evaporation onto a native oxide silicon wafer in ultrahigh vacuum (10-9 mbar). Our STM measurements show a single peak at photon energy 1.6 eV in the tunneling mode and two peaks at 2.2 eV (connected with the Mie plasmon) and 1.45 eV (a new peak which was not discussed in literature before) in the field emission mode.
Nanoscale, 2014
Preformed Co clusters with an average diameter of 2.5 nm are produced in the gas phase and are deposited under controlled ultra-high vacuum conditions onto a thin insulating NaCl film on Au(111). Relying on a combined experimental and theoretical investigation, we demonstrate visualization of the threedimensional atomic structure of the Co clusters by high-resolution scanning tunneling microscopy (STM) using a Cl functionalized STM tip that can be obtained on the NaCl surface. More generally, use of a functionalized STM tip may allow for systematic atomic structure determination with STM of nanoparticles that are deposited on metal surfaces.
Photon emission from nano-granular gold excited by electron tunneling
Surface Science, 1992
Using a scanning tunneling microscope, photon emission induced by electron tunneling into a granular gold surface was investigated. The samples consisted of aggregated small particles ~ 25 nm in diameter. We measured the intensity of light emission as a function of the applied bias voltage and observed resonance peaks at 1.9 and 2.7 V. The maxima lie at energies corresponding to the local and the extended plasmons of the granular gold surface.
Light emission from small metal particles and thin metal films excited by tunneling electrons
Physical Review B
We have measured the light intensity versus photon energy of six types of electron tunnel junctions and compared the experimental results to the localized plasmon model of Rendell, Muhlschlegel, and Scalapino, and to the smooth and slightly roughened junction model of Laks and Mills. The types of junctions used to test the theories were Al-Al, O, junctions completed with a top electrode consisting of either an evaporated metal film of Au or Ag, or evaporated Au or Ag particles that were electrically connected by an evaporated Au or Ag film. The p-s-polarized light emitted by junctions with Au or Ag particles is consistent with the localized plasmon model. The "s"-polarized light of the particle junctions and the essentially unpolarized light of the Au and Ag film junctions may be consistent with the theory of Laks and Mills for slightly roughened junctions.
Size and Shape Dependence of the Electronic Structure of Gold Nanoclusters on TiO2
Understanding the mechanism behind the superior catalytic power of single- or few-atom heterogeneous catalysts has become an important topic in surface chemistry. This is particularly the case for gold, with TiO2 being an efficient support. Here we use scanning tunneling microscopy/spectroscopy with theoretical calculations to investigate the adsorption geometry and local electronic structure of several-atom Au clusters on rutile TiO2(110), with the clusters fabricated by controlled manipulation of single atoms. Our study confirms that Au1 and Au2 clusters prefer adsorption at surface O vacancies. Au3 clusters adsorb at O vacancies in a linear-chain configuration parallel to the surface; in the absence of O vacancies they adsorb at Ti5c sites with a structure of a vertically pointing upright triangle. We find that both the electronic structure and cluster-substrate charge transfer depend critically on the cluster size, bonding configuration, and local environment. This suggests the possibility of engineering cluster selectivity for specific catalytic reactions.
Physical Review B
We have investigated the scanning-tunneling microscope ͑STM͒ light-emission mechanism of the Au(110)-(2ϫ1) surface. We found that the light stimulated by the STM is emitted through three different channels. The first channel is the emission through excitation of localized surface plasmons ͑LSP͒. The other two channels are through the recombination of d-band holes and s-p electrons in Au. When the sample bias voltage is positive ͑i.e., electrons are injected into the sample͒, d-band holes are created by impact ionization. The intensity due to this process is greater when the tip is located between the Au atomic rows than over the row. This process is the origin of the atomic-site-dependent spectra that we reported in a previous paper ͓Y.
Scanning tunneling microscope (STM) light emission spectroscopy of surface nanostructures
Journal of Electron Spectroscopy and Related Phenomena, 2000
We present an overview of the experimental method and physical principles of scanning tunneling microscope (STM) light emission spectroscopy (STM-LES). By this new spectroscopic technique one can obtain the optical emission spectra of specific and individual surface nanostructures that are imaged by the STM. This method has been used to investigate the electronic transitions in surface nanostructures such as the protrusions of porous Si, the quantum wells of a semiconductor, and the rows and valleys of the reconstructed Au(110) surface.
Effects of plasmon energetics on light emission induced by scanning tunneling microscopy
Journal of Physics: Condensed Matter, 2014
Luminescence from systems containing coupled molecular excitons and plasmons has attracted much attention in the studies of interaction of light with nanomaterials. Intense electromagnetic fields generated by interface plasmons are exploited to enhance the luminescence intensity of target molecules [1-3]. Recent studies have also suggested that the dynamics of molecules including luminescence and energy absorption can affect the optical properties mediated by interface plasmons [4-6]. Interplay between the dynamics of molecular excitons and interface plasmons gives rise to peculiar phenomena that cannot be explained by taking into account only the individual field properties. Understanding of their interplay on the microscopic level is a prerequisite to interpretation of complex optical properties of these systems, enables novel insight into the complicated aspects of light-matter interaction and helps in developing new technologies utilizing the control of energy conversion among plasmons, excitons, and photons. The highly localized tunneling current of a scanning tunneling microscope (STM) can be used as an atomic-scale source to induce light emission (LE) from the system. In STM-LE from clean and molecule-covered metal substrate, interface plasmons localized near the tip-sample gap region play important roles. It is well established that light emission from clean metal surfaces is due to the radiative decay of interface plasmons [7-9].
Giant Emission Enhancement of Solid‐State Gold Nanoclusters by Surface Engineering
Angewandte Chemie International Edition, 2020
Ligand‐induced surface restructuring with heteroatomic doping is used to precisely modify the surface of a prototypical [Au25(SR1)18]− cluster (1) while maintaining its icosahedral Au13 core for the synthesis of a new bimetallic [Au19Cd3(SR2)18]− cluster (2). Single‐crystal X‐ray diffraction studies reveal that six bidentate Au2(SR1)3 motifs (L2) attached to the Au13 core of 1 were replaced by three quadridentate Au2Cd(SR2)6 motifs (L4) to create a bimetallic cluster 2. Experimental and theoretical results demonstrate a stronger electronic interaction between the surface motifs (Au2Cd(SR2)6) and the Au13 core, attributed to a more compact cluster structure and a larger energy gap of 2 compared to that of 1. These factors dramatically enhance the photoluminescence quantum efficiency and lifetime of crystal of the cluster 2. This work provides a new route for the design of a wide range of bimetallic/alloy metal nanoclusters with superior optoelectronic properties and functionality.
Plasmon modes in light emission from silver nanoparticles induced by a scanning tunneling microscope
Surface Science, 2008
This paper deals with light emission induced by a scanning tunneling microscope using a silver nanoparticles film as a sample. We measured both two photon maps of different spectral ranges along with a topography and light emission spectra corresponding to different spots of the samples. The spectra revealed two distinct peaks, corresponding to different-order tip-induced plasmon modes of the tunneling junction.