The effects of Au nanoparticle size (5–60 nm) and shape (sphere, rod, cube) over electronic states and photocatalytic activities of TiO2studied by far- and deep-ultraviolet spectroscopy

RSC Advances ◽  
2015 ◽  
Vol 5 (18) ◽  
pp. 13648-13652 ◽  
Author(s):  
Ichiro Tanabe ◽  
Takayuki Ryoki ◽  
Yukihiro Ozaki
Keyword(s):  
Electronic State ◽  
Au Nanoparticles ◽  
Electronic States ◽  
Au Nanoparticle ◽  
Ultraviolet Spectroscopy ◽  
Shape Dependence ◽  
Photocatalytic Activities ◽  
Deep Ultraviolet ◽  
State Changes ◽  
Shape Sphere

While there was little shape dependence, smaller Au nanoparticles induced larger electronic state changes and higher photocatalytic activities.

Consistent changes in electronic states and photocatalytic activities of metal (Au, Pd, Pt)-modified TiO2studied by far-ultraviolet spectroscopy

2014 ◽  
Vol 50 (17) ◽  
pp. 2117-2119 ◽  
Author(s):  
Ichiro Tanabe ◽  
Yukihiro Ozaki
Keyword(s):  
Au Nanoparticles ◽  
Electronic States ◽  
Ultraviolet Spectroscopy ◽  
Photocatalytic Activities ◽  
Far Ultraviolet

TiO2and TiO2modified with metal (Pt, Pd, and Au) nanoparticles showed consistent changes in electronic states and photocatalytic activities.

scholarly journals Electroless Deposited Gold Nanoparticles on Glass Plates as Sensors for Measuring the Dielectric Constant of Solutions

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Y. Kobayashi ◽  
Y. Ishii
Keyword(s):  
Dielectric Constant ◽  
Au Nanoparticles ◽  
Glass Plate ◽  
Au Nanoparticle ◽  
Peak Wavelength ◽  
Nanoparticle Deposition ◽  
Metal Plating ◽  
Large Dielectric Constant ◽  
Electroless Metal Plating ◽  
Glass Plates

This work describes a method for the deposition of Au nanoparticles on glass plates (Au-glass). An electroless metal plating technique was extended to the Au nanoparticle deposition. The technique consisted of three steps that took place on the glass plate: (1) adsorption of Sn2+ ions, (2) deposition of metallic Ag nuclei generated by reducing Ag+ ions with Sn2+ ions on the Sn-adsorbed sites, and (3) deposition of Au nanoparticles by reducing Au+ ions on the Ag surface. TEM observation revealed that metallic Au nanoparticles with a size of  nm were formed on the glass surface. A surface plasmon resonance absorption peak was observed, and its peak wavelength redshifted by immersing the Au-glass into a solution with a large dielectric constant. The redshift corresponded qualitatively to the calculation by the Mie theory accompanying the Drude expression, which was based on the change of the dielectric constant of the solution. The obtained results indicated that the Au-glass functioned as a sensor for measuring the dielectric constant of the solution.

Coalescence and shape oscillations of Au nanoparticles in CO2 hydrogenation for methanol reaction

Nanoscale ◽  
2021 ◽  
Author(s):  
Shengnan Yue ◽  
Yongli Shen ◽  
Ziliang Deng ◽  
Wenjuan Yuan ◽  
Wei Xi
Keyword(s):  
Au Nanoparticles ◽  
High Selectivity ◽  
Co2 Hydrogenation ◽  
Au Nanoparticle ◽  
Limited Knowledge ◽  
Shape Oscillations

Recently, there has been renewed interest in Au nanoparticle (Au NP) catalysts owing to their high selectivity for CO2 hydrogenation to methanol. However, there is still limited knowledge on the...

THE ABSORPTION SPECTRUM OF CF2

1967 ◽  
Vol 45 (7) ◽  
pp. 2355-2374 ◽  
Author(s):  
C. Weldon Mathews
Keyword(s):  
Absorption Spectrum ◽  
Electronic State ◽  
Ground State ◽  
Band System ◽  
Electronic States ◽  
Vibrational Structure ◽  
Rotational Structure ◽  
Transition Moment ◽  
High Dispersion ◽  
Parallel Type

The absorption spectrum of CF2 in the 2 500 Å region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed. The analysis of the well-resolved subbands establishes that these are perpendicular- rather than parallel-type bands, as previously assigned. Further analysis shows that the upper and lower electronic states are of 1B1 and 1A1symmetries respectively, corresponding to a transition moment that is perpendicular to the plane of the molecule. In the upper electronic state, r0(CF) = 1.32 Å and [Formula: see text], while in the ground state, r0(CF) = 1.300 Å and [Formula: see text]. An investigation of the vibrational structure of the band system has shown that the vibrational numbering in ν2′ must be increased by one unit from earlier assignments, thus placing the 000–000 band near 2 687 Å (37 220 cm−1). A search between 1 300 and 8 500 Å showed two new band systems near 1 350 and 1 500 Å which have been assigned tentatively to the CF2 molecule.

Size and Shape Dependence of the Vibrational Spectrum and Low-Temperature Specific Heat of Au Nanoparticles

2013 ◽  
Vol 117 (47) ◽  
pp. 25160-25168 ◽  
Author(s):  
Huziel E. Sauceda ◽  
Fernando Salazar ◽  
Luis A. Pérez ◽  
Ignacio L. Garzón
Keyword(s):  
Low Temperature ◽  
Vibrational Spectrum ◽  
Specific Heat ◽  
Au Nanoparticles ◽  
Size And Shape ◽  
Shape Dependence ◽  
Low Temperature Specific Heat

scholarly journals Effect of Conditions of Sol-Gel Synthesis and Post-Synthetic Treatment on Photoelectrochemical and Electro-Catalytic Properties of Titanium Oxide Nanostructures and Tio2-Au Nanocomposites

2021 ◽  
Vol 57 (4) ◽  
pp. 1-14
Author(s):  
N.I. Romanovska ◽  
◽  
P.A. Manorik ◽  
V.S. Vorobets ◽  
G.Ya. Kolbasov ◽  
...  
Keyword(s):  
Visible Light ◽  
Au Nanoparticles ◽  
Sol Gel ◽  
Au Nanoparticle ◽  
Chemical Compositions ◽  
High Catalytic Activity ◽  
Electron Microscopies ◽  
Treatment Conditions ◽  
Carboxylate Groups ◽  
Tio2 Nanostructures

Carbon-doped mesoporous TiO2 nanostructures and TiO2-Au nanocomposites with stabilized Au nanoparticles have been synthesized by the sol-gel template method and characterized by X-ray diffraction, scanning and transmission electron microscopies, Fourier-transform infrared spectroscopy, N2 adsorption/desorption, ultraviolet-visible spectroscopy, and photoelectrochemical current spectroscopy. The synthesis hydrothermal treatment conditions affected the particle size, electronic structure, morphology, phase, and chemical compositions, as well as the texture of the synthesized materials. The TiO2 and TiO2-Au based electrodes were light-sensitive in a wavelength range of 250–412 nm and were distinguished by a high catalytic activity during oxygen electroreduction. The presence of -ol and carboxylate groups in the amorphous phase is the main factor affecting the photosensitivity of TiO2 nanostructures to visible light and an increase in their photoactivity during the decomposition of methylene blue upon irradiation with ultraviolet and visible light relative to pure anatase. The higher photosensitivity and photoactivity of TiO2-Au nanocomposites compared with those of the corresponding starting TiO2 is due to the synergistic effect of Au nanoparticles and interstitial Ti-O-C groups, which depends on the Au nanoparticle content of the composite and on the mesopore size.

scholarly journals X-ray spectroscopy study of ThO2 and ThF4

2010 ◽  
Vol 25 (1) ◽  
pp. 8-12
Author(s):  
Anton Teterin ◽  
Mikhail Ryzhkov ◽  
Yury Teterin ◽  
Ernst Kurmaev ◽  
Konstantin Maslakov ◽  
...  
Keyword(s):  
Binding Energy ◽  
Energy Range ◽  
Density Distribution ◽  
Electronic State ◽  
Electronic States ◽  
State Density ◽  
Molecular Orbitals ◽  
Spectral Structure ◽  
X Ray ◽  
Electronic State Density

The structure of the X-ray photoelectron, X-ray O(F)Ka-emission spectra from ThO2 and ThF4 as well as the Auger OKLL spectra from ThO2 was studied. The spectral structure was analyzed by using fully relativistic cluster discrete variational calculations of the electronic structure of the ThO8 D4h) and ThF8 (C2) clusters reflecting thorium close environment in solid ThO2 and ThF4. As a result it was theoretically found and experimentally confirmed that during the chemical bond formation the filled O(F)2p electronic states are distributed mainly in the binding energy range of the outer valence molecular orbitals from 0-13 eV, while the filled O(F)2s electronic states - in the binding energy range of the inner valence molecular orbitals from 13-35 eV. It was shown that the Auger OKLL spectral structure from ThO2 characterizes not only the O2p electronic state density distribution, but also the O2s electronic state density distribution. It agrees with the suggestion that O2s electrons participate in formation of the inner valence molecular orbitals, in the binding energy range of 13-35 eV. The relative Auger OKL2-3L2-3 peak intensity was shown to reflect quantitatively the O2p electronic state density of the oxygen ion in ThO2.

Potential Energy Surfaces

1996 ◽  
Author(s):  
Tomas Baer ◽  
William L. Hase
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electronic State ◽  
Diatomic Molecule ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Electronic States ◽  
Dissociation Energies ◽  
State Potential ◽  
Energy Surfaces

Properties of potential energy surfaces are integral to understanding the dynamics of unimolecular reactions. As discussed in chapter 2, the concept of a potential energy surface arises from the Born-Oppenheimer approximation, which separates electronic motion from vibrational/rotational motion. Potential energy surfaces are calculated by solving Eq. (2.3) in chapter 2 at fixed values for the nuclear coordinates R. Solving this equation gives electronic energies Eie(R) at the configuration R for the different electronic states of the molecule. Combining Eie(R) with the nuclear repulsive potential energy VNN(R) gives the potential energy surface Vi(R) for electronic state i (Hirst, 1985). Each state is identified by its spin angular momentum and orbital symmetry. Since the electronic density between nuclei is different for each electronic state, each state has its own equilibrium geometry, sets of vibrational frequencies, and bond dissociation energies. To illustrate this effect, vibrational frequencies for the ground singlet state (S0) and first excited singlet state (S1) of H2CO are compared in table 3.1. For a diatomic molecule, potential energy surfaces only depend on the internuclear separation, so that a potential energy curve results instead of a surface. Possible potential energy curves for a diatomic molecule are depicted in figure 3.1. Of particular interest in this figure are the different equilibrium bond lengths and dissociation energies for the different electronic states. The lowest potential curve is referred to as the ground electronic state potential. The primary focus of this chapter is the ground electronic state potential energy surface. In the last section potential energy surfaces are considered for excited electronic states. A unimolecular reactant molecule consisting of N atoms has a multidimensional potential energy surface which depends on 3N-6 independent coordinates. For the smallest nondiatomic reactant, a triatomic molecule, the potential energy surface is four-dimensional (three independent coordinates plus the energy). Since it is difficult, if not impossible, to visualize surfaces with more than three dimensions, methods are used to reduce the dimensionality of the problem in portraying surfaces. In a graphical representation of a surface the potential energy is depicted as a function of two coordinates with constraints placed on the remaining 3N-8 coordinates.

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