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The present study is aimed to the formation and optical study of new types of nanomaterial based on Pt nanoparticles in a SiO2 matrix. An original technique of ion-assisted stimulating co-deposition of metal and dielectric in vacuum was used. It was shown by electron microscopy and microdiffraction methods that as a result of deposition Pt nanoparticles in SiO2 were synthesized. The optical absorption of the synthesized composite nanosystem was measured. It was also found by the Z-scan method that when laser probing of the sample with nanosecond pulses at a wavelength of 1064 nm a positive nonlinear optical absorption was recorded, which characterized by a coefficient of 2.9·10–7 m/W. [ABSTRACT FROM AUTHOR]

Performance of the material depends directly on the electronic and energy band structure, to improve the photoactivity of TiO2 and decrease carrier recombination centers induced by monodoping, the TiO2 thin film has been modified with V and N codopants by ion implantation for tailing and controlling the electronic structure and energy band structure. Compared to monodopant, codopants of V and N exhibit a synergistic effect in the photoactivity enhancement of TiO2. X-ray photoelectron spectroscopy (XPS) studies demonstrate that the implanted V and N ions are introduced into the lattice of TiO2 through V and N substituting Ti and O, respectively. The electronic structure of V/N codoped TiO2 was calculated by First-principles calculations based on density-functional theory, the results show the band edges of TiO2 can be tailored by V and N codopants. UV-vis spectra consistently show the absorption edge of V/N codoped TiO2 film is widen to visible light region. More importantly, the photoactivity of TiO2 film has been significantly improved after V/N codoping. The enhanced photocatalytic performance is believed to be due to the V and N codopants induced synergistic effect that not only enhances the absorption of visible light but also promotes the separation of photogenerated electrons and holes in TiO2. Besides, there exists an optimum for V/N ions implantation fluence. The capability of improving TiO2 photoactivity by V/N codoping could open up new opportunities in the development of highly efficient photocatalysts and photoelectrodes for solar energy and environmental applications. [ABSTRACT FROM AUTHOR]

Low-energy high-current ion implantation in silica at a well-controlled substrate temperature has been used to produce composites containing a large concentration of spherical Cu clusters with an average diameter of 4 nm and a very narrow size distribution. A very large value for the third-order optical susceptibility, χ[sup (3)]=10[sup -7] esu, has been measured in the vicinity of the surface plasmon resonance by degenerate four-wave mixing at 585 nm. This value is among the largest values ever reported for Cu nanocomposites. Additionally, the response time of the nonlinearity has been found to be shorter than 2 ps. The superior nonlinear optical response of these implants is discussed in terms of the implantation conditions. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Polymethylmethacrylate (PMMA) and polyimide (PI) samples are implanted by 40 keV Cu+ ions with high fluences to synthesize copper nanoparticles in shallow polymer layers. The produced metal/polymer nanocomposites are studied using atomic force and scanning electron microscopies as well as optical transmission spectroscopy. It is found that nucleation and growth of copper nanoparticles are strongly fluence-dependent as well as they are affected by the polymer properties, in particular, by radiation stability yielding different nanostructures for the implanted PI and PMMA. Shallow synthesized nanoparticles are observed to partly tower above the sample surface due to a side effect of high-fluence irradiation leading to considerable sputtering of polymers. Implantation and particle formation significantly change optical properties of both polymers reducing transmittance in the UV–visible range due to structural and compositional change as well as causing an absorption band related to localized surface plasmon resonance (LSPR) of the nanoparticles. The role of polymer type and its degradation under the implantation on LSPR is studied to optimize conditions for the formation of nanoplasmonic materials. [ABSTRACT FROM PUBLISHER]

Single-crystal Al2O3(0001) and Al2O3(1120) substrates are implanted by 160-keV Au+ ions with doses from 1015 to 1017 cm−2. Some of the implanted samples are air-annealed at 800–1200°C. The properties of the synthesized composite layers are studied by Rutherford backscattering and linear optical reflection measurements, and their nonlinear optical characteristics are examined by RZ-scanning using a picosecond Nd: YAG laser operating at a wavelength of 1064 nm. The Rutherford backscattering spectra indicate that the implanted impurity concentrates near the surface of the Al2O3. The formation of gold nanoparticles in the Al2O3 can be judged from the characteristic optical plasmon resonance band in the reflectance spectra of the samples irradiated to a dose higher than 6.0 × 1016 cm−2. The synthesized particles are shown to be responsible for nonlinear optical refraction in the samples. The nonlinear refractive index, n 2, and the real part of the third-order susceptibility, Rex(3), of the composite layers are determined. [ABSTRACT FROM AUTHOR]

Single crystal Al2O3 substrates have been implanted with 160-keV Au+ to a dose of 0.6 × 1017 or 1.0 × 1017cm–2, with a postimplantation annealing for 1 h at 800°C in air. The obtained composite layers were studied by the method of linear optical reflection; the nonlinear optical characteristics were determined by the RZ-scan technique using picosecond radiation pulses of an Nd:YAG laser operating at 1064 nm. The appearance of a characteristic surface optical plasmon resonance band in the linear reflection spectra was indicative of the formation of gold nanoparticles in a subsurface layer of ion-irradiated Al2O3 . It is shown that the synthesized particles are responsible for the observed manifestations of nonlinear refraction. The composite layers were characterized by the nonlinear refractive index (n2) and the real part of the third-order nonlinear susceptibility (Re χ(3)). © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

We have investigated the process of metal nanoparticle (NP) synthesis in SiO2 by implanting Ag+ ions with an energy of 30 keV depending on the dose ((2–8)·1016 cm−2) and the ionic current density (4–15 µA/cm2). Analysis of the composite materials formed was performed with the use of optical spectroscopy and atomic-force microscopy (AFM). The NPs synthesized in the glass demonstrate a characteristic absorption line associated with the surface plasma resonance effect. A correlation of the spectral shift of the lines caused by a change in the NP size with the diameter of the hemispherical asperities on the SiO2 surface registered by the AFM method has been revealed. It has been found that for the case of a fixed current density in the ion beam the silver NP sizes remain practically unaltered with increasing ion dose up to a certain value (6·1016 cm−2), and only an increase in the concentration of NPs is observed thereby. However, a further increase in the dose causes a decrease in both the NP density and size. On the other hand, at a fixed high dose an increase in the ionic current density leads to a gradual enlargement of the NPs. We have considered the mechanisms explaining the change in the NP sizes with increasing dose and ionic current density and evaluated the possibilities of carrying out controlled synthesis by varying the implantation conditions. [ABSTRACT FROM AUTHOR]

The effect of bombardment with heavy Xe ions (energy E[SUBi] = 80 keV) on the optical properties, low-temperature conductivity, and nanostructure of diamond-like carbon (DLC) films is studied. A number of specific features have been ascertained in the behavior of graphite-like nanoclusters which are not observed upon bombardment of the films with light ions. At low irradiation doses (D < 6 × 10[SUP13]cm[SUP-2]), the concentration and size of nanoclusters decrease. At relatively high bombardment doses (D > 1.2 × 10[SUP15]cm[SUP-2]) the effective optical gap, found from the Tauc plot, becomes negative, which is due to the high density of electronic defect states within the gap. In this range, the temperature dependence of conductivity changes, although the conduction mechanism itself remains of the hopping type. The width of the band of defect states, which is formed upon irradiation and in which charge transport occurs, is 0.07 eV, which is close to a value obtained previously by the authors. [ABSTRACT FROM AUTHOR]

Performance of the material depends directly on the electronic and energy band structure, to improve the photoactivity of TiO2 and decrease carrier recombination centers induced by monodoping, the TiO2 thin film has been modified with V and N codopants by ion implantation for tailing and controlling the electronic structure and energy band structure. Compared to monodopant, codopants of V and N exhibit a synergistic effect in the photoactivity enhancement of TiO2. X-ray photoelectron spectroscopy (XPS) studies demonstrate that the implanted V and N ions are introduced into the lattice of TiO2 through V and N substituting Ti and O, respectively. The electronic structure of V/N codoped TiO2 was calculated by First-principles calculations based on density-functional theory, the results show the band edges of TiO2 can be tailored by V and N codopants. UV-vis spectra consistently show the absorption edge of V/N codoped TiO2 film is widen to visible light region. More importantly, the photoactivity of TiO2 film has been significantly improved after V/N codoping. The enhanced photocatalytic performance is believed to be due to the V and N codopants induced synergistic effect that not only enhances the absorption of visible light but also promotes the separation of photogenerated electrons and holes in TiO2. Besides, there exists an optimum for V/N ions implantation fluence. The capability of improving TiO2 photoactivity by V/N codoping could open up new opportunities in the development of highly efficient photocatalysts and photoelectrodes for solar energy and environmental applications. [ABSTRACT FROM AUTHOR]