共查询到20条相似文献,搜索用时 31 毫秒
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A. V. Kalenskii A. A. Zvekov A. P. Nikitin 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(2):282-287
An improved model of the laser initiation of the explosive decomposition of energetic materials containing light-absorbing nanoparticles is investigated. The model takes into account how the light absorption efficiency factor changes with an increasing temperature. It is demonstrated that, as the temperature of an aluminum nanoparticle in pentaerythritol tetranitrate increases from 300 to 700 K, the light absorption efficiency factor increases by a factor of over 2. It is also shown that, for each particular nanoparticle radius in the 40–150 nm range, the temperature dependence of the light absorption efficiency factor over the relevant temperature range can be interpolated well by a second-order polynomial. Taking into account the variation of the efficiency of light absorption by the aluminum nanoparticle in the initiation of the explosive decomposition of pentaerythritol tetranitrate by a 12-ns-long neodymium laser pulse reduces the calculated critical energy density by a factor of 2.11 and decreases the optimum nanoparticle radius from 98 to 92 nm. 相似文献
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N. M. Ushakov G. Yu. Yurkov D. A. Baranov K. V. Zapsis M. N. Zhuravleva V. I. Kochubeĭ I. D. Kosobudskiĭ S. P. Gubin 《Optics and Spectroscopy》2006,101(2):248-252
The spectral characteristics of absorption and photoluminescence of synthetic composite materials based on cadmium sulfide nanoparticles and polyethylene are studied in the visible and near-IR wavelength ranges. It is shown that the quantum efficiency of a material with CdS nanoparticles about 6 nm in size in a matrix of high-pressure polyethylene is the highest. The estimation of the photoluminescence linewidth shows that the linewidth of this material is the smallest, amounting to 0.55 eV, which indicates that the structure of these nanoparticles is more perfect. 相似文献
4.
Sviatlana Viarbitskaya Linus Ryderfors Therese Mikaelsson Emad Mukhtar Lennart B.-?. Johansson 《Journal of fluorescence》2011,21(1):257-264
Multi-photon absorption induced luminescence (MAIL) from bare gold nanoparticles, silica-coated particles, as well as silica-coated agglomerated gold nanoparticles suspended in aqueous solution was studied by using time-resolved and steady-state luminescence spectroscopy. The nanoparticles were excited by femtosecond pulses of wavelengths ranging from 630 nm to 900 nm. The luminescence from the particles exhibits a broad spectrum in the UV and VIS region. The time-resolved measurements indicate a luminescence lifetime of a few ps, limited by the response of the experimental system. The studied dependence of the MAIL efficiency on the excitation wavelength showed that the luminescence from silica-coated agglomerates was enhanced over the whole range of excitation wavelengths, when compared to the luminescence from individual gold nanoparticles. The agglomerates show an almost excitation wavelength independent efficiency of the MAIL, while for individual nanoparticles a rapid decrease of the MAIL efficiency was observed with increasing excitation wavelength. The observed enhancement of the MAIL from the agglomerated nanostructures can be attributed to the presence of localized surface plasmon resonances in the spectral region corresponding to the excitation wavelengths. The high MAIL efficiency from the agglomerated nanoparticle structures in the near-infrared could be an advantage in the expanding field of luminescence-based-imaging, as well as in biosensor technology. 相似文献
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K. A. Gonchar A. V. Kondakova Subhra Jana V. Yu. Timoshenko A. N. Vasiliev 《Physics of the Solid State》2016,58(3):601-605
Halloysite nanotube composites covered by silver nanoparticles with the average diameters of 5 nm and 9 nm have been studied by methods of optical spectroscopy of reflectance/transmittance and Raman spectroscopy. It has been established that silver significantly increases the light absorption by nanocomposites in the range of 300 to 700 nm with a maximum near 400 nm, especially for the samples with the nanoparticle size of 9 nm, which is explained by plasmonic effects. The optical absorption increases also in the long-wavelength spectral range, which seems to be due to the localized electronic states in an alumosilicate halloysite matrix after deposition of nanoparticles. Raman spectra of nanocomposites reveal intense scattering peaks at the local phonons, whose intensities are maxima for the samples with the silver nanoparticle sizes of 9 nm, which can be caused by plasmonic enhancement of the light scattering efficiency. The results show the ability to use halloysite nanotube nanocomposites in photonics and biomedicine. 相似文献
6.
Data in the literature on the optical properties of aluminum in the range of 198–1173 K are analyzed. Analytical expressions describing the dependences of aluminum permittivity on photon energy and temperature are proposed and tested. The spectral dependences of the aluminum absorption coefficient and specular reflectance at normal incidence, as well as of the absorption-efficiency coefficients of aluminum nanoparticles in a lithium-fluoride matrix, are calculated at different temperatures. The results obtained indicate the appearance of unusual nonlinear absorption effects in nanocomposites containing aluminum nanoparticles, which manifest themselves in a decrease in the absorption efficiency with increasing temperature at photon energies exceeding 1.40 eV. 相似文献
7.
金纳米颗粒的紫外、蓝紫光波段光致荧光特性 总被引:4,自引:1,他引:3
采用电化学方法制备出粒径在20~30 nm的悬浮胶体金纳米颗粒。研究了金纳米颗粒的荧光发射光谱特性。在377和459 nm观察到两个荧光发射峰,分别位于紫外和蓝紫光波段,对应的敏感激发波长为220 nm。减小激发光强度或降低金纳米颗粒的粒子数密度都会使377 nm处的荧光发射峰强度减弱。位于459 nm处的荧光发射峰对激发光强度和颗粒数密度变化更为敏感,并且在激发光强度降低到一定阈值或粒子数密度高于一定阈值后消失。随着激发光强度的增加,位于377和459 nm处的两发射峰强度逐渐靠近,其比值逼近于1。实验结果与随机分布介质的自组织散射式谐振腔理论符合得较好。这表明胶体金纳米颗粒中存在循环多重散射,并由此引发了蓝光及紫外波段的荧光增强,这在光存储和全色显示等方面具有潜在的应用前景。 相似文献
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Coupled optical Tamm states localized at the edges of a photonic crystal enclosed with a nanocomposite are theoretically studied. The nanocomposite consists of nanoparticles with a dielectric core and a metal shell, which are dispersed in a transparent matrix. It is shown that the positions of the spectral peaks are sensitive to the thickness of the outermost photonic crystal layer. 相似文献
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F. Quéré P. Grua H. Bercegol P. Martin J.P. Morreeuw J.L. Rullier 《Applied physics. B, Lasers and optics》2004,78(7-8):825-828
In order to understand the role played by nanodefects in optical breakdown of dielectrics, the interaction of an intense laser field with model dielectric samples containing metallic nanoparticles is studied both theoretically and experimentally. A theoretical study of the metal conduction electrons dynamics in the laser field predicts an efficient injection of carriers from the metallic inclusion to the conduction band of the dielectric, which leads to a strong local increase of the optical absorption in the initially transparent matrix. This prediction is tested experimentally by using time-resolved spectral interferometry to measure excitation densities as a function of the laser intensity in silica samples doped with gold nanoparticles, which are compared with similar measurements in pure silica. PACS 61.80.Ba; 42.70.-a; 78.47.+p 相似文献
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N. V. Kurbatova M. F. Galyautdinov N. A. Ivanov S. S. Kolesnikov V. L. Papernyi Yu. N. Osin A. L. Stepanov 《Physics of the Solid State》2013,55(9):1899-1902
Results of the Raman spectroscopy analysis of a new composite material based on a thin polycrystalline LiF film containing gold nanoparticles are presented. The formation of spherical gold nanoparticles in the film has been confirmed by the X-ray structural analysis and observation of the optical plasmon resonance absorption spectrum with a maximum at 534 nm. The obtained composite layers have been subjected to annealing by ruby laser (λ = 694 nm) in the spectral region on a descending long-wavelength wing of the plasmon absorption band of gold nanoparticles. Raman spectroscopy has been applied for the first time to the investigation of the modification of the shape of gold nanoparticles in LiF during laser annealing. The experimental Raman spectra are compared with calculated modes of in-phase bending vibrations generated in gold nanoparticles. 相似文献
11.
Temporal and spectral characteristics of laser-induced breakdown plasma in colloidal solutions of gold nanoparticles were experimentally studied. Near-infrared laser sources of nanosecond pulses were used. It was shown that under certain experimental conditions nanosized plasma around nanoparticles might change to laser-induced breakdown plasma in liquid. The dependencies of the plasma temporal and spectral characteristics on laser pulse duration as well as resulting nanoparticles properties were studied. Laser-induced breakdown plasma lifetime was shown to be comparable with laser pulse duration. The efficiency of gold nanoparticles fragmentation was shown to depend on laser pulse duration. Similar experiments were carried out under reduced external pressure. It turned out to affect the properties of both plasma plume and nanoparticles. Transmission electron microscopy and disc measuring centrifuge were used for nanoparticle morphology and size analysis. Extinction spectra of colloidal solutions and emission spectra of plasma were studied by means of optical spectroscopy. 相似文献
12.
Arbouet A Christofilos D Del Fatti N Vallée F Huntzinger JR Arnaud L Billaud P Broyer M 《Physical review letters》2004,93(12):127401
The absorption of a single isolated metal cluster is directly measured using a novel far-field optical technique based on modulation of its position. Single gold nanoparticles with average diameters down to 5 nm, dispersed on a transparent substrate, are optically detected and their absolute absorption cross section determined. 相似文献
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Evaldas Stankevičius Mantas Garliauskas Mindaugas Gedvilas Nikolai Tarasenko Gediminas Račiukaitis 《Annalen der Physik》2017,529(12)
Here, the structuring of surfaces with gold nanoparticles by using Bessel‐like beam array is demonstrated. The experimental results show that the fabricated microring structures containing gold nanoparticles have a surface plasmon resonance in the spectral range of 520–540 nm, which can be tuned by selecting the laser treatment parameters. Fabricated microring structures exhibit a lower light transmittance comparing with the randomly distributed gold nanoparticles for wavelengths 500–570 nm due to the growth in the size of nanoparticles. In the spectral range of 600–700 nm, the light transmittance through microring structures is higher compared with the randomly distributed gold nanoparticles because of the removal of gold nanoparticles as gold has high reflectivity for wavelengths longer than 600 nm. The demonstrated method enables an easy fabrication of microring structures having tunable plasmonic properties. 相似文献
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S. N. Nikolaev V. S. Krivobok V. S. Bagaev E. E. Onishchenko 《Bulletin of the Lebedev Physics Institute》2017,44(12):371-373
The possibility of increasing the photoluminescence signal of Si1?xGex/Si quantum wells in the visible spectral range due to a change in the conduction band structure and the interaction of many-body states with plasma oscillations of metal nanoparticles is studied. The sample band structure was controlled using a uniaxial strain of ~10?4. It is found that such an approach allows an increase in the emission intensity of biexcitons in the quantum well (x = 9%) by a factor of 2.4 at a temperature of 5 K. Metal nanoparticles deposited on the sample surface with a protective layer thickness of 20 nm allowed us to increase the luminescence intensity of quantum wells approximately by a factor of 2.7. 相似文献
15.
It is shown by numerical simulation that the enhancement of the field near metallic nanoparticles is most significant in the
transparency region of the matrix material and falls off as the absorption coefficient rises. In an absorbing matrix medium
this leads both to an increase in the fraction of energy absorbed by the matrix material and to a substantial transformation
in its spectral distribution. This is illustrated for the case of copper phthalocyanine with silver nanoparticles. By choosing
the size of the introduced plasmon nanoparticles it is possible to enhance the absorption in the visible for the materials
used in solar cells and thereby increase their energy efficiency. 相似文献
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For spherical Cu, Ag, and Au nanoparticles with a radius of 1–3 nm in copper phthalocyanine (CuPc), with allowance for internal
size effects, we calculate the scattering efficiency factor in the near zone, the extinction efficiency factor due to scattering
and absorption of incident radiation, and the efficiency of the increase in absorption by the matrix material. This occurs
in the CuPc absorption bands, as well as in the weak absorption region of CuPc, where, owing to surface plasmon resonance,
an additional absorption band arises for nanoparticles of all three materials. For Ag nanoparticles, the increase in absorption
is twice as high as for Cu and Au nanoparticles; for these it differs inconsiderably. 相似文献
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Andrea R. da Silva Ricardo Q. Aucélio Rosa I. Rodríguez-Cotto Mario G. Ortiz-Martínez Evasomary Rivera-Ramírez Daniela Perroni Frias Mariangela Macchione Braulio Jiménez-Vélez Adriana Gioda 《Journal of nanoparticle research》2014,16(10):1-11
The synthesis procedure represents a key aspect in designing the physical and chemical properties of gold nanoparticles. The current study proposes a simple approach for gold nanoparticles synthesis using non-thermal plasma. The novelty of the setup consists in producing an in-liquid plasma discharge in argon bubbles that are externally generated in the solution exposed to treatment. Because plasma is the source of active species which are directly involved in gold reduction, no additional reducing agent was necessary. Collagen protein was used as capping agent. A plasma treatment of 10 min is sufficient for obtaining stable colloidal solutions with UV-Vis absorption maximum at 530 nm. Transmission electron microscopy images revealed preponderant spherical nanoparticles with dimensions in the range of 6–20 nm. The method of synthesis distinguishes by its good reproducibility, facility, efficiency, and ability to generate stable colloidal nanoparticles after several minutes of plasma exposure. 相似文献
18.
大气压氩气介质阻挡放电中的电子激发温度 总被引:8,自引:4,他引:4
采用发射光谱强度比法,测量了大气压氩气介质阻挡放电(DBD)中的电子激发温度。实验在690~800 nm的范围内测量了大气压氩气DBD的发射光谱,经分析发现这些谱线全部是氩原子的发射谱线。为了测量电子激发温度,选用相距较近的763.51 nm(2P6→1S5),772.42 nm(2P2→1S3)的两条光谱线。结果发现电子温度的范围为0.1~0.5 eV,电子激发温度随电压的增加而增加,随流量的增加而减小。实验还发现氩气流动与非流动时电子激发温度有明显的差别。上述结果对介质阻挡放电在工业领域上的应用具有重要意义。 相似文献
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Nonlinear optical response of silver and copper nanoparticles in the near-ultraviolet spectral range
R. A. Ganeev A. I. Ryasnyansky A. L. Stepanov T. Usmanov 《Physics of the Solid State》2004,46(2):351-356
The nonlinear optical response of silver and copper nanoparticles synthesized by ion implantation in silica glasses is studied in the near-ultraviolet spectral range at a wavelength of 354.7 nm. The real and imaginary parts of the third-order nonlinear susceptibility χ(3) of composite materials are measured. It is shown that the quantity Imχ(3) is due to saturated absorption, while Reχ(3) is due to the self-defocusing effect in composite materials. 相似文献
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S. Masala S. Del Gobbo C. Borriello V. Bizzarro V. La Ferrara M. Re E. Pesce C. Minarini M. De Crescenzi T. Di Luccio 《Journal of nanoparticle research》2011,13(12):6537-6544
The integration of semiconductor nanoparticles (NPs) into a polymeric matrix has the potential to enhance the performance
of polymer-based solar cells taking advantage of the physical properties of NPs and polymers. We synthesize a new class of
CdS-NPs-based active layer employing a low-cost and low temperature route compatible with large-scale device manufacturing.
Our approach is based on the controlled in situ thermal decomposition of a cadmium thiolate precursor in poly(3-hexylthiophene)
(P3HT). The casted P3HT:precursor solid foils were heated up from 200 to 300 °C to allow the precursor decomposition and the
CdS-NP formation within the polymer matrix. The CdS-NP growth was controlled by varying the annealing temperature. The polymer:precursor
weight ratio was also varied to investigate the effects of increasing the NP volume fraction on the solar cell performances.
The optical properties were studied by using UV–Vis absorption and photoluminescence (PL) spectroscopy at room temperature.
To investigate the photocurrent response of P3HT:CdS nanocomposites, ITO/P3HT:CdS/Al solar cell devices were realized. We
measured the external quantum efficiency (EQE) as a function of the wavelength. The photovoltaic response of the devices containing
CdS-NPs showed a variation compared with the devices with P3HT only. By changing the annealing temperature the EQE is enhanced
in the 400–600 nm spectral region. By increasing the NPs volume fraction remarkable changes in the EQE spectra were observed.
The data are discussed also in relation to morphological features of the interfaces studied by Focused Ion Beam technique. 相似文献