共查询到20条相似文献,搜索用时 15 毫秒
1.
Hrant Yeritsyan Aram Sahakyan Sergey Nikoghosyan Vachagan Harutiunian Volodia Gevorkyan Norair Grigoryan Eleonora Hakhverdyan Yeghis Keheyan Rudolf Gevorgyan Hakob Sargisyan 《Central European Journal of Physics》2005,3(4):610-622
The results of dielectric properties and direct current specific electric conductivity measurements in Armenian natural clinoptilolite
samples are presented. Electron irradiation with energy 8 MeV and thermal treatment of samples are performed to elucidate
possible enhancement mechanisms of clinoptilolite parameters. The results are discussed on the basis of new point structural
defects formation and recombination of initial ones in samples. It was shown that the irradiation dose of 3·1016 el/cm2 is critical for natural zeolite structural change, which is manifested by significant changes in dielectric properties and
other characteristics. The samples subjected to high temperature heating after electron irradiation, in comparison with an
unquenched one, have a significantly higher (about an order of magnitude) value of specific conductivity. 相似文献
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T. Shevchenko Kiev State University, 6, Acad. Glushkov Ave., Kiev, 252127, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 239–248, May–June, 1995. 相似文献
4.
M. W. Evans 《Foundations of Physics Letters》1994,7(5):467-474
It is shown that the vector potential of a circularly polarized laser causes the optical equivalent of the Aharonov-Bohm effect. An estimate is made of the expected fringe shift due to a circularly polarized laser directed through an optical fiber in an electron diffraction experiment, and it is shown that the effect is equivalent to that of a magnetic field. 相似文献
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M. Moakafi R. Khenata A. Bouhemadou H. Khachai B. Amrani D. Rached M. Rérat 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):35-42
We report results of first-principles calculations for the electronic and optical properties under pressure effect of Li2O, Na2O, Ki2O and Rb2O compounds in the cubic antifluorite structure, using a full relativistic version of the full-potential augmented plane-wave
plus local orbitals (FP-APW+lo) method based on density functional theory, within the local density approximation (LDA) and
the generalized gradient approximation (GGA). Moreover, the alternative form of GGA proposed by Engel and Vosko (GGA-EV) is
also used for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with
the available data. Band structure, density of states, and pressure coefficients of the fundamental energy gap are given.
The critical point structure of the frequency dependent complex dielectric function is also calculated and analyzed to identify
the optical transitions. The pressure dependence of the static optical dielectric constant is also investigated. 相似文献
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Daohua Song Feng Wang Gordana Dukovic Ming Zheng E. D. Semke Louis E. Brus Tony F. Heinz 《Applied Physics A: Materials Science & Processing》2009,96(2):283-287
A strong optical Stark effect has been observed in (6,5) semiconducting single-walled carbon nanotubes by femtosecond pump-probe
spectroscopy. The response is characterized by an instantaneous blueshift of the excitonic resonance upon application of pump
radiation at photon energy well below the band gap. The large Stark effect is attributed to the enhanced Coulomb interactions
present in these one-dimensional materials. 相似文献
10.
N. K. Morozova E. I. Smirnova I. A. Karetnikov O. R. Golovanova V. G. Galstyan V. S. Zimogorskii 《Journal of Applied Spectroscopy》1996,63(4):543-547
Moscow Power Engineering Institute, 14, Krasnokazarmennaya Str., Moscow, GSP, 105835, Russia. Translated from Zhurnal Prikladnois
Spektroskopii, Vol. 63, No. 4, pp. 646–651, July–August, 1996. 相似文献
11.
Summary In the framework of the hydrodynamic approximation, we study the Langmuir oscillations of an ion density ripple background
plasma under the influence of a single external harmonic r.f. field. An analytic frequency response curve is derived for the
late-time behaviour exhibiting multistability and hysteresis. 相似文献
12.
We prepared polycrystalline AgInSe2 thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. The samples were subjected to the irradiation of 1.26 MeV protons (H+). The effect of irradiation on the optical properties has been investigated for different doses of H+. It is observed that the band gap of silver indium selenide thin films decreases gradually with ion irradiation dose. 相似文献
13.
Xiao Chen Fei Zhou Jingxia Wang Mingzhu Li Lei Jiang Yanlin Song Zhiyuan Li Daoben Zhu 《Applied Physics A: Materials Science & Processing》2008,93(2):489-493
Tungsten (W) photonic crystals are very attractive because of their potential applications in the conventional lighting field.
In this work we show that W nanostructures have dominative effects on optical properties of W inverse opal. The nanoparticle
structure of W phase can cause intensive optical absorption and breakdown of the photonic band gap; on the contrary, W inverse
opal made from bulk and compact W phase would have weak absorption and possess a good photonic band gap. The results will
throw a new light on the study and application of W photonic crystals and development of other photonic crystal and black-body
materials.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
14.
The microstructure of vanadium oxide nanotubes (VONTs) have been characterized using FTIR spectroscopy and Raman spectroscopy. The temperature effects on the VONTs were studies by changing the laser irradiation power and thermal annealing temperature in air. Raman spectroscopy studies showed that the VONTs could be decomposed even at low laser power irradiation. Also, together with scanning electron microscopy, it was found that thermal annealing in air could lead to the collapse of the tubular structure and convert the nanotubes into V2O5 nanoparticle. It was found that the thermal stability of VONTs was relatively low and the tubular morphology was destroyed at temperatures higher than 300 °C. The spectroscopic analyses showed that the Raman signature of the VONTs could be established for probing tubular structure. 相似文献
15.
Gaurav Shukla 《Applied Physics A: Materials Science & Processing》2009,97(1):115-118
In this paper, we report on pulsed laser deposition of n-type Cu-doped ZnO thin films on c-plane sapphire substrates at 700°C.
XRD and HRTEM were employed to study the epitaxial growth relationship between the Zn1−x
Cu
x
O film and sapphire substrate. Absorption measurements showed excitonic nature of the thin films and a decrease in the bandgap
energy with increased Cu concentration was observed. Such as-deposited films showed room temperature ferromagnetism with Curie
temperature (T
c
) at around 320 K. The moment per Cu atom decreases as the Cu concentration increases. The largest magnetic moment about 0.81μ
B
/Cu atom was observed for Zn0.95Cu0.05O thin films. The presence of any magnetic second phase was ruled out and the ferromagnetism was attributed to Cu ions substituted
directly into the ZnO lattice. 相似文献
16.
S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
17.
Summary This paper presents an investigation of the growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam
in a collisionless magnetoplasma. The effect of the magnetic field and the intensity of the laser on the growth of the ripple
is presented in some detail. The effect of the presence of the ripple on the excitation of an electron plasma wave is also
investigated. Coupling of a weak plasma wave with the main laser beam is through the modified background density. The combined
effect of increased intensity of the laser beam and magnetic field is observed to suppress the growth of the ripple as well
as the excitation of the plasma wave.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
18.
Poly vinylidene chloride (PVDC) irradiated with lithium (50 MeV), carbon (85 MeV), nickel (120 MeV) and silver ions (120 MeV) having fluence range of 1 × 1011 ions/cm2 to 3 × 1012 ions/cm2 have been studied using different techniques i.e. XRD (X-ray diffraction), FTIR (Fourier transform infrared), UV–Visible and TGA (thermo-gravimetric analysis). In XRD analysis, the intensity of diffraction peaks of PVDC irradiated with lithium ions was enhanced at lower fluence as compared to pristine. The shift in optical absorption edge in irradiated PVDC was correlated with the decrease in optical band gap energy. The distinguishable characteristic peaks were observed due to UV–Vis analysis, in lithium irradiated samples of PVDC at higher fluences. The % age decrease in optical band gap energy for the respective ions were 30.9%, 34.16%, 81.1%, 87.02% respectively. Formation of double carbon bonds and breaking of C–O and C–Cl bonds with the release of Cl in irradiated PVDC was observed in FTIR spectra. In Thermogravimetric analysis (TGA), the % age weight loss observed for irradiated samples with increase in ion fluence was lesser than the % age weight loss observed in pristine sample. 相似文献
19.
D. Knabben N. Weber B. Raab Th. Koop F.U. Hillebrecht E. Kisker G.Y. Guo 《Journal of magnetism and magnetic materials》1998,190(3):1184
The transverse magneto-optical Kerr effect (T-MOKE) was investigated for thin epitaxial Fe films grown on Ag(0 0 1) in the region of the 2p excitation threshold. The experimental reflectivity and asymmetry spectra are compared to those derived from the complex dielectric function tensor calculated by using the first-principles spin-polarized relativistic band theory. We found that the T-MOKE asymmetry in general is a mixture of both the real and imaginary parts of the off-diagonal element of the dielectric function tensor, depending sensitively on the relative magnitudes of real and imaginary parts of the diagonal element. For angles of incidence larger than about 5° the influence of the Ag-substrate is significant. The major features in experimental and calculated reflectivity and asymmetry spectra are in agreement. 相似文献
20.
A flux fusion method was used to obtain the various sizes of Eu3+-activated Y2O3 red phosphors. The flux material was selected as an independent variable to control the physical properties of phosphor particles and their effects on the morphology and size distribution of phosphors were examined by scanning electron microscopy. The concentration of the flux materials and synthetic temperature were optimized for maximal photoluminescence intensity. Fluoride-based flux materials were found to work for the crystal formation of Eu3+-activated Y2O3. In particular, when a BaF2 flux was used during the reaction at 1450 °C for 3 h, the photoluminescence (PL) intensity of Eu3+-activated Y2O3 was 25% higher than that without a flux and spherical phosphors had a mean particle size of 4-5 μm. The morphology and size distribution of the synthesized Eu3+-activated Y2O3 phosphor were predominantly dependent upon the type and concentration of flux material and synthetic temperature. 相似文献