共查询到20条相似文献,搜索用时 0 毫秒
1.
M.M. El-Nahass Abdul-Basit A. Saleh A.A.A. Darwish M.H. Bahlol 《Optics Communications》2012,285(6):1221-1224
Thin films of InSe were prepared by thermal evaporation technique. The as-deposited films have nano-scale crystalline nature and the annealing enhanced the degree of crystallinity. The optical properties of nanocrystalline thin films of InSe were studied using spectrophotometric measurements of transmittance, T, and reflectance, R, at normal incidence of light in the wavelength range 200–2500 nm. The optical constants (refractive index, n, and absorption index, k) were calculated using a computer program based on Murmann's exact equations. The calculated optical constants are independent of the film thickness. The optical dispersion parameters have been analysed by single oscillator model. The type of transition in InSe films is indirect allowed with a value of energy gap equals to 1.10 eV, which increased to 1.23 eV upon annealing. 相似文献
2.
A. A. Zolotukhin A. N. Obraztsov A. O. Ustinov A. P. Volkov 《Journal of Experimental and Theoretical Physics》2003,97(6):1154-1158
Deposition of carbon materials from methane-hydrogen gas mixtures in a DC gas discharge is investigated. Parameters ensuring stable discharge conditions and synthesis of diamond and graphite-like films are determined. Optical emission spectroscopy is used to analyze the composition of the activated gas phase in the course of carbon film deposition. Synthesis of graphite-like carbon nanotubes and nanocrystallites is shown to correlate with the presence of C2 dimers in the plasma. A noncatalytic mechanism of synthesis of nanostructured graphite in a carbon-containing gas phase is proposed. 相似文献
3.
I.M. Catalano A. Cingolani C. Arnone S. Riva-Sanseverino 《Solid State Communications》1984,49(12):1139-1141
Optical rectification non-linear process in CdS single crystals at the Nd-YA1G and CO2 frequencies is reported. VOR signal measurements versus θ angle, between radiation E-field and crystal c-axis, give non-zero terms values of the optical rectification tensor. The frequency dispersion effect of this non-linear process is discussed. 相似文献
4.
研究了CHF3C6H6沉积的氟化非晶碳(αC∶F)薄膜的光学带隙.发现αC∶F薄膜光学带隙的大小取决于薄膜中C—F,CC的相对含量.这是由于CC形成的窄带隙π键和C—F形成的宽带隙σ键含量的相对变化,改变了带边态密度分布的结果.在微波功率为140—700W、沉积气压为01—10Pa、源气体CHF3∶C6H6流量比为1∶1—10∶1条件下沉积的αC∶F薄膜,光学带隙在176—398eV之间
关键词:
氟化非晶碳(αC∶F)薄膜
光学带隙
键结构 相似文献
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The emission of freely propagating terahertz (THz) radiation coming from optical rectification at metallic surfaces has been detected and characterized for the first time to the authors' knowledge. The observed THz transients are induced through nonlinear electronic processes at gold and silver surfaces on intense pulsed optical photoexcitation and exhibit a peak electric field of as much as 200 V/cm. This finding opens a qualitatively new way to investigate nonlinear phenomena at metal surfaces and also can be exploited for the development of new THz emitters. 相似文献
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E. Barborini C. Lenardi P. Piseri P. Milani R. G. Agostino T. Caruso E. Colavita S. La Rosa M. Bertolo C. Ducati 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):273-276
Inclusions of metals in the growth process of carbon
cluster assembled materials (ns-C) induce modifications in the
structural and electronic properties of the material. A novel
pulsed microplasma cluster source (PMCS) is able to deliver
highly intense, collimated and stable beams suitable for
producing bulk quantities of cluster-assembled nanocomposite
films. Loading of metal nanoparticles into carbon cluster based
films is obtained either by mixing a gas phase metallorganic
compound with the carrier gas (He) before entering into the
source (for example molybdenum (V) isopropoxide), or by using a
double component sputtering target (metal (Ti, Ni)/graphite). The study of film
morphology on nanometer scale, carried out by transmission
electron microscopy (TEM), reveals the dispersion in a ns-C
matrix of metallic particles and, in the case of molybdenum
containing films, also of carbide particles. Spatially resolved
ultraviolet photoemission spectroscopy confirms the segregation
of metal particles and exhibits evident anisotropy in the
Mo:ns-C films, mainly ascribable to the formation of carbide
nanoparticles. 相似文献
11.
《中国光学快报(英文版)》2018,(10)
In this Letter, we have demonstrated significant electric field induced(EFI) optical rectification(OR) effects existing in the surface layers of germanium(Ge) and measured the distributions of EFI OR signals along the normal directions of surface layers of Ge samples. Based on the experimental results, the ratios of the twoe-order susceptibility components χ2 effTzzz∕χe2 effTeffective secondzxxfor Ge(001), Ge(110), and Ge(111) surface layers can be estimated to be about 0.92, 0.91, and 1.07, respectively. The results indicate that the EFI OR can be used for analyzing the properties on surface layers of Ge, which has potential applications in Ge photonics and optoelectronics. 相似文献
12.
Vortex pinning and rectification effect in a nanostructured superconducting film with a square array of antidot triplets
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We study the stability of vortices pinning and dynamics in a superconducting thin strip containing a square array of antidot triplets by using the nonlinear Ginzburg–Landau(GL) theory. Compared with the regular square array of circular holes, the vortices are no longer pinned inside the circular holes, but instead stabilized at the center of the antidot triplets depending on the geometry parameters. Moreover, the influences of the geometry parameters and the polarity of the applied current on the current–voltage(I–V) characteristics are also studied. The critical current for the sample turning into a normal state becomes smaller when the hole diameter D is smaller and the spacing B between the holes is larger. Due to the asymmetric pinning sites, our numerical simulations demonstrate that the positive and negative rectified voltages appear alternately in the resistive state of the sample under an ac current of square pulses. 相似文献
13.
We have studied the electrical conduction in nanostructured carbon (ns-C) films produced by deposition of a supersonic beam of neutral carbon clusters. The d.c. conduction properties of these films have been measured in situ during the deposition process and ex situ as a function of the temperature in vacuum and in ambient of different gases (H2, N2, CH4, He). The ns-C films exhibit an ohmic behavior with a room temperature resistivity in the range of 107-109
W{\rm\Omega}
cm depending on the growth and storage conditions. Conductivity vs. temperature measured in vacuum in the range 290-400 K is characterized by activation energies in the range of 0.3-1.7 eV, the current response does not differ significantly in gas atmosphere. Nanocomposite carbon-metal films have been obtained by adding small amounts of metallorganic precursors containing molybdenum and cobalt during the formation of carbon clusters prior to deposition. The films are characterized by porous carbon networks containing small metal and metal carbide clusters. Electrical transport properties of these films have been studied as a function of temperature, gas pressure and relative humidity. In particular, the electrical conductivity of the sample produced with molybdenum showed to be much sensitive to changes in gas pressure and relative humidity, being characterised by fast and reversible responses. 相似文献
14.
We have developed a method for the quantitative evaluation of
the chemisorbed fraction of hydrogen in nanostructured carbon films using Near Edge X-ray Absorption
Spectroscopy (NEXAFS). In the carbon K-edge spectrum the peak related to carbon bonded to hydrogen is
assumed to be correlated with the amount of hydrogen bonded to carbon. This
assumption is supported by a comparative analysis of gas-phase
hydrocarbons obtained via Electron Energy Loss Spectroscopy
(EELS). We applied the method to nanostructured carbon (ns-C)
films synthesized by supersonic cluster beam deposition. The
evaluated quantity of chemisorbed hydrogen in different samples
exposed to molecular hydrogen (pressure of 0.12 MPa, for 3 hours
at room temperature) is ∼1.5 wt.%. 相似文献
15.
A. A. Ezhov S. A. Magnitskii N. S. Maslova D. A. Muzychenko A. A. Nikulin V. I. Panov 《JETP Letters》2005,82(9):599-602
Light scattering by a small protrusion on a metal surface is analyzed within the framework of perturbation theory. Upon normal incidence of a linearly polarized monochromatic wave, slight deviations of the protrusion’s shape from a circularly symmetric one lead to the formation of optical vortices in the near-field region due to resonant excitation of circular surface plasmons. This agrees with the results of scanning near-field optical microscopy experiments revealing distinct spiral patterns in the in-plane near-field intensity distribution for metallized nanostructured polymer substrates. 相似文献
16.
The optical properties of graded chiral sculptured TiO2 thin films in axial and non-axial excited states are calculated using the rigorous coupled wave analysis method (RCWA) in conjunction with the Bruggeman homogenization formalism. The filtering frequency and polarization selectivity of these graded nanostructured TiO2 sculptured thin films showed dependence on both structural and deposition parameters. The results achieved are consistent with the experimental data [K. M. Krause and M. J. Bret, Adv. Funct. Mater. 18 (2008) 3111]. 相似文献
17.
V. P. Kochanov 《Journal of Experimental and Theoretical Physics》2008,107(2):190-202
It is theoretically shown that, under conditions of two-photon absorption of radiation by metal vapors, the medium becomes considerably polarized and efficiently doubles the radiation frequency. Two physical mechanisms by which these effects can occur are detected. The first of them results from the ring frequency mixing, while the second one is caused by a polarization nonlinearity that is quadratic in the field amplitude and that is formed as a result of the electric quadrupole absorption due to the forbidden transition. The effects predicted can form the basis for new optical methods for measuring the electric quadrupole and magnetic dipole moments for forbidden atomic transitions. 相似文献
18.
Optical rectification in single crystals of tellurium produced by infra-red radiation at 10.6 μm has been observed. The value
of |χ0
111| is found to be 0.9×10−6 esu. Preliminary experiments to test the usefulness of the effect to monitor mode-locked infra-red laser pulses have been
inconclusive. 相似文献
19.
We carried out an experimental and numerical investigation of photoinduced voltage at normal incidence in the nondiffraction regime, which was not predicted to occur by the simple momentum conservation model. We prepared two samples: one having space inversion symmetry and the other without this feature. At normal incidence in the nondiffraction regime, we observed a finite signal only for the asymmetric structure. We found that surface plasmon polaritons (SPPs) are excited by the signal and are attributed to the origin of the voltage. We also evaluated the radiation force of light by using the Maxwell stress tensor and found that pressure of light and not shear force is mainly induced in the structure due to the asymmetric excitation of SPPs. 相似文献
20.
A. V. Svalov V. O. Vas’kovskiy K. G. Balymov A. N. Sorokin G. V. Kurlyandskaya 《Technical Physics》2014,59(4):530-534
The hysteretic properties of terbium films subjected to layered structuring by introducing nonmagnetic Ti and Si layers of a fixed thickness (2 nm) are studied in the temperature range 2–230 K. It is found that the variation of the Tb layer thickness in the range 1.5–360 nm and the nonmagnetic layer material leads to substantial changes in the magnetic hysteresis of the films and its temperature behavior. These changes are related to a change in the structural composition of the films, which consists of nanocrystalline, granulated, and amorphous Tb phases. 相似文献