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991.
The formation of free-standing gold nanosieves by ablation with ultra-short laser pulses is demonstrated. Macroscopic areas are generated fast and efficiently by the application of a parallel production technique. The technique is based on a lens array formed by self-assembling quartz microspheres on a thin metal foil. The evaporated foils have a final thickness of 400 nm, and the hole spacing is set by the diameter of the microspheres (∼7 eight="11" border="0" style="vertical-align:bottom" width="12" alt="View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0169433208023660-si2.gif">m) while the pore size is ∼700 nm. The characteristic spacing of the generated hole structure is verified by an optical diffraction technique. 相似文献
992.
An antireflective structure with two-dimensional 300-nm periodicity was fabricated on a phosphate glass surface using an imprinting process with a SiC mold. The optimized structure designed using RCWA calculation was a convex circular cone sharing the ridge line of adjacent cones. The SiC mold was fabricated using electron beam drawing and subsequent reactive ion etching with CHF3 and O2 gases. The glass’ surface reflectance was estimated as 0.2% at 530 nm wavelength, which was approximately 1/20 that of the optically polished surface. 相似文献
993.
Ba(Zr0.05Ti0.95)O3 (BZT) thin films grown on Pt/Ti/SiO2/Si(1 0 0) substrates were prepared by chemical solution deposition. The structural and surface morphology of BZT thin films has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the random oriented BZT thin film grown on Pt/Ti/SiO2/Si(1 0 0) substrate with a perovskite phase. The SEM surface image showed that the BZT thin film was crack-free. And the average grain size and thickness of the BZT film are 35 and 400 nm, respectively. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Ti, and Zr exist mainly in the forms of BZT perovskite structure. 相似文献
994.
Recent progress in the accelerator structure studies at SLAC is reported. This paper covers the room temperature accelerator structures for the ILC e+/e- sources; RF structures for some photon science projects including RF deflectors and the LCLS RF gun; the high gradient accelerator R &; D in a global CLIC collaboration for the future multi-TeV linear colliders. 相似文献
995.
Complementary to the conventional experimental studies on N* from πN and γ(*)N reactions, the e+e-, pp and pp collisions can give novel insights into these N* resonances. While the e+e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N*, △*, ∧*, ∑* and 2*, the pp collisions should be the best place for producing those △*++ with large coupling to p+p though pp →nA*++ reaction, and the pp collisions should be the best place for looking for those N* with large coupling to σN. 相似文献
996.
The generalized liquid drop model (GLDM) is extended to the region around deformed shell closure ^270Hs by taking into account the excitation energy EI+ of the residual daughter nucleus and the centrifugal potential energy Vcen(r). The branching ratios of a decays from the ground state of a parent nucleus to the ground state 0^+ of its deformed daughter nucleus and to the first excited state 2^+ are calculated in the framework of the GLDM. The results support the proposal that a measurement of a spectroscopy is a feasible method to extract information on nuclear deformation of superheavy nuclei around the deformed nucleus ^270Hs. 相似文献
997.
We study the nonlinear dynamics of a DNA molecular system at physiological temperature in a viscous media by using the Peyrard-Bishop model. The nonlinear dynamics of the above system is shown to be governed by the discrete complex Cinzburg-Landau equation. In the non-viscous limit, the equation reduces to the nonlinear Schroedinger equation. Modulational instability criteria are derived for both the cases. On the basis of these criteria, numerical simulations are made, which confirm the analytical predictions. The planar wave solution used as the initial condition makes localized oscillations of base pairs and causes energy localization. The results also show that the viscosity of the solvent in the surrounding damps out the amplitude of wave patterns. 相似文献
998.
This paper reports on the absorption, visible and near-infrared luminescence properties of Nd3+, Er3+, Er3+/2Yb3+, and Tm3+ doped oxyfluoride aluminosilicate glasses. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (<em>Ωem>2, <em>Ωem>4 and <em>Ωem>6) have been calculated for all the studied ions. Decay lifetime curves were measured for the visible emissions of Er3+ (558 nm, green), and Tm3+ (650 and 795 nm), respectively. The near infrared emission spectrum of Nd3+ doped glass has shown full width at half maximum (FWHM) around 45 nm (for the 4F3/2→4I9/2 transition), 45 nm (for the 4F3/2→4I11/2 transition), and 60 nm (for the 4F3/2→4I13/2 transition), respectively, with 800 nm laser diode (LD) excitation. For Er3+, and Er3+/2Yb3+ co-doped glasses, the characteristic near infrared emission bands were spectrally centered at 1532 and 1544 nm, respectively, with 980 nm laser diode excitation, exhibiting full width at half maximum around 50 and 90 nm for the erbium 4I13/2→4I15/2 transition. The measured maximum decay times of 4I13/2→4I15/2 transition (at wavelength 1532 and 1544 nm) are about 5.280 and 5.719 ms for 1Er3+ and 1Er3+/2Yb3+ (mol%) co-doped glasses, respectively. The maximum stimulated emission cross sections for 4I13/2→4I15/2 transition of Er3+ and Er3+/Yb3+ are 10.81×10−21 and 5.723×10-21 cm2. These glasses with better thermal stability, bright visible emissions and broad near-infrared emissions should have potential applications in broadly tunable laser sources, interesting optical luminescent materials and broadband optical amplification at low-loss telecommunication windows. 相似文献
999.
Girma Hailu Genene Tessema Balla Diop Ngom Ncholu Manyala Malik Maaza 《Applied Physics A: Materials Science & Processing》2009,96(3):685-689
The nonlinear absorption (NLA) properties of five different types of porphyrins were studied using the Z-scan technique. The
porphyrins under investigation were confined into Nafion column matrix membrane in order to protect them from possible degradation.
The results of the experiments have indicated that all the porphyrins tested exhibited interesting NLA properties. The nonlinear
absorption coefficients (β’s) were determined at different porphyrin concentrations by comparing the Z-scan data with the theoretical functions. 相似文献
1000.