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排序方式: 共有239条查询结果,搜索用时 15 毫秒
1.
2.
We study chargino and neutralino pair production at the Next Linear e+ e− Collider in a supersymmetric left-right model. We investigateon- and off-resonance signals via the processes:
and
. These reactions could lead to observable signals as they compare with the background signal from W± -pair production. 相似文献
3.
Haque SA Palomares E Cho BM Green AN Hirata N Klug DR Durrant JR 《Journal of the American Chemical Society》2005,127(10):3456-3462
In this paper we focus upon the electron injection dynamics in complete dye-sensitized nanocrystalline metal oxide solar cells (DSSCs). Electron injection dynamics are studied by transient absorption and emission studies of DSSCs and correlated with device photovoltaic performance and charge recombination dynamics. We find that the electron injection dynamics are dependent upon the composition of the redox electrolyte employed in the device. In a device with an electrolyte composition yielding optimum photovoltaic device efficiency, electron injection kinetics exhibit a half time of 150 ps. This half time is 20 times slower than that for control dye-sensitized films covered in inert organic liquids. This retardation is shown to result from the influence of the electrolyte upon the conduction band energetics of the TiO2 electrode. We conclude that optimum DSSC device performance is obtained when the charge separation kinetics are just fast enough to compete successfully with the dye excited-state decay. These conditions allow a high injection yield while minimizing interfacial charge recombination losses, thereby minimizing "kinetic redundancy" in the device. We show furthermore that the nonexponential nature of the injection dynamics can be simulated by a simple inhomogeneous disorder model and discuss the relevance of our findings to the optimization of both dye-sensitized and polymer based photovoltaic devices. 相似文献
4.
S. M. Al-Jobori R. K. Itawi A. Saad K. M. Shihab M. Jalil S. S. Farhan 《Journal of Radioanalytical and Nuclear Chemistry》1990,144(3):229-239
As a part of the Iraqi Food Analysis Programme /I.F.A.P./ the concentration of Na, Mg, P, Cl, K, Ca, Zn, Se, Br, Rb and I in natural milk collected from different regions of Iraq, and in milk powder samples have been determined by using the NAA technique. It was found that except for the elements I, Rb and Br the concentration of the elements was approximately identical in both the natural milks and milk powders. 相似文献
5.
In order to scan nanostructures on a surface, we present a new recurrence tracking microscope based on an atomic trap. An evanescent wave trap is formed by the total internal reflection of two laser fields having different signs of detuning and penetration depths into the vacuum. The microscope employs the quantum recurrence phenomena of trapped atoms. Recurrence times depend on the initial energy of the wave packet in the trap and vary following the nanostructures on the surface under investigation. 相似文献
6.
We prove an invariant Harnack’s inequality for operators in non-divergence form structured on Heisenberg vector fields when the coe?cient matrix is uniformly positive definite, continuous, and symplectic. The method consists in constructing appropriate barriers to obtain pointwise-to-measure estimates for supersolutions in small balls, and then invoking the axiomatic approach developed by Di Fazio, Gutiérrez, and Lanconelli to obtain Harnack’s inequality. 相似文献
7.
Energetic ion beams are proving to be versatile tools for modification and depth profiling of materials. The energy and ion species are the deciding factor in the ion-beam-induced materials modification. Among the various parameters such as electronic energy loss, fluence and heat of mixing, velocity of the ions used for irradiation plays an important role in mixing at the interface. The present study is carried out to find the effect of the velocity of swift heavy ions on interface mixing of a Ti/Bi bilayer system. Ti/Bi/C was deposited on Si substrate at room temperature by an electron gun in a high-vacuum deposition system. Carbon layer is deposited on top to avoid oxidation of the samples. Eighty mega electron volts Au ions and 100?MeV Ag ions with same value of Se for Ti are used for the irradiation of samples at the fluences 1?×?1013–1?×?1014 ions/cm2. Different techniques like Rutherford backscattering spectroscopy, atomic force microscopy and grazing incidence X-ray diffraction were used to characterize the pristine and irradiated samples. The mixing effect is explained in the framework of the thermal spike model. It has been found that the mixing rate is higher for low-velocity Au ions in comparison to high-velocity Ag ions. The result could be explained as due to less energy deposition in thermal spike by high-velocity ions. 相似文献
8.
We introduce a recurrence tracing microscope based on the reflection of cold atoms from two magnetic mirrors placed in parallel. A cantilever is attached perpendicularly to one of the two mirrors at the lower end that probes surface structures. The quantum dynamics in the system provides the matter waves to store information on the height and spacing between the nanostructures. We use the recurrence tracking microscope in static and dynamic modes to study arbitrary and periodic nanostructures. 相似文献
9.
Shahid Iqbal Paula Rivière Farhan Saif 《International Journal of Theoretical Physics》2010,49(10):2540-2557
Gazeau-Klauder coherent states are developed for power-law potentials and their evolution in space and time is analyzed. We
show that these states follow classical dynamics as long as the underlying energy spectrum is linear, otherwise they follow
a classical-like evolution upto a few classical periods and disperse thereafter, despite its special construction. Auto-correlation
function and probability density as a function of space and time explain the spatio-temporal behavior of these states. 相似文献
10.
A new synthetic method leading to N-heterocyclic carbene–silver(I) complexes [(R2-NHC)2Ag]+ [AgX2]? is developed by using benzimidazolium compounds, NaOH (as a base), silver salts and water (as the reaction medium). Single-crystal X-ray structure revealed that compound 1 comprises a linear [Ag-(Et2-Bimy)2]+ cation and a linear [AgBr2]? anion. These two ions are linked through an AgI–AgI association and staggered at an angle of 90.3°. 相似文献