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We demonstrate that the electroluminescent performances of organic light-emitting diodes (OLEDs) are significantly improved by evaporating a thin F4-TCNQ film as an anode buffer layer on the ITO anode. The optimum Alq3-based OLEDs with F4-TCNQ buffer layer exhibit a lower turn-on voltage of 2.6 V, a higher brightness of 39820 cd/m2 at 13 V, and a higher current efficiency of 5.96 cd/A at 6 V, which are obviously superior to those of the conventional device (turn-on voltage of 4.1 V, brightness of 18230 cd/m2 at 13 V, and maximum current efficiency of 2.74 cd/A at 10 V). Furthermore, the buffered devices with F4-TCNQ as the buffer layer could not only increase the efficiency but also simplify the fabrication process compared with the p-doped devices in which F4-TCNQ is doped into b-NPB as p-HTL (3.11 cd/A at 7V). The reason why the current efficiency of the p-doped devices is lower than that of the buffered devices is analyzed based on the concept of doping, the measurement of absorption and photoluminescence spectra of the organic materials, and the current density-voltage characteristics of the corresponding hole-only devices. [ABSTRACT FROM AUTHOR]

We use two parallel nano-slits in a silver film to form a surface plasmon Mach-Zehnder interferometer (MZI), based on the interference of two surface plasmon waves propagating along the two surfaces of the silver film. Coating the silver film with a photoinduced birefringence polymer film, we achieve optical modulation of the MZI output by changing the refractive index of the polymer film with a pump beam. An on/off ratio of 2.7 is obtained for a probe wavelength of 865 nm. [ABSTRACT FROM AUTHOR]

A zero-crossing dynamic speckle method is proposed to determine the velocities of nanoparticles in nanofluids. A Gaussian laser beam is used to illuminate nanofluids in a pipe, and the dynamic speckles are detected by a spatially integrating detector with an aperture. The integrated speckle intensity signal is processed by a computer and the zero-crossing rate is counted. The velocity of the nanoparticles can be determined from its relationship to zero-crossing rate. The results show that the nanoparticles exhibit features of flowing nanofluids, and when the average velocity of the nanofluids is 53.4 mm/s, the average velocity of the nanoparticles is 51.8 ± 5.1 mm/s. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the principle fluctuation modes of the global stock market, which is regarded as a complex system. It is proposed that the systematic risk can be reflected by the trace calculated from the cross-correlation matrix, and the integrity can be classified into clusters according to the plus-minus signs of the elements of the eigenvectors corresponding to several top largest eigenvalues whose total value accounts for more than 60 percent of the trace. The principle fluctuation modes of 30 stock markets are in the same direction in each year of 2005-2010. According to the classification criteria proposed here, the stock markets of the Americas, Europe and Asia & Oceania are automatically classified into different clusters, while Brazil, Russia and China are separated. [ABSTRACT FROM AUTHOR]

The reflectometry is a common method used to measure the thickness of thin films. Using a conventional method, its measurable range is limited due to the low resolution of the current spectrometer embedded in the reflectometer. We present a simple method, using cubic spline interpolation to resample the spectrum with a high resolution, to extend the measurable transparent film thickness. A large measuring range up to 385 μm in optical thickness is achieved with the commonly used system. The numerical calculation and experimental results demonstrate that using the FFT method combined with cubic spline interpolation resampling in reflectrometry, a simple, easy-to-operate, economic measuring system can be achieved with high measuring accuracy and replicability. [ABSTRACT FROM AUTHOR]

We experimentally find that the ZnO thin films deposited by dc-magnetron sputtering have different conduction types after annealing at high temperature in different ambient. Hall measurements show that ZnO films annealed at 1100degC in N2 and in O2 ambient become n-type and p-type, respectively. This is due to the generation of different intrinsic defects by annealing in different ambient. X-ray photoelectron spectroscopy and photolumi-nescence measurements indicate that zinc interstitial becomes a main defects after annealing at 1100degC in N2 ambient, and these defects play an important role for n-type conductivity of ZnO. While the ZnO films annealed at 1100degC in O2 ambient, the oxygen antisite contributes ZnO films to p-type. [ABSTRACT FROM AUTHOR]

High spin states in odd-odd98 Tc nuclei are studied by in-beam g-ray spectroscopy with the 96Zr(6Li, 4n) fusion-evaporation reaction at a beam energy of 35 MeV. The previous level scheme is updated. A band based on 1090.7 keV is expanded, and another band based on 1920.6 keV is newly identified. The observed two negative parity bands in 98Tc are proposed to be a pair of chiral doublet bands with the configuration pg9/2 [?] nh11/2. The evidence supporting the assignment of the chiral doublet bands is discussed. Signature splitting and signature inversion are observed in the pg9/2 [?] nh11/2 band in 98Tc. [ABSTRACT FROM AUTHOR]

Low-lying and high-spin states of 124Cs are studied through the 116 Sn(11 B,3n)124 Cs reaction at a beam energy of 45 MeV. Several new linking transitions are observed, including three transitions between the yrast and ph11/2 [?] nd3/2 bands and two transitions between the yrast and ph11/2 [?] n(d5/2, g7/2) bands. These transitions fix the excitation energy of the yrast band and its decay path, and confirm the existence of eight E1 linking transitions between the yrast and ph11/2 [?] n(d5/2, g7/2) bands observed before. These E1 linking transitions infer the octupole correlation in Cs. The decay paths of the yrast band are investigated, and discrepancies in the level scheme of 124Cs in the latest two studies are clarified. The reason for the discrepancies is discussed. A new decoupled band is established and temporarily assigned as the unfavored signature partner of ph11/2 [?] nd3/2 configuration. [ABSTRACT FROM AUTHOR]