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Hydrogenation Properties of Zr Films Under Various Conditions
of Hydrogen Plasma
YAN Guo-Qiang, SHI Li-Qun, ZHOU Zhu-Ying, HAO Guo-Qing, HU Pei-Gang, LUO Shun-Zhong, PENG Shu-Ming, DING Wei, LONG Xing-Gui
Chin. Phys. Lett. 2002, 19 (6):
775-778
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The hydrogenation properties of Zr samples with and without an Ni overlayer under various plasma conditions were investigated by means of non-Rutherford backscattering (non-RBS) and elastic recoil detection analysis. The theoretical maximum hydrogen capacity, 66.7at.%, could be achieved at a hydrogen absolute pressure of ~2 Pa and a substrate temperature of ~393 K for a plasma irradiation of only 10 min; this was significantly greater than that for gas hydrogenation under the same hydrogen pressure and substrate temperature. It was also found that the C and O contamination on the sample surface strongly influences the hydrogenation, and that the maximum equilibrium hydrogen content drops dramatically with the increasing total contamination. In addition, the influence of the Ni overlayer on the plasma hydrogenation is discussed.
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Violet to Infrared Multiwavelength Generation in Periodically
Poled Lithium Niobate Pumped by a Q-Switched Nd:YVO4 Laser
XU Zu-Yan, LIANG Xiao-Yan, LI Jian, YAO Ai-Yun, LIN Xue-Chun, CUI Da-Fu, WU Ling-An
Chin. Phys. Lett. 2002, 19 (6):
801-803
.
Six output wavelengths from violet to infrared have been observed simultaneously from an all-solid-state laser pumped optical parametric oscillator in a periodically poled lithium niobate crystal. The output wavelengths can be tuned by varying the quasi-phase matched period and/or temperature. The pump laser is a diode-pumped passive Q-switched Nd:YVO4 laser operated at 1064 nm. Using a crystal with a 29.9μm grating period, we measured six wavelengths at 448, 515, 532, 630, 773 and 1546 nm and obtained efficient output. We explain the multiwavelength generation by multiwave coupling theory. This phenomenon may have novel applications in photonic devices.
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Parameter Optimization of a 9 x 9 Polymer Arrayed Waveguide Grating Multiplexer
GUO Wen-Bin, MA Chun-Sheng, CHEN Wei-You, ZHANG Da-Ming, CHEN Cai-Xin, CUI Zhan-Chen, ZHAO Yu, LIU Shi-Yong
Chin. Phys. Lett. 2002, 19 (6):
810-813
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Some important parameters are optimized for a 9 x 9 polymer arrayed waveguide grating multiplexer around the central wavelength of 1.55μm with the wavelength spacing of 1.6 nm. These parameters include the thickness and width of the guide core, diffraction order, pitch of adjacent waveguides, path length difference of adjacent arrayed waveguides, focal length of slab waveguides, free spectral range, the number of input/output channels and that of arrayed waveguides. Finally, a schematic waveguide layout of this device is presented, which contains 2 slabs, 9 input and 9 output channels, and 91 arrayed waveguides.
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Giant Magnetoresistance Effect of the Nanoscale Layered-Perovskite La2.5-xK0.5+xMn2O7 (0 < x < 0.5)
ZHONG Wei, ZHANG Ning, LIU Xian-Song, ZHAO Li-Juan, ZHANG Jian-Rong, DU You-Wei
Chin. Phys. Lett. 2002, 19 (6):
857-860
.
Nanoscale layered-perovskite La2.5-xK0.5+xMn2O7 (0 < x < 0.5) have been prepared by the modified sol-gel method, and their structures, magnetic and electric properties have been studied. The experimental results show that these materials exhibit paramagnetic-to-ferromagnetic phase transitions at 183, 216, 230, 238, and 249 K for x = 0.05, 0.15, 0.25, 0.35, and 0.45, respectively. For all compositions of La2.5-xK0.5+xMn2O7 investigated here, we have not observed the metal-nonmetal transition phenomena for the whole temperature region (80 - 300 K). The nanoscale samples exhibit highly enhanced magnetoresistance (MR) effects especially at low temperatures (< TC). The MR behaviour can be explained by taking account of the two-dimensionality with anisotropy of the Mn-O networks and nanoscale grain size effect in the layered manganese perovskites.
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Raman Spectra of the Calix[n]arene-C60 Complex
CHENG Guang-Xu, GU Gang, ZHANG Wei, ZANG Wen-Cheng, DU You-Wei, WU Yong, XU Zheng, CHENG Jia, CHU Hao-Yu
Chin. Phys. Lett. 2002, 19 (6):
861-863
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We have obtained the Raman spectra of the calix[n]arene C60 complex of anti-conformation. Very different interactions between C60 and calix[n]arene (n = 4,8) have been found from the vibratory spectroscopy, which are more complicated than that reported in previous works. It is of interest to find three low frequency modes, i.e., the spheroidal, torsional and E2 clearly shown at 39, 130 and 208 cm-1, respectively. It is primarily interpreted as relaxation effect of calix[8]arene framework for C60 where the intramolecular bridge between C60 and calix[8]arene are partly packed and two axes of C60 ([100] and [101]) are changed from the original configuration. The change of vibratory environment of carbon atom of C60 made some new modes create. The Hg5 mode (at 1101cm-1) and Hg2 (at 431cm-1) have been split and some modes (the Ag2 and other six Hg modes) were hidden.
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41 articles
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