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Rotational State g-Factors in 84Zr
ZHU Sheng-Yun, LUO Qi, LI Guang-Sheng, FAN Zhi-Guo, XU Yong-Jun, GAO Zao-Chun, WEN Shu-Xian, WU Xiao-Guang, LIU Xiang-An, XU Guo-Ji, ZHU Jia-Zheng, CHEN Yong-Shou, K. Matsuta*, M. Fukuda*, M. Mihara*, T. Minamisono*
Chin. Phys. Lett. 2000, 17 (8):
560-561
.
The g-factors of the rotational states along the positive parity yrast band in even-even nuclei 84Zr were measured up to a spin I = 16+ by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model. A peak structure of the g-factors has been observed for the first time. The measured g-factors confirm the mixed configuration of proton and neutron alignments.
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Study on Excitation Function and Isospin Dependencies of Total Reaction Cross Section via the Boltzmann-Uehling-Uhlenbeck Model
CAI Xiang-Zhou, SHEN Wen-Qing, FENG Jun, FANG De-Qing, MA Yu-Gang, SU Qian-Min, ZHANG Hu-Yong, HU Peng-Yun
Chin. Phys. Lett. 2000, 17 (8):
565-567
.
The excitation function and isospin dependencies of σR have been investigated by using the Boltzmann-Uehling-Uhlenbeck (BUU) model with a square-type density distribution. When the width parameter of the square distribution is obtained by fitting σR at relativistic energies, the BUU-model can reproduce the experimental data at intermediate energies better than Glauber model. The systematical underestimation of σR at intermediate energy by Glauber model was removed out now by BUU calculation framework. It is also found that σR is sensitive to nuclear equation of state and σNNin-medium . The difference factor d defined in text is sensitive to the nuclear structure such as neutron halo and neutron skin, etc.
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Internal Subharmonic Resonance in Faraday Experiment
WANG Xin-Long, CHEN Yi-Huang, WEI Rong-Jue,
Chin. Phys. Lett. 2000, 17 (8):
580-582
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The classical Faraday experiment is a tractable problem in nonlinear physics, and its rich spectrum of nonlinear phenomena has made it a prototype in studying nonlinear wave dynamics in general. Here we report the observation of a new type of subharmonic resonances which occurs at some smaller fractional frequencies, such as ν/3 , ν/4, and ν/6, where ν is the forcing frequency. As a result of these resonances, the lower-order surface-wave modes whose eigenfrequencies are close to the fractional frequencies participate into the wave motions. Our theory involving quadratically nonlinear mode couplings shows that an already excited mode itself can act as a parametric source on the lower-order primary modes, thus leading to the cascading subharmonic resonances.
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Superconductivity of Nd1.85Ce0.15CuO4-y by Electrochemical Oxidation
CHEN Ling, CHE Guang-Can, LI Hong, DONG Cheng, Zhou Fang, Huang Yu-Zhen, ZHAO Zhong-Xian
Chin. Phys. Lett. 2000, 17 (8):
601-602
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Superconductivity of n-type superconductor Nd1.85Ce0.15CuO4-y(NCCO) by electrochemical oxidation is reported for the first time and the cyclic voltammogram curve for NCCO as working electrode is presented. Investifations indicate that after oxidation, superconductivity of NCCO is improved: Tc is raised from 20K up to 26K, the superconducting volume fraction is increased also. The valence electronic states of oxygen and copper in NCCO are studied by x-ray photoelectron spectroscopy. It is found that the Cu-2p3/2 peak shifts to the higher binding energy side about 0.4eV, which indicates that the valence-state of copper ions is risen up after oxidation. These results imply that hole-carriers exist in n-type superconductor.
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Spin-Polarized Electron Injection in Co/Cu/Fe Sandwich Structure
WANG Shou-Guo, CHEN Yan-Xue, WANG Zhi-He, CHEN Qiang, CHEN Jing-Lin, SHEN Hong-Lie, LIU Yi-Hua, XIE Shi-Jie, MEI Liang-Mo
Chin. Phys. Lett. 2000, 17 (8):
603-605
.
A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K. The sample performance was demonstrated to be analogous to that of a bipolar transistor. The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of several μV when the bias current between Co and Cu layers was 10μA. The interface roughness, photograph of material, magnetic loop and injection characteristic curves have been measured. Some important points on this topic have been discussed.
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Raman Scattering Study of PbSe Grown on (111) BaF2 Substrate
YANG Ai-Ling, WU Hui-Zhen, LI Zhi-Feng, QIU Dong-Jiang, CHANG Yong, LI Jian-Feng, P. J. McCann, X. M. Fang
Chin. Phys. Lett. 2000, 17 (8):
606-608
.
PbSe films were grown on (111)-oriented BaF2 substrates by using molecular beam epitaxy. High resolution x-ray diffraction characterization showed good crystalline quality of PbSe films. Both longitudinal optical phonon at 135cm-1 and transverse optical phonon at 47.6cm-1 were observed by Raman scattering measurements. The Raman tensor calculation demonstrates that both transverse-optical and longitudinal-optical (LO) phonons in PbSe crystal are Raman active on (111)-oriented surface. Furthermore, 2LO phonon a t about 270cm-1 and polaron at about 800cm-1 in PbSe, were also observed. The observed Raman frequencies are in good agreement with theoretical calculations using point ion model.
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Optical Transitions in Cubic GaN Grown by Metalorganic Chemical Vapor Deposition on GaAs (100) Substrate
CHEN Ye, LI Guo-Hua, HAN He-Xiang, WANG Zhao-Ping, XU Da-Peng, YANG Hui
Chin. Phys. Lett. 2000, 17 (8):
612-614
.
Photoluminescence measurements have been performed on cubic GaN films with carrier concentration as low as 3x1013 cm-3. From the temperature and excitation intensity dependence, the emission lines at 3.268, 3.150 and 3.081 eV were assigned to the excitonic, donor-acceptor pair, and free-to-acceptor transitions, respectively. Additionallx we observed two additional emission lines at 2.926 and 2.821 eV, and suggested that they belong to donor-acceptor pair transitions. Furthermore, from the temperature dependence of integral intensities, we confirmed that three donor-acceptor pair transitions (3.150, 2.926, and 2.821 eV) are from a common shallow donor to three different acceptors. The excitonic emission at 3.216 eV has a full-width-at-half-maximum value of 41 meV at room temperature, which indicates a good optical quality of our sample.
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Preparation of AlGaN/GaN Heterostructures on Sapphire Using Light Radiation Heating Metal-Organic Chemical Vapor Deposition at Low Pressure
ZHOU Yu-Gang, SHEN Bo, ZHANG Rong, LI Wei-Ping, CHEN Peng, CHEN Zhi-Zhong, GU Shu-Lin, SHI Yi, Z. C. Huang, ZHENG You-Dou
Chin. Phys. Lett. 2000, 17 (8):
617-618
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AlGaN/GaN heterostructures on sapphire substrate were fabricated by using light radiation heating metalor-ganic chemical vapor deposition. Photoluminescence excitation spectra show that there are two abrupt slopes corresponding to the absorption edges of AlGaN and GaN, respectively. X-ray diffraction spectra clearly exhibit the GaN (0002), (0004), and AlGaN (0002), (0004) diffraction peaks, and no diffraction peak other than those from the GaN {0001} and AlGaN {0001} planes is found. Reciprocal space mapping indicates that there is notilt between the AlGaN layer and the GaN layer. All results also indicate that the sample is of sound quality and the A1 composition in the AlGaN layer is of high uniformity.
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29 articles
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