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Observation of Low-Lying and Linking Transitions124 Cs
LU Jing-Bin, LIU Yun-Zuo, YIN Li-Chang, ZHANG Fan, WU Xiao-Guang, WEN Shu-Xian, LI Guang-Sheng, YANG Chun-Xiang
Chin. Phys. Lett. 2001, 18 (1):
21-23
.
The level states of the nucleus 124Cs have been populated through the 116Sn(11B,3n) reaction at a beam energy of 45 MeV, provided by the HI-13 tandem accelerator of the China Institute of Atomic Energy. A number of low-lying states are constructed. The level states in the πh11/2 vg7/2 side band are extended down to lower spin by one h. The level energies and spins in the rotational bands are determined through the establishment of various connections, which confirm the spin assignment of the yrast band in124Cs based on excitation energy systematics. It is revealed that with the present spin assignment, the πh11/2 vg7/2 side band shows signature inversion at low-spin region and the inversion occurs at a spin of about 16ħ.
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Collective Bands in Neutron-Rich 104Mo Nucleus
YANG Li-Ming, ZHU Sheng-Jiang,
LI Ke, J. H. Hamilton
A. V.Ramayya, J. K. Hwang,
X.Q. Zhang, ZHU Ling-Yan,
GAN Cui-Yun, M. Sakhaee,
LONG Gui-Lu, XU Rui-Qing,
HANG Zheng, JIANG Zhuo,
JON Myong-Gil, W. C. Ma,
B. R. S. Babu, J. Komicki,
E. F. Jones, J. D. Cole,
R. Aryaeinejad, M. W. Drigert,
I. Y. Lee, J. O. Rasmussen,
M. A. Stoyer, G. M. Ter-Akopian,
A. V. Daniel
Chin. Phys. Lett. 2001, 18 (1):
24-26
.
Levels in the neutron-rich 104Mo nucleus have been investigated by observing prompt γ-rays from the spontaneous fission of 252Cf with the Gammasphere detector array. The ground-state band, the one-phonon and the two-phonon γ-vibrational bands as well as a quasiparticle band have been confirmed and expanded with spin up to 14ħ. Other two side bands probably built on new quasiparticle states are identified. The possible configurations for the quasiparticle bands are discussed. Two of the quasiparticle bands show larger moments of inertia and may have pair-free characteristics. The levels of the ground-state band, the one-phonon γ-band and the two-phonon γ-band calculated from a general collective model are in close agreement with the experimental data.
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Doubly Decoupled Structure in Odd--Odd 178-186Ir Nuclei
ZHANG Yu-Hu, T. Hayakawa, M. Oshima, Y. Toh, J.Katakura, Y. Hatsukawa, M.Matsuda, N. Shinohara, T.Ishii, H. Kusakari, M.Sugawara, T. Komatsubara
Chin. Phys. Lett. 2001, 18 (1):
27-29
.
High-spin states in 178,180Ir have been studied via the 152,154Sm(31P, 5nγ) reactions through excitation functions, x-γ and γ -γ-t coincidence measurements. A doubly decoupled band has been identified in each of the isotopes. The level spacings for such structures in odd--odd
178-186Ir have been inspected and thus a regular level staggering as a function of the neutron number is revealed. This particular phenomenon may be associated with bandmixing at lower excitation energies.
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High-Spin States in the Odd-Proton Nucleus135Pm
WENG Pei-Kun, YUAN Guan-Jun, ZHANG Zhan-Jun, LI Sheng-Gang, WEN Shu-Xian, LI Guang-Sheng, DAI Zheng-Yu, YANG Chun-Xiang, PENG Zhao-Hua, LIU Xiang-An, WU Xiao-Guang, PU Yun-Wei,
Chin. Phys. Lett. 2001, 18 (1):
30-32
.
High-spin states in the odd-proton nucleus 135Pm have been investigated using the 107Ag(32S, 2p2n)135Pm reaction. Seven rotational bands have been observed in 135Pm. The yrast band based on a decoupled h11/2 proton is found to have a band crossing ωc ~ 0.43MeV/ħ. Two positive-parity bands based on the two signature components of the πg7/25/2+[413] Nilsson orbital have been observed in the main sidebands. The favoured band with (π,α)=(+,-1/2) has been shown to populate below the first pair of proton alignment. Both bands have shown upbend at ω1 ~ 0.26 MeV/ħ and ω2 ~ 0.43 MeV/ħ. These crossing frequencies can be attributed to the decoupling of the first pair of H11/2 quasi-proton and H11/2 quasi-neutron, respectively. Four weaker bands have been observed in sidebands too. Among them, two states are possibly built on a πd5/23/2+[411]configuration.
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Influence of Temperature and Species in the Feedstock on the
Growth of Single-Wall Carbon Nanotubes
ZHAO Ming-Wen, XIA Yue-Yuan, MA Yu-Chen, LI Su-Yan, WANG Rui-Jin, ZHANG Hua-Dong, MEI Liang-Mo
Chin. Phys. Lett. 2001, 18 (1):
82-84
.
A molecular dynamics simulation method is used to study the growth of narrow single-wall carbon nanotubes. It is found that the growth temperature and the species of small carbon clusters in the feedstock are important for the quality of the nanotubes grown. There is a temperature range of 1000-1500K in which the narrow armchair single-wall carbon nanotubes can grow rapidly via adduction of C2 dimers, even without the existence of catalysts. The narrow zigzag tubes cannot keep open-ended growth. If the feedstock consists of various species of carbon clusters, the tubes cannot keep open-ended growth. At higher temperatures, the narrow nanotubes close rapidly in the noncatalytic environment, and the products grown are fullerene-like capsules.
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Restudy of Grüneisen Parameter of Iron in the Pressure Range of 90-160GPa
LI Xi-Jun, ZHOU Xian-Ming, WANG Fan-Hou, JING Fu-Qian,
Chin. Phys. Lett. 2001, 18 (1):
85-87
.
The Hugoniot equation-of-state (EOS) of porous iron with an average initial density of 6.904g/cm3 has been measured in the pressure range from 90 to 160GPa, and a good straight fitting D = 2.997+1.603μ has accordingly been obtained, where D is the shock wave velocity and μ the particle velocity, both in units of km/s. Combining this with the Hugoniot EOS of non-porous iron, the Grüneisen EOS and the Rankine-Hugoniot energy conservation relation, and taking the possible solid--liquid transition correction, we have calculated the Grüneisen parameter γ of iron and obtained the γ0ρ0 = γρ =const, with γ0 = 1.945 and ρ0 = 7.856cm3, ρ being the density.
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Pits on the Surfaces of Epitaxial c-Axis YBa2Cu3O7-δ Thin Films Grown on Vicinal SrTiO3 Substrates
HU Wen-Fei, LI Lin,
ZHAO Xin-Jie, LIU Wei,
CHEN Ying-Fei, WANG Tian-Sheng,
QIU Xiang-Gang
Chin. Phys. Lett. 2001, 18 (1):
91-93
.
The reoccurrence of pits has been found on the surfaces of c-axis YBa2Cu3O7-δ (YBCO) films grown epitaxially on 10°vicinal SrTiO3 substrates by pulsed laser deposition. They are always associated with films with a step-terrace structure, while polycrystalline films have no pits. Pit formation is attributed to the large interfacial stress induced by vicinal substrate and oxygen deficiency of the YBCO film during the tetragonal-to-orthorhombic (T-O) phase transition, which cannot be released by forming twins, and leads to rupturing of the film surface. By reducing the oxidation partial pressure for the T-O phase transition to 80Pa, no pits were formed, and the YBCO film is superconducting at 60K.
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Evidence for Local Interaction of Cs and CO on Ru(0001)
HE Pei-Mo, ZHANG Han-Jie, LI Bo, ZHUANG You-Yi, WU Yue, BAO Shi-Ning, LI Hai-Yang, ZHANG Xun-Sheng, XU Ya-Bo
Chin. Phys. Lett. 2001, 18 (1):
97-99
.
Ultra-violet photoemission spectroscopy measurements for CO
adsorption on the (2×2)-Cs precovered Ru (0001) surface were performed. The Cs 5p(5p3/2) level (Cs state) locates at 11.3 eV in binding energy for the (2×2)-Cs overlayer on Ru (0001). Upon the CO adsorption, a new peak, which is associated with the Cs 5p state for the Cs adatoms influenced by the neighbouring CO adsorbed (the Cs+CO state), appears at the lower binding energy side of the Cs state. This new peak is at 10.8,eV for the CO saturation where the (2×2)-Cs+2CO compound layer is formed. This result gives clear evidence for local interaction of Cs and CO on the Ru (0001) surface.
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Thermal Modification of a-SiC:H Films Deposited by Plasma Enhanced Chemical Vapour Deposition from CH4+SiH4 Mixtures
LIU Yi-Chun, WANG Ning-Hui, LIU Yu-Xue, SHEN De-Zhen, FAN Xi-Wu, LEE Kyung-Sup
Chin. Phys. Lett. 2001, 18 (1):
117-119
.
The effects of thermal annealing on photoluminescence (PL) and structural properties of a-Si1-xCx:H films deposited by plasma enhanced chemical vapour deposition from CH4+SiH4 mixtures are studied by using infrared, PL and transmittance-reflectance spectra. In a-SiC:H network, high-temperature annealing gives rise to the effusion of hydrogen from strongly bonded hydrogen in SiH, SiH2, (SiH2)n, SiCHn and CHn configurations and the break of weak C-C, Si-Si and C-Si bonds. A structural rearrangement will occur, which causes a significant correlation of the position and intensity of the PL signal with the annealing temperature.The redshift of the PL peak is related to the destruction of the confining power of barriers.However, the PL intensity does not have a significant correlation with the annealing temperature for a C-rich a-SiC:H network, which refers to the formation of π-bond cluster as increasing carbon content. It is indicated that the thermal stability of C-rich a-Si1-xCx:H films is better than that of Si-like a-Si1-xCx:H films.
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Hypercooling and the Specific Heat Capacity of Cu-Ni Alloy
YANG Chun, CHEN Min, GUO Zeng-Yuan, WEI Bing-Bo
Chin. Phys. Lett. 2001, 18 (1):
126-128
.
The average heat capacities of the undercooled Cu-25%Ni, Cu-50%Ni,Cu-50%Ni and Cu-75%Ni melts were derived by using the glass fluxing technique. The undercoolings of the above alloys were 381, 380, 349 and 431K, respectively, which exceed the critical undercooling of the classical nucleation theory. A detailed analysis of the heat transfer condition during the solidification process was carried out, which suggested a linear relationship between the time duration of thermal arrest ta and the undercooling ΔT. The hypercooling points of the alloys, derived from the relationship between ta and ΔT, were determined to be 457.7, 461.1, 448.4 and 528.K, respectively.
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54 articles
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