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Laser Induced Light-Force Interaction in the Optical Near-Field Region
ZHU Xing, LING Yong, HUANG Gui-song, ZHOU He-tian, DAI Yuan-dong, WU Ke, GAN Zi-zhao
Chin. Phys. Lett. 1998, 15 (3):
165-167
.
Laser light can induce many effects on the vicinity of the sample surface due to the proximity effects, such as the field enhancement at the surface of a small conducting particle; plasma exchange effect between the metallic tip and substrate surface. We have observed a new optical tip-sample interaction: laser induced force as the results of light pressure in the near-field region. Under the side illumination of a laser light, an additional attractive force was observed between a dielectric tip and various samples of C60, optical glass, YBa2Cu3O7-d(YBCO) thin film. No such effect was observed in metallic samples. This optical binding force is due to the multiple scattering of light between two close objects. The results are in good agreement with the recent theoretical calculation. The effects of the optical refraction index, thermal expansion of probe tip due to laser radiation are discussed.
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Collective Behavior of Negative Parity States in 126Ba at High Spin
LI Guang-sheng, DAI Zheng-yu, LIU Xiang-an, ZHANG Lan-kuan, WEN Shu-xian, WU Xiao-guang, YUAN Guan-jun, WENG Pei-kun, LI Sheng-gang, YANG Chun-xiang
Chin. Phys. Lett. 1998, 15 (3):
168-169
.
Lifetimes of the high spin states in the negative parity band of 126Ba were measured by using the Doppler shift attenuation method in conjunction with the reaction 116Sn(16O, 2p4n)126Ba at a beam energy of 73 MeV. This band shows a typically collective behavior and possesses a near-axial prolate shape with a deformation parameter β2 = 0.27 ± 0.01 and triaxiality γ ~ -5°.
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Changes in Mean Square Nuclear Charge Radii of Nd II from Optical Isotope Shifts by Collinear Fast-Ion-Beam Laser Spectroscopy
MA Hong-liang, SHI Wei, YAN Bing, CHEN Miao-hua, CHEN Zhi-jun, FANG Du-fei, LU Fu-quan, TANG Jia-yong, YANG Fu-jia
Chin. Phys. Lett. 1998, 15 (3):
178-179
.
High-resolution collinear fast-ion-beam-laser spectroscopy has been applied to investigate the optical isotope shifts for transition 4f45d6K11/2-(24445)°11/2 of Nd II. From the measured optical isotope shifts, changes in mean-square nuclear charge radii δ(r2) (fm2) among five even-even neodymium isotopes have been deduced: (142,144) 0.282, (144, 146) 0.242, (146, 148) 0.274, (148, 150) 0.404. The results are in good agreement with experimental data from electronic x-ray spectroscopy and combined optical and x-ray spectroscopy.
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Nonlinear Optical Properties of Some New Conjugated Copolymers
YANG Qi-guang, SI Jin-hai, LIU Xu-chun, XU Gang, YE Pei-xian, LEI Zi-qiang, ZHAN Xiao-wei, YANG Mu-jie
Chin. Phys. Lett. 1998, 15 (3):
189-191
.
The ground- and the excited-state nonlinearities of two new copolymers are investigated in nanosecond scale at 1064 nm. It is found that the excited-state susceptibility is dramatically larger than the corresponding ground-state susceptibility for each sample. The experimental results also give evidence that superlattice structure of the copolymers can enhance, especially for the excited state, the molecular hyperpolarizabilities significantly. This enhancement may be attributed to the confinement effect of the pump-induced carriers.
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Solid/Liquid Interface of Ag/Sn/Ag Trilayers by In Situ Resistivity Measurement
ZHAO Jian-hua, LIU Ri-ping, ZHANG Xiang-yi, CAO Li-min, ZHANG Ming, HE Duan-wei, DAI Dao-yang, XU Ying-fan, WANG Wen-kui,
Chin. Phys. Lett. 1998, 15 (3):
205-207
.
The in situ four-point probe resistivity measurement was used as a main method to study the solid/liquid interfacial characteristics in Ag/Sn/Ag trilayers at temperatures ranging from 150 to 305°C. It is found from the variation of resistivity that three processes take place on annealing: the dissolution of silver atoms, the diffusion of silver atoms, and the formation of Ag3Sn in liquid tin layer. The first one plays the leading role in the variation of resistivity during annealing process. The apparent diffusivity of silver in liquid tin at 305°C is determined to be 7.3×10-17cm2/s.
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Magnetic Properties of Gd2Co17-xSix Compounds
SHEN Bao-gen, LIANG Bing, CHENG Zhao-hua, ZHANG Shao-ying, ZHANG Hong-wei, ZHAN Wen-shan, ZHANG Li-gang
Chin. Phys. Lett. 1998, 15 (3):
223-225
.
Effects of substituting small amounts of Si for Co on the structure and magnetic properties of Gd2CO17 compounds were studied by means of x-ray diffraction and magnetization measurements. All samples are of single phase with the rhombohedra1 Th2Zn17, type structure. The substitution of Si for Co leads to an approximately linear decrease in the unit cell volume. The saturation moment at 1.5 K decreases linearly with increasing Si concentration, being an approximately linear rate of about 4.1μB per substituted Si. The Curie temperature of Gd2Co17-xSix is found to decrease monotonously from 1213 to 651 K, as x increases from 0 to 3. X-ray diffraction measurements on magnetically aligned powders show that the easy magnetization direction of Gd2Co17-xSix compounds changes from basal plane to c-axis with increasing Si concentcation. The samples with x = 2, 3 exhibit a room temperature uniaxial anisotropy.
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Positron Annihilation Studies in the Sm2/3Sr1/3MnO3+δ
JI Yuan, CAO Guo-hui, , LI Yang, MA Qing-zhu, LI Shen, WANG Yun-bo, SHEN Bao-gen
Chin. Phys. Lett. 1998, 15 (3):
226-227
.
We measured lifetime and doppler broadening spectra of Sm2/3Sr1/3MnO3+δ as functions of temperature by positron annihilation technology In terms of lifetime spectrum, we found that the lattice effects triggered by ferromagnetic transition give rise to the change of the coefficient of the average linear thermal expansion of Sm2/3Sr1/3MnO3+δ at Tc. In terms of doppler broadening spectrum, we found the delocalization of low-momentum electrons occurs in Sm2/3Sr1/3MnO3+δ at metal-insulator transition temperature.
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30 articles
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