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Effects of Flavour-Dependent qq Annihilation on the Mixing Angle of the Isoscalar Octet--Singlet and Schwinger’s Nonet Mass Formula
LI De-Min, YU Hong, SHEN Qi-Xing,
Chin. Phys. Lett. 2001, 18 (2):
184-186
.
By incorporating the flavour-dependent quark--antiquark annihilation amplitude into the mass-squared matrix describing the mixing of the isoscalar states of a meson nonet, the new version of Schwinger's nonet mass formula, which holds with a high accuracy for the 0-+, 1--, 2++, 2-+ and 3-- nonets, is derived and the mixing angle of the isoscalar octet--singlet for these nonets is obtained. In particular, the mixing angle of the isoscalar octet--singlet for the pseudoscalar nonet is determined to take the value of -12.92°, which is in agreement with the value range from -13° to -17° deduced from a rather exhaustive and up-to-date analysis of data. It is also pointed out that the omission of the flavour-dependent qq annihilation effect might be a factor resulting in the invalidity of Schwinger’s original nonet mass formula for the pseudoscalar nonet.
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Two-Photon Absorption and Fluorescence of a Novel Compound
Trans-1,3,5-tri-(4-N,N-Dimethylaminobenzylstyryl)-Acetylacetone
LI Yun-Jing, ZHAN Chuan-Lang, ZHAO Li-Zeng, WANG Duo-Yuan, LU Zhen-Zhong, NIE Yu-Xin
Chin. Phys. Lett. 2001, 18 (2):
205-207
.
Large two-photon absorption cross section of a novel compound
trans-1,3,5-tri-(4-N,N-dimethylaminobenzylstyryl)-acetylacetone is measured to be σ2=8.4 x 10-20cm4/GW or σ'2=1.594 x 10-47cm4/(photon.s) by using a 1064 nm Nd:YAG laser with 35 ps pulse width based on the intensity-dependent transmissivity measurement. The frequency upconversion fluorescence is observed by two-photon laser pumping. This material is an ideal candidate for optical limiting and upconversion fluorescence.
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Measurements of Laser Absorption and Ion Energy in Femtosecond Laser--Cluster Interaction
LIN Jing-Quan, ZHANG Jie, LI Ying-Jun, CHEN Li-Ming, LÜ, Tie-Zheng, TENG Hao, MAN Bao-Yuan, ZHAO Li-Zeng
Chin. Phys. Lett. 2001, 18 (2):
211-213
.
Laser absorption is measured in Xe, Ar and He clusters irradiated by 5 mJ laser pulses in 150 fs. The measurements show that the absorption efficiency strongly depends on the backing pressure of the gas jets, the laser pulse duration and the atomic number Z of the working gas. The laser absorption for Xe clusters is found to be as high as 45% at a backing pressure of 20 atm and a laser intensity of 1 x 1015 W/cm2. Significant numbers of ions with energies up to 100 keV are detected from Xe cluster explosion. The variation trend of the average ion energy at different backing pressures is consistent with that of the laser energy absorption.
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Tunable Solid-State Dye Laser with Narrow Linewidth Operation
HONG Zhi, WANG Zhi-Yu, YANG Yu, CHEN Jun, WANG Min-Quan, BAO Cheng-Fang, QIU Wen-Fa
Chin. Phys. Lett. 2001, 18 (2):
225-227
.
Tunable radiation with a linewidth of 0.014 nm was obtained in Rhodamine B, Rhodamine 6G, Perylene orange and Pyrromethene 567-doped GPTMS solid-state dye materials using intracavity grating dispersive oscillation. The solid dye samples were specially designed in the way in which they are gelling, drying and ageing between two anti-reflection coated disks, thus without any mechanical and optical processing. The conversion efficiency of 4.6% and the tunable range of 40 nm from 589--629 nm have been achieved in Rhodamine B-doped samples. The broadband lasing of 4.4 nm and 54% slope efficiency were also demonstrated in the experiment.
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Classical Dynamics of Harmonic Generation of the Hydrogen
Molecular Ion Interacting with Ultrashort Intense Laser Pulses
LI Chao-Hong, DUAN Yi-Wu, Wing-Ki Liu, Jian-Min Yuan
Chin. Phys. Lett. 2001, 18 (2):
236-238
.
Within Born--Oppenheimer approximation, by using the classical trajectory theory, a description for the high-order harmonic generation of the hydrogen molecular ion interacting with ultrashort laser pulses has been presented. The Coulomb singularities have been remedied by the regularization. The action-angle variables have been used to generate the initial inversion symmetry microcanonical distribution. Within a proper intensity range, a harmonic plateau with only odd harmonics appears. For a larger intensity, because of the existence of chaos, the harmonic spectra become noisier. For a large enough intensity, the ionization takes place and the harmonics disappear. So the chaos causes the noises, the ionization suppresses the harmonic generation, and the onset of the ionization follows the onset of chaos.
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Numerical Study of the Apodization Profile Functions, Optimal
Profiles and Lengths of a Linearly Chirped Fibre Bragg Grating
QIN Zi-Xiong, ZENG Qing-Ke, FENG De-Jun, XIANG Yang, DING Lei,
KAI Gui-Yun, LIU Zhi-Guo, YUAN Shu-Zhong, DONG Xiao-Yi, LIU Ning, LIAO Chang-Jun, LIU Song-Hao
Chin. Phys. Lett. 2001, 18 (2):
239-241
.
Starting from our definition of apodization profile functions, we discover the optimal profiles and the characteristics of defined apodization functions in sidelobe suppression. It is shown by numerical analysis that the optimal grating length is 45 mm to compensate for dispersion induced by 100 km fibres and the smoothness of the ripples in time-delay characteristics is related to the defined parameters.
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Optical Waveguide Formation in LiNbO3 by the 2.6 MeV
Nickel Ions Implantation
HU Hui, CHEN Feng, LU Fei, ZHANG Jian-Hua, LIU Ji-Tian, WANG Ke-Ming, SHI Bo-Rong, SHEN Ding-Yu, WANG Xue-Mei
Chin. Phys. Lett. 2001, 18 (2):
242-244
.
The optical waveguide was formed on an LiNbO3 substrate by 2.6 MeV nickel ions implantation to the dose of 9 x 1014 ions/cm2. Five dark modes were observed by the prism coupling technique. The refractive index profile was obtained by using the reflectivity calculation method. A large index decrease was found in the guiding region and in the optical barrier, which is somewhat different from that of the LiNbO3 waveguide formed by the MeV He+ ions. The position of the optical barrier is deeper than that of the damage peak calculated by TRIM'90 (Transport of Ions in Matter) code. The crystal lattice damage in the guiding region caused by the Ni+ ion implantation was analysed by the Rutherford backscattering/channelling technique.
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Generation of Radial Electric Field with Electrode Biasing
WANG Cheng, PAN Ge-Sheng, WEN Yi-Zhi, YU Chang-Xuan, WAN Shu-De, LIU Wan-Dong, WANG Zhi-Jiang, SUN Xuan
Chin. Phys. Lett. 2001, 18 (2):
257-259
.
Time and space resolved measurements of the radial electric field (Er) have been conducted during the electrode biasing experiments on the KT-5C tokamak. The suppression of the turbulent transport with the change of Er induced by the biased electrode is observed. It is found that the poloidal flow contributes to the main part of the Er, and the change of the poloidal flow has a lead of about 20μs to the formation of Er. These observations suggest that a radial current, responding to an induced voltage on the electrode, drives a poloidal flow which in turn drives the radial electric field.
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52 articles
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