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61.
W. J. Guo Y. F. Lin X. H. Gong Y. J. Chen Z. D. Luo Y. D. Huang 《Applied physics. B, Lasers and optics》2009,94(1):155-163
A Pr3+:NaGd(MoO4)2 single crystal has been grown by the Czochralski method. The polarized absorption spectra, polarized fluorescence spectra,
and fluorescence decay curves of the crystal were measured at room temperature. The Judd–Ofelt intensity parameters Ω
t,q
(t=2,4,6) and the spectroscopic parameters related to the 3
P
0 and 1
D
2 multiplets were obtained and analyzed. The decay mechanisms for the 3
P
0 and 1
D
2 multiplets were also discussed. 相似文献
62.
Ting Chen Ying Chen Ming Gong Chuan Liu Liuming Liu Yu-Bin Liu Zhaofeng Liu Jian-Ping Ma Markus Werner Jian-Bo Zhang 《中国物理C(英文版)》2019,43(10):103103-103103-14
In this exploratory study, near-threshold scattering of D and \begin{document}$\bar{D}^*$\end{document} ![]()
![]()
meson is investigated using lattice QCD with \begin{document}$N_f=2+1+1$\end{document} ![]()
![]()
twisted mass fermion configurations. The calculation is performed in the coupled-channel Lüscher finite-size formalism. The study focuses on the channel with \begin{document}$I^G(J^{PC})=1^+(1^{+-})$\end{document} ![]()
![]()
where the resonance-like structure \begin{document}$Z_c(3900)$\end{document} ![]()
![]()
was discovered. We first identify the two most relevant channels and the lattice study is performed in the two-channel scattering model. Combined with the two-channel Ross-Shaw theory, scattering parameters are extracted from the energy levels by solving the generalized eigenvalue problem. Our results for the scattering length parameters suggest that for the particular lattice parameters that we studied, the best fit parameters do not correspond to the peak in the elastic scattering cross-section near the threshold. Furthermore, in the zero-range Ross-Shaw theory, the scenario of a narrow resonance close to the threshold is disfavored beyond the 3\begin{document}$\sigma$\end{document} ![]()
![]()
level. 相似文献
63.
64.
应用ICP-AES法研究云南普洱茶稀土含量 总被引:7,自引:0,他引:7
应用电感耦合等离子体发射光谱法(ICP-AES)对云南省普洱茶主产地采集的150份普洱茶样品的稀土含量进行检测研究.检测样品中稀土的含量在0.26~4.07 mg·kg-1范围.依据国家标准GB 2762-2005<食品中污染物限量>中稀土限量标准2 mg·kg-1考核,43%的普洱茶样品被检出稀土含量超标.云南普洱熟茶和生茶不同的生产工艺会造成普洱茶稀土含量的差异,并影响产品质量.云南普洱茶不同主产地区之间的稀土含量存在差异,个别地区的普洱茶稀土质量安全控制情况不容乐观. 相似文献
65.
Gold nanoparticle arrays are fabricated for surface-enhanced Raman scattering (SERS) and the effect of the annealing temperature, the thickness of nanoparticle array and the exciting power on the SERS signals are investigated. The particle distribution and particle size are dense and uniform on the glass substrate when the 10 nm gold film was annealed at 250 °C and strong SERS signals for Rhodamine 6G were achieved via a 532 nm excitation with a 10 mW power. The SERS signal at 1650 cm−1 is enhanced more than 10 times as compared to that of the gold film without annealing. The strong SERS behavior of gold nanoparticle arrays may broaden the SERS applications in biomedical and analytical chemistry. 相似文献
66.
环境卫星HJlA超光谱成像仪在轨辐射定标及光谱响应函数敏感性分析 总被引:1,自引:0,他引:1
环境卫星HJIA搭载的超光谱成像仪HSI是我国第一个对地观测的星载高光谱传感器,针对超光谱成像仪缺乏各通道光谱响应函数这一问题,对传统的反射率基法予以改进,提出一种不使用光谱响应函数的场地定标方法.利用敦煌场地2009年8月定标实验数据,实现超光谱成像仪在轨辐射定标.通过构建不同形状的光谱响应函数,分析光谱响应函数形状对最终辐射定标结果产生的误差.结果表明,利用新提出的场地定标方法可以实现超光谱成像仪绝对辐射定标,除水汽和氧气吸收通道外,光谱响应函数对定标结果的影响小于3%,采用新定标方法得到的定标系数可以满足应用的需求. 相似文献
67.
This paper presents a car-following model that considers the asymmetric characteristic of the velocity differences of the vehicles in a traffic stream. The problems of the prevalent general force (GF) model and the full velocity difference (FVD) model were solved. Furthermore, the optimal velocity (OV) model, the GF model, and the FVD model are proved to be the special cases of the proposed asymmetric full velocity difference (AFVD) model. The mathematical model is presented, followed by simulation analysis which demonstrates the properties of the AFVD model. 相似文献
68.
Difference-frequency ultrasound generation from microbubbles under dual-frequency excitation 下载免费PDF全文
The difference-frequency (DF) ultrasound generated by using parametric effect promises to improve detection depth owing to its low attenuation, which is beneficial for deep tissue imaging. With ultrasound contrast agents infusion, the harmonic components scattered from the microbubbles, including DF, can be generated due to the nonlinear vibration. A theoretical study on the DF generation from microbubbles under the dual-frequency excitation is proposed in formula based on the solution of the RPNNP equation. The optimisation of the DF generation is discussed associated with the applied acoustic pressure, frequency, and the microbubble size. Experiments are performed to validate the theoretical predictions by using a dual-frequency signal to excite microbubbles. Both the numerical and experimental results demonstrate that the optimised DF ultrasound can be achieved as the difference frequency is close to the resonance frequency of the microbubble and improve the contrast-to-tissue ratio in imaging. 相似文献
69.
70.