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201.
Qinan Li Sumei Wang Yuxian Shi Dongxiang Zhang Zhiguo Zhang 《Optics Communications》2008,281(8):2184-2188
A simultaneous self-Q-switched and mode-locked diode-pumped 946 nm laser by using a Cr,Nd:YAG crystal as gain medium as well as saturable absorber is demonstrated for the first time as we know. The maximum average output power of 751 mW with a slope efficiency of 18.38% is obtained at an intra-cavity average peak power intensity of 4.83 × 106 W/cm2. Under this circumstance, the repetition rate of Q-switched envelopes is 9.63 kHz and the pulse width is about 460 ns. Almost 100% mode-locked modulation depth is obtained at all time in the experiment process whether the incident pump power is low or high. The repetition rate of mode-locked pulses within a Q-switched envelope is 135.13 MHz and the mode-locked pulse width is within 600 ps. The laser produces high-quality pulses in TEM00-mode in the simultaneous self-Q-switched and mode-locked experiment. 相似文献
202.
Monte Carlo Simulation on Measurements of Branching Fractions for Some Exclusive Semileptonic Decays of Neutral D Mesons on BES-III 下载免费PDF全文
LIU Hui-Hui CHEN Jiang-Chuan RONG Gang MA Hai-Long ZHAO Ming-Gang LIU Jian 《中国物理快报》2008,25(4):1231-1234
Using the Monte Carlo samples of about 800 pb-1 and 500pb-1 generated at and around 3.773GeV with BOSS (BESIII Offline Software System) 6.0.2 and BOSS 6.1.0, we have studied the branching fractions for D0 →K-l+νl and D0 →πi-l+νl (l=e, μ). According to the simulation results, the expected precision of these measurements for 20fb-1 ψ(3770) data which will be collected on BESIII are well estimated. 相似文献
203.
Origin of Room-Temperature Ferromagnetism for Cobalt-Doped ZnO Diluted Magnetic Semiconductor 下载免费PDF全文
The pure single phase of Zn0.95 Co0.05 O bulks is successfully prepared by solid-state reaction method. The effects of annealing atmosphere on room-temperature ferromagnetic behaviour for the Zn0.95 Co0.05 O bulks are investigated. The results show that the air-annealed samples has similar weak ferromagnetic behaviour with the as-sintered samples, but the obvious ferromagnetic behaviour is observed for the samples annealed in vacuum or Ar/H2 gas, indicating that the strong ferromagnetism is associated with high oxygen vacancies density. High saturation magnetization Ms = 0.73μg/Co and coercivity Hc = 233.8 Oe are obtained for the Ar/H2 annealed samples with pure single phase structure. The enhanced room-temperature ferromagnetic behaviour is also found in the samples with high carrier concentration controlled by doping interstitials Zn (Zni). 相似文献
204.
The optical-phase-locked-loop (OPLL) at 9.2GHz between two independent narrow linewidth diode lasers is realized. Ultrabroad servo bandwidth at 4MHz is first achieved and it is guaranteed that the full spectral characteristics of the master laser can be transferred to the slave laser. The experimental results prove that the coherence between two lasers is about 99%. This offers a new method to study the interaction between lasers and atoms based on the ground hyperfine structure of caesium atoms. 相似文献
205.
Passively Mode-Locked Quasi-Three-Level Nd:LuVO4Laser with Semiconductor Saturable Absorber Mirror 下载免费PDF全文
We demonstrate a passively a Z-folded resonator. Using device, we achieve stable cw average output power under cw mode-locked Nd:LuVO4 laser operating on the quasi-three-level at 916nm with a semiconductor saturable absorber mirror (SESAM) as the passive mode-locking mode locking with 6.7ps pulse duration at repetition rate of 133 MHz and 88mW the pump power of 17.1 W. 相似文献
206.
The high-order perturbation formulas of electron paramagnetic resonance (EPR) parameters (g factors g∥,g⊥ and zero-field splitting D) for 3d8 ions in trigonal octahedral clusters are established. These formulas contain the contributions not only from the crystal-field (CF) mechanism, but also from the charge-transfer (CT) mechanism (which is not considered in the widely used CF theory). From these formulas, the EPR parameters and the impurity-induced defect structures for Ni2+ ions in CdX2 (X=Cl, Br) crystals are studied. The calculated EPR parameters are coincident with the experimental values, and the defect structure of Ni2+ impurity center obtained from the calculation is different from the corresponding structure in the host crystal. The sign of QCT (Q=Δg∥, Δg⊥, or D) due to CT mechanism agrees with that of the corresponding QCF due to CF mechanism and the relative importance of CT mechanism (characterized by QCT/QCF) increases with increasing covalence of 3d8 clusters and hence with raising atomic number of ligand X. So, in the explanations of the EPR parameters of 3d8 (or other 3dn) ions in crystals with the heavy-element ligand ion (e.g., Br−), the calculated formulas based on the two-mechanism (CF and CT mechanisms) model are preferable to those based on only the CF mechanism in the CF theory. 相似文献
207.
A. Mischke 《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):159-162
In this contribution a first STAR measurement on two heavy-flavor particle correlations in p+p collisions at RHIC is presented.
Heavy-flavor (charm and bottom) events are identified and separated on a statistical basis by the azimuthal correlation of
their decay electrons and open charm mesons, which provide decisive information about the underlying production process. The
azimuthal correlation distribution exhibits a two-peak structure which can be attributed to B decays on the near side and predominantly charm pair production on the away side. These assumptions are supported by dedicated
simulations using PYTHIA and MC@NLO event generators. This new correlation method has the potential for comprehensive energy
loss measurements of heavy quarks in heavy-ion collisions.
Original article based on material presented at HADRON 2007. 相似文献
208.
Zhengcai Ju Jia Li Qian Lu Yingbo Yang Li Yang Zhengtao Wang 《Journal of separation science》2019,42(9):1740-1749
Notoginsenoside Fc, which is a protopanaxdiol‐type saponin isolated from the leaves of Panax notoginseng, exhibits an exceptional antiplatelet aggregatory effect. To study the modulating effect of gastrointestinal contents on the metabolic profile and pharmacokinetics, pseudo germ‐free rats were used to study the influence of the bacterial community structure on the metabolic profile. Glycosidase activities were measured using the spectrophotometric method. Biotransformations of notoginsenoside Fc in normal and pseudo germ‐free rat intestinal microflora were systematically investigated using ultra high performance liquid chromatography with tandem quadrupole/time‐of‐flight mass spectrometry. Moreover, a liquid chromatography with tandem mass spectrometry method was established for simultaneous determination of the notoginsenoside Fc prototype and its degradation products. Through an in vivo pharmacokinetic study, the pharmacokinetic characteristics were compared between normal rats and pseudo germ‐free rats. During the in vitro biotransformation, seven deglycosylated products were detected and identified after incubation in the intestinal bacteria of normal rats. In pseudo germ‐free rats, glycosidase activities were significantly decreased, and no obvious degradation occurred. In an in vivo study, the systemic exposure was significantly increased 40%, as evidenced by the area under the blood concentration–time curve from time zero to infinity value and half‐life value, which were prolonged more in the pseudo germ‐free group than in normal rats. The results demonstrate that patients who use intestinal bacteria‐metabolized herbs, such as panax notoginseng, should understand the profile of intestinal bacteria to ensure therapeutic efficacy. 相似文献
209.
Soliton-like pulse-shaping mechanism in passively mode-locked surface-emitting semiconductor lasers 总被引:1,自引:0,他引:1
R. Paschotta R. Häring A. Garnache S. Hoogland A.C. Tropper U. Keller 《Applied physics. B, Lasers and optics》2002,75(4-5):445-451
We discuss a mechanism that allows the formation of nearly transform-limited soliton-like pulses in passively mode-locked
optically pumped external-cavity surface-emitting semiconductor lasers. It involves the interplay of positive dispersion and
the nonlinear index changes in gain medium and saturable absorber, while ordinary solitons are based on dispersion and the
Kerr effect. The obtained quasi-soliton pulses share some of the properties of ordinary solitons (in particular, their stability
and near bandwidth-limited nature), while other properties are different. In particular, the pulse duration scales with the
square root of the cavity dispersion, and an excessive drift of the laser wavelength must be avoided by proper design.
Received: 23 April 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1059, E-mail: Paschotta@iqe.phys.ethz.ch 相似文献
210.
2 -laser radiation from an AFM tip. In the microscopic images we find and identify a new type of AFM-induced artifact (crosstalk
via the tapping amplitude). Minimizing this by proper scan parameters we obtain evidence of true infrared contrast. The results
demonstrate the material-sensitive potential of infrared-spectroscopic imaging and a spatial resolving power of better than
100 nm.
Received: 18 November 1997/Accepted: 5 January 1998 相似文献