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41.
Experimental results are presented from vacuum-ultraviolet free-electron laser (FEL) operating in the self-amplified spontaneous emission (SASE) mode. The generation of ultrashort radiation pulses became possible due to specific tailoring of the bunch charge distribution. A complete characterization of the linear and nonlinear modes of the SASE FEL operation was performed. At saturation the FEL produces ultrashort pulses (30-100 fs FWHM) with a peak radiation power in the GW level and with full transverse coherence. The wavelength was tuned in the range of 95-105 nm.  相似文献   
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Experimental data that are used to determine rate coefficients depend not only upon reaction rates but also the physical properties of the measured species. Sensitivity coefficients are presented for the physical parameters of three general experimental techniques: a signal linearly dependent on the concentration of a species, a signal quadratically dependent on concentration, and a schlieren signal, which depends upon a bulk property of the system. With these, both the physical and chemical parameters of a model may be treated on a comparable basis. The similarities and differences between these techniques are illustrated in a simple example of radical formation via first-order precursor decomposition followed by second-order recombination. The results are then applied to two important examples: H2 + O2 and CH3 + CH3. In almost all cases, the experimental data contains more information about the physical parameters, such as the optical cross section, than the kinetic rate coefficients. Furthermore, if a physical parameter is not properly treated; strong correlations between it and rate coefficients will introduce significant systematic biases in the rate coefficient. © 1995 John Wiley & Sons, Inc.  相似文献   
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The Large Hadron Collider will allow studies of hard probes in nucleus-nucleus collisions which were not accessible at the Relativistic Heavy Ion Collider—even the study of small cross-section Z 0-tagged jets becomes possible. Going beyond the measurement of back-to-back correlations of two strongly interacting particles to measure plasma properties, we replace one side by an electromagnetic probe which propagates through the plasma undisturbed and therefore provides a measurement of the energy of the initial hard scattering. We show that at sufficiently high transverse momentum the Z 0-tagged jets originate predominately from the fragmentation of quarks and anti-quarks while gluon jets are suppressed. We propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation functions to determine the opacity of the quark gluon plasma.  相似文献   
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The first fluorescence lifetime studies in a trivalent rare earth-metal vapor complex NdCl3 · (AlCl3)χ are reported. The observed, temperature-dependent, nonradiative deactivation and the inferred radiative lifetime are discussed in terms of various models. At 803 K, corresponding to a density of 4.6 × 1017 Nd3+ ions/cm3 and a total system pressure ≈5 atm, the measured lifetime is 46 μs.  相似文献   
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钛酸钡纳米粉体样品用盐酸溶解,在所得样品溶液中用电感耦合等离子体原子发射光谱法测定了以氧化物存在于样品中的7种杂质元素(包括镁、锶、钾、钠、铝、硅及铁),对测定的光谱条件进行了试验并优化达到上述各元素的测定上限为0.1%(质量分数).测得方法的检出限(3S/b)为(单位μg·L-1):2.0(铝),1.0(铁),20.0(钾),0.2(镁),4.0(钠),3.0(硅)及0.5(锶).应用此方法分析了两件实样,所得结果的相对标准偏差(n=6)小于等于2.0%,对其中4种杂质元素(镁、钾、钠和锶)同时用HG/T 3587-1999标准中的方法作分析校核,所得结果与此方法结果一致.  相似文献   
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