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《Comptes Rendus de l''Academie des Sciences Series IV Physics》2000,1(3):297-303
The effects of hot electrons on the thermal radiative properties (brightness, duration and spectral shape) and dynamics of solid density plasmas, generated during the interaction of a femtosecond laser and a solid target, are assessed. Line and broadband thermal emissions with duration between 500 fs and 700 fs, have been successfully produced with peak power between 1 and 10 MW, when the fraction of laser energy in the hot electron population was less than 2%, and when the hot electron energy density at the target surface was less than 1 KJ / cm 2 . 相似文献
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Ultrafast laser and amplifier sources 总被引:1,自引:0,他引:1
A. Rundquist C. Durfee Z. Chang G. Taft E. Zeek S. Backus M.M. Murnane H.C. Kapteyn I. Christov V. Stoev 《Applied physics. B, Lasers and optics》1997,65(2):161-174
Received: 28 April 1997/Revised version: 15 May 1997 相似文献
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David Reis 《Synchrotron Radiation News》2013,26(6)
The Third Annual Ultrafast X-ray Summer School (UXSS 2009) was held from June 15–19, 2009, at the SLAC National Accelerator Laboratory (SLAC) and sponsored by the PULSE Institute for Ultrafast Energy Science. The summer school was a weeklong residential event that brought together about 100 students, post-doctoral researchers, and other young and established scientists from diverse backgrounds. Particular emphasis was given to new scientific opportunities enabled by the world's first hard X-ray free electron laser, the Linac Coherent Light Source (LCLS), which underwent a spectacular start-up only months before. 相似文献
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D. de Martino L. B. F. M. Waters G. M. H. J. Habets A. R. Taylor 《Il Nuovo Cimento C》1990,13(2):471-479
Summary The X-ray variability of transient X-ray binaries is analyzed in terms of the orbital motion of the neutron star, centrifugal
inhibition of accretion and of the variable moss loss rate due to activity of the optical counterpart. The systems A0535+26
and V0332+53 are studied in this respect.
To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee. 相似文献
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光电子显微镜是一种基于光电效应的电子显微镜,利用样品不同空间位置光电子产量的差异作为图像衬度进行投影成像。其成像速度快、空间分辨率高、探测无损伤等特点和优势,在表面科学、表面等离激元学、半导体学等学科有着广泛应用。另外,结合超快光泵浦探测技术为光电子显微镜提供了高时间分辨能力,特别适用于高时空分辨的动力学过程研究。时间分辨光电子显微镜是具备多维度直观测量的技术方法,为研究人员开辟了新的道路。文章首先简要回顾电子显微成像技术的发展,然后介绍在表面等离激元学和半导体物理领域中应用光电子显微镜的最新进展,最后介绍北京大学最近建设的超快光电子显微镜系统和相关研究工作及展望。 相似文献
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Ultrafast pulse sources based on multi-mode optical fibers are discussed. High-power passively mode-locked fiber lasers based on multi-mode rare-earth-doped optical fibers greatly exceed the power limitations of single-mode oscillators. Ultrafast multi-mode fiber amplifiers operating in conjunction with multi-mode oscillators provide even higher power levels, where nonlinear propagation effects enable pulse compression to below 100 fs. Multi-mode fiber oscillators can be combined with single-mode Raman-shifting fibers to produce widely wavelength-tunable sources of femtosecond pulses. Further amplification in Yb fibers allows for the generation of sub-100-fs pulses with W-level average powers. 相似文献
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Donald P. Umstadter 《Contemporary Physics》2013,54(4):417-431
We discuss the development of a new generation of accelerator-based hard X-ray sources driven exclusively by laser light. High-intensity laser pulses serve the dual roles: first, accelerating electrons by laser-driven plasma wakefields, and second, generating X-rays by inverse Compton scattering. Such all-laser-driven X-rays have recently been demonstrated to be energetic, tunable, relatively narrow in bandwidth, short pulsed and well collimated. Such characteristics, especially from a compact source, are highly advantageous for numerous advanced X-ray applications – in metrology, biomedicine, materials, ultrafast phenomena, radiology and fundamental physics. 相似文献
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J. Larsson P.A. Heimann A.M. Lindenberg P.J. Schuck P.H. Bucksbaum R.W. Lee H.A. Padmore J.S. Wark R.W. Falcone 《Applied Physics A: Materials Science & Processing》1998,66(6):587-591
Received: 17 April 1998/Accepted: 17 April 1998 相似文献
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在光电器件的工作单元已经小到微米甚至纳米尺寸的今天,只有充分研究和了解单一元件及其复合系统的光物理性质,才能为进一步提高器件性能提出更好的可行性方案。将研究物质激发态过程的超快光谱技术引入微纳光子学,用来研究可能成为微纳光电器件中基本功能单元的纳米光电材料的光物理特性,探索微纳尺度下光与物质的相互作用基本规律,便能为更好地理解现有微纳光电器件的工作机理提供重要的研究手段,为以后新型微纳光电器件的制备和改进提供可靠的实验依据。文章简单介绍了超快光谱的工作原理,重点介绍了超快光谱技术在半导体纳米晶和荧光碳纳米材料的光物理性质研究中的应用及其在微纳光子学中的应用前景。最后,对同时具有高时间分辨与高空间分辨能力的四维时间分辨显微光谱进行了简要介绍。 相似文献
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R. W. Schoenlein A. H. Chin H. H. W. Chong R. W. Falcone T. E. Glover P. A. Heimann 《Synchrotron Radiation News》2013,26(1):20-27
On May 19, 2004, 250 guests from all over the world joined the DESY research center to celebrate 40 years of research with synchrotron radiation at DESY in Hamburg. “The first measurements with the light beam from the DESY ring accelerator started in 1964. DESY was one of the seed laboratories in which the worldwide success story of research with synchrotron radiation began,” Albrecht Wagner, chairman of the DESY Board of Directors, explained in his welcoming address. “Today, more than 1,900 scientists from 31 countries come to DESY every year to carry out experiments with synchrotron radiation.” Forty years ago, synchrotron radiation at DESY started from scratch. At the beginning of the 1960s, the radiation generated by the electrons in the bending magnets of their new 6 GeV electron synchrotron was regarded by DESY particle physicists as an unwanted, disruptive effect. 相似文献
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Markus Gühr 《Synchrotron Radiation News》2016,29(5):8-12
The molecular ability to selectively and efficiently convert sunlight into other forms of energy like heat, bond change, or charge separation is truly remarkable. The decisive steps in these transformations often happen on a femtosecond timescale and require transitions among different electronic states that violate the Born-Oppenheimer approximation (BOA) [1]. Non-BOA transitions pose challenges to both theory and experiment. From a theoretical point of view, excited state dynamics and nonadiabatic transitions both are difficult problems [2, 3] (see Figure 1(a)). However, the theory on non-BOA dynamics has advanced significantly over the last two decades. Full dynamical simulations for molecules of the size of nucleobases have been possible for a couple of years [4, 5] and allow predictions of experimental observables like photoelectron energy [6] or ion yield [7–9]. The availability of these calculations for isolated molecules has spurred new experimental efforts to develop methods that are sufficiently different from all optical techniques. For determination of transient molecular structure, femtosecond X-ray diffraction [10, 11] and electron diffraction [12] have been implemented on optically excited molecules. 相似文献
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A. Föhlisch 《Applied Physics A: Materials Science & Processing》2006,85(4):351-359
In complex systems, composed from many atomic units, it is of equal importance to determine the time scales of dynamic processes and to have control at which atomic site a dynamic process was initiated. With resonant X-ray spectroscopic tools like autoionization and resonant inelastic X-ray scattering, an atomically localized excited state can be created and its dynamics monitored in comparison to the ultrafast time scale of the transient core-hole resonance. With this core-hole-clock method, charge transfer dynamics of only 320±90 attoseconds could be determined for Sulphur adsorbed on the Ru(0001) surface, extending the core-hole-clock method into the range of attoseconds. Exploiting the symmetry selection rules of resonant inelastic X-ray scattering, ultrafast atomic motion can also be investigated, which changes the molecular symmetry during a transient core-excited state. With this approach the vibrational dynamics of C2H4 on the time scale of a Carbon 1s core-hole resonance has been investigated. PACS 73.20.Jc; 32.80.Dz; 33.20.Rm; 33.20.Tp; 33.20.Fb 相似文献
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超亮X射线源是在邻近星系中发现的一类特殊的辐射X射线的天体.它们类似银河系中的黑洞双星,但却具有更高的亮度,因此可能包含更高质量的黑洞,即所谓的中等质量黑洞.中等质量黑洞并不像恒星级质量黑洞一样,可以是大质量恒星演化末期核塌缩的产物,因此在天体物理中具有重要意义.文章描述了超亮X射线源的一些基本性质,综述了近年来对这些源多波段观测的重要结果,以及这些结果对这些天体本质的暗示. 相似文献
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X-ray free electron lasers (XFELs) offer new ways to probe the structure and dynamics of matter with unprecedented details and in ways that were previously impossible. Continued development and upgrades to existing sources, together with the upcoming commissioning of several new sources, will rapidly expand the possibilities XFELs present for materials science. In this review, we discuss some recent experiments that exploit the unique features of XFELs—coherence, brightness, and time resolution—in order to highlight the opportunities in materials science presented by these facilities. 相似文献
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