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排序方式: 共有725条查询结果,搜索用时 31 毫秒
31.
Ba2MgGe2O7:Cr4+晶体中荷移激发态对g因子贡献的研究 总被引:1,自引:1,他引:0
文章建立了立方四面体3d2络合物g因子的完全高阶微扰公式.在这个公式中,除了与d-d跃迁光谱(晶场激发态)有关的晶场(CF)机制的贡献(包括近年发展的双旋-轨耦合参量模型)外,与电荷转移光谱(荷移激发态)有关的荷移(CT)机制的贡献也被考虑.将这个公式应用于Ba2MgGe2O7:Cr4 晶体平均g因子的计算,发现理论计算值与实验值很好的一致,同时,荷移机制对g移动△g(=g-2.002 3)的贡献△gCT在符号上与晶场机制的贡献△gCF相反,而在大小上约为晶场机制贡献的38%.因此,在对高价态过渡金属离子络合物的g因子计算时应考虑CF机制和CT机制的贡献. 相似文献
32.
Abstract Kinetics of post recoil isothermal annealing of crystalline Ba/CoEDTA/2 irradiated in a nuclear reactor or doped by 60Co(II) reveals a combination of a monotonous and an oscillatory part amounting 1-3% of the total. The permanent recombination has been found to consist of two first order processes leading to the octahedral structure of the six-co-ordinated 60Co(III). 相似文献
33.
巴金以笔代刀,无情地解剖自己,清醒地深思"文革"产生的原因,自我反省,处处洋溢着浓郁的忏悔意识。《随想录》问世后褒贬不一,正反双方激烈交锋,形成百家争鸣局面,汇成了一股思想解放的洪流。《随想录》作为"灵魂的呼号",呼啸于天地间,遗响于中华大地,经久而不绝。巴金的《随想录》被誉为中国的"忏悔录"。 相似文献
34.
Study of structural properties of (Ba0.5Sr0.5)PbO3 has been carried out in a wide temperature range from 10 to 1223 K using the X-ray powder diffraction technique. Two temperature-induced structural phase transitions at 948 and 1198 K have been found. For polycrystallines the XPS and electrical resistivity measurements have been performed. 相似文献
35.
陈果 《重庆三峡学院学报》2006,22(1):28-32
文章首先阐述了巴文化起源是居住在巫山、巫溪境内的原大溪文化的居民;其次阐述巴文化的形成阶段,并论证它就是由于巫山、巫溪一带的新石器时代文化发展而来;再次提出了巴文化的发展阶段,是由峡内分别向东、向西发展;最后解释了巴文化如此发展的原因。 相似文献
36.
Formation of Compounds in the Quasi-binary Systems AcX4? MX2 (Ac = Th, U; M = Ca, Sr, Ba, Eu, Ge, Sn, Pb; X = Br, I) T,x-phase diagrams of the systems ThI4? SnI2, ThI4? PbI2, ThI4? CaI2, and ThI4? SrI2 were established using thermoanalysis and x-ray methods. The only ternary compounds have a 1:1 composition. Further AcMX6 compounds (Ac: Th, U; M: Ca, Sr, Ba, Eu, Ge, Sn, Pb; X: Br, I) were synthesized and their structures investigated. Four structure types are found depending on the temperature and the Ac/M combinations. The structures of γ-ThSnI6 and β-ThSnI6 were determined with single crystal methods as representatives of a whole series of isotypic compounds. 相似文献
37.
Ultrashort-laser-pulse-driven rewritable phase-change optical recording in Sb-based films 总被引:1,自引:0,他引:1
This paper reviews the work we have carried out over the last years on the development of ultrashort-laser-pulse-driven, rewritable,
phase-change optical memories. The materials we have tailored for this application are non-stoichiometric, Sb-rich amorphous
thin films, which can be crystallized upon irradiation with ultrashort laser pulses, showing a large optical contrast upon
transformation. This result makes them very promising for the development of rewritable phase-change optical memories under
ultrashort pulses, since the reversibility of the process has also been demonstrated. Adequate control of the heat-flow conditions
has allowed us to achieve a full transformation time faster than 400 ps for crystallization/amorphization using 30-ps pulses.
The crystallization threshold fluence has been found to decrease upon irradiation with pulses shorter than 800 fs, thus suggesting
the relevance of high-electronic-excitation-induced processes in the amorphous-to-crystalline phase transition. This has been
confirmed by the observation of an ultrafast, non-thermal phase transition occurring 200–300 fs after the arrival of the laser
pulse at the surface, for fluences above the crystallization threshold. The presence of this transient phase conditions the
final state induced therefore enabling the applicability of this material as a rewritable recording medium using femtosecond
pulses.
Received: 11 October 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +34-91/564-5557, E-mail: J.Solis@io.cfmac.csic.es 相似文献
38.
Surface nanostructuring of silicon 总被引:1,自引:0,他引:1
A.J. Pedraza J.D. Fowlkes Y.-F. Guan 《Applied Physics A: Materials Science & Processing》2003,77(2):277-284
Irradiation with polarized laser light of 248-nm wavelength induces the formation of periodic undulations ∼10-nm-highon flat
silicon substrates. The wavelength of these periodic structures is a function of the light wavelength and the angle of incidence
of the laser beam. Linear arrays of silicon nanoparticles with fairly uniform size that extended up to a millimeter were formed
if the irradiation was performed using polarized light. When non-polarized laser light with the same fluence was used to illuminate
an initially flat surface, non-aligned nanoparticle strings were obtained. However, if part of the irradiated area was microstructured,
nanoparticle linear arrays resulted in the vicinity of the microstructured region. An analysis on the evolution of these nanostructures
is presented. Nanocolumns could be grown on top of every cone of a microstructured surface upon cumulative laser irradiation
with non-polarized light, reaching a height of ∼3 μm and a diameter of 100–200 nm. The mechanisms of nanocolumn origin and
growth are analyzed.
Received: 16 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-865/974-4115, E-mail: apedraza@utk.edu 相似文献
39.
A. Athanassiou K. Lakiotaki V. Tornari S. Georgiou C. Fotakis 《Applied Physics A: Materials Science & Processing》2003,76(1):97-100
This work examines volume changes at the sub-micron scale, induced photochemically in polymeric matrices doped with photochromic
molecules. To achieve this, spiropyran is employed as a photochromic molecule embedded in polyethylmethacrylate-co-methylacrylate (PEMMA) matrices. Spiropyran can be reversibly interconverted to merocyanine, its coloured isomer, by irradiation at 248 nm
and 532 nm, correspondingly. It is demonstrated that the interconversion between the two forms activates volume changes in
the polymer matrix. To this end, off-axis reflection holographic interferometry is employed as a sensitive probe of the induced
volume changes. This scheme provides a novel method for controlling sub-micron volume changes reversibly, as required in several
microactuator designs.
Received: 17 April 2002 / Accepted: 18 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +30-810/391-318, E-mail: nassia@iesl.forth.gr 相似文献
40.
A. Borowiec M. MacKenzie G.C. Weatherly H.K. Haugen 《Applied Physics A: Materials Science & Processing》2003,76(2):201-207
The final state of the material resulting from laser irradiation of silicon using 130 fs pulses at 790 nm was studied using
a number of techniques including scanning and transmission electron microscopies, as well as atomic force microscopy. Structural
details and the level of damage to the nearby solid following irradiation were characterized and are discussed in the context
of recent dynamical studies.
Received: 28 September 2001 / Accepted: 3 March 2002 / Published online: 19 July 2002
RID="*"
ID="*"Department of Engineering Physics, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
RID="**"
ID="**"Corresponding author. Fax: +1-905/521-2773, E-mail: borowia@mcmaster.ca
RID="***"
ID="***"Present address: Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
RID="****"
ID="****"Department of Materials Science and the CEMD, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
RID="*****"
ID="*****"Departments of Engineering Physics, and Physics and Astronomy, and the CEMD, McMaster University, Hamilton, Ontario,
L8S 4M1, Canada 相似文献