排序方式: 共有20条查询结果,搜索用时 19 毫秒
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Romanato Filippo Berti Marina Mazzer Massimo Drigo Antonio Vittorio Lazzarini Laura Franzosi Paolo Salviati Giancarlo Bertone Daniele 《Mikrochimica acta》1994,114(1):431-440
A combined method for structural characterization of strained epitaxial heterostructures involving different techniques such as Rutherford backscattering spectrometry (RBS), multiple crystal X-ray diffractometry (MCD) and transmission electron microscopy (TEM) is presented. In order to obtain a complete characterization of the analysed structure, three different quantities are measured independently: the epilayer thickness, the density of misfit dislocations which may appear at the interface, and the significant components of the strain tensor, mainly the tetragonal distortion, affecting the epilayer lattice. In this way the thermodynamic state and the mechanisms of plastic deformation of the structures can be fully investigated. In this contribution we present and discuss the experimental results concerning a set of InP/GaAs samples having different layer thicknesses ranging from 5 to 500 nm. The thickness of the samples has been determined by RBS. Measurements of in-plane strain and tetragonal distortion have been performed by MCD and RBS-channelling respectively, finally TEM has been used for determining the defects densities and distribution. 相似文献
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Bertone PF Champagne AE Powell DC Iliadis C Hale SE Hansper VY 《Physical review letters》2001,87(15):152501
The energy derived from the CN cycle at low stellar temperatures is regulated by the 14N(p,gamma)15O reaction. A previous direct measurement of this reaction has been interpreted as showing evidence for a subthreshold resonance which makes a major contribution to the reaction rate at low temperatures. This resonance, at E(c.m.) = -504 keV would correspond to the known Ex = 6793-keV state in 15O. We have measured a mean lifetime of 1.60(+0.75)(-0.72) fs (90% C.L.) for this state using the Doppler-shift attenuation method. This lifetime is a factor of 15 longer than that inferred from the (p,gamma) data and implies that the contribution of the subthreshold resonance is negligible. 相似文献
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Alcorta M Rehm KE Back BB Bedoor S Bertone PF Deibel CM DiGiovine B Esbensen H Greene JP Hoffmann CR Jiang CL Lighthall JC Marley ST Pardo RC Paul M Rogers AM Ugalde C Wuosmaa AH 《Physical review letters》2011,106(17):172701
The structure of (15)C, with an s(1/2) neutron weakly bound to a closed-neutron shell nucleus (14)C, makes it a prime candidate for a one-neutron halo nucleus. We have for the first time studied the cross section for the fusion-fission reaction (15)C+(232)Th at energies in the vicinity of the Coulomb barrier and compared it to the yield of the neighboring (14)C+(232)Th system measured in the same experiment. At sub-barrier energies, an enhancement of the fusion yield by factors of 2-5 was observed for (15)C, while the cross sections for (14)C match the trends measured for (12,13)C. 相似文献
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Redondo Mara Julia Romn Lucrecia Rossi Bertone Fiorela Verdecchia Melina 《Algebras and Representation Theory》2022,25(4):1037-1059
Algebras and Representation Theory - Let A and B be two Morita equivalent finite dimensional associative algebras over a field . It is well known that Hochschild cohomology is... 相似文献
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Lew CS Wong DF Johnston LJ Bertone M Hopkinson AC Lee-Ruff E 《The Journal of organic chemistry》1996,61(20):6805-6808
The 9-[N,N-dimethyl(thioformamidyl)]-9-fluorenyl cation was generated under stable ion conditions and characterized by UV/visible and NMR spectroscopy and methanol trapping reactions. The same cation was generated by laser excitation of the appropriate chloride precursor in 2,2,2-trifluoroethanol, and rate constants for nucleophilic quenching by alcohols and several anions were measured. The quenching data for this and other 9-fluorenyl cations demonstrate that the reactivity decreases for 9-substituents in the order H > carbomethoxy > N,N-dimethyl(thioformamidyl), demonstrating that the thioamidyl group imparts substantial kinetic stabilization to an adjacent cationic center. Both steric and electronic factors are suggested to be important in determining this reactivity order. 相似文献
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Oelke AJ Antonietti F Bertone L Cranwell PB France DJ Goss RJ Hofmann T Knauer S Moss SJ Skelton PC Turner RM Wuitschik G Ley SV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(15):4183-4194
Here we describe in full our investigations into the synthesis of the dimeric cyclohexapeptide chloptosin in 17 linear steps. Particularly, this work features an organocatalytic tandem process for the synthesis of the embedded piperazic acids, in which a differentially protected azodicarboxylate is used together with pyrrolidinyl tetrazole as the catalyst. The central biaryl bond is being formed by Stille coupling of two sterically demanding ortho-chloropyrroloindole fragments. The inherent flexibility of the synthetic strategy proved beneficial as the route could be adjusted smoothly during the progression of the synthesis programme. 相似文献