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171.
V.B. Timofeev A.V. Larionov J. Zeman G. Martinez V.I. Falko M. Bayer A. Forchel 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):39-43
Magnetooptical studies performed on a wide InGaAs/GaAs single quantum well indicate that optically non-active (dark) excitons
with total angular momentum play the role of a reservoir for the creation of free multiparticle excitonic complexes. After analyzing the magnetic field
evolution of the circularly polarized components of the low energy structure appearing in the main excitonic luminescence
line we assign this feature to the excitonic trion formation. The binding energy of the excitonic trions was estimated to
be of the order of 1 meV.
Received: 29 October 1997 / Received in final form: 20 February 1998 / Accepted: 21 February 1998 相似文献
172.
Low coherence multiple-quantum well edge-emitting light-emitting diodes were obtained using selective-area metalorganic vapor-phase
epitaxial growth, which utilized growth rate enhancement on an open stripe region between mask stripes. An optical absorption
region, which was controlled by selective-area growth, was introduced to suppress optical feedback. At a driving current of
100 mA and an ambient temperature of 25°C, a power of 55 μW was coupled into a single-mode fiber, and a broad spectrum without
spectral ripple was observed. Low coherence characteristics and very small temperature dependence were obtained in the temperature
range from -40°C to 85°C. The modulation bandwidth was 210 MHz at a bias current of 100 mA. 相似文献
173.
G. Pizzella 《Il Nuovo Cimento C》1995,18(3):285-294
Summary A brief historical survey of the GW experiments is presented. In particular, the experiments with resonant detectors are illustrated
and the problems arising when comparing data of different detectors for the search of coincidences are discussed. The experimental
results so far obtained are shown, among them the correlation during the SN1987A with various GW and neutrino detectors. Finally
a warning for the long times needed to improve the sensitivity of the GW detectors is given and the improvements expected
with spherical resonant detectors are mentioned. 相似文献
174.
Dong Ya Yang Chun Pu Hu Sheng Kang Ying 《Journal of polymer science. Part A, Polymer chemistry》2005,43(12):2606-2614
A series of polyester‐based poly(urethane urea) (PUU) aqueous dispersions with well‐defined hard segments were prepared from polyester polyol, 4,4′‐diphenylmethane diisocyanate, dimethylolpropionic acid, 1,4‐butanediol, isophorone diisocyanate, and ethylenediamine. These anionic‐type aqueous dispersions had good dispersity in water and were stable at the ambient temperature for more than 1 year. For these aqueous dispersions, the particle size decreased as the hard‐segment content increased, and the polydispersity index was very narrow (<1.10). Films prepared with the PUU aqueous dispersions exhibited excellent waterproof performance: the amount of water absorption was as low as 5.0 wt %, and the contact angle of water on the surface of this kind of film was as high as 103° (this led to a hydrophobic surface). The water‐resistant property of these waterborne PUU films could be well correlated with some crystallites and ordered structures of the well‐defined hard segments formed by hydrogen bonding between the urethane/urethane groups and urethane/ester groups, as well as the degree of microphase separation between the hard and soft segments in the PUU systems. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2606–2614, 2005 相似文献
175.
Here we report on high-resolution photoemission of iron layers grown on a W(1 1 0) substrate. The evolution of the substrate states upon sub-monolayer adsorption of Fe atoms leads to a shift in surface state binding energy. For thicker (1 1 0) films, sharp metallic surface states are obtained. Their dispersion displays the signature of quasiparticle renormalization due to dressing with excitations. The energy scale is characteristic for the spin wave spectrum in iron, thereby giving evidence of electron-magnon coupling. Furthermore, it is found that quantum well states occur as a function of layer thickness. These modify the spin density of states at the Fermi level in the ferromagnetic film. 相似文献
176.
Fabrication and 4.2 K mobility measurements of silicon-on-insulator (SOI) metal–oxide-field-effect-transistors are reported. The three sets of samples fabricated in this work include devices for which the SOI film thicknesses (tSOI) are in the ranges of 10–15, 16–19 and 56–61 nm. The peak mobility of the devices that have the SOI film thickness above 16.5 nm is 1.9 m2/V s. The set of devices with thinnest channel (tSOI=10–15 nm) suggest that the peak mobility decreases with decreasing tSOI. 相似文献
177.
本文用Floquet理论分析了多量子阱(阱垒数N>>1)波导的传输和色散特性,给出了适用于TE和TM两种偏振态的等效三层平板波导芯子折射率的解析公式,该公式清楚地说明了多量子阱波导的本征双折射行为。 相似文献
178.
lect, the pronunciation of the characters with entering tone is unique: it has neither the glottal stop nor the characteristic 相似文献
179.
本文介绍在分子束外延系统中,沿[311]面原位生长GaAs/AIAs量子线结构的一种简单方法及其拉曼和发光特性。这一方法能克服目前纳米尺度光刻技术的困难,因此,是一种制备低维样品的有希望的方法。 相似文献
180.
Jing Qin 《Annals of the Institute of Statistical Mathematics》1994,46(1):117-126
We all know that we can use the likelihood ratio statistic to test hypotheses and construct confidence intervals in full parametric models. Recently, Owen (1988,Biometrika,75, 237–249; 1990,Ann. Statist.,18, 90–120) has introduced the empirical likelihood method in nonparametric models. In this paper, we combine these two likelihoods together and use the likelihood ratio to construct confidence intervals in a semiparametric problem, in which one model is parametric, and the other is nonparametric. A version of Wilks's theorem is developed. 相似文献