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81.
J. Bellessa V. Voliotis T. Guillet D. Roditchev R. Grousson X.L. Wang M. Ogura 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):499-505
We report on time-resolved microphotoluminescence experiments in a single GaAs/GaAlAs V-shaped quantum wire as a function
of optical excitation intensity. At low pump power we observe that excitons are localized in quantum boxes formed by the local
potential minima existing along the wire axis. As the pump power is increased, state filling of the lowest lying levels of
the boxes appears. When two carriers occupy the first excited level of the box, a very efficient Auger scattering occurs,
leading to a transfer of carriers from one box to another neighbouring one. The intradot Auger scattering time has been measured
and is of the same order of magnitude as the LA-phonon emission rate.
Received 5 February 2001 相似文献
82.
A. Komnik R. Egger 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):271-280
We study nonlinear transport for two coupled one-dimensional quantum wires or carbon nanotubes described by Luttinger liquid
theory. Transport properties are shown to crucially depend on the contact length L
c. For a special interaction strength, the problem can be solved analytically for arbitrary L
c. For point-like contacts and strong interactions, a qualitatively different picture compared to a Fermi liquid emerges, characterized
by zero-bias anomalies and strong dependence on the applied cross voltage. In addition, pronounced Coulomb drag phenomena
are important for extended contacts.
Received 28 July 2000 相似文献
83.
S. Pleutin A. Ovchinnikov 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):521-531
The static polarizability of cylindrical systems is shown to have a strong dependence on a uniform magnetic field applied
parallel to the tube axis. This dependence is demonstrated by performing exact numerical diagonalizations of simple cylinders
(rolled square lattices), armchair and zig-zag carbon nanotubes (rolled honeycomb lattices) for different electron-fillings.
At low temperature, the polarizability as function of the magnetic field has a discontinuous character where plateau-like
region are separated by sudden jumps or peaks. A one to one correspondence is pointed out between each discontinuity of the
polarizability and the magnetic-field induced cross-over between the ground state and the first excited state. Our results
suggest the possibility to use measurements of the static polarizability under magnetic field to get important informations
about excited states of cylindrical systems such as carbon nanotubes.
Received 29 March 2001 and Received in final form 8 August 2001 相似文献
84.
V.I. Yukalov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):83-91
An ensemble of resonance atoms is considered, which are doped into a medium with well developed polariton effect, when in
the spectrum of polariton states there is a band gap. If an atom with a resonance frequency inside the polariton gap is placed
into the medium, the atomic spontaneous emission is suppressed. However, a system of resonance atoms inside the polariton
gap can radiate when their coherent interaction is sufficiently strong. Thus the suppression of spontaneous emission for a
single atom can be overcome by a collective of atoms radiating coherently. Conditions when such collective effects can appear
and their dynamics are analysed.
Received 7 June 2000 相似文献
85.
CHEN Huanyin 《中国科学A辑(英文版)》2000,43(8):795-802
We introduce the notion of separativity of modules and show that many classes of modules possess the separativity. The present
work generalizes many known results. 相似文献
86.
A new ultra-high-performance liquid chromatography method was developed using quality-by-design principles for quantifying trace-level impurities of ibrutinib. The method utilized an ACQUITY UPLC BEH C18 column with a mobile phase consisting of equal parts of 0.02 M formic acid in water and 0.02 M formic acid in acetonitrile. The critical method parameters, including mobile phase pH, column temperature, and flow rate, were optimized using the design of experiments. Statistical analysis revealed the impact of these parameters on critical quality attributes. Perturbation and response surface plots illustrated the individual and interactive effects of the parameters. The optimal parameter levels were determined to be pH, 2.5; column temperature, 28°C; and flow rate, 0.55 mL/min. Confirmation experiments demonstrated the method's robustness, with the separation of impurities and unknown degradation products within a 5-min runtime. The optimized ultra-performance liquid chromatography method was validated according to ICH guidelines. The method exhibited linear response within the range of 0.025–100 μg/mL for ibrutinib and 0.0187–0.225 μg/mL for impurities (r2 > 0.9995), with limits of detection/limits of quantification of 0.01/0.025 and 0.015/0.0187 for ibrutinib and four impurities, respectively. Recoveries for the drug and impurities ranged from 92.69 to 102.7%, and precision was below 2% and 8% relative standard deviation for ibrutinib and impurities, respectively. 相似文献
87.
5l.TheMedianFormulaAseveryoneknows:in6ABC,letal=BC,a2=CA,a3=AB,;)11,)n2,n13aremedian1inesseparatelyonthethreeedgesBC,CA,AB,tI1entheequalityistrueasfollowsTheequality(l)iscalledmedianformulaofQABC,andwecanobtainfrom(l)Inthispaper,wesha1lextendtheequality(l)and(2)to,l-simplexin)l-EuclideanspaceH.Itisobtainedthemedianformulaof)I-simplex,andusingthisformula.wegetsomein-equalities.Themedianformulaofn-simp1exisobtainedasfollows:TheoremlFork=1,2,--',It 1andl相似文献
88.
R. Schuster M. Knupfer D. R.T. Zahn H. Berger 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):25-28
We have investigated the polarization and momentum
dependence of singlet excitons in pentacene molecular crystals
using inelastic electron scattering. Our results demonstrate that
both the direction as well as the absolute value of the momentum
are decisive for the spectral intensity of these excitons.
Possible implications of this observation for a microscopic
understanding of excitons in organic molecular crystals are
discussed. 相似文献
89.
针对相关系数的本质含义和相关性的概念与分类、相关关系与因果关系的区别、回归分析中应注意的问题、单边检验的原假设选择等财经类专业学生在使用时易弄错的一些数理统计概念性问题,进行了分析和讨论. 相似文献
90.
Summary The cohesive and anharmonic elastic properties of four mixed fluorite crystals (Ca
x
Sr1−x
F2, Sr
x
Ba1−x
F2 Ba
x
Ca1−x
F2 and Cd
x
Pb1−x
F2) have been investigated by means of a three-body potential (TBP) model which consists of the long-range Coulomb and three-body
interactions and the short-range van der Waals attraction and overlap repulsion effective up to the second-neighbour ions.
Due to the lack of measured data on cohesive energy, third-order elastic constants and pressure derivatives of the secondorder
elastic constants of mixed fluorites, the accuracy of the present results has been tested by comparing them with the so-called
experimental results generated by the application of Vegard’s law to their corresponding experimental values for the host
fluorites.
Riassunto Sono state ricercate le proprietà elastiche coesive e anarmoniche di quattro cristalli misti di fluorite (Ca x Sr1∮x F2, Sr x Ba1−x F2, Ba x Ca1−x F2 e Cd x Pb1−x F2) per mezzo di un modello del potenziale a tre corpi (TBP) che consiste di interazioni di Coulomb a lungo raggio e a tre corpi, di attrazione di van der Waals a corto raggio e di repulsione di sovrapposizione efficace fino agli ioni del secondo vicino. A causa della mancanza di dati misurati sull’energia coesiva, di costanti elastiche di terz’ordine e di derivate di pressione delle costanti elastiche di secondo ordine, l’accuratezza dei risultati attuali è stata provocata confrontandoli con i cosidetti risultati sperimentali generati dalla applicazione della legge di Vegard ai loro valori sperimentali corrispondenti per i fluoriti ospiti.
Резюме С помощью трех-частичной потенциальной модели исследуются когезионные и ангармоничные упрыгие свойства четырех смешанных кристаллов флюорита (Ca x Sr1−x F2, Sr x Ba1−x F2, Ba x Ca1−x F2 и Cd x Pb1−x F2). Используемая модель состои т из длиннодейтсвующего кулоновского и трех-частичного веаимодействий и короткодействующего притяжения Ван дер Ваальса и перекрывающегося отталкивания, эффективного вплоть до вторых соседних ионов. Из-за недостатка зкспериментальных данных для когезионной энергии упругих постоянных третьего порядка и производных по давлехию упрутих постоянных второго поядка для смешанных флюоритов, проверяется точность полученных результатов посредством сравнения их с так называемыми экспериментальными результатами, образованными с помощью применения закона Вегарда к соответствующим экспериментальным величинам для первичных кристаллов флюоритов.相似文献