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51.
We study electron transmission through a periodic array of quantum dots (QD) sandwiched between doped semiconductor leads. When the Fermi wavelength of tunneling electron exceeds the array lattice constant, the off-resonant per QD conductance is enhanced by several orders of magnitude relative to the single-QD conductance. The physical mechanism of the enhancement is delocalization of a small fraction of system eigenstates caused by coherent coupling of QDs via the electron continuum in the leads. 相似文献
52.
Aram Kh. Manaselyan Albert A. Kirakosyan 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):462-470
Within the framework of effective mass approximation and variational method, the electronic and impurity states in spherical quantum dots with convex bottom in magnetic field are calculated. Calculations are carried out both for on-center and off-center impurities. The impurity binding energy dependencies on radius, measure of convexity of quantum dot bottom, impurity position and magnetic field induction are obtained for the Ga1-xAlxAs/Ga1-yAlyAs system. 相似文献
53.
Arshak L. Vartanian Anna L. Asatryan Albert A. Kirakosyan 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):545-551
The hot-electron energy-loss rate (ELR) conditioned by confined and interface polar-optical (PO) phonons for a quasi-one-dimensional cylindrical quantum wire embedded in a dielectric medium is investigated analytically. It is shown that the inclusion of the PO-phonon confinement effects is crucial for accurate calculation of the ELR in quantum wire. Taking into account the nonequilibrium phonon populations, the hot-electron ELR is derived by a model, which includes the lowest subband occupation and the phonon confinement effects. The contribution of intersubband transitions to electron ELR for the GaAs quantum wire embedded in AlxGa1−xAs is estimated. The extrema on the ELR dependences on electron density are obtained. 相似文献
54.
MARTI´NEZ C. Encinas-Sanz F. Serna J. MEJI´AS P. M. MARTI´NEZ-HERRERO R. 《Optical and Quantum Electronics》1997,29(9):923-931
A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric
pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order
intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model
has been applied to high-quality TEA CO2 laser pulses.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
55.
195Pt, 1H, and 13C NMR spectroscopy was used to study the structure of binuclear platinum(III) acetamidate complexes with 1,10-phenanthroline and 2,2′-bipyridine ligands [Pt2(phen)2(acam)4](NO3)2 (1) and [Pt2(bipy)2(acam)4](NO3)2 (2) in aqueous solutions. The 195Pt NMR spectra of solutions of complexes 1 and 2 in D2O exhibit two signals with satellites due to the 195Pt–195Pt spin-spin coupling (1 J(Pt–Pt) ≈ 6345 Hz), whereas their 1H and 13C NMR spectra contain four sets of signals for the protons and the carbon atoms of the heterocyclic and acetamidate ligands. The signals were assigned using the COSY, NOESY, and HSQC/ HMBC experiments and comparing the coordination shifts of the signals for the protons of heterocycles. These data allowed us to draw a conclusion that binuclear complexes 1 and 2 in solution have a head-to-head structure with nonequivalent platinum(III) atoms (coordination cores PtN5 and PtN3O2), the axial-equatorial coordination of the bidentate heterocyclic molecules, and two bridging and two terminal acetamidate ligands. 相似文献
56.
R. M. Kirakosyan 《International Applied Mechanics》2008,44(4):448-458
The existence of two correction coefficients traditionally introduced to account for the effect of the distribution of tangential
stresses over the thickness of a plate is discussed. The virtual-work principle is used to generalize the expressions for
the coefficients to the case of arbitrary loading. These expressions and hypotheses for displacements help to derive equations
for orthotropic rectangular plates subject to tangential surface loads. These equations account for the effect of the distribution
of tangential stresses over the thickness of the plate. Numerical examples are given. The results obtained are compared with
those produced by other theories
__________
Translated from Prikladnaya Mekhanika, Vol. 44, No. 4, pp. 107–119, April 2008. 相似文献
57.
I. V. Ajinenko Yu. A. Belokopytov H. Bialkowska H. Boettcher F. Botterweck P. V. Chliapnikov F. Crijns A. De Roeck E. A. De Wolf K. Dziunikowska A. Eskreys W. Friebel Z. C. Garutchava G. V. Gevorkyan H. Graessler P. van Hal T. Haupt Z. A. Kirakosyan W. Kittel J. M?kel? F. Meijers A. B. Michalowska V. I. Nikolaenko L. C. S. Oliveira K. Olkiewicz L. P. Petrovikh V. M. Ronjin A. M. Rybin H. M. T. Saarikko W. Schmitz L. Scholten N. N. Sotnikova O. G. Tchikilev L. A. Tikhonova A. G. Tomaradze V. A. Uvarov F. Verbeure R. Wischnewski Y. V. Yarba EHS-NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(1):15-23
Data on the reactions (K +/π+)p→(K +/π+)pπ+π- and (K +/π+)p→(K +/π+)p2π+2π-, obtained with the European Hybrid Spectrometer, are presented and compared with data at lower energies. The contribution of beam and target diffractive dissociation and double Pomeron exchange, and porperties of these reactions are discussed. 相似文献
58.
A. Kh. Manaselyan A. V. Ghazaryan A. A. Kirakosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2014,49(4):168-175
The exciton states in a CdTe semiconductor quantum ring containing a single magnetic impurity are considered in an external magnetic field. The electron-hole spin interaction and s,p-d interactions between electron, hole and magnetic impurity are also taken into account in the calculations. It is shown that due to the s,p-d spin interactions the ground state exciton energy splits into 12 doubly degenerated energy levels. The external magnetic field removes this degeneracy. A novel method is proposed here to determine the values of the strengths of s,p-d interactions. The optical spectrum of the system for different polarizations of the incident light and for different initial states of the magnetic impurity spin projection is also studied. 相似文献
59.
V. N. Mughnetsyan M. G. Barseghyan A. A. Kirakosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2007,42(6):287-291
The effect of a longitudinal magnetic and a transverse electric fields on the binding energy of a hydrogen-like donor impurity is studied for a semiconductor quantum well-wire approximated by a cylindrical well of finite depth. It is shown that the magnetic and electric fields as well as the impurity distance from the wire axis are the effective tools for the influence on the binding energy. 相似文献
60.
Let pn be the nth prime. Then this paper is concerned with provingthe following result on the distribution of consecutive primes. The exponent of x in this theorem improves on the work of Heath-Brownwho proved (1) with exponent . Under the Riemann hypothesisone can prove (1) with exponent .The proof of the theorem startswith the Heath-BrownLinnik identity which leads to aformula giving the number of primes in an interval in termsof coefficients of certain Dirichlet series. I then estimatethe coefficients by using, among other things, the informationwhich can be gained from Montgomery's mean value theorem andHuxley's version of the Hal' asz lemma. Furthermore, by usingfamiliar sieve arguments I am able to discard some of the coefficientsallowing us to gain an improvement over the previous resultof Heath-Brown. 1991 Mathematics Subject Classification: 11N05. 相似文献