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991.
We report that two-photon absorption (TPA) properties of semiconductor CdSe-core CdS/ZnS-multishell quantum dots (QDs) in
toluene under excitation of femtosecond laser at 800 nm. The results show efficient TPA process and large TPA cross section
of three types of size QDs, which is 1900, 5710, and 16060 GM (1 GM = 10−50 cm4 s photon−1), respectively. TPA cross section dramatically increases with increased core size, showing a strong size-dependence effect.
Furthermore, two-photon excitation (TPE) fluorescence intensity not only depends on TPA capacity, but also relies on improved
quantum yield resulting from passivation of QD surface by different coated monolayers (MLs). These facts in combination with
the narrow fluorescence bandwidth make these QDs as promising probes for multicolor two-photon microscopy. 相似文献
992.
N. S. Pavlov V. A. Galkin I. A. Nekrasov E. Z. Kurmaev 《Physics of the Solid State》2009,51(11):2207-2210
A numerical electronic band structure calculations for sulfides NiS, CuS, and ZnS are carried out. Using the results a detailed
analysis of a valence states is performed; obtained partial densities of states are compared with X-ray SL
2,3 and $
SK_{\beta _{1,3} }
$
SK_{\beta _{1,3} }
-emission spectra. We showed that spectrum lineshape depends on hybridization strength between various Me(3d)-orbitals and 3p-states of sulfur. The hybridization strength and the symmetry of hybrid Me(3d)-orbitals are defined by crystal lattice structure. Finally a well splitted in energy bonding and antibonding states Me(3d)-S(3p) appear while weakly hybridized Me(3d)-states mainly contribute to spectra intensity in the energy between them. A good agreement between the theoretical and the
experimental spectra of valence band for considered sulfides is obtained. 相似文献
993.
Khizar-ul-Haq M.A. Khan Z.L. Zhang X.W. Zhang J.M. Wei Jun Li 《Journal of luminescence》2009,129(10):1158-1162
Blue organic light-emitting devices based on wide bandgap host material, 2-(t-butyl)-9, 10-di-(2-naphthyl) anthracene (TBADN), blue fluorescent styrylamine dopant, p-bis(p-N,N-diphenyl-amino-styryl)benzene (DSA-Ph) have been realized by using molybdenum oxide (MoO3) as a buffer layer and 4,7-diphenyl-1,10-phenanthroline (BPhen) as the ETL. The typical device structure used was glass substrate/ITO/MoO3 (5 nm)/NPB (30 nm)/[TBADN: DSA-Ph (3 wt%)](35 nm)/BPhen (12 nm)/LiF (0.8 nm)/Al (100 nm). It was found that the MoO3∥BPhen-based device shows the lowest driving voltage and highest power efficiency among the referenced devices. At the current density of 20 mA/cm2, its driving voltage and power efficiency are 5.4 V and 4.7 Lm/W, respectively, which is independently reduced 46%, and improved 74% compared with those the m-MTDATA∥Alq3 is based on, respectively. The J-V curves of ‘hole-only’ devices reveal that a small hole injection barrier between MoO3∥NPB leads to a strong hole injection, resulting low driving voltage and high power efficiency. The results strongly indicate that carrier injection ability and balance shows a key significance in OLED performance. 相似文献
994.
Youssef Z. Boutros Mina B. Abd-el-Malek Nagwa A. Badran Hossam S. Hassan 《Applied Mathematical Modelling》2007
The non-linear equations of motion describing the laminar, isothermal and incompressible flow in a rectangular domain bounded by two weakly permeable, moving porous walls, which enable the fluid to enter or exit during successive expansions or contractions, are considered. We apply Lie-group method for determining symmetry reductions of partial differential equations. Lie-group method starts out with a general infinitesimal group of transformations under which given partial differential equations are invariant, then, the determining equations are derived. The determining equations are a set of linear differential equations, the solution of which gives the infinitesimals of the dependent and independent variables. After the group has been determined, a solution to the given partial differential equation may be found from the invariant surface condition such that its solution leads to similarity variables that reduce the number of independent variables in the system. Effect of the permeation Reynolds number Re and the dimensionless wall dilation rate α on self-axial velocity have been studied both analytically and numerically and the results are plotted. 相似文献
995.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 1, pp. 158–162, January, 1989. 相似文献
996.
Existence of the perfect transmission resonances of spin waves in a one-dimensional Thue–Morse magnonic quasicrystal is proposed. We find that occurrence of the perfect transmission just corresponds to the repeated bandedges in the bandedge map. Frequencies at the perfect transmissions for system with arbitrary generation order can be predicted by the bandedge map of the second and third order systems using two iterative schemes. These results show that density of the perfect transmission resonance increases exponentially for increasing the order of the system. However, the perfect transmissions are kept for higher order systems even if the peaks become denser. 相似文献
997.
A. Karneyeu L. Mijovic S. Prestel P. Z. Skands 《The European Physical Journal C - Particles and Fields》2014,74(2):1-22
The mcplots.cern.ch web site (mcplots) provides a simple online repository of plots made with high-energy-physics event generators, comparing them to a wide variety of experimental data. The repository is based on the hepdata online database of experimental results and on the rivet Monte Carlo analysis tool. The repository is continually updated and relies on computing power donated by volunteers, via the lhc@home 2.0 platform. 相似文献
998.
999.
Пустьq∈(1, 2) иL=(q?1)?1. Дляz∈[0,L] обозначимδ(z) функцию, для которойδ(z)=1, еслиz≧1/q иδ(z)=0, еслиz<1/q. Пустьy(z) определяется из урав ненияz= =δ(z)q ?1+y(z)q ?1, и регулярное представление \(\mathop \Sigma \limits_{n = 1}^\infty \varepsilon _n \left( x \right)q^{ - n} \) аргументах определя ется из следующих соотношен ий: $$x = x_0 , \varepsilon _n \left( x \right) = \delta \left( {x_n } \right), x_{n + 1} = y\left( {x_n } \right).$$ ФункцияF: [0,L]→C называе тся аддитивной, если о на представляется в вид е $$F\left( x \right) = \mathop \Sigma \limits_{n = 1}^\infty \varepsilon _n \left( x \right)a_n ,$$ где ε ¦a n ¦<∞. «Бесконеч ное» представление 1=εl i q ?1 числа 1 определяется с ледующим образом: еслие n (1)=1 для б есконечно многихп, т оl n =ε n (1) (n=1, 2, ...); если ? максим альный индекс, для которогоε s (1)=1, то $$l_{ks + 1} = \left\{ \begin{gathered} \varepsilon _i \left( 1 \right) \left( {k = 0, 1, 2, ...; i = 1, ..., s - 1} \right) \hfill \\ 0 \left( {i = 0; k = 1, 2, ...} \right). \hfill \\ \end{gathered} \right.$$ В более ранней работе, опубликованной в это м журнале, авторы доказали, что а ддитивная функция является неп рерывной на отрезке [0,L] тогда и только тогда, когда ра венство $$a_n = \mathop \Sigma \limits_{i = 1}^\infty l_i a_{n + 1} $$ выполняется для всехn∈N. В настоящей работе ра ссматриваются непре рывные функции для которых в ыполняются дополнительные усло вия видаa n =O(q ??n ) (0≦1),a n ≧0. Анализируются их свя зи с корнями функцииG(z)=1 +ε l i z i . Доказы вается, что непрерывн ая аддитивная функция и ли вляется линейной, или нигде не дифференцир уема на отрезке [0,L]. 相似文献
1000.
Let ? be a family ofk-subsets on ann-setX andc be a real number 0 <c<1. Suppose that anyt members of ? have a common element (t ≧ 2) and every element ofX is contained in at mostc|?| members of ?. One of the results in this paper is (Theorem 2.9): If $$c = {{(q^{t - 1} + ... + q + 1)} \mathord{\left/ {\vphantom {{(q^{t - 1} + ... + q + 1)} {(q^t + ... + q + 1)}}} \right. \kern-\nulldelimiterspace} {(q^t + ... + q + 1)}}$$ . whereq is a prime power andn is sufficiently large, (n >n (k, c)) then The corresponding lower bound is given by the following construction. LetY be a (q t + ... +q + 1)-subset ofX andH 1,H 2, ...,H |Y| the hyperplanes of thet-dimensional projective space of orderq onY. Let ? consist of thosek-subsets which intersectY in a hyperplane, i.e., ?={F∈( k X ): there exists ani, 1≦i≦|Y|, such thatY∩F=H i }. 相似文献