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991.
We report the n x n' coherence-like state solutions in the cases of n, n' = 1, 2,... for the system including two Coulomb-correlated ions confined in a one-dimensional Paul trap with a time-dependent harmonic potential. One of the n' exact solutions of the centre-of-mass motion describes a generalized coherent state. For a small driving strength the n approximate solutions of relative motion are constructed, which describe the coherent oscillations of the two ions around the classical equilibrium position. 相似文献
992.
The electronic band structures of wurtzite GaN with Ga and N vacancy defects are investigated by means of the first-principles total energy calculations in the neutral charge state. Our results show that the band structures can be significantly modified by the Ga and N vacancies in the GaN samples. Generally, the width of the valence band is reduced and the band gap is enlarged. The defect-induced bands can be introduced in the band gap of GMV due to the Ga and N vacancies. Moreover, the GaN with high density of N vacancies becomes an indirect gap semiconductor. Three defect bands due to Ga vacancy defects are created within the band gap and near the top of the valence band. In contrast, the N vacancies introduce four defect bands within the band gap. One is in the vicinity of the top of the valence band, and the others are near the bottom of the conduction band. The physical origin of the defect bands and modification of the band structures due to the Ga and N vacancies are analysed in depth. 相似文献
993.
Full potential linearized augmented plane wave (FPLAPW) method calculations are carried out for semiconducting orthorhombic BaSi2. The optical properties and the origin of the different optical transitions are investigated. Our calculated band gap of 1.0918eV is indirect, which is in good agreement with the experimental result. The bonds between Ba and Si are considered to be electrovalent bond. The anlsotropy in the imaginary part ε2(w) and real part εl(w) of the optical dielectric tensor are analysed. The contributions of various transition peaks are explained from the imagnary part of the dielectric function. 相似文献
994.
Ordered InAs Quantum Dots with Controllable Periods Grown on Stripe-Patterned GaAs Substrates 下载免费PDF全文
GaAs (001) substrates are patterned by electron beam lithography and wet chemical etching to control the nucleation of lnAs quantum dots (QDs). InAs dots are grown on the stripe-patterned substrates by solid source molecular beam epitaxy. A thick buffer layer is deposited on the strip pattern before the deposition of InAs. To enhance the surface diffusion length of the In atoms, InAs is deposited with low growth rate and low As pressure. The AFM images show that distinct one-dimensionally ordered InAs QDs with homogeneous size distribution are created, and the QDs preferentiMly nucleate along the trench. With the increasing amount of deposited InAs and the spacing of the trenches, a number of QDs are formed beside the trenches. The distribution of additional QDs is long-range ordered, always along the trenchs rather than across the spacing regions. 相似文献
995.
Intense Green Upconversion Luminescence in Er^3+:Yb^3+ Codoped Fluorophosphate Glass Ceramic Containing SrTe5O11 Nanocrystals 下载免费PDF全文
Er^3+ :Yb^3+ codoped tellurite-fluorophosphate (TFP) glass ceramic exhibits much stronger upconversion luminescence. The intensity of the 540nm green light and 651 nm red light of the TFP glass ceramic is 120 times and 44 times stronger than that of the fluorophospahte (FP) glass, respectively. XRD analysis shows that the nanocrystal in TFP glass ceramic is SrTe5O11. TFP glass ceramic also displays much higher upconversion fluorescence lifetime and crystallization stability. The narrow and strong peak at 540nm is very ideal for practical upconversion luminescence realization. This work is a new trial for exploring non-PbF2 involved nanocrystal upconversion glass ceramics. 相似文献
996.
We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Particularly, when the single-photon-added coherent state is observed by developing the novel technique of Zavatta et al (2004 Science 306 660), we can simultar/eously obtain the generalized N-qubit W state. 相似文献
997.
Solvent and electric field dependence of the photocurrent generation in donor:acceptor blend system 下载免费PDF全文
This paper reports that the blend films of poly
(2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV)
and N,N'-bis(1-ethylpropyl)-3,4: 9,10-perylene bis
(tetracarboxyl diimide) (EP-PDI) with the weight ratio of 1:2.5
have been prepared by spin-coating from chloroform (CF) and
chlorobenzene (CB) solutions respectively. The absorption
spectra and the morphology of the blend films show that large
crystal-like EP-PDI aggregates are formed in film prepared from
CB solution, which corresponds to a new absorption shoulder near
590nm, while there is no shoulder around 590\,nm in the
UV--Vis absorption spectra of the blend film from CF solution.
The electric-field dependence spectra of the photocurrent
generation quantum yield of the film from CB solution shows that
at weak electric field the EP-PDI aggregates act as more
efficient sensitizers, but at strong electric field the quantum
yields become almost invariable over the entire spectral range
no matter what the state of EP-PDI, monomer or aggregate. At
strong electric field, the photocurrent generation yields of
both films from CF and CB solution saturate and their yield
spectra become spectrally similar, mentioning that at strong
electric field the photoexcitons dissociate efficiently and the
free charges are collected by the electrodes almost completely. 相似文献
998.
The lattice dynamics of rhombohedral GaG6 is studied as a function orpressure to probe Its high pressure phase with low superconducting transition temperature using the density functional liner-response theory. The pressureinduced phase transition in CaC6 is attributable to the softening transverse acoustic (TA) phonon mode at the zone boundary X (0.5, 0.0, 0.5) point. The high pressure phase is then explored by performing fully structural optimization in the supercell which accommodates the atomic displacements corresponding to the eigenvectors of the unstable mode of TA(X). The high-pressure phase is predicted to be a monoclinic unit cell with space group P21/m. 相似文献
999.
GU Jian-Fa GUO Hua LI Xi-Guo LIU Yu-Xin XU Fu-Rong 《理论物理通讯》2007,47(1):111-118
Antikaon condensation and kaon and antikaon production in protoneutron stars are investigated in a chiral hadronic model (also referred to as the FST model in this paper). The effects of neutrino trapping on protoneutron stars are analyzed systematically. It is shown that neutrino trapping makes the critical density of K^- condensation delay to higher density and fifo condensation not occur. The equation of state (EOS) of (proto)neutron star matter with neutrino trapping is stiffer than that without neutrino trapping. As a result, the maximum masses of (proto)neutron stars with neutrino trapping are larger than those without neutrino trapping. If hyperons are taken into account, antikaon does not form a condensate in (proto)neutron stars. Meanwhile, the corresponding EOS becomes much softer, and the maximum masses of (proto)neutron stars are smaller than those without hyprons. Finally, our results illustrate that the Q values for K^+ and K^- production in (proto)neutron stars are not sensitive to neutrino trapping and inclusion of hyperons. 相似文献
1000.
发红色荧光铽配合物的合成及荧光性能的研究 总被引:2,自引:0,他引:2
以二苯甲酰甲烷(HDBM)为第一配体,邻菲罗啉(phen)和二吡啶并[3,2-a:2',3'-c]哇喔啉(dpq)为第二配体合成两种三元铽配合物,并进行元素分析、稀土络合滴定、摩尔电导率、红外光谱、紫外光谱、荧光激发和发射光谱的测定,推测化合物的组成分别为:Tb(DBM)3phen,Tb(DBM)3dpq.DBM通过氧... 相似文献