Characterization of Cd1−xFexS diluted magnetic semiconductors grown at near phase conversion temperature

Fe-based cadmium sulfide alloy thin films have been grown on c-plane sapphire substrates by a low-pressure metalorganic chemical vapor deposition technique at different growth temperatures. From X-ray diffraction and absorption spectra of the samples, the evolutions with growth temperature show an inflexion at the growth temperature of 300 ^°C. This was attributed to the phase transformation from zinc-blende to wurtzite. With increasing growth temperature from 270 ^°C to 360 ^°C, Fe concentration in the films increases monotonously. The electronic states of Cd_1−xFe_xS were investigated by X-ray photoelectron spectroscopy. Magnetic measurement shows Van Vleck paramagnetism of the Cd_1−xFe_xS thin film in the temperature region below 7 K.     

Teleportation of an n-bit one-photon and vacuum entangled GHZ cavity-field state

A scheme for teleporting an arbitrary n-bit one-photon and vacuum entangled Greenberger-Horne-Zeilinger （GHZ） state is proposed. In this scheme, the maximum entanglement GHZ state is used as a quantum channel. We find a method of distinguishing four Bell states just by detecting the atomic states three times, which is irrelevant to the qubit number of the state to be teleported.     

Ag-SiO2复合薄膜形貌和吸收特性的研究

通过分层镀膜的方式制备Ag和SiO2的分层结构,经过快速热退火后,Ag颗粒扩散到复合薄膜的表面附近.通过改变Ag颗粒扩散的距离(SiO2的膜厚),可很好地控制Ag颗粒在复合薄膜表面附近的大小,浓度和形貌,进而对共振吸收特性产生影响.在实验中,根据Ag颗粒扩散的长度来调节退火的时间.发现经过足够长的时间(17.5 min)后,Ag颗粒会形成平行于衬底的平面团簇.由于Ag原子在平面团簇之间容易扩散,使得Ag颗粒的粒径平均值变小并趋于某一特定的半径,且粒径分布范围变小,导致吸收谱发生蓝移,吸收带变窄,且强度增加.     

Laser-induced damage of high reflectors for Ti:sapphire laser system

A broadband (～ 176 nm, R ＞ 98%, λ0 = 800 nm) and high laser-induced damage threshold (LIDT =2.4 J/cm2) TiO2/HfO2/SiO2 high reflector (HR) for Ti:sapphire chirped-pulse amplification (CPA) laser system is fabricated by the electron beam evaporation. The refractive index and extinction coefficient of TiO2 and HfO2 films are calculated from single-layer films' transmittance spectra. The properties of HR are mainly determined by the high refractive index material. The high refractive index leads to wide bandwidth. A low extinction coefficient indicates low absorption and high LIDT. The possible damage mechanism of HR is discussed.     

Newton-Leibniz integration for ket-bra operators (II)—application in deriving density operator and generalized partition function formula

Via the route of applying Newton-Leibniz integration rule to Dirac’s symbolic operators, we show that the density operator e^−βH, where H is multi-mode quadratic interacting boson operators, is a mapping of symplectic transformation in the coherent state representation appearing in the form of non-symmetric ket-bra operator integration. By virtue of the technique of integration within an ordered product (IWOP) of operators, we deduce its normally ordered form which directly leads to the generalized partition function formula and the Wigner function. Some new representations, such as displacement-squeezing correlated squeezed coherent states, constructed by the IWOP technique, also bring convenience in deriving partition functions.     

Functional Carbazole-Fullerene Complexes: A New Perspective of Carbazoles Acting as Nano-Octopus to Capture Globular Fullerenes

Fullerene host-guest constructs have attracted increasing attention owing to their molecular-level hybrid arrangements. However, the usage of simple carbazolic derivatives to bind with fullerenes is rare. In this research, three novel carbazolic derivatives, containing a tunable bridging linker and carbazole units for the capturing of fullerenes, are rationally designed. Unlike the general concave-convex interactions, fullerenes could interact with the planar carbazole subunits to form 2-dimensional hexagonal/quadrilateral cocrystals with alternating stacking patterns of 1 : 1 or 1 : 2 stoichiometry, as well as the controllable fullerene packing modes. At the meanwhile, good electron-transporting performances and significant photovoltaic effects were realized when a continuous C_60⋅⋅⋅C₆₀ interaction channel existed. The results indicate that the introduction of such carbazolic system into fullerene receptor would provide new insights into novel fullerene host-guest architectures for versatile applications.     

Enzyme-Inspired Chiral Secondary-Phosphine-Oxide Ligand with Dual Noncovalent Interactions for Asymmetric Hydrogenation

Inspired by the unique character of enzymes, we developed novel chiral SPO (secondary-phosphine-oxide) ligand (SPO-Wudaphos) which can enter into both ion pair and H-bond noncovalent interactions. The novel chiral SPO-Wudaphos exhibited excellent results in the asymmetric hydrogenation of α-methylene-γ-keto carboxylic acids, affording the chiral γ-keto acids with up to over 99 % ee. A series of control experiments and DFT calculations were conducted to illustrate the critical roles of both the ion pair and H-bond noncovalent interactions.     

Synthesis and chiroptical properties of chiral binaphthyl‐containing polyfluorene derivatives

New chiral binaphthyl‐containing polyfluorene (PF) derivatives, PFOH , PFMOM , and PFP , bearing different binaphthyl units ((S)‐2,2′‐bis(methoxymethoxy)‐1,1′‐binaphthyl for PFMOM , (S)‐1,1′‐binaphthyl‐2,2′‐diol for PFOH , and (S)‐2,2′‐bis(diphenylphosphinyl)‐1,1′‐binaphthyl for PFP ) in the backbone have been designed and synthesized through Pd‐catalyzed Suzuki polycondensation. Their properties have been investigated in detail by ¹H NMR, ¹³C NMR, TGA, DSC, UV–vis, photoluminescence (in solutions, in thin films before and after annealing), and circular dichroism (CD) spectroscopic methods compared with poly(9,9‐dihexylfluorene‐2,7‐diyl) ( PF ). The resulting copolymers possessed excellent solubility in organic solvents and emitted strong blue light. The phosphine oxide‐containing copolymers PFP and PFMOM exhibited higher quantum yields and better thermal spectral stability in comparison with PF . All the copolymers exhibited obviously the linearly polarized photoluminescent properties both in solutions and in solid states. High emission polarization ratios (R_PL) of PFP were observed with no obvious decrease upon thermal annealing. In addition, investigation of the CD spectroscopic properties of these copolymers in THF solutions indicated that the chirality of the binaphthyls could be transferred to the whole PF backbone. All these results demonstrated that introduction of the chiral binaphthyls, particularly BINAPO, into the backbone could effectively improve the performances of the copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011