The InP nano inner cladding fiber is fabricated by the method of modified chemical vapor deposition. The thickness of the InP nano thin film is about 16 nm. A 20 dB supercontinuum over 100nm in the telecommunication band is generated by infecting 1550nm, 120fs, 50MHz repetition rate optical pulse into this kind of fiber. Moreover, the results indicate that the width of the supercontinuum spectra can be influenced by the fiber length and pump power. The longer fiber at higher pump power can produce broader supercontinuum spectrum. 相似文献
The nascent CaH product in the reaction Ca(4s4p1P1) + H2 --> CaH(X2Sigma+) + H is obtained using a pump-probe technique. The CaH(v = 0,1) distributions, with a population ratio of CaH(v = 0)/CaH(v = 1) = 2.7+/-0.2, may be characterized by low Boltzmann rotational temperature. According to Arrhenius theory, the temperature dependence measurement yields a potential barrier of 3820+/-480 cm(-1) for the current reaction. As a result of the potential energy surfaces (PES) calculations, the reaction pathway favors a Ca insertion into the H2 bond along a (near) C2v geometric approach. As the H2 bond is elongated, the configurational mixing between the orbital components of the 4p and nearby low-lying 3d state with the same symmetry makes significant the nonadiabatic transition between the 5A' and 2A' surface in the repulsive limbs. Therefore, the collision species are anticipated to track along the 5A' surface, then undergo nonadiabatic transition to the inner limb of the 2A' surface, and finally cross to the reactive 1A' surface. The observed energy barrier probably accounts for the energy requirement to surmount the repulsive hill in the entrance. The findings of the nascent CaH product distributions may be reasonably interpreted from the nature of the intermediate structure and lifetime after the 2A'-1A' surface transition. The distinct product distributions between the Ca(4 1P1) and Mg(3 1P1) reactions with H2 may also be realized with the aid of the PES calculations. 相似文献
An investigation of the use of La- and Zn-promoters for Ru/SiO2 F-T catalysts has been carried out. It was found that, while the use of a La-promoter did not result in any improvement over the use of a K one, Zn-promotion resulted in much higher yields of olefins. The CH4 and olefin selectivities of the Zn-promoted Ru/SiO2 were essentially insensitive to temperature over the range 250–320 °C. The Zn-promoted catalyst was found to have many of the same catalytic properties previously found for Ru/ZnO, but was much more active. Thus, it is possible to achieve certain interesting catalytic properties for Ru by the use of Zn-promotion without having to make use of the low surface area support ZnO.
We study the one-dimensional deformed
model in terms of the continuum field theories. We found that at low doping concentration and far away from the phase separation regime, there are two phases: the Luttinger liquid and the Luther-Emery liquid, depending on
or
, where
. Moreover, the singlet superconducting correlations are dominant in the Luther-Emery liquid.Received: 12 October 2003, Published online: 19 February 2004PACS:
71.10.Fd Lattice fermion models - 71.10.Hf Non-Fermi-liquid ground states - 74.20.Mn Non-conventional mechanisms 相似文献
A method to prepare iron oxide material which has a higher surface area and nanosized particle was developed. It was used as a catalyst for CO oxidation at low temperature. Iron oxide materials were prepared by precipitation under constant pH value. The effects of preparation parameters, such as iron salt (FeCl3, Fe(NO3)3 and FeCl2), pH value (between 8 and 12), drying temperature (between 120°C and 300°C), and feeding rate of the aqueous solution of the iron salt, on the characteristics of iron oxide have been investigated. The materials were characterized by N2 sorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The surface area of iron oxide was greater than 400 m2/g using FeCl3 as the starting material with very low feeding rate of 10 ml/min, the pH value of 11, and drying at 120°C. The XRD patterns indicated that the iron oxide samples heated at a temperature below 180°C was either amorphous or of a particle size too small (<4 nm) for the samples prepared with FeCl3. Depending on the preparation conditions, the iron oxide samples showed a phase transition from amorphous to various crystalline phases. Large amount of hydroxyl groups were preserved if the drying temperature was below 200°C. TEM images showed that the particle diameters were less than 4 nm for the samples prepared with FeCl3 at pH value of 11 with a low feeding rate of 10 ml/min, and heated below 200°C. XPS Fe 2p3/2 spectra showed the phase transition of iron oxide from Fe3O4 to FeO. The feeding rate of starting material and pH value during precipitation played the important roles to obtain iron oxide with high surface area. The nanosized iron oxide demonstrated high activity for CO oxidation even at ambient condition. The higher activity of FexOy nanoparticles in CO oxidation was attributed to a small particle size, high surface area, high concentration of hydroxyl groups, and more densely populated surface coordination unsaturated sites.This revised version was published online in August 2005 with a corrected issue number. 相似文献
Hydrothermally reaction of Cd(NO3)2·4H2O, pimelic acid (H2Pim) mixed with two N-containing ligands of 1,2-bis(2-methyl-imidazol-1-ylmethyl)benzene (1,2-mbix) or 1,3-bis(2-methyl-imidazol-1-ylmethyl)benzene (1,3-mbix) gave rise to two new Cd(II) MOFs, [Cd(Pim)(1,2-mbix)] (1) and [Cd(Pim)(1,3-mbix)]·H2O (2). Both MOFs were structurally characterized by IR and UV–Vis spectra, single-crystal and powder X-ray diffraction, thermogravimetric analyses. MOF 1 shows a fourfold interpenetrating dia network. Differently, MOF 2 shows a 2D?→?3D interdigitated architecture base on the 63hcb layer when 1,2-mbix was replaced by 1,3-mbix. The luminescent properties of 1 and 2 have been investigated. Furthermore, the luminescent quenching experiments suggest both MOFs exhibit good selectivity and sensitivity to detect Fe3+ and Cr2O72? in water.