The preparation of amylopectin tris(phenylcarbamate) (ATP) chiral stationary phases(CSPs) coated on a small-particle (5μm, 120Å) spherical silica support, according to a process that is reported, is presented. A new chiral tetrahedral cluster (μ₃-Se)RuCoW(CO)₈C₅H₄C(O)CH₃ 2 which was synthesized by the thermal reaction of the precursor (μ₃-Se)RuCo₂(CO)₉ 1 with the functionally substituted cyclopentadienyl tricarbonyl metal complex anions [W(CO)₃C₅H₄C(O)CH₃]^- is resolved on the amylopectin tris (phenylcarbamate) chiral stationary phases.

志强 周;E. R. Ding;建国 侯;L. R. Chen;Y. Q. Yin

Journal of Liquid Chromatography and Related Technologies

1998

Long beltlike nanowires were successfully synthesized for a semiconducting oxide of vanadium by a hydrothermal route at 180°C for 5 h and were characterized by x-ray powder diffraction, energy dispersive x-ray spectroscopy, and electron diffraction microscopy. The product is mainly layered V₂O₅ · 0.3H₂O with a small fraction of V₂O₅ · 0.3H₂O (0.3 < x < 1.7) and V₂O₅ phases. The obtained nanowires, several tens of micrometers long and a few of tens of nanometers wide, are crystallized well, growing along the [010] direction. The effects of preparation conditions on the formation of the nanowires are discussed.

Dengyu Pan;Zhang Shuyuan;翌庆 陈;建国 侯

Journal of Materials Research

2002-8

In this letter, Cu-C₆₀ granular film is prepared with coevaporation method at room temperature. The conductance of the film is measured by in situ method, and its microstructure is characterized by transmission electron microscopy. The charge transfer from Cu to C₆₀ is investigated with Raman spectroscopy. The results indicate that the sample has the uniformly granular microstructure. The interaction between C₆₀ and Cu at the Cu-C₆₀ interfaces, which significantly affects the orientational order-disorder phase transition of C₆₀ and induces the phase transition of C₆₀ in the temperature range from 219 to 248 K. The mechanism of the characteristic of such phase transition is discussed.

Xiang Li;Y. J. Tang;H. W. Zhao;文山 詹;Haiqian Wang;建国 侯

Applied Physics Letters

2000-8-14

We present the fabrication and scanning tunneling microscopy (STM) characterization of suspended monolayer graphene (SMG) on periodic Si nanostructure. Monolayer graphene (MG) was grown on Cu foils by chemical vapor deposition (CVD) and transferred onto a Si substrate with etched array of periodic nanopillars, obtaining partly suspended MG. Low-temperature STM characterization was performed on the suspension area of the MG with atomic resolution images obtained. The scanning tunneling spectroscopy of SMG shows a nonlinear behavior near the Fermi level (E_F), which is attributed to the Dirac cone reshaped by electron-electron interaction.

Xin Zhao;Xiaofang Zhai;Aidi Zhao;Bing Wang;建国 侯

Applied Physics Letters

2013-5-20

The fractal formation and V-I behavior of the Au/Ge bilayer film have been investigated with a transmission electron microscope and by the two-probe configuration method. The experimental results suggest that the Au/Ge bilayer film, after the fractal crystallization, shows a nonlinear V-I behavior. This phenomenon was explained by the random tunneling junction model.

Zhiwen Chen;Shuyuan Zhang;Shun Tan;建国 侯;Yuheng Zhang;Hisashi Sekine

Journal of Applied Physics

2001-1-1

In this paper, C₆₀/Ag bilayers were prepared on mica and NaCl substrates by thermal evaporation, the temperature of the substrates was kept at 300 K during the fabrication of the sample. The electrical conductance of the film was measured during C₆₀ covering. An anomalous peak of conductivity was observed when the thickness of the C₆₀ overlayer was around 1.6 nm, implying that 1-2 monolayer(s) of the C₆₀ coverlayer were "metallic". A possible mechanism is discussed.

X. Li;Y. J. Tang;H. Wang;H. W. Zhao;文山 詹;建国 侯

Physica Status Solidi (A) Applied Research

2001-7

For polar/nonpolar heterostructures, Maxwell's theory dictates that the electric potential in the polar components will increase divergently with the film thickness. For LaAlO₃/SrTiO₃, a conceptually intriguing route, termed charge reconstruction, has been proposed to avert such "polar catastrophe". The existence of a polar potential in LaAlO ₃ is a prerequisite for the validity of the charge reconstruction picture, yet to date, its direct measurement remains a major challenge. Here we establish unambiguously the existence of the residual polar potential in ultrathin LaAlO₃ films on SrTiO₃, using a novel photovoltaic device design as an effective probe. The measured lower bound of the residual polar potential is 1.0 V. Such a direct observation of the giant residual polar potential within the unit-cell-scale LaAlO₃ films amounts to a definitive experimental evidence for the charge reconstruction picture, and also points to new technological significance of oxide heterostructures in photovoltaic and sensing devices with atomic-scale control.

Haixing Liang;Long Cheng;Xiaofang Zhai;Nan Pan;Hongli Guo;Jin Zhao;Hui Zhang;Lin Li;Xiaoqiang Zhang;Xiaoping Wang;长淦 曾;Zhenyu Zhang;建国 侯

Scientific Reports

2013

We studied the growth of C₆₀ thin films on a layer of surfactant Sb which was predeposited on mica substrates with vacuum vapor deposition method. It was found that the growth behaviors of C₆₀ films are significantly affected by the surfactant Sb and the substrate temperature. (112)- and (111)-oriented C₆₀ single-crystal films with large C₆₀ single crystals were obtained when the substrate temperatures were 200 and 215°C, respectively. The growth mechanisms of the Sb mediated C₆₀ films were attributed to the reduced surface diffusion rate of adsorbed C₆₀ molecules and the lowered boundary potential energy of C₆₀ islands by surfactant Sb.

Wentao Xu;建国 侯;Z. Q. Wu

Applied Physics Letters

1998

We have measured the (effective) specific heat of single crystals of O60 using ac calorimetry. For an fcc crystal prepared by sublimation, there is a sharp hysteretic lambda-shaped anomaly at 260 K, reflecting a latent heat spread over 3 K, similar to what is observed in powders using differential scanning calorimetry. There is also a discontinuity of 11.6R in the specific heat. For orthorhombic crystals prepared by slow evaporation from a toluene-hexane solution, a nonhysteretic, apparently second-order, transition is observed at 239 K. There is a peak in the specific heat consistent with a transition entropy of R ln12.

M. Chung;Yiqin Wang;J. W. Brill;X. D. Xiang;R. Mostovoy;建国 侯;A. Zettl

Physical Review B

1992

The recent rapid advances in nanotechnology, especially those based on molecules, are due in large part to our newly acquired abilities to measure and manipulate individual molecules and their assemblies. Among all the approaches for the study of single molecules, scanning tunneling microscopy (STM) is unique and powerful owing to its ability to accurately probe and control single molecules. High-resolution spatial imaging combined with scanning tunneling spectroscopy (STS) helps scientists investigate and resolve many chemical and physical problems at the molecular level. In this paper, we review our recent studies of single molecules and their assemblies by combining STM experiments and theoretical simulations based on the density functional theory (DFT).

建国 侯;Kedong Wang

Pure and Applied Chemistry

2006-5