Yj Li

Preparation and characterization of a novel dumbbell-type [60]fullerene dimer containing a cyanine dye

Two* [60]fullerene units were covalently linked by a cyanine dye to form a novel dumbbell-type molecule whose structure was observed by STM.

Self-assembly of Nanoparticles via Conjugated Polymer Film Matrix

The self-assembly film of a dendrimer-like polymer, hyper-branched conjugated poly(phenylene vinylene), is used as template to deposit CdS nanoparticles in-situ. The formation of CdS nanoparticles is characterized by TEM and XPS The nano-interiors of this polymer are the reactor site for the growth of CdS nanoparticles with the diameter of ca. 4 nm.

cis-trans Driven organized reorientation of an azobenzene derivative monolayer at the liquid/graphite interfaceElectronic supplementary information (ESI) available: comparison data with 4-hydroxy-3?-trifluoromethylazobenzene. See http://www.rsc.org/suppdata/nj/b2/b212060g/

An azobenzene derivative, 2-hydroxy-4,4′-dihexyloxyazobenzene, in which a hydroxy group is introduced at the 2-position of the phenyl ring, forms an ordered monolayer at the liquid/graphite interface. Upon light irradiation, this monolayer can undergo a reversible cis-trans driven cooperative reorientation as observed by scanning tunneling microscopy.

Electron-positron pair creation induced by quantum-mechanical tunneling

We study the creation of electron-positron pairs from the vacuum induced by two spatially displaced static electric fields. The strength and spatial width of each localized field is less than required for pair creation. If, however, the separation between the fields is less than the quantum-mechanical tunneling length associated with the corresponding quantum scattering system, the system produces a steady flux of electron-positron pairs. We compute the time dependence of the pair-creation probability by solving the Dirac equation numerically for various external field sequences. For the special case of two very narrow fields we provide an analytical expression for the pair-creation rate in the long-time limit.

Two-dimensional hydrodynamic characteristics of X-ray lasers plasmas

The two-dimensional hydrodynamic behavior of an X-ray laser plasma on a slab under non-equilibrium conditions is studied in a novel way combining numerical calculations with analytical results from a one-dimensional similar equation. Changes of both electron density and temperature with time were studied. It is found that the inhomogeneity of temperature along the z-direction due to the non-uniformity of the foci line can be relaxed by the hydrodynamic behavior and usually this process takes more than 1 ns to become uniform, while the density distribution takes several hundred picoseconds. As a result of the inhomogeneity hydrodynamic oscillation of the plasma in the z-direction was obtained.

Molecular organization and electric property of azobenzene derivative at liquid/graphite interface studied by scanning tunneling microscopy

Topography and electric property of the physisorbed monolayer of an azobenzene derivative, 4,4′-dihexyloxy-2-hydroxy-azobenzene (Azo), at the liquid/graphite interface were investigated by scanning tunneling microscopy (STM). The STM observations show that the azobenzene derivative can form an ordered row-like structure at the interface and the periodicity of the row is 3.0 nm, corresponding to the length of the molecule. Electric property of this organic tunnel junction at the liquid/graphite interface was examined by the measurement of the current–voltage (I–V) curve. The I–V curve is asymmetric for positive and negative voltages, indicating the rectifying behavior of the adlayer.

Effects of Inhomogeneous Incident Line Focus on 2D Hydrodynamic Behaviour of X-Ray Laser Plasma on Slab

Two dimensional hydrodynamic behavior of x-ray laser plasma on slab under non-equilibrium condition was studied in a novel way. Changes of the characters of plasma with time were investigated. It is found that the inhomogeneity of plasma along the line focus can be relaxed by the hydrodynamic motion. Usually the process takes more than 1ns for temperature to get uniform and several hundreds picoseconds for electron density. Hydrodynamic oscillation of plasma due to the non-uniformity of line focus was obtained.

Photophysical properties of a novel crowned [60]fulleropyrrolidine

Abstract The photophysical properties of the first crown ether-bearing [60]fulleropyrrolidine(CFP) have been studied. The absorption and fluorescence spectra are hypsochromically shifted by metal ions complexation via intramolecular electron transfer. The third-order optical nonlinearity of CFP is measured by time-resolved degenerate four-wave mixing experiment. The third-order optical susceptibility χ 3 of CFP is 8.97x10 −14 esu. The nonlinear optical temporal response is second-order exponential, the fast process is determined as 120 ps.