Zhao You-Yuan

Synthesis and photophysical characterization of terbium-polymer complexes containing salicylate ligand

Abstract Tb-polymer complexes containing salicylate ligand were synthesized through copolymerization of Tb(Sal) 2 AA with MMA or styrene and characterized by IR, UV, GPC, TG, DSC, XRD, and emission and excitation spectra. Copolymers showed noticeable changes on excitation and UV absorption spectra when compared with Tb(Sal) 2 AA monomer, suggesting efficient energy transfer from both salicylate moiety and polymer matrices to Tb 3+ ion. The emission intensities of PMM/AATb(Sal) 2 and PS/AATb(Sal) 2 copolymers were much stronger than that of Tb(Sal) 2 AA-doped polymers of the same Tb content. Energy transfer processes and environment effects were found to contribute to the luminescence enhancement. Typical relationships between emission intensity and Tb content exhibited some extent of concentration quenching in our studies. However, 5 D 4 lifetime results suggested that these quenching phenomena cannot be accounted for by deactivation of 5 D 4 state through exchange or multipolar interaction. Ligand energy migration along or across many chains can interpret the emission concentration quenching phenomena reasonably.

Electroluminescence of Si Nanocrystal-Doped SiO2

We perform a comparative study on the electroluminescence (EL) and photoluminescence (PL) of Si nanocrystal-doped SiO2 (nc-Si:SiO2) and SiO2, and clarify whether the contribution from Si nanocrystals in the EL of nc-Si:SiO2 truly exists. The results unambiguously indicate the presence of EL of Si nanocrystals. The difference of peak positions between the EL and PL spectra are discussed. It is found that the normal method of passivation to enhance the PL of Si nanocrystals is not equally effective for the EL, hence new methods need to be explored to promote the EL of Si nanocrystals.

Photoinduced Birefringence and Broadband All-Optical Photonic Switch in a Bacteriorhodopsin/Polymer Composite Film

Photoinduced birefringence with large optical nonlinearity in a bacteriorhodopsin/polymer composite film is observed. A high refractive index change of 8.5 ? 10?5 photoinduced by 476 nm pumping beam is reached at the low intensity of 6.5 mW/cm2. Based on it, a broadband all-optical photonic switch is realized with an optical controlling switch system. Because of controlling beams selectivity in switching, the transporting beams of different wavelengths with different intensities and shapes can be modulated by adjusting the wavelength and intensity of the controlling beam.

A Model for Light-Driven Proton Pump and Transfer in Bacteriorhodopsin

A theoretical model was assumed to describe the kinetic processes of light-driven proton pump and motion. The calculation shows that the photovoltage signals are greatly affected by experimental conditions including pulse width of excitation and impedance of measurement system. At the same excitation, only a negative photovoltage signal can be observed with small impedance and both the negative and positive signals can be observed with large impedance. With the same impedance, shorter response time of the pulsed photoelectric signals is responsible for shorter pulsed excitation. All these phenomena are in good agreement with the experimental results.

Photoluminescence of SiOx Thin Films After Annealing at Various Temperatures

We study photoluminescence (PL) of SiOx (0<x<2) thin films after annealing at temperatures in the range of 700–1100 degrees C. The SiOx thin films were prepared by evaporation of SiO powder onto the substrate of Si(100). Two PL emission structures were observed in the measuring range of 580–755 nm. The one centred around ~730 nm was confirmed to be due to Si nanocrystals. The origin for the other one spanning the range of 580–650 nm was investigated by using hydrogen and oxygen passivations, and by short time annealing at 1100 degrees C followed by hydrogenation. Our results support the model of structural defects in SiO2 matrix for the origin of the 580–650 nm PL peak.

Light-Induced Charge Separation and Transfer in Bacteriorhodopsin

The photo-voltage signals in bacteriorhodopsin(bR) excited by 1064 nm pulse laser are different from those by 532 or 355 nm. It shows that the positive and negative photoelectric signals are produced by the motion of the positive and negative charges, respectively, and more energy is needed for producing the positive charges than the negative. The mechanism of light-induced charge generation and charge transfer in bR was studied and analyzed by measuring the photoelectric signals with different impedance of measuring circuit and different pulse-width of 532 nm laser as pump light.

A PVK-based high-performance photorefractive polymer composite under a low external electric field

We describe a PVK-based photorefractive polymer composite doped with disperse red 1, poly-butylacrylate and TNF. Using the two-beam coupling experiment, we investigate its photorefractive properties as well as the dynamic process of the index gratings in the sample. We observe the photorefractive effect in the absence of an applied external electric field. The two-beam coupling gain coefficient was measured to reach a value as high as 140 cm-1 in the absence of an external applied electric field and a value of 470 cm-1 at a poling dc electric field of 25V/µm.

The parity non-conservation E1 matrix of barium-a semi-empirical calculation

A number of works have reported on the calculation of the parity non-conservation E1 matrix for Cs and Tl atoms. However little has been done on other more complex atoms. The authors give a MQDT wavefunction for an alkaline-earth atom at the origin, and upon this base a semi-empirical calculation of Im E1pn c of atomic barium. The results show that the Im E1pnc of the 0 to 32480 cm-1 transition is 8.9 *10-11 ea0, which implies that the barium atom might be a possible candidate for PNC investigation in atomic spectroscopy.

Spectral Hole-Burning of Eu3+:Y2SiO5 Crystal at 16 K

By using an Ar+ ion laser, a tunable Rh 6 G dye laser (linewidth 0.5 cm−1) pumped by the second harmonic of a YAG:Nd laser and a Coherent 899-21 dye laser as light sources and using a monochromator, a phase-locking amplifier and a computer as the data detecting system, we detect the optical properties of Eu3+-doped Y2SiO5 crystal. Persistent spectral hole burning (PSHB) are observed in the Eu3+ ions spectral lines (5D0−7F0 transition) in the crystal at the temperature of 16 K. For 15 mW dye laser burning the crystal for 0.1 s spectral holes with hole width about 80 MHz both at 579.62 nm and at 579.82 nm are detected and the holes can remain for a long time, more than 10 h.

Orientation-enhanced nonlinear optical properties and phase-conjugate reflective system of a novel Azobenzene doped polymer film

This paper reports that the nonlinear refractive index of a novel organic optical storage film doped azo-diphenylamine polymer is measured by using the Z-scan technique. The nonlinear refractive index up to 3.7 × 10−6 cm2/W induced by thermo-optical effect is obtained. It indicates that the sample has excellent optical nonlinear properties. The physical mechanism of the great nonlinear optical effect is analysed and the optical conjugate characteristic is also discussed with degenerate four-wave-mixing. The phase conjugate wave diffracted from the formative refractive index grating in the sample is acquired and its equivalent reflectivity reaches about 22%. On this basis, the reflective wave phase-conjugated mirror system was designed, and the image aberration experienced in propagation in the storage experiment is corrected by using the system.