Monolithic Integration DFB Laser Array by Angling Active Stripe and Using Thin-Film Stripe Heater

国家863计划

A semiconductor laser suitably fabricated by planar technology

The semiconductor microlasers with an equilateral triangle resonator which can be fabricated by dry etching technique from the laser wafer of the edge emitting laser, are analyzed by FDTD technique and rate equations. The results show that ETR microlaser is suitable to realize single mode operation. By connecting an output waveguide to one of the vertices of the ETR, we still can get the confined modes with high quality factors. The EM microlasers are potential light sources for photonic integrated circuits.

Design, simulation and testing of large area silicon drift detectors and detector array for X-ray spectroscopy

Large area (25 mm(2)) silicon drift detectors and detector arrays (5x5) have been designed, simulated, and fabricated for X-ray spectroscopy. On the anode side, the hexagonal drift detector was designed with self-biasing spiral cathode rings (p(+)) of fixed resistance between rings and with a grounded guard anode to separate surface current from the anode current. Two designs have been used for the P-side: symmetric self-biasing spiral cathode rings (p(+)) and a uniform backside p(+) implant. Only 3 to 5 electrodes are needed to bias the detector plus an anode for signal collection. With graded electrical potential, a sub-nanoamper anode current, and a very small anode capacitance, an initial FWHM of 1.3 keV, without optimization of all parameters, has been obtained for 5.9 keV Fe-55 X-ray at RT using a uniform backside detector.

Efficiency calibration of neutron detector array for beta decay of exotic nuclei

The research of the in-beam efficiency calibration of Neutron Detector Array of Peking University using N-17 and C-16 beams was introduced in this paper. The efficiency of neutron wall and ball are comparable to the foreign similar devices and neutrons can be detected from low to high energies in high efficiency.

8×8单元CsI(Tl)探测阵列研制；Development of 88 CsI(Tl) array detector

描述了1个8×8单元CsI(Tl)探测阵列的结构和工作原理。探测阵列的每个单元是由1块前表面21 mm×21 mm、后表面23.1 mm×23.1 mm、高50 mm的CsI(Tl)棱台、1块光导和光电倍增管组成。在兰州放射性次级束流线(RIBLL)上对探测阵列进行测试,得到探测阵列对30 MeV质子的能量分辨可达2.7%,对170 MeV7Be可达1.5%,可很好地用于放射性束物理实验中带电粒子的鉴别。

Determination and identification of isoflavonoids in Radix astragali by matrix solid-phase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection

The isoflavonoids in Radix astragali were determined and identified by HPLC-photodiode array detection-MS after extraction employing matrix solid-phase dispersion (MSPD). As a new sample preparation method for R. astragali, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and Soxhlet extraction. The amounts of two major components in this herb, formononetin (6) and ononin (2), were determined based on their authentic standards. Four major isoflavonoids, formononetin (6), ononin (2), calycosin (5) and its glycoside (1), and three minor isoflavonoids, (6aR,11aR)-3-hydroxy-9, 10-dimethoxypterocarpan (7), its glycoside (3), and (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavone-7-O-beta-D-glycoside (4), were identified based on their characteristic two-band UV spectra and [M + H](+), [aglycone + H](+) and [A1 + H](+) ions, etc. The combined MSPD and HPLC-DAD-MS method was suitable for quantitative and qualitative determination of the isoflavonoids in R. astragali. (C) 2003 Elsevier B.V. All rights reserved.

Capillary array electrophoresis with confocal fluorescence rotary scanner

A capillary array electrophoresis system with rotary corifocal fluorescence scanner was reported. High speed direct current rotary motor combined with a rotary encoder and the reflection mirror has been designed to direct exactly the excitation laser beam. to the array of capillaries, which are symmetrically distributed around the motor. The rotary encoder is introduced to accurately orient the position of each capillary and its output signal triggers the data acquiring system to record. the fluorescence signal corresponding to each capillary. Separations of several amino acids are demonstrated by eight-channel capillary array electrophoresis built by ourselves.

Synthesis of novel ferrocenylphosphine-amidine ligands with central and planar chirality and their diastereomeric effect in Pd-catalyzed asymmetric allylic alkylation

Some novel ferrocenylphosphine-amidine ligands with central and planar chirality were prepared from (R,S-p)-PPFNH2-R 3 and its diastereomer (S,S-p)-PPFNH2 3a. The efficiency and diastereomeric impact of these ferrocenylphosphine-amidine ligands in the palladium-catalyzed asymmetric allylic substitution was examined, and up to 96% e.e. with 98% yield was achieved by the use of ligand (R,S-p)-4a with a methyl group in the amidino moiety. The results also indicated that (R)-central chirality and (S-p)-planar chirality in these ferrocenylphosphine-amidine ligands were matched for the palladium-catalyzed asymmetric allylic alkylation. (C) 2003 Elsevier Ltd. All rights reserved.

Synthesis of novel P-ketimine bidentate ferrocenyl ligands with central and planar chirality and comparsion in the catalytic activity between P-ketimine and P-aldimine

A series of novel ferrocenylphosphine-ketimine ligands 6 were prepared by reaction of (R,S-p)-PPFNH2-R or (S,S-p)-PPFNH2 with a variety of m-substituted acetophenones. A different catalytic activity was observed between ferrocenylphosphine-ketimine ligands and corresponding aldimine ligands. The efficiency and diastereomeric impact of these ferrocenylphosphine-ketimine ligands in Pd-catalyzed asymmetric allylic alkylation were first investigated, and higher enantioselectivity of over 98% e.e. with 95% yield was obtained by the use of ferrocenylphosphine-ketimine ligands. However, in Rh-catalyzed asymmetric hydrosilylation of aryl ketones, only 42% e.e. was obtained by the use of ferrocenylphosphine-ketimine ligands compared to 90% e.e. with the use of aldimine ligands. (C) 2003 Elsevier Ltd. All rights reserved.

A 2-kW COIL with a square pipe-array JSOG and nitrogen buffer gas

A 2-kW-class chemical oxygen-iodine laser (COIL) using nitrogen buffer gas has been developed and tested since industrial applications of COIL devices will require the use of nitrogen as the buffer gas. The laser, with a gain length of 11.7 cm, is energized by a square pipe-array jet-type singlet oxygen generator (SPJSOG) and employs a nozzle bank with a designed Mach number of 2.5. The SPJSOG has advantages over the traditional plate-type JSOG in that it has less requirements on basic hydrogen peroxide (BHP) pump, and more important, it has much better operational stability. The SPJSOG without a cold trap and a gas-liquid separator could provide reliable operations for a total gas flow rate up to 450 mmol/s and with a low liquid driving pressure of around 0.7 atm or even lower. The nozzle bank was specially designed for a COIL using nitrogen as the buffer gas. The cavity was designed for a Mach number of 2.5, in order to provide a gas speed and static temperature in the cavity similar to that for a traditional COIL with helium buffer gas and a Mach 2 nozzle. An output power of 2.6 kW was obtained for a chlorine flow rate of 140 mmol/s, corresponding to a chemical efficiency of 20.4%. When the chlorine flow rate was reduced to 115 mmol/s, a higher chemical efficiency of 22.7% was attained. Measurements showed that the SPJSOG during normal operation could provide a singlet oxygen yield Y greater than or equal to 55%, a chlorine utilization U greater than or equal to 85%, and a relative water vapor concentration w = [H2O]/([O-2] + [Cl-2]) less than or equal to 0.1.

A Simple and Inexpensive Method for Fabrication of Ultramicroelectrode Array and Its Application for the Detection of Dissolved Oxygen

Herein, we report a simple and inexpensive way for fabrication of ultra microelectrode arrays (UMEAs) and the relative characterization methods. The fabrication of UMEAs involves only a few steps of handwork. Since only metal wires and epoxy are used through the fabrication process, it is supposed to be a quite straightforward method for preparing UMEAs. A dissolved oxygen (DO) sensor based on UMEAs was constructed.

Monodisperse raspberry-like gold submicrometer spheres: Large-scale synthesis and interface assembling for colloid sphere array

We first suggested a one-pot method to synthesize monodisperse raspberry-like submicrometer gold spheres (MRSGS) with high yield. The resulting gold spheres were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersed X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical technology. It was found that the rough structure provided by raspberry-like gold spheres led to a tremendous electrochemical active area, which was very important because these novel hierarchical gold spheres will probably find important applications in biosensors, electrocatalysis, and others.

Weak epitaxy growth and phase behavior of planar phthalocyanines on p-sexiphenyl monolayer film

We systematically investigated the weak epitaxy growth (WEG) behavior of a series of planar phthalocyanine compounds (MPc), i.e., metal-free phthalocyanine (H2PC), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), iron phthalocyanine (FePc); cobalt phthalocyanine (CoPc), grown on a p-sexiphenyl (p-6P) monolayer film by selected area electron diffraction (SAED) and atomic force microscopy (AFM). Two types of epitaxial relations, named as incommensurate epitaxy and commensurate epitaxy, were identified between phthalocyanine compounds and the substrate of the p-6P film.