便携式光离子化有害气体检测仪的设计

针对室内空气污染源的多样性与传统气体检测器检测种类的单一性的矛盾,设计了一种能够同时检测多种气体的新型便携式光离子化气体检测仪.该检测仪采用了MEMS结构的离子化室和混合信号级微处理器C8051F040,减小了仪器体积,降低了仪器功耗.利用单片机控制电流跨导增益的方法,实现了仪器的双量程数据采集功能,保证了仪器在两个量...     

异喹啉的脉冲辐解和激光光解研究

用脉冲辐解和激光光解相结合,研究了异喹啉这种难降解杂环化合物在紫外光作用下的变化和与HO·的反应.结果表明,在波长为266nm的激光作用下,异喹啉不仅发生光激发,而且发生单光子电离,其量子产额为1.58×10-4.异喹啉光电离产生的阳离子自由基可以脱去质子,其pKa为5.50.异喹啉可以与HO·发生反应,其反应速率常数为3.4×109 mol-1·dm3·s-1.本工作的研究将为photo-Fenton法降解异喹啉提供理论上的依据.     

An experimental and kinetic modeling study of 2-methyltetrahydrofuran flames

Clean combustion processes are of paramount importance in the transition of the energy system towards increased sustainability. In an attempt to partially replace conventional fossil fuels, bio-derived oxygenates attract rising attention as alternative transportation fuels. Among this class of fuels, cyclic structures that can be derived from cellulosic biomass are particularly interesting. Here we present a study of premixed, laminar low-pressure flames of 2-methyltetrahydrofuran (2-MTHF) with an equivalence ratio of ? = 1.7 at 40 mbar. Time-of-flight molecular-beam mass spectrometry (MBMS) with electron ionization (EI) was used to analyze and quantify mole fraction profiles of reactants, products, and most intermediate species including radicals involved in the combustion process. As a valuable complement, MBMS using single-photon ionization (PI) by vacuum ultraviolet radiation permitted isomer identification as well as independent concentration information under similar flame conditions. A detailed combustion model for 2-MTHF was developed, and the flame structure and species information were examined in conjunction with these experiments.     

THE ON-LINE CHEMICAL ANALYSIS OF SINGLE PARTICLES USING AEROSOL BEAMS AND TIME OF FLIGHT MASS SPECTROMETRY

This paper describes an on-line instrument, capable of measuring the size and chemical composition of single, aerosol particles. Possible applications include monitoring aerosol reactors and studying atmospheric chemistry. The main conclusion is that a working prototype has been built and tested. It uses a three stage vacuum system to generate an aerosol beam with a low divergence angle and a high transmittance. The pressure is reduced sufficiently to allow the application of a time-of-flight mass analyzer. The aerosol beam is probed in the analysis section by the focused beam of a low-power helium-neon laser. Every particle crossing the laser beam scatters light, which is detected by two photomultiplier tubes, mounted at angles of 45 and 90°. The signal is stored when both detectors produce a pulse simultaneously, and this event triggers the chemical analysis cycle. A pulsed Nd: YAG laser vaporizes the particle and generates ions, which are next analyzed by a time-of-flight mass spectrometer. In this way combined information on the size and the composition of the particle is obtained.