微波放电脱除 NO

报道一种不用催化剂,一步脱除NO的新方法--常压微波放电法。探讨在(NO,He),(NO.O₂,He)和(NO,O₂,H₂O,He)体系中微波放电脱除NO的差异。研究结果表明,在(NO,He)条件下可实现一步高效脱除NO,在(NO,O₂,He)条件下也可实现80%左右的NO转化,其中N₂的选择性高达80%,而H₂O的加入并未影响N₂的产率。同时发现,随着微波功率的加大,NO转化率也增大,而N₂的选择性增大得更多。最终可达到一个平衡值。最后研究了NO和O₂浓度及气体流量对NO脱除的影响。     

离子液体与微波协同促进有机合成反应

介绍了离子液体作溶剂、助溶剂、催化剂和反应试剂与微波协同促进有机合成的研究进展。离子液体与微波协同促进有机合成反应,缩短了反应时间,提高了反应的选择性和产率,对环境更加友好。     

微波等离子体增强辉光放电光源激发温度的研究

研究了一种改进型的微波等离子体增强辉光放电光源在光谱分析中的应用，对其重要的参数指标－激发温度进行了较为较细的考察。结果表明引入微波等离子体后辉光放电的激发温度明显高于单纯辉光放电时的激发温度。     

微波辅助离子液体合成法在亲核氟化中的应用

采用微波辅助合成法快捷、高效地制备了系列咪唑类和吡啶类离子液体,并对其在亲核氟化中的应用进行了研究.结果表明,N-苄基吡啶四氟硼酸盐([bepy]BF4)是一种稳定性高、使用效果好的离子液体.在微波作用下,以N-苄基吡啶四氟硼酸盐和乙腈为共溶剂,以氟化铯为氟化试剂,高效合成了系列含氟化合物.在优化反应条件下,其收率为54.1%～76.3%,反应时间较常规油浴加热最好时可缩短50%以上.     

单电极介质阻挡放电离子源研究

介质阻挡放电离子源是一种常压敞开式离子源,由于免试剂、适用范围广、易于小型化等特点而备受关注.该类离子源多采用表面双电极或针-环电极设计方式.表面双电极的接地电极会减弱氦气在强电场中电离形成的流注崩头能量,缩短等离子束喷射距离.针-环电极的电场主要集中在针电极尖端,流注崩头能量小,等离子束喷射距离比表面双电极还短.本研究对放电影响因素进行分析,通过改变电极形状和增加绝缘介质部件进行电场调整,使强电场区域集中于电极一侧,解决了单电极回流放电问题,从而获得稳定、高效的等离子束,其最大长度可达8 cm以上.基于电场调整技术,研制出单电极介质阻挡放电离子源,它主要由惰性载气、高压电极、绝缘介质管、气控以及温控部分组成.使用新型离子源对咖啡因液态样品和扑热息痛固体药片进行了质谱分析,前者的定量曲线R2值为99.66％,100 μg/L的信噪比为23;后者的主要成分对乙酰氨基酚可在质谱中快速检出,响应强度为1.26×106.上述结果表明,新型离子源可以实现样品的定量和快速原位分析.     

测定潮湿空气中粒子所含硫酸和硝酸根离子的方法

对复合薄膜法进行了改进，将人工粒子通过干燥器去除水蒸汽的不利影响，采集在镀有硝酸灵（Ｎｉｔｒｏｎ，Ｃ２０Ｈ１６Ｎ４）的膜片上。用真空镀膜法镀上氯化钡薄膜。用该法采集了高湿度下的大气粒子，对硫酸根和硝酸根两类粒子在透射电镜中进行观察，根据生成物的形态，测定出潮湿空气中粒子所含的酸性离子。     

微波辅助离子液体法在液相合成中的应用

作为一种新型的绿色化学合成方法,微波辅助离子液体法融合了离子液体与微波加热法的优点,具有合成快速、操作简便、产率高,绿色环保等特点,在液相合成方面体现出明显的优势。本文综述了离子液体作为微波吸收剂在液相有机合成、无机纳米材料合成方面的研究进展,对比分析了微波辅助离子液体法同多种传统方法的应用效果,阐明了该方法的优势,并展望该领域今后的发展方向。     

微波消解-氟离子选择电极法测定树叶中氟离子含量

采用微波消解处理样品,氟离子选择电极法测定了树叶中氟离子含量;通过正交实验考察了微波功率、消解时间、固液比、冷却时间等条件对微波消解的影响,对消解试剂和微波消解条件进行了筛选和优化。结果表明,其相对标准偏差小于0.46%,加标回收率在95.5%~103.3%之间。该法简单快速、准确可靠,对测定植物树叶中氟离子含量十分有效。     

室温离子液体作为微波吸收剂用于促进Knoevenagel反应

采用催化量的室温离子液体正丁基吡啶硝酸盐 ( [BPy]NO3 ) ,1 正丁基 3 甲基咪唑四氟硼酸盐 ( [bmim]BF4)和1 正丁基 3 甲基咪唑六氟磷酸盐 ( [bmim]PF6)作为微波吸收剂 (敏化剂 ) ,在微波辐射下能顺利地促使一系列芳醛与活泼亚甲基化合物进行Knoevenagel缩合反应 ,以中等到良好产率生成相应E 式烯烃 .     

离子液体中微波促进的Biginelli缩合反应

在微波辐射下,以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)为催化剂,三组分一锅法Bigi-nelli缩合反应快速地合成了10种高收率的5-乙氧羰基4-芳基二氢嘧啶酮衍生物的缩合产物,其结构经IR和^1H NMR确证。     

The efficacy of heating low-pressure H2 in a microwave discharge

The relative ease with which a low-pressure hydrogen stream may be heated in an electrical discharge suggests that such a system be considered in current efforts to develop thrusters for spacecraft orbit raising purposes. In this work a detailed model of a microwave discharge in flowing, low-pressure hydrogen is used to interpret and clarify experimental measurements of atom concentration, electron energy, and electron density. The radially averaged, constant-pressure model accurately reproduces the experimental data and also calculated the rates of a number of gas-heating and wall-heating processes as well as rates of energy deposition into coolant and working fluid streams. The calculated gas-heating rates indicate that the gas heating is due primarily to the thermalization of the energetic atoms produced by dissociation of H₂ via excitation of theb ³∑ _u ⁺ state. The calculations also indicate that the energy flux to the quartz tube is significantly influenced by Lyman and Werner band radiation and by heterogeneous atomic recombination processes and, to a much lesser degree, by electron-ion recombination processes. The fraction of power input which is ultimately transferred to the gas stream is a decreasing function of the power input and varies from 0.24 to 0.12.     

RF-pulsed glow discharge time-of-flight mass spectrometry for glass analysis: Investigation of the ion source design

Radiofrequency (RF) millisecond pulsed glow discharge (PGD) coupled to time-of-flight mass spectrometry (TOFMS) was investigated for direct elemental analysis of glass samples. Aiming at achieving highest elemental sensitivity, appropriate discrimination from polyatomics, and good crater shapes on glasses, a new Grimm-type GD chamber (termed from now “UNIOVI GD”, designed and constructed in our laboratory) was coupled to TOFMS, and the results compared with those obtained with the former GD design (here denominated as “GD.1”) of the initial RF-PGD-TOFMS prototype. The critical differences distinguishing the two GDs under scrutiny are the GD chamber thickness (15.5 mm for the GD.1 and 7 mm for the UNIOVI GD) and the “flow tube” which is inserted in the GD.1 and inexistent in UNIOVI GD.     

单向气流负电晕放电离子迁移谱的研究及其在爆炸物检测中的应用

基于离子迁移谱的爆炸物探测仪多采用放射性电离源,发展非放射性电离源一直是该技术的研究热点。本研究基于电晕放电原理设计了一种新型负电晕放电电离源结构,结合自行研制的离子迁移谱仪,应用于痕量爆炸物的快速、高灵敏检测。单向气流模式下,对此电离源的气流、放电电压等运行参数进行了系统优化,得到最佳实验条件为：电晕放电电离源结构的电极环孔直径为3 mm,针-环距离为2 mm,放电电压为2400 V,漂气流速为1200 mL/min。在此条件下,避免了放电副产物氮氧化物和臭氧等引发的一系列复杂反应,得到了单一的反应试剂离子O-2(H2O)n。将其应用于爆炸物,如2,4,6-三硝基甲苯(TNT)、硝酸铵(AN)、硝化甘油( NG)、太安( PETN)、黑索金( RDX)等的高灵敏快速直接检测,对TNT的检测限达到200 pg/μL。结果表明,此负电晕放电电离源具有灵敏度高、结构简单、无辐射性、反应试剂离子单一等优点,在爆炸物快速高灵敏检测、公共安全保障等方面具有广阔的应用前景。     

Gas-phase combination reactions of SF4 and SF5 with F in plasmas of SF6

Reactions of both SF₄ and SF₅ with F have been studied at 295 K in a gas-flow reactor sampled by a mass spectrometer. The rate coefficient for the combination reaction of F with SF₄ to produce SF₅ was found to increase from (0.9 to 3.0)×10^–12 cm³ s^–1 when the helium bath gas number density was increased from (2 to 26)×10¹⁶ cm^–3. The values obtained here are three orders of magnitude higher than a recent estimate of the high-pressure value based on the modelling of photochemical studies. The experimental results have been compared with RRKM and master equation calculations in which a simplified Gorin model has been used to determine the structure of the transition state. These calculations show that reasonable agreement can be obtained between the experimental data and the calculation if a small (2 KJ/mol) activation energy is assumed. The rate coefficient for the reaction between SF₅ and F to produce SF₆ was found to be independent of helium bath gas number density within the range given above. The value obtained for the rate coefficient was 9×10^–12 cm³ s^–1 with an uncertainty of a factor of 2. This value is close to that of 1×10^–11 cm³ s^–1 computed from the simplified Gorin model and to the value of 1.7×10^–11 cm³ s^–1 deduced from modelling of photochemical experiments.     

微波辅助水解反应的研究进展

相比于传统的加热方式,微波加热最大的优点是缩短了反应时间,提高了反应收率和选择性.本文简介了微波加热的特点、原理和促进反应的机理.重点总结了微波加热在有机水解反应中的研究进展,并展望了微波的工业化前景.     

A rapid efficient microwave-assisted synthesis of a 3′,5′-pentathymidine by copper(I)-catalyzed [3+2] cycloaddition

Starting from 5′-O-tosylthymidine, sequential azidation and Cu-catalyzed [3+2] azide–alkyne 1,3-dipolar cycloaddition led to the formation of a 3′,5′-pentathymidine in high yield. The whole process needed only work-up/precipitation steps and was completed within just 18 min, thanks to microwave activation.     

Production of XeO* in a CW microwave discharge

A low-power CW microwave discharge at 2.45 GHz was used to produce XeO^* excimer molecules. It was found that a total gas pressure between 5 and 20 Torr, absorbed power of about 20–100 W, and an oxygen-to-xenon ratio of 1100 maximized the XeO(¹S–¹D) green emission at 5200 to 5600 Å. The XeO^* emission appeared in the cooler parts of the discharge near the containment tube walls and in the electric field nodes of the TM₀₁₂ resonant mode.