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利用可调谐同步辐射真空紫外光电离和分子束质谱技术研究了当量为1的低压、预混乙烯/氧气/氩气火焰.利用光电离效率谱和光电离质谱,探测了火焰中燃烧中间物,并鉴别了C3H4、C2H4O和C4H4等中间物的同分异构体.在近电离阈值光予能量下,通过扫描燃烧炉的位置测量了火焰中物质的摩尔分数曲线,并利用Pt/Pt-13%Rh热电偶测得了火焰的温度曲线.与以前的工作相比,观察到很多新的燃烧中间物,如C3H2、C3H3、C3H5、C2H6O、C4H2、C4H4、C4H6、C3H4O、C3H6O、C3H8O、C5H6、C4H8O和C7H8等.同时,在火焰中检测到了包括CH3、C2H3、C2H5、HCO、C3H3以及C3H5在内的一系列自由基.在实验工作的基础上,发展了一个包含40种火焰物质和223个基元反应的简化动力学模型来对火焰进行模拟.对主要物质和大部分中间产物的拟合结果与实验值相当吻合. 相似文献
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《化学物理学报》2018,(5)
本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程,在9.0~15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线.通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03eV,并确认碎片离子为:C_5H_7O~+,C_4H_5O~+,C_4H_8~+,C_3H_3O~+,C_4H_6~+,C_2H_4O~+,C_3H_6~+, C_3H_5~+,C_3H_4~+, C_3H_3~+, C_2H_5~+,C_2H-4~+.利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C_5H_8O~+的解离机制.通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径. 相似文献
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利用可调谐真空紫外同步辐射和分子束实验装置在8.0~15.5 eV的光子能量范围内,研究2-甲基-2-内烯-1-醇的光电离解离.测出母体离子和碎片离子:C_4H_8O~+、C_4H_7O~+、C_3H_5O~+、C_4H_7~+、C_4H_6~+、C_4H_5~+、C_2H_4O~+、C_2H_3O~+、C_3H_6~+、C_3H_5~+、C_3H_3~+、CH_3O~+和CHO~+的光电离效率曲线,并获得母体分子的电离能和碎片离子的实验出现势.在B3LYP/6-31+G(d,p)理论水平上,计算光电离过程中母体分子、过渡态和中间体的稳定结构.采用CCSD(T)/cc-pVTZ耦合簇方法计算零点能,得到母体电离能和碎片离子的出现势.通过实验和理论研究,提出2-甲基-2-丙烯-1-醇的光解离路径,分子内氢转移是其中大部分解离途径中的主要过程. 相似文献
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《化学物理学报》2019,(3)
利用可调谐真空紫外同步辐射和分子束实验装置在8.0~15.5 eV的光子能量范围内,研究2-甲基-2-内烯-1-醇的光电离解离.测出母体离子和碎片离子:C_4H_8O~+、C_4H_7O~+、C_3H_5O~+、C_4H_7~+、C_4H_6~+、C_4H_5~+、C_2H_4O~+、C_2H_3O~+、C_3H_6~+、C_3H_5~+、C_3H_3~+、CH_3O~+和CHO~+的光电离效率曲线,并获得母体分子的电离能和碎片离子的实验出现势.在B3LYP/6-31+G(d,p)理论水平上,计算光电离过程中母体分子、过渡态和中间体的稳定结构.采用CCSD(T)/cc-pVTZ耦合簇方法计算零点能,得到母体电离能和碎片离子的出现势.通过实验和理论研究,提出2-甲基-2-丙烯-1-醇的光解离路径,分子内氢转移是其中大部分解离途径中的主要过程. 相似文献
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Identification of Intermediates in Pyridine Pyrolysis with Molecular-beam Mass Spectrometry and Tunable Synchrotron VUV Photoionization 下载免费PDF全文
利用可调谐同步辐射真空紫外光电离结合分子束取样技术研究吡啶的热解,温度是1255―1765 K、压力为267 Pa. 通过测量光电离质谱和光电离效率谱,鉴别了近20种产物和中间物,并给出了物种随温度变化的摩尔分数. 主要的产物为H2、HCN、C2H2、C5H3N、C4H2和C3H3N. 根据实验结果分析了吡啶热解的一些主要反应路径. 相似文献
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甲烷针-板放电与重油加氢耦合形成甲烷转化重油加氢,可实现重油高效加氢并增产高附加值低碳烯烃,有实践应用前景和科学研究意义.建立二维流体模型,对大气压甲烷针-板放电等离子体进行数值模拟,得到电场强度、电子温度和粒子密度的空间与轴向分布,总结反应产额并提炼生成各种带电和中性粒子的关键路径.模拟结果表明,CH_3~+和CH_4~+密度与电场强度和电子温度的轴向演化接近且密切相关;CH_5~+和C_2H_5~+密度沿轴向先增大后减小;CH_3与H密度的空间和轴向分布几乎相同;CH_2,C_2H_4与C_2H_5的粒子密度分布在靠近阴极的区域内明显不同而在正柱区内较为相像;电子与CH_4发生电子碰撞电离生成的CH_3~+和CH_4~+,CH_3~+和CH_4~+分别与CH_4发生分子碰撞解离生成C_2H_5~+和CH_5~+;电子与CH_4间的电子碰撞分解是生成CH_3,CH_2,CH和H的主导反应;CH_2与CH_4和电子与C_2H_4发生的反应分别是生成C_2H_4和C_2H_2的关键路径;电子与CH_4间的电子碰撞分解反应和CH_2与CH_4发生的反应的产额各占H_2总产额的52.15%和47.85%. 相似文献
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Application of spontaneous Raman and Rayleigh scattering and 2D LIF for the characterization of a turbulent CH4/H2/N2 jet diffusion flame 总被引:1,自引:0,他引:1
4 /H2/N2 diffusion flame. Important aspects of the measuring technique, such as accuracy, cross talk between different Raman bands,
and the correction procedure for background from laser-induced fluorescence are discussed. In addition, a 2D LIF and Rayleigh
imaging system were used to study the structures of OH, CH, NO, and temperature distributions in the flame. A comparison between
two different CH detection schemes is presented. A main goal of the investigations was a detailed and accurate characterization
of the investigated flame as well as the study of experimental techniques. Joint pdfs of the temperature and major species
concentrations were determined at nearly 100 measuring locations covering the complete flame. Parts of the results are presented
in the paper in order to discuss effects of differential diffusion, flame extinction, and interaction between flow field and
chemistry. The measured data sets which are available on the Internet are well suited for testing and validating mathematical
flame models.
Received: 8 July 1997/Revised version: 23 October 1997 相似文献
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Zhenyu Tian 《Proceedings of the Combustion Institute》2009,32(1):311-318
A premixed nitromethane/oxygen/argon flame at low pressure (4.67 kPa) has been investigated using tunable vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry. About 30 flame species including hydrocarbons, oxygenated and nitrogenous intermediates have been identified by measurements of photoionization efficiency spectra. Mole fraction profiles of the flame species have been determined by scanning burner position at some selected photon energies. The results indicate that N2 and NO are the major nitrogenous products in the nitromethane flame. Compared with previous studies on nitromethane combustion, a number of unreported intermediates, including C3H4, C4H6, C4H8, C2H2O, C2H4O, CH3CN, H2CNHO, C3H3N and C3H7N, are observed in this work. Based on our experimental results and previous modeling studies, a detailed oxidation mechanism including 69 species and 314 reactions has been developed to simulate the flame structure. Despite some small discrepancies, the predictions by the modeling study are in reasonable agreement with the experimental results. 相似文献
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燃烧:一个不息的话题--同步辐射单光子电离技术在燃烧研究中的应用 总被引:6,自引:0,他引:6
燃烧应用于工业、农业、交通运输、国防等各个领域,提供了当今社会极大部分的能量需求。100多万年前人类就开始利用燃烧,人类研究燃烧已经有150多年的历史。本文介绍了将同步辐射真空紫外单光子电离技术结合分子束取样,应用于燃烧研究中,可以探测到燃烧中的各种中间物,包括稳定的和不稳定的产物。通过扫描光子能量,测量产物的光电离效率谱,可以区分其同分异构体,因此,利用这种新的诊断技术,在150年后的今天,我们仍然可以在火焰中发现很多新的燃烧中间体,为发展燃烧动力学模型提供精确的实验数据。最后,展望该方法在其它学科中的可能应用。 相似文献
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Terrill A. Cool Juan Wang Phillip R. Westmoreland Zhenwei Zhao Tina Kasper 《Proceedings of the Combustion Institute》2007,31(1):285-293
Reaction paths are identified for dimethyl ether (DME) combustion using modeling of new data from fuel-rich DME flat flames. A molecular-beam flame-sampling photoionization mass spectrometer, employing VUV synchrotron radiation, is applied to the measurement of mole fractions for 21 flame species in low-pressure premixed fuel-rich (Φ = 1.2, 1.68) DME/oxygen/argon flat flames. This approach is capable of resolving and identifying isomers and other flame species of near equal masses with ionization thresholds that differ by as little as 0.1 eV. The measurements agree well with flame modeling predictions, using a recently revised high-temperature DME kinetic mechanism, which identify reaction paths quite analogous to alkane combustion. They further reveal the presence of ethyl methyl ether, a molecule previously unobserved in flames and not included in present flame models. 相似文献
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汽油/氧气预混火焰中烯丙基自由基的真空紫外光电离研究 总被引:1,自引:0,他引:1
分子束取样结合同步辐射光电离质谱技术研究了低压汽油/氧气/氩气预混火焰中的烯丙基自由基,测得了它的光电离效率曲线,通过光电离效率曲线得到烯丙基的电离阈值为(8.13±0.02)eV。另外,用从头算分子轨道理论得到了烯丙基及其阳离子的构型和能量,给出了烯丙基自由基的绝热电离能为8.18 eV。计算的电离能与实验得到的电离能符合得很好,这一结果有助于今后鉴别和分析其它火焰中的烯丙基自由基,且对研究火焰燃烧机理有十分重要的价值。 相似文献
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Bin Yang 《Proceedings of the Combustion Institute》2007,31(1):555-563
A comprehensive experimental study of the premixed benzene/oxygen/argon flame at 4.0 kPa with a fuel equivalence ratio (?) of 1.78 has been performed with the tunable synchrotron photoionization and molecular-beam sampling mass spectrometry. Isomers of most observed species in the flame have been unambiguously identified by measurements of the photoionization efficiency spectra. Mole fraction profiles of species up to C16H10 have been measured at the selective photon energies near ionization thresholds, and the flame temperature profile is obtained using Pt/Pt-13%Rh thermocouple. Compared with previous studies on benzene flames by Bittner and Howard, and by Defoeux et al., a number of new species are observed in the present work. These new combustion intermediates should be included in the kinetic models of the growth of polycyclic aromatic hydrocarbons (PAHs) and benzene oxidation. Free radicals detected in the flame include CH3, C2H, C2H3, C2H5, C3H, C3H3, C3H5, C4H, C4H3, C4H5, C4H7, C5H3, C5H5, C5H7, C6H5, C6H5O, C7H7, and C9H7. More significantly, isomers of some PAHs have been identified, which should be of importance in understanding the mechanism of soot formation. 相似文献
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A slightly sooting premixed ethylbenzene flame with an equivalence ratio of 1.90 was investigated at low pressure (4.0 kPa) using molecular-beam mass spectrometry (MBMS) and tunable synchrotron vacuum ultraviolet (VUV) photoionization. Basing on the ionization threshold measurements of photoionization efficiency (PIE) spectra, combustion intermediates up to C19H12 were identified, including a number of radicals and isomeric species. Mole fraction profiles of observed flame species were evaluated from the measurements of burner scan at the photon energies near ionization thresholds. Besides, the flame temperature profile was measured by a Pt/Pt-13%Rh thermocouple. From the intermediate identification and mole fraction measurements, the degradation of ethylbenzene, as well as the formation of some interested polycyclic aromatic hydrocarbons (PAHs), was discussed in detail. It is suggested that the formation of most typical PAHs observed in this work can be related to the H-abstraction/C2H2-addition (HACA) mechanism. Furthermore, the high concentration levels of intermediates in this flame is ascribed to the weak C-C bonds in the sidechain of ethylbenzene, which provides a potential explanation of the high sooting tendencies of ethylbenzene and other monocyclic aromatic fuels with complex sidechain structure. This study is anticipated to be constructive for combustion investigations of aromatic fuels, and the discussion is hoped to be helpful for further modeling studies concerning PAHs formation in combustion process. 相似文献
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《Proceedings of the Combustion Institute》2023,39(2):1699-1708
The combustion chemistry of tetramethylethylene (TME) was studied in a premixed laminar low-pressure hydrogen flame by combined photoionization molecular-beam mass spectrometry (PI-MBMS) and photoelectron photoion coincidence (PEPICO) spectroscopy at the Swiss Light Source (SLS) of the Paul Scherrer Institute in Villigen, Switzerland. This hexene isomer with the chemical formula C6H12 has a special structure with only allylic CH bonds. Several combustion intermediate species were identified by their photoionization and threshold photoelectron spectra, respectively. The experimental mole fraction profiles were compared to modeling results from a recently published kinetic reaction mechanism that includes a TME sub-mechanism to describe the TME/H2 flame structure. The first stable intermediate species formed early in the flame front during the combustion of TME are 2-methyl-2-butene (C5H10) at a mass-to-charge ratio (m/z) of 70, 2,3-dimethylbutane (C6H14) at m/z 86, and 3-methyl-1,2-butadiene (C5H8) at m/z 68. Isobutene (C4H8) is also a dominant intermediate in the combustion of TME and results from consumption of 2-methyl-2-butene. In addition to these hydrocarbons, some oxygenated species are formed due to low-temperature combustion chemistry in the consumption pathway of TME under the investigated flame conditions. 相似文献