共查询到19条相似文献,搜索用时 296 毫秒
1.
采用辉光放电技术和等离子体质谱诊断技术,研究了H2/C4H8混合气体等离子体中正离子成分及主要正离子能量随射频功率的变化规律,并分析了H2/C4H8混合气体主要的离解机理和形成过程.研究表明:随着射频功率的增加,碳氢碎片离子的浓度增加,在20 W时达到最大值,25 W后有所减小.当射频功率小于10 W时,H2/C4H8混合气体等离子体中C4H9+相对浓度最大,当功率大于或等于10 W时,C3H3+相对浓度最大.随着射频功率的增大,碳氢碎片离子的能量逐渐增加.对H2/C4H8混合气体等离子体的组成与能量进行的定性分析,将为H2/C4H8混合气体辉光放电聚合物涂层工艺参数优化提供参考. 相似文献
2.
射频辉光放电CH4等离子体一维流体动力学模拟 总被引:1,自引:1,他引:0
完整建立一个关于射频辉光放电CH4等离子体的流体动力学模型.模型包括基于迁移-扩散近似的粒子平衡方程、电子能量平衡方程,共包含了20种粒子(环境气体粒子,激发态粒子,离子和电子)和49类化学反应(电子-中性环境粒子、离子-中性环境粒子、激发态粒子-激发态粒子(中性环境粒子)).结果表明,在强电场区域有较高的电子反应率系数;等离子体中除源气体CH4外,H2,C2H6,C3H8,C2H4和C2H2也有较高的密度含量;激发态粒子中,CH3含量最高,密度约为1019m-3;在较低放电压力时(如18 Pa),CH5+在离子成分中密度含量最高,当放电压力较高时(如67Pa),C2H5+在离子成分中占主导地位;除C2H5+外,其它各离子和激发态粒子在极板上的粒子流量随功率的增大逐渐升高. 相似文献
3.
通过用Monte Carlo方法模拟N2-H2 混合气体直流辉光放电等离子体快电子行为,从不同H2浓度的电子能量分布函数,电子密度以及ef-N2碰撞率等方面,研究了加H2对氮辉光放电等离子体过程的影响. 研究结果表明: 随着H2浓度的升高,电子的平均能量增加, 电子密度及ef-N2的各种非弹性碰撞率减小; 但在
关键词:
2-H2辉光放电')" href="#">N2-H2辉光放电
Monte Carlo模拟
2碰撞率')" href="#">e-N2碰撞率 相似文献
4.
对高气压(约100 Torr) 直流辉光碳氢等离子体的气相过程进行了光谱和质谱原位诊断. 在高气压下, 等离子体不同区域光发射特性存在明显差异. 正柱区存在着以C2和CH为主的多个带状谱和分立谱线, 阳极区粒子发射谱线明显减少, 而在阴极区则出现大量复杂的光谱成分, 表明高气压情形下等离子体与阴极间强烈的相互作用将导致复杂的原子分子过程. 从低气压到高气压演变过程中, 电子激发温度降低而气体分子转动温度升高. 在高气压下, 高甲烷浓度导致C2, C2H2及C2H4增多而C2H6减少. 表明在高气压条件下, 气体温度对气相过程的影响作用显著增强.
关键词:
高气压直流等离子体
光发射谱
质谱 相似文献
5.
利用反应显微成像谱仪开展了50-keV/u Ne8+离子与C3H4分子碰撞实验,研究了丙二烯(CH2CCH2)和丙炔(CH3CCH)两种同分异构分子形成C3H42+二价离子并解离产生H+C3H2+H的过程.实验获得了H+和C3H2+的动量,进而通过动量守恒得到第3个碎片的动量.通过分析3个碎片的动能及解离的动能释放鉴别出未被探测的碎片为中性H原子的事件.借助Dalitz图、Newton图以及碎片产物的角分布等分析了该通道的动力学机制.结果表明,次序解离是该解离通道的主要机制,在碎裂过程中二价母体离子先解离成H+和C3H3+,中间体的... 相似文献
6.
采用两维PIC/MCC模型模拟了氮气微空心阴极放电以及轰击离子 (N2+,N+) 的钛阴极溅射. 主要计算了氮气微空心阴极放电离子 (N2+,N+) 及溅射原子Ti的行为分布, 并研究了溅射Ti 原子的热化过程. 结果表明: 在模拟条件下, 空心阴极效应是负辉区叠加的电子震荡; 在对应条件下, 微空心较传统空心放电两种离子 (N2+,N+) 密度均大两个量级, 两种离子的平均能量的分布及大小几乎相同; 在放电空间N+的密度约为N2+的1/6, 最大能量约大2倍; 在不同参数 (P, T, V)下, 轰击阴极内表面的氮离子(N2+,N+)的密度近似均匀, 其平均能量几乎相等; 从阴极溅射出的Ti原子的初始平均能量约6.8 eV, 离开阴极约0.15 mm处几乎完全被热化. 模拟结果为N2微空心阴极放电等离子体特性的认识提供了参考依据.
关键词:
微空心阴极放电
PIC/MC模拟
2等离子体')" href="#">N2等离子体 相似文献
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卤代烷烃会破坏臭氧层,而碘乙烷(C2H5I)是卤代烷烃中重要代表物质之一.采用离子速度成像技术、飞秒激光技术和飞行时间质谱技术,探究了C2H5I的多光子电离解离动力学.通过分析C2H5I在强场作用下多光子电离解离得到的解离通道、碎片的动能、角度分布和各向异性参数等信息来研究碘乙烷离子(C2H5I+)C–I键裂解机理.根据飞行时间质谱实验,C2H5I在飞秒激光脉冲作用下发生多光子电离解离得到的碎片有C2H5+,I+,CH2I+,C2H2+,C2H3+,C2H4+等.与C–I键相关的碎片为C2H5+和I+,解离机制分别对应于C2H5I+→C2H5++I和C2H5I+→C2H5+I+.同时,采用离子速度成像技术研究C2H5I+的C–I键裂解产生的C2H5+和I+的速度影像,得出两者的速度分布和动能分布,分析结果表明C–I键裂解产生C2H5+和I+的过程都存在高能通道和低能通道.进一步分析解离碎片离子的角度分布发现C2H5+解离时各向异性参数接近于0,可能对应于慢速的振动预解离过程.I+在解离时各向异性参数较高,可能源于排斥势能面上的快速解离过程.最后采用密度泛函理论计算了C2H5I分子电离前后构型变化、离子态的能级强度及谐振强度,对C2H5I+的解离机制做了更进一步的分析和讨论. 相似文献
9.
实验上,利用纯CH4及CH4+Ar在几百帕量级气压下的介质阻挡放电 制备类金刚石膜,研究了气压p与放电间隙d乘积(pd值)以及Ar的体积百分比RAr 对膜硬度的影响.理论上,从离子与气体分子的双体碰撞出发,利用较高折合电场强度E/n( 电场强度与粒子数密度之比)下离子及中性粒子速度分布的双温模型、离子在其他气体中运 动时遵守的朗之万方程及离子在混合气体中运动时遵守的布兰克法则,对CH+4和Ar+离子能量进行了分析.结果表明:1)CH4介质阻挡 放电中,pd值由1.862×103Pa mm降低至2.66×102Pa mm时,CH+4能量由5.4eV增加到163eV,类金刚石膜硬度由2.1GPa提高到17.6GPa ; 2) 保持总气压p=100Pa,放电间距d=5mm不变,在CH4中加入Ar气,当RAr 由20%增加至83%时,CH+4的能量由69eV增加到92eV,而Ar+能量由93eV降低至72eV.虽然CH+4能量增加有助于提高 沉积膜硬度,但当RAr大于67%,高强度Ar+轰击会导致膜表面石墨 化,膜硬度降低.为了验证离子能量理论模型的正确性,实验测量了H2介质阻挡 放电中离子能量,测量结果与理论计算之间最大相对误差为16%.
关键词:
离子能量
介质阻挡放电
类金刚石膜 相似文献
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11.
在射频输入功率为400W,气压为0.8Pa的条件下,使用光强标定的发射光谱方法研究了感应耦合H2/C4F8等离子体中CF, CF2, H和F基团的相对密度随流量比R=H2/(H2+C4F8)的变化情况,而HF基团相对密度的变化由四级质谱仪探测得到。结果表明等离子体活性先随着R的增加而升高,然后随着R的进一步增加而下降。在流量比从0逐渐上升到0.625的过程中,CF和CF2基团的相对密度不断降低。实验中测得的CF基团的相对密度[CF]与理论计算得到的[CF]有很好的一致性说明了电子与CF2基团的碰撞反应是CF基团产生的主要原因。文中还讨论了HF基团。 相似文献
12.
Nobuaki Kitazawa Masami Aono Yoshihisa Watanabe 《Journal of Physics and Chemistry of Solids》2011,72(12):1467-1471
This paper describes the synthesis and characterization of organic–inorganic layered perovskite compounds, (CnH2n+1NH3)2PbI4 (n=4, 5, 7, 8 and 9). The effect of the number of carbon atoms on luminescence properties has been examined. Thin films of microcrystalline (CnH2n+1NH3)2PbI4 fabricated by spin-coating are highly oriented, with the c-axis perpendicular to the substrate surface. Temperature-dependent optical absorption spectra reveal that (CnH2n+1NH3)2PbI4 films (n=4, 7, 8 and 9) show the structural phase transitions. The excitonic structures of (CnH2n+1NH3)2PbI4 vary with the number of carbon atoms of the alkyl chain length. At low temperatures below 100 K, the lowest-energy free-exciton band of (CnH2n+1NH3)2PbI4 (n=7, 8 and 9) split into three fine-structure levels. In contrast to (CnH2n+1NH3)2PbBr4 films, (CnH2n+1NH3)2PbI4 (n=7, 8 and 9) shows no triplet exciton emission, but it shows the Stokes-shifted emission from bound excitons. 相似文献
13.
C. Sourisseau J.P. Forgerit Y. Mathey 《Journal of Physics and Chemistry of Solids》1983,44(2):119-124
Infrared and Raman spectra (10–3100 cm?1) of the layered ZnPSs compound and of intercalates with [Co(η5 ? C5H5)2+] and [Cr(η6 ? C6H6)2+] cations in the polycrystalline state have been recorded 300–10 K temperature range. A complete assignment of the spectra is proposed in terms of PSs group motions, Zn2+ ion translations and [Co(η5 ? C5H5)2+] or [Cr(η6 ? C6H6)2+] internal vibrations. New low frequency for the [Co(η5-C5H5)2+] intercalate at low temperature are assigned to librational and torsional modes of C5H5 rings. Moreover, the preresonance Raman spectra of this intercalate show a selective enhancement for the metal-ligand vibrations when the charge transfer band of the cobalticenium is approached. One concludes that guest molecules are intercalated under their cationic form, are weakly interacting with the host lattice and seem to be dynamically disordered at room temperature. 相似文献
14.
B. I. Reznikov N. I. Alekseev S. V. Bobashev B. G. Zhukov S. A. Ponyaev R. O. Kurakin S. I. Rozov 《Technical Physics》2011,56(8):1106-1111
The equilibrium composition and the effective adiabatic exponent of a low-temperature carbon plasma containing eight components
(C, C2, C3, C4, C5, C+, C2+, and e) are calculated. The temperature and pressure ranges are found in which polyatomic clusters form in a gas flow. It is shown
that the effective adiabatic exponent of the carbon plasma is a nonmonotonic function of temperature. In the parameter range
where the plasma consists largely of polyatomic clusters, the adiabatic exponent is close to unity. It is noted that anomalously
low values of the effective adiabatic exponent indicate a considerable concentration of polyatomic molecules in the plasma
jet. Such values can be observed in experiments with a low-temperature carbon plasma flowing about bodies. 相似文献
15.
The interaction of O2, CO2, CO, C2H4 AND C2H4O with Ag(110) has been studied by low energy electron diffraction (LEED), temperature programmed desorption (TPD) and electron energy loss spectroscopy (EELS). For adsorbed oxygen the EELS and TPD signals are measured as a function of coverage (θ). Up to θ = 0.25 the EELS signal is proportional to coverage; above 0.25 evidence is found for dipole-dipole interaction as the EELS signal is no longer proportional to coverage. The TPD signal is not directly proportional to the oxygen coverage, which is explained by diffusion of part of the adsorbed oxygen into the bulk. Oxygen has been adsorbed both at pressures of less than 10-4 Pa in an ultrahigh vacuum chamber and at pressures up to 103 Pa in a preparation chamber. After desorption at 103 Pa a new type of weakly bound subsurface oxygen is identified, which can be transferred to the surface by heating the crystal to 470 K. CO2 is not adsorbed as such on clean silver at 300 K. However, it is adsorbed in the form of a carbonate ion if the surface is first exposed to oxygen. If the crystal is heated this complex decomposes into Oad and CO2 with an activation energy of 27 kcal/mol(1 kcal = 4.187 kJ). Up to an oxygen coverage of 0.25 one CO2 molecule is adsorbed per two oxygen atoms on the surface. At higher oxygen coverages the amount of CO2 adsorbed becomes smaller. CO readily reacts with Oad at room temperature to form CO2. This reaction has been used to measure the number of O atoms present on the surface at 300 K relative to the amount of CO2 that is adsorbed at 300 K by the formation of a carbonate ion. Weakly bound subsurface oxygen does not react with CO at 300 K. Adsorption of C2H4O at 110 K is promoted by the presence of atomic oxygen. The activation energy for desorption of C2H4O from clean silver is ~ 9 kcal/mol, whereas on the oxygen-precovered surface two states are found with activation energies of 8.5 and 12.5 kcal/mol. The results are discussed in terms of the mechanism of ethylene epoxidation over unpromoted and unmoderated silver. 相似文献
16.
The inelastic neutron scattering spectra of C2H2 and C2D2 adsorbed on a Ag+ exchanged 13X zeolite (0–800 cm?1) and of C2H2 on the Na+ form (0–300 cm?1) have been obtained. For the Na-13X system no distinct vibrational modes were observed, however for the Ag-13X systems the low frequency intramolecular modes of the adsorbed gas and some of the vibrations of the adsorbed gas relative to the surface have been assigned. From the deuteration shifts it appears that C2H2 and C2D2, adsorbed on Ag-13X, are non-linear. 相似文献
17.
C. Renard 《Proceedings of the Combustion Institute》2009,32(1):631-637
Structures of several premixed ethylene-oxygen-argon rich flat flames burning at 50 mbar have been established by using molecular beam mass spectrometry in order to investigate the effect of CO2, or NH3, or H2O addition on species concentration profiles. The aim of this study is to examine the eventual changes of profiles of detected hydrocarbon intermediates which could be considered as soot precursors (C2H2, C4H2, C5H4, C5H6, C6H2, C6H4, C6H6, C7H8, C6H6O, C8H6, C8H8, C9H8 and C10H8). The comparative study has been achieved on four flames with an equivalence ratio (f) of 2.50: one without any additive (F2.50), one with 15% of CO2 replacing the same quantity of argon (F2.50C), one with 3.3% of NH3 in partial replacement of argon (F2.50N) and one with 13% of H2O in replacement of the same quantity of argon (F2.50H). The four flat flames have similar final flame temperatures (1800 K).CO2, or NH3, or H2O addition to the fresh gas inlet causes a shift downstream of the flame front and thus flame inhibition. Endothermic processes CO2 + H = CO + OH and H2O + H = H2 + OH are responsible of the reduction of the hydrocarbon intermediates in the CO2 and H2O added flames through the supplementary formation of hydroxyl radicals. It has been demonstrated that such processes begin to play at the end of the flame front and becomes more efficient in the burnt gases region.The replacement of some Ar by NH3 is responsible only for a slight decrease of the maximum mole fraction of C2H2, but NH3 becomes much more efficient for C4H2 and C5 to C10 species. Moreover, the efficiency of NH3 as a reducing agent of C5 to C10 intermediates is larger than that of CO2 and H2O for equal quantities added. 相似文献
18.
Fr. Shindo Y. Bnilan P. Chaquin J.-C. Guillemin A. Jolly Fr. Raulin 《Journal of Molecular Spectroscopy》2001,210(2):191
Polyynes are of astrophysical interest since they appear to be involved in organic chemistry in very different mediums. In Titan's atmosphere, the lightest polyyne, C4H2, was detected by Voyager. Recently C4H2 and C6H2 have been discovered in a protoplanetary nebula, suggesting polyynes as a possible chemical pathway to PAH (polycyclic aromatic hydrocarbons). Moreover, several experimental simulations and modeling imply their production from the photochemistry of methane and their involvement in the formation of organic aerosols. After the study of C4H2 and C6H2 spectra in the UV and IR wavelength range, we report here the first spectrum of gaseous C8H2 in the range 400–4000 cm−1 at room temperature and low resolution. The task was hardly achieved because of the high instability of this molecule with temperature and pressure. To avoid exothermic polymerization, the compound as mixed with a solvent. We have performed a separate spectroscopic study of the solvent to determine C8H2 partial pressure within the mixture. This allowed us to calculate C8H2 integrated band intensities. In the studied wavelength range, C8H2 presents three main bands similar to those of C6H2 in terms of vibrational type, position, and relative intensity. To study the possible identification of these polyynes by spatial observatories (Cassini–Huygens, ISO), we have also measured the C6H2 and C8H2 infrared spectra in the range 400–1500 cm−1 at 0.35 cm−1 resolution. 相似文献
19.
Fei-Hui Li 《Applied Surface Science》2009,255(16):7394-7402
The reduction process of Bi3+, HTeO2+ and their mixtures on Au electrode surface was studied by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. XRD and EDS methods were also used to measure the reductive products prepared under different potentials and provide the evidences of the reactions. The results indicate that the reduction of HTeO2+ occurs at more positive potential than that of Bi3+, but its reduction rate is slower and adsorption phenomenon exists during its reduction process. Bi2Te3 compound can be obtained potentiostatically at a proper potential in all the mixed solutions with concentration ratio CHTe+O2/CBi3+ in our research range (0.1-10). But pure Bi2Te3 compound can only be obtained at 42 mV in the solution with concentration ratio CHTe+O2/CBi3+ equaling to 1. And the formation of Bi2Te3 compound is an inductive co-depositing process: (1) HTeO2+ + 4e− + 3H+ → Te0 + 2H2O, (2) 3Te0 + 2Bi3+ + 6e− → Bi2Te3. 相似文献