Wing profile measurements of the Na-doublet lines in C2H2/O2/N2, H2/O2/N2 and H2/O2/Ar frames at 1 atm

Fluorescence-excitation (wing) profiles of the Na-D doublet lines were measured over a wavelength range extending from 0.3 to 200 Å from the line center for the red D₁ and blue D₂ wings and from 0.3 to 3 Å for the red D₂ and the blue D₁ wings, respectively. The line profiles were determined with the aid of a tunable CW dye-laser as a background source by measuring the total fluorescence intensity observed on detuning the laser wavelength. The flames were premixed, laminar, shielded flames at 1 atm, with temperatures ranging from 1860 to 2270 K; N₂ and Ar served as diluent gases. The line core and near-wing profiles (i.e. the region covering 0.3<Δλ<7 Å for the outer wings and 0.3<Δλ<3 Å for the inner ones) in all of the flames studied appeared to have the same frequency dependence, regardless of the nature and concentrations of the gases used. The blue D₂-line profile followed an unexpected (-2.2) law, while the other three profiles obeyed the theoretically expected (-2) law (the dispersion profile function). The line profile in the Δλ range between the impact and quasistatic regions was found to depend on the main perturbers involved. We found that the far blue D₂- and red D₁-wings in the Ar-diluted H₂/O₂ flame obeyed the (-$\text{5}\text{4}$) and (-$\text{3}\text{2}$) laws, respectively, as predicted by the quasi-static theory for the Lennard-Jones interaction. For the N₂-diluted C₂H₂/O₂ and H₂/O₂ flames, we did not find these wing dependences in the Δλ range investigated.     

Combustion properties of H2/N2/O2/steam mixtures

The present work reports new experimental and numerical results of the combustion properties of hydrogen based mixtures diluted by nitrogen and steam. Spherical expanding flames have been studied in a spherical bomb over a large domain of equivalence ratios, initial temperatures and dilutions at an initial pressure of 100 kPa (T_ini = 296, 363, 413 K; N₂/O₂ = 3.76, 5.67, 9; %Steam = 0, 20, 30). From these experiments, the laminar flame speed $S_L^0$, the Markstein length L’, the activation energy Ea and the Zel'dovich β number have been determined. These parameters were also simulated using COSILAB^® in order to verify the validity of the Mével et al. [1] detailed kinetic mechanism. Other parameters as the laminar flame thickness δ and the effective Lewis number Le_eff were also simulated. These new results aim at providing an extended database that will be very useful in the hydrogen combustion hazard assessment for nuclear reactor power plant new design.     

Opto-galvanic spectroscopy of some molecules in discharges: NH2, NO2, H2 and N2

The change of the discharge voltage when laser light crossing the discharge is tuned to a molecular transition has been measured. Experiments have been performed in the wavelength region between 570 nm and 620 nm with discharges in NH₃, NO₂, H₂, N₂, O₂ and argon. Transitions from the ground states of NH₂ and NO₂ and transitions from metastable states of N₂ and H₂ have been detected. The spacial dependence of the opto galvanic in a low pressure dc-discharge of H₂ and N₂ has been studied.     

Temperature dependence of pressure broadening of NH3 perturbed by H2 and N2

The temperature dependence of pressure broadening of 134 rovibrational transitions of several branches in the ν₄ and 2ν₂ bands of ammonia perturbed by H₂ and N₂ has been measured using a high-resolution Fourier transform spectrometer. The temperature range covered during the experiments was between 235 and 296 K. The pressure-broadening linewidths were obtained using the method of multipressure fitting to the measured shapes of the lines. These broadenings were also calculated using a semiclassical model leading to a reasonable agreement with the observations and reproduces well the strong systematic experimental J and K quantum number dependencies. The retrieved values of the linewidths, along with those previously determined from the spectra at room temperature, were used to derive the temperature dependence of both H₂ and N₂ broadening of NH₃ lines. The broadening coefficients were shown to fit closely the well-known exponential law. For both experimental and theoretical results, the temperature exponent n has been obtained. Careful inspection of the experimental values shows that, contrary to the linewidths, the coefficient n is nearly K independent within each J multiplet. Also for a given J it does not seem to exhibit any noticeable variation with the type of rotational transition. On the other hand, the calculated n values exhibit a strong J and K systematic dependencies. n increases with K for a given J, decreases with J for a given K and are independent of the type of rotational transition.     

Microwave linewidths of C2H4O perturbed by H2, N2, O2 and CO2

Microwave linewidths of C₂H₄O (κ = -0.41) broadened by H₂, N₂, O₂, and CO₂ and considering dipole-quadrupole interactions have been calculated using the Mehrotra-Boggs theory (1977). This theory accounts satisfactorily for observed linewidths     

Photoelectron angular distributions from H2 and D2

The photoelectron asymmetry parameters of H₂ and D₂ have been measured using synchrotron radiation over the photon energy range 19–27 eV. The results are compared with previous measurements and several theoretical calculations. A few of the theoretical calculations are in good agreement with experiment, but most of them predict asymmetries which are too large. Essentially identical β values were measured for H₂ and D₂. This result is discussed in terms of differences which could arise due to vibrational and rotational structure.     

低温等离子体分解N2/O2/NO气氛中NO试验研究

利用自行设计的介质阻挡放电型低温等离子体反应器,研究了NO初始浓度、O₂初始浓度、放电功率、电源频率等因素对NTP转化N₂/O₂/NO气氛中NO的影响规律。研究发现,NO去除率随功率增大而升高,到达一最大值后随功率增大而降低;NO去除率随O₂初始浓度增加而降低,随NO初始浓度增大而减小。相同放电功率下,同一组分中NO去除率随电源频率的增加而降低,因此相同放电功率下降低电源频率可提高NO去除率。O₂初始浓度不高于5%时,NO_x大部分为NO,NO₂和O₃浓度均随放电功率增大而降低,NO₂、O₃生成量随O₂初始浓度升高而增多。     

Second-order conditional moment closure modeling of a turbulent CH4/H2/N2 jet diffusion flame

The second-order CMC model for a detailed chemical mechanism is used to model a turbulent CH₄/H₂/N₂ jet diffusion flame. Second-order corrections are made to the three rate limiting steps of methane–air combustion, while first-order closure is employed for all the other steps. Elementary reaction steps have a wide range of timescales with only a few of them slow enough to interact with turbulent mixing. Those steps with relatively large timescales require higher-order correction to represent the effect of fluctuating scalar dissipation rates. Results show improved prediction of conditional mean temperature and mass fractions of OH and NO. Major species are not much influenced by second-order corrections except near the nozzle exit. A parametric study is performed to evaluate the effects of the variance parameter in log-normal scalar dissipation PDF and the constants for the dissipation term in conditional variance and covariance equations.     

一维湍流模型对He平面羽流和CH4/H2/N2射流火焰的数值模拟

本文采用一维湍流模型（ODT）对氦气平面羽流和CH₄/H₂/N₂射流火焰进行数值模拟,和前人的实验结果进行定量地对比。结果表明,ODT模型能够准确地预测平面羽流基本特征,湍流涡团的分布同流场拉伸率之间具有密切的关系,涡团强度的分布能够直观地表明当地的湍流强度。ODT模型埘CH₄/H₂/N₂瞬态火焰的模拟定性反应了火焰特性及其与湍流作用的规律,对温度-混合分数的预测值和实测值进行比较,发现甲烷火焰燃烧在富燃料侧并未达到平衡状态,因而基元反应对火焰特性的预测具有重要作用。     

Reaction products from a discharge of N2 and H2S: The microwave spectrum of NH2SH

Thiohydroxylamine has been identified as one of the reaction products from the discharge reaction of N₂ + H₂S. Both cis and trans conformers have been observed. The rotational spectra have been studied from 56 to 170 GHz for the normal species and several deuterated isotopic species of each conformer. The electric dipole moments of both conformers have been determined. A number of the transitions of the cis conformer exhibit splittings due to the nuclear quadrupole moment of the ¹⁴N nucleus. A least squares fit of the frequency splittings have led to an analysis of the eQq values. Ab initio calculations using a 4-31G basis set both with and without polarization functions have been carried out to aid in the analysis and to provide a final structural comparison with the microwave results.     

Collision-induced simultaneous transitions in H2+CF4 and H2+SF6 mixtures

The simultaneous transitions of the v₃ fundamental vibrations of CF₄ and SF₆ with the fundamental Q branch and S(1) line of H₂ have been studied for various H₂+CF₄ and H₂+SF₆ mixtures at total pressures up to 185 bars. The integrated intensities are found to be proportional to the partial densities of the gas mixture components. The agreement between experimental and calculated intensities is generally better for the Kihara potential than for the Lennard-Jones potential.     

Effects of O2 and N2/H2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

The O₂ and N₂/H₂ plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.     

Positronium yields in gaseous N2 and N2Ne mixtures at 77 K

The positronium yield in pure N₂ and in N₂Ne mixtures at 77 K for N₂ densities in the range 0.9–3.7 amagat is measured to be 73% greater than that recently reported for the same densities of pure N₂ at 297 K.     

N2…HF的结构及其氟化氢谐振频率的变化

应用密度泛函理论方法(B3LYP)和QCISD方法,对N2…HF弱结合复合体系在不同的基组下进行abinitio计算,得到了该复合物分子分别在QCISD及B3LYP水平下的平衡结构为:RNN=0.1104nm,0.1095nm,RNN=0.2198nm,0.2094nm和RHF=0.0922nm,0.0931nm,计算了复合物中HF的谐振频率为3899.399cm-1以及HF谐振频率红移量为62.755cm-1,所计算的结果与近期的实验数据和理论值相符合,还考查了不同基组和方法对N2…HF弱结合体系的影响.     

Linewidth and intensity measurements of SO2 lines at 94 GHz with self-broadening and broadening by H2O and N2

In the frequency range between 91.5 and 95.5 GHz, three rotational lines of the ³²S¹⁶O₂ and two rotational lines of the ³⁴S¹⁶O₂ molecules in the fundamental vibrational state, and also two lines of the ³²S¹⁶O₂ molecule in the v₂ vibrational state, have been investigated. Center frequencies and absolute absorptions have been measured and compared with theoretical values. Furthermore, the self-broadening and broadening by H₂O and N₂ of the transition 23(6,18)–24(5,19) with the line center at 94.064 GHz have been investigated. The following linewidth parameters were found: SO₂-SO₂, 18.2±0.3 MHz/torr; SO₂-N₂, 3.8±0.1 MHz/torr; SO₂-H₂O, 15.2±0.2 MHz/torr. The bridge spectrometer and the measuring method used are also described.     

Electronic-excitation transfer collisions in flames—V. Cross sections for quenching and doublet-mixing of K(42P)-doublet by N2, O2, H2 and H2O

Weighted average cross sections for quenching of the K(4²P)-doublet by N₂, H₂, O₂ and H₂O, measured in flames, show no significant temperature dependence in the range from 1500 to 2500K. Doublet mixing cross sections for K(4²P$\text{3}\text{2}$?4²P$\text{1}\text{2}$) transitions were measured at 1720K for N₂, O₂, H₂O. The ratios of both mixing cross sections were measured independently and were found to agree with the detailed balance condition within 2 per cent. It is shown that an ionic intermediate-state model cannot explain the large magnitude of N_2? mixing cross sections.     

Largeurs des raies spectrales de CO autoperturbe et perturbe par N2, O2, H2, HCI,NO et CO2

Linewidths of CO self-broadening and broadened by N₂, O₂, H₂, HCI, NO, and CO₂ have been calculated using different contributions in the intermolecular dispersion potential.The quadrupole moment of some perturbers has been determined by comparison between calculated and observed linewidths. The values obtained for the quadrupole moments may depend on the dispersion potential, especially when it is low (as is the case for N₂, O₂ and H₂). For CO-CO and CO-NO, the electrostatic interactions including the octupole moment yield good results for the linewidths for high |m|-values.     

Comparison of CH4/H2 and C2H6/H2 inductively coupled plasma etching of ZnO

CH₄/H₂-based discharges are attractive for dry etching of single crystal ZnO because of their non-corrosive nature. We show that substitution of C₂H₆ for CH₄ increases the ZnO etch rate by approximately a factor of 2 both with and without any inert gas additive. The C₂H₆/H₂/Ar mixture provides a strong enhancement over pure Ar sputtering, in sharp contrast to the case of CH₄/H₂/Ar. The threshold ion energy for initiating etching is 42.4 eV for C₂H₆/H₂/Ar and 59.8 eV for CH₄/H₂/Ar. The etched surface morphologies were smooth, independent of the chemistry and the Zn/O ratio in the near-surface region was unchanged within experimental error after etching with both chemistries. The plasma etching improved the band-edge photoluminescence intensity and suppressed the deep level emission from the bulk ZnO under our conditions, due possibly to removal of surface contamination layer.     

The adsorption of CO,H2, H2, CO2 and H2O on carburized and graphitized Ni(110)

A study of the adsorption/desorption behavior of CO, H₂O, CO₂ and H₂ on Ni(110)(4 × 5)-C and Ni(110)-graphite was made in order to assess the importance of desorption as a rate-limiting step for the decomposition of formic acid and to identify available reaction channels for the decomposition. The carbide surface adsorbed CO and H₂O in amounts comparable to the clean surface, whereas this surface, unlike clean Ni(110), did not appreciably adsorb H₂. The binding energy of CO on the carbide was coverage sensitive, decreasing from 21 to 12 $\text{kcal}\text{mol}$ as the CO coverage approached 1.1 × 10¹⁵ molecules cm^?2 at 200K. The initial sticking probability and maximum coverage of CO on the carbide surface were close to that observed for clean Ni(110). The amount of H₂, CO, CO₂ and H₂O adsorbed on the graphitized surface was insignificant relative to the clean surface. The kinetics of adsorption/desorption of the states observed are discussed.