Ab initio calculations of nitrogen oxide reactions: formation of N2O2, N2O3, N2O4, N2O5, and N4O2 from NO, NO2, NO3, and N2O

Ab initio computational methods were used to obtain Delta(r)H(o), Delta(r)G(o), and Delta(r)S(o) for the reactions 2 NO <=> N(2)O(2) (I), NO+NO(2) <=> N(2)O(3) (II), 2 NO(2) <=> N(2)O(4) (III), NO(2)+NO(3) <=> N(2)O(5) (IV), and 2 N(2)O <=> N(4)O(2) (V) at 298.15 K. Optimized geometries and frequencies were obtained at the CCSD(T) level for all molecules except for NO, NO(2), and NO(3), for which UCCSD(T) was used. In all cases the aug-cc-pVDZ (avdz) basis set was employed. The electronic energies of all species were obtained from complete basis set extrapolations (to aug-cc-pV5Z) using five different extrapolation methods. The [U]CCSD(T)/avdz geometries and frequencies of the N(x)O(y) compounds are compared with literature values, and problems associated with the values and assignments of low-frequency modes are discussed. The standard entropies are compared with values cited in the NIST/JANAF tables [NIST-JANAF Thermochemical Tables, J. Phys. Chem. Ref. Data Monograph No. 9, 4th ed. edited by M. W. Chase, Jr. (American Chemical Society and American Institute of Physics, Woodbury, NY, 1988)]. With the exception of I, in which the dimer is weakly bound, and V, for which thermodynamic data appears to be lacking, the calculated standard thermodynamic functions of reaction are in good agreement with literature values obtained both from statistical mechanical and various equilibrium methods. A multireference-configuration interaction calculation (MRCI+Q) for I provides a D(e) value that is consistent with previous calculations. The combined uncertainties of the NIST/JANAF values for Delta(r)H(o), Delta(r)G(o), and Delta(r)S(o) of II, III, and IV are discussed. The potential surface for the dissociation of N(2)O(4) was explored using multireference methods. No evidence of a barrier to dissociation was found.     

A spectroscopic study of the equilibrium NO2 + NO3 + M 2 N2O5 + M and the kinetics of the O3/N2O5/NO3/NO2/ air system

The equilibrium constant, K_eq of the reaction NO₂ + NO₃ + M 2 N₂O₅ + M has been determined for a small range of temperatures around room temperature in air at 740 torr by direct spectroscopical measurements of NO₂, NO₃, and N₂O₅. At 298 K, K_eq was determined as (3.73 ± 0.61) × 10⁻¹¹ cm³ molecule⁻¹. Averaging this and 11 other independent evaluations of K_eq yields K_eq = (3.31 ± 0.82) × 10⁻¹¹ cm³ molecule⁻¹, where the uncertainty is given as one standard deviation. The kinetics of the O₃/NO₂/N₂O₅/NO₃/ air system was studied in a static chamber at room temperature and 740 torr total pressure. Evidence of a unimolecular decay reaction of NO₃, NO₃ → NO + O₂, was found and its rate coefficient was estimated as (1.6 ± 0.7) × 10⁻³ s⁻¹ at 295 ± 2 K.     

对流层大气NO3与N2O5的实地测量

大气硝基(NO₃)自由基和五氧化二氮(N₂O₅)是对流层大气化学反应的核心物种,对于理解大气氧化性、二次有机气溶胶生成、活性卤素化学和全球硫素循环等对流层大气化学研究的关键问题具有重要意义。大气NO₃自由基和N₂O反应活性高、大气寿命短、浓度低,其定量分析非常具有挑战性。本文总结了大气NO₃自由基与N₂O₅的实地测量方法,并对差分光学吸收光谱(DOAS)、腔衰荡光谱(CRDS)、腔增强光谱(CEAS)、激光诱导荧光光谱(LIF)、电子顺磁共振谱(MIESR)和化学离子化质谱(CIMS)等六类技术方法的准确度、精确度、时间分辨率、测量干扰、标定方法和系统稳定性等方面进行了系统比较。综合分析认为吸收光谱法是对流层NO₃自由基与N₂O₅测量技术的发展方向,其中近期发展起来的腔技术(CRDS和CEAS)显示出较好的应用潜力。但是我国实际大气环境中普遍存在高浓度的颗粒物污染,如何在高颗粒物条件下实现NO₃自由基与N₂O₅的精密准确测量具有挑战性。本文进一步归纳了NO₃自由基与N₂O₅在城市、森林、自由大气和海洋海岸等典型大气环境条件下的浓度水平和主要科学发现,探讨了一些亟待解决的问题和可能的重点研究方向。     

Heterogeneous oxidation kinetics of organic biomass burning aerosol surrogates by O3, NO2, N2O5, and NO3

The reactive uptake coefficients (γ) of O(3), NO(2), N(2)O(5), and NO(3) by levoglucosan, abietic acid, nitroguaiacol, and an atmospherically relevant mixture of those species serving as surrogates for biomass burning aerosol have been determined employing a chemical ionization mass spectrometer coupled to a rotating-wall flow-tube reactor. γ of O(3), NO(2), N(2)O(5), and NO(3) in the presence of O(2) are in the range of 1-8 × 10(-5), <10(-6)-5 × 10(-5), 4-6 × 10(-5), and 1-26 × 10(-3), respectively, for the investigated organic substrates. Within experimental uncertainties the uptake of NO(3) was not sensitive to relative humidity levels of 30 and 60%. NO(3) uptake experiments involving substrates of levoglucosan, abietic acid, and the mixture exhibit an initial strong uptake of NO(3) followed by NO(3) gas-phase recovery as a function of NO(3) exposure. In contrast, the uptake of NO(3) by nitroguaiacol continuously proceeds at the same efficiency for investigated NO(3) exposures. The derived oxidative power, i.e. the product of γ and atmospheric oxidant concentration, for applied oxidants is similar or significantly larger in magnitude than for OH, emphasizing the potential importance of these oxidants for particle oxidation. Estimated atmospheric lifetimes for the topmost organic layer with respect to O(3), NO(2), N(2)O(5), and NO(3) oxidation for typical polluted conditions range between 1-112 min, indicating the potential for significant chemical transformation during atmospheric transport. The contact angles determined prior to, and after heterogeneous oxidation by NO(3), representative of 50 ppt for 1 day, do not decrease and thus do not indicate a significant increase in hygroscopicity with potential impacts on water uptake and cloud formation processes.     

Heterogeneous chemistry of the NO3 free radical and N2O5 on decane flame soot at ambient temperature: reaction products and kinetics

The interaction of NO3 free radical and N2O5 with laboratory flame soot was investigated in a Knudsen flow reactor at T = 298 K equipped with beam-sampling mass spectrometry and in situ REMPI detection of NO2 and NO. Decane (C10H22) has been used as a fuel in a co-flow device for the generation of gray and black soot from a rich and a lean diffusion flame, respectively. The gas-phase reaction products of NO3 reacting with gray soot were NO, N2O5, HONO, and HNO3 with HONO being absent on black soot. The major loss of NO3 is adsorption on gray and black soot at yields of 65 and 59%, respectively, and the main gas-phase reaction product is N2O5 owing to heterogeneous recombination of NO3 with NO2 and NO according to NO3 + {C} --> NO + products. HONO was quantitatively accounted for by the interaction of NO2 with gray soot in agreement with previous work. Product N2O5 was generated through heterogeneous recombination of NO3 with excess NO2, and the small quantity of HNO3 was explained by heterogeneous hydrolysis of N2O5. The reaction products of N2O5 on both types of soot were equimolar amounts of NO and NO2, which suggest the reaction N2O5 + {C} --> N2O3(ads) + products with N2O3(ads) decomposing into NO + NO2. The initial and steady-state uptake coefficients gamma 0 and gamma ss of both NO3 and N2O5 based on the geometric surface area continuously increase with decreasing concentration at a concentration threshold for both types of soot. gamma ss of NO3 extrapolated to [NO3] --> 0 is independent of the type of soot and is 0.33 +/- 0.06 whereas gamma ss for [N2O5] --> 0 is (2.7 +/- 1.0) x 10(-2) and (5.2 +/- 0.2) x 10(-2) for gray and black soot, respectively. Above the concentration threshold of both NO3 and N2O5, gamma ss is independent of concentration with gamma ss(NO3) = 5.0 x 10(-2) and gamma ss(N2O5) = 5.0 x 10(-3). The inverse concentration dependence of gamma below the concentration threshold reveals a complex reaction mechanism for both NO3 and N2O5. The atmospheric significance of these results is briefly discussed.     

The reactions of isotopically labeled N15NO+ with CO,NO, O2, N2, NO2, and N2O

The reactions of labeled N¹⁵NO⁺ with CO, NO, O₂, ¹⁸O₂, N₂, NO₂, and N₂O have been investigated using a tandem ICR instrument. In each case the total rate coefficient, product distribution, and kinetic energy dependence were measured. The results indicate that very specific reaction mechanisms govern these reactions. This conclusion is suggested by the lack of isotopic scrambling in many cases and by the complete absence of energetically allowed products in almost all of the systems. The kinetic energy studies indicate that most of the reaction channels proceed through an intermediate complex at low energies and via a direct mechanism at higher kinetic energies. Such direct mechanisms include long range charge transfer and atom or ion transfer.     

Ionization gauge sensitivities of N2, O2, N2O,NO, NO2, NH3, CClF3 and CH3OH

A Bayard-Alpert (BA) gauge was used to determine apparent relative sensitivites S_rel,X for O₂, N₂O, NO, NO₂, NH₃, CClF₃ and CH₃OH from gauge calibration measurements in the range 1.3×10^?1 Pa≤p≤1.3·10^?3Pa. Nitrogen was used as a calibration standard.     

Reactive uptake of NO3, N2O5, NO2, HNO3, and O3 on three types of polycyclic aromatic hydrocarbon surfaces

We investigated the reactive uptake of NO3, N2O5, NO2, HNO3, and O3 on three types of solid polycyclic aromatic hydrocarbons (PAHs) using a coated wall flow tube reactor coupled to a chemical ionization mass spectrometer. The PAH surfaces studied were the 4-ring systems pyrene, benz[a]anthracene, and fluoranthene. Reaction of NO3 radicals with all three PAHs was observed to be very fast with the reactive uptake coefficient, gamma, ranging from 0.059 (+0.11/-0.049) for benz[a]anthracene at 273 K to 0.79 (+0.21/-0.67) for pyrene at room temperature. In contrast to the NO3 reactions, reactions of the different PAHs with the other gas-phase species (N2O5, NO2, HNO3, and O3) were at or below the detection limit (gamma 相似文献   

NO 和 NO2 在 V2O5/AC 催化剂表面的反应行为

 采用程序升温脱附、在线质谱和原位漫反射红外光谱等手段, 比较了 NO 和 NO2 在 V2O5 及 V2O5/AC 催化剂表面的选择催化还原 (SCR) 反应行为. 结果表明, 氨以质子态 NH4+和共价态 NH3 分子两种形态吸附于纯 V2O5 表面, V=O 为氨的主要吸附活性位. 无氧状态下, NO 和 NO2 皆可与吸附于 V2O5 表面的 NH3 反应, 并且 NO2 与吸附态 NH3 的反应活性高于 NO. 但在 V2O5/AC 催化剂表面, 同样在无氧条件下, NO 几乎不与吸附态 NH3 反应, 而 NO2 却可以反应并生成 N2. 在 V2O5/AC 表面, NO 很容易被气相 O2 氧化为 NO2, 然后参与 SCR 反应. 可见, NO2 是 NO 在 V2O5/AC 表面发生 SCR 反应的中间体.     

A study of the reaction NO3 + NO2 + M → N2O5 + M(M = N2, O2)

The gas-phase reaction of the NO₃ radical with NO₂ was investigated, using a flash photolysis-visible absorption technique, over the total pressure range 25–400 Torr of nitrogen or oxygen diluent at 298 ± 2 K. The absolute rate constants determined (in units of 10^?13 cm³ molecule^?1 s^?1) at 25, 100, and 400 Torr total pressure were, respectively, (4.0 ± 0.5), (7.0 ± 0.7), and (10 ± 2) for M = N₂ and (4.5 ± 0.5), (8.0 ± 0.4), and (8.8 ± 2.0) for M = O₂. These data show that the third-body efficiencies of N₂ and O₂ are identical, within the error limits, and that previous evaluations for M = N₂ are applicable to the atmosphere. In addition, upper limits were determined for the rate constants of the reactions of the NO₃ radical with methanol, ethanol, and propan-2-ol of ?6 × 10^?16, ?9 × 10^?16, and ?2.3 × 10^?15 cm³ molecule^?1 s^?1, respectively, at 298 ± 2 K.     

Two scandium–biuret complexes: [Sc(C2H5N3O2)(H2O)5]Cl3·H2O and [Sc(C2H5N3O2)4](NO3)3

The scandium(III) cations in the structures of pentaaqua(biuret‐κ²O,O′)scandium(III) trichloride monohydrate, [Sc(C₂H₅N₃O₂)(H₂O)₅]Cl₃·H₂O, (I), and tetrakis(biuret‐κ²O,O′)scandium(III) trinitrate, [Sc(C₂H₅N₃O₂)₄](NO₃)₃, (II), are found to adopt very different coordinations with the same biuret ligand. The roles of hydrogen bonding and the counter‐ion in the establishment of the structures are described. In (I), the Sc³⁺ cation adopts a fairly regular pentagonal bipyramidal coordination geometry arising from one O,O′‐bidentate biuret molecule and five water molecules. A dense network of N—H...Cl, O—H...O and O—H...Cl hydrogen bonds help to establish the packing, resulting in dimeric associations of two cations and two water molecules. In (II), the Sc³⁺ cation (site symmetry 2) adopts a slightly squashed square‐antiprismatic geometry arising from four O,O′‐bidentate biuret molecules. A network of N—H...O hydrogen bonds help to establish the packing, which features [010] chains of cations. One of the nitrate ions is disordered about an inversion centre. Both structures form three‐dimensional hydrogen‐bond networks.     

Atmospheric chemistry of acetone: Kinetic study of the CH3C(O)CH2O2+NO/NO2 reactions and decomposition of CH3C(O)CH2O2NO2

Pulse radiolysis was used to study the kinetics of the reactions of CH₃C(O)CH₂O₂ radicals with NO and NO₂ at 295 K. By monitoring the rate of formation and decay of NO₂ using its absorption at 400 and 450 nm the rate constants k(CH₃C(O)CH₂O₂+NO)=(8±2)×10⁻¹² and k(CH₃C(O)CH₂O₂+NO₂)=(6.4±0.6)×10⁻¹² cm³ molecule⁻¹ s⁻¹ were determined. Long path length Fourier transform infrared spectrometers were used to investigate the IR spectrum and thermal stability of the peroxynitrate, CH₃C(O)CH₂O₂NO₂. A value of k₋₆≈3 s⁻¹ was determined for the rate of thermal decomposition of CH₃C(O)CH₂O₂NO₂ in 700 torr total pressure of O₂ diluent at 295 K. When combined with lower temperature studies (250–275 K) a decomposition rate of k₋₆=1.9×10¹⁶ exp (−10830/T) s⁻¹ is determined. Density functional theory was used to calculate the IR spectrum of CH₃C(O)CH₂O₂NO₂. Finally, the rate constants for reactions of the CH₃C(O)CH₂ radical with NO and NO₂ were determined to be k(CH₃C(O)CH₂+NO)=(2.6±0.3)×10⁻¹¹ and k(CH₃C(O)CH₂+NO₂)=(1.6±0.4)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹. The results are discussed in the context of the atmospheric chemistry of acetone and the long range atmospheric transport of NO_x. © John Wiley & Sons, Inc. Int J Chem Kinet: 30: 475–489, 1998     

Toward synthetic tubes for NO2/N2O4: design, synthesis, and host-guest chemistry

Design of molecular nanotubes is proposed for entrapment and conversion of NO2/N2O4 gases. Synthesis of 1,3-alternate bis-calix[4]arene tube 3 of 5 x 11 A internal dimensions is presented, and its reversible reactions with NO2/N2O4 in solution are studied. Exposure of 3 to NO2/N2O4 in chlorinated solvents results in the rapid encapsulation of nitrosonium (NO+) cations within its interior. Mono- and dinitrosonium complexes 4 and 5, respectively, were isolated and characterized by UV-vis, FTIR, and 1H NMR spectroscopies, and also molecular modeling. The NO+ entrapment process is reversible, and addition of water quickly recovered starting tube 3. Encapsulated within the tube NO+ species act as nitrosating agents for secondary amides. These findings open wider perspectives toward NO2/NOx storing and converting materials and also offer a promise for further development of supramolecular chemistry of synthetic nanotubes.     

(C26H40N2O4)[Ln(NO3)5H2O]的合成及其铕缔合物的晶体结构

合成了4个新型的稀土化合物(C₂₆H₄₀N₂O₄)[Ln(NO₃)₅H₂O](Ln=Pr,Nd,Sm,Eu),采用元素分析和红外光谱表征,用四圆衍射仪测定了其中(C₂₆H₄₀N₂O₄)[Eu(NO₃)₅H₂O]的晶体结构,属三斜晶系,P1空间群,晶胞参数:α=0.9100(4)nm,b=1.3560(3)nm,c=1.6463(4)nm;α=68.62(2)°,β=74.84(3)°,γ=87.50(2)°;Z=2.中心铕离子由5个硝酸根的10个氧原子和1个水分子中的氧原子配位,配位数是11.1,7,10,16-四氧-4,13-二氮杂-N,N'-二苄基环十八烷(N,N'-二苄基穴醚(2,2))未参与配位.     

Reactions of NO3-naphthalene adducts with O2 and NO2

The kinetics of the gas-phase reaction of the NO₃ radical with naphthalene have been investigated at 150 torr O₂ + 590 torr N₂ and 600 torr O₂ + 140 torr N₂ at 298 ± 2 K. Relative rate measurements were carried out in reacting NO₃? N₂O₅-naphthalene-propene-O₂? N₂ mixtures by longpath Fourier transform infrared absorption spectroscopy. A rate constant ratio for the reactions of O₂ and NO₂ with the NO₃-naphthalene adduct of k/k < 4 × 10^?7 was obtained from the competition between O₂ and NO₂ for reaction with the NO₃-naphthalene adduct and thermal decomposition of the adduct back to reactants. Atmospheric pressure ionization MS/MS measurements of the nitronaphthalene products of the NO₃ radical-initiated reaction of naphthalene are consistent with the proposed reaction mechanism, and the atmospheric implications of the data are discussed. © 1994 John Wiley & Sons, Inc.     

Raman spectra of complexes of HNO3 and NO3- with NO2 at surfaces and with N2O4 in solution

Raman spectra of HNO(3).NO(2) have been detected on liquid and solid surfaces in the presence of concentrated HNO(3) and NO(2) gas. The Raman spectrum of HNO(3) solutions containing N(2)O(4) has been partly reinterpreted in terms of contributions from HNO(3).N(2)O(4) and N(2)O(4).NO(3)(-) complexes.     

Analysis of the unimolecular reaction N2O5 + M ⇌ NO2 + NO3 + M

Recent experimental results on the thermal decomposition of N₂O₅ in N₂ are evaluated in terms of unimolecular rate theory. A theoretically consistent set of fall-off curves is constructed which allows to identify experimental errors or misinterpretations. Limiting rate constants k₀ = [N₂] 2.2 × 10^?3 (T/300)^?4.4 exp(?11,080/T) cm³/molec·s over the range of 220–300 K, k_∞ = 9.7 × 10¹⁴ (T/300)^+0.1 exp(?11,080/T) s^?1 over the range of 220–300 K, and broadening factors of the fall-off curve F_cent = exp(-T/250) + exp(?1050/T) over the range of 220–520 K have been derived. NO₂ + NO₃ recombination rate constants over the range of 200–300 K are k_rec,0 = [N₂] 3.7 × 10^?30 (T/300)^?4.1 cm⁶/molec²·s and k_rec,∞ = 1.6 × 10^?12 (T/300)^+0.2 cm³/molec·s.     

Removal of NO in NO/N2, NO/N2/O2, NO/CH4/N2, and NO/CH4/O2/N2 systems by flowing microwave discharges

In this paper, continuing previous work, we report on experiments carried out to investigate the removal of NO from simulated flue gas in nonthermal plasmas. The plasma-induced decomposition of small concentrations of NO in N2 used as the carrier gas and O2 and CH4 as minority components has been studied in a surface wave discharge induced with a surfatron launcher. The reaction products and efficiency have been monitored by mass spectrometry as a function of the composition of the mixture. NO is effectively decomposed into N2 and O2 even in the presence of O2, provided always that enough CH4 is also present in the mixture. Other majority products of the plasma reactions under these conditions are NH3, CO, and H2. In the absence of O2, decomposition of NO also occurs, although in that case HCN accompanies the other reaction products as a majority component. The plasma for the different reaction mixtures has been characterized by optical emission spectroscopy. Intermediate excited species of NO*, C*, CN*, NH*, and CH* have been monitored depending on the gas mixture. The type of species detected and their evolution with the gas composition are in agreement with the reaction products detected in each case. The observations by mass spectrometry and optical emission spectroscopy are in agreement with the kinetic reaction models available in literature for simple plasma reactions in simple reaction mixtures.