13774-92-0Relevant articles and documents
Absolute rate constants for the reactions of CH with O and N atoms
Messing, I.,Filseth, S. V.,Sadowski, C. M.,Carrington, Tucker
, p. 3874 - 3881 (1981)
CH(X 2Π) was produced by multiple infrared photon dissociation of CH3OH in the presence of excess atomic oxygen or nitrogen.Time-resolved measurements of relative CH concentrations were made at 298 K with a tunable dye laser.Rate constants deduced from the dependence of CH decay rate on atom concentration are (9.5 +/- 1.4) * 10-11 cm3 s-1 for CH + O and (2.1 +/- .5) * 10-11 cm3 s-1 for CH + N.
Ionization potential of the NH free radical by mass spectrometry: Production of ground state and electronically excited NH by F-atom reactions
Foner, S. N.,Hudson, R. L.
, p. 5017 - 5021 (1981)
Sequential F-atom reactions with ammonia were used to produce NH radicals in the X 3Σ- ground state and the a 1Δ excited state.Ionizaton potential measurements on both of these species lead to the determination I(NH) = 13.47 +/- 0.05 eV, indicating that the error limits in at least one the previous studies was seriously understimated.The F-atom reactions also produced ground and electronically excited N atoms.Efforts to obtain an independent measurement of the heat of formation of NH using dissociative ionization of NH3 were unsuccessful, apparently because of excess energy involved in the ionization process.Some important N-N and N-H bond dissociation energies have been updated
Very Low Pressure Reactor Chemiluminescence Studies on N Atom Reactions with CHCl3 and CDCl3
Jeoung, Sae Chae,Choo, Kwang Yul,Benson, Sidney W.
, p. 7282 - 7290 (1991)
Ground-state (N(S4)) nitrogen reactions with chloroform-h and chloroform-d were studied by using the VLPR technique at room temperature.Relative N atom concentrations were monitored via mass spectrometry, and their absolute values were determined by the chemical titration reaction with nitric oxide.It was possible to obtain a more accurate rate constant for the bimolecular reaction: N + NO ---> N2 + O, kNO = (2.4 +/- 0.2) x 10-11 cm3 molecule-1 s-1 at298 K.N atom decay in the presence of CHCl3 and CDCl3 was found to have an apparent induction period and to have a large isotope effect.Chemiluminescence signals emitted from the reactor in the range 300-600 nm were also observed, and identified as coming from the excited CN radical.The detailed study of reaction products, intermediates, N atom decay kinetics, and chemiluminescence signals are interpreted by slow reaction of Cl atoms with CHCl3 followed by fast branching chain reactions of N atoms with the intermediate radicals.A successful numerical simulation of the experimental results supports the suggested chain branching mechanism.The following rate constants were estimated from the experimental results: k1(N + CHCl3 ---> NCl + CHCl2), 1.00 x 10-16, k2(N + NCl ---> N + Cl), 2.57 x 10-11, k3(Cl + CHCl3 ---> HCl + CCl3), 3.70 x 10-14, k3D(Cl + CDCl3 ---> DCl + CCl3),0.95 x 10-14, k4(N + CHCl2 ---> HCN + 2Cl), 1.98 x 10-11, k5(N + CCl3 ---> ClCN + 2Cl), 1.67 x 10-11, k6(N + ClCN ---> CCl + N2), 1.00 x 10-14, and k7(N + CCl ---> CN(B2Σu+) + Cl), 5.70 x 10-13, all in the units of cm3 molecule-1 s-1.
Quantification of the 248 nm photolysis products of HCNO (fulminic Acid)
Feng, Wenhui,Hershberger, John F.
, p. 829 - 837 (2014/03/21)
IR diode laser spectroscopy was used to detect the products of HCNO (fulminic acid) photolysis at 248 nm. Five product channels are energetically possible at this photolysis wavelength: O + HCN, H + (NCO), CN + OH, CO + NH, and HNCO. In some experiments, isotopically labeled 18O2, 15N18O and C2D6 reagents were included into the photolysis mixture in order to suppress and/or isotopically label possible secondary reactions. HCN, OC18O, C18O, NCO, DCN, and NH molecules were detected upon laser photolysis of HCNO/reagents/buffer gas mixtures. Analysis of the yields of product molecules leads to the following photolysis quantum yields: 1a (O + HCN) = 0.39 ± 0.07, 1b (H + (NCO)) = 0.21 ± 0.04, 1c (CN + OH) = 0.16 ± 0.04, 1d (CN + NH(a1Δ)) = 0.19 0.03, and 1e (HNCO) = 0.05 ± 0.02, respectively. The uncertainties include both random errors (1σ) and consideration of major sources of systematic error. In conjunction with the photolysis experiment, the H + HCNO reaction was investigated. Experimental data demonstrate that this reaction is very slow and does not contribute significantly to the secondary chemistry.
Determination of the rate constant for the NH2(X 2B1) + NH2(X2B1) recombination reaction with collision partners He, Ne, Ar, and N2at low pressures and 296 K. Part 1
Altinay, Gokhan,MacDonald, R. Glen
, p. 1353 - 1367 (2012/04/23)
The recombination rate constant for the NH2(X2B 1) + NH2(X2B1) → N 2H4(X1A1) reaction in He, Ne, Ar, and N2 was measured over the pressure range 1-20 Torr at a temperature of 296 K. The NH2 radical was produced by 193 nm laser photolysis of NH3 dilute in the third-body gas. The production of NH2 and the loss of NH3 were monitored by high-resolution continuous-wave absorption spectroscopy: NH2 on the 1221 ← 1331 rotational transition of the (0,7,0)A2A1 ← (0,0,0) X 2B1 vibronic band and NH3 on either inversion doublet of the qQ3(3) rotational transition of the ν1 fundamental. Both species were detected simultaneously following the photolysis laser pulse. The broader Doppler width of the NH 2 spectral transition allowed temporal concentration measurements to be extended up to 20 Torr before pressure broadening effects became significant. Fall-off behavior was identified and the bimolecular rate constants for each collision partner were fit to a simple Troe form defined by the parameters, k0, kinf, and Fcent. This work is the first part of a two part series in which part 2 will discuss the measurements with more efficient energy transfer collision partners CH4, C 2H6, CO2, CF4, and SF6. The pressure range was too limited to extract any new information on k inf, and kinf was taken from the theoretical calculations of Klippenstein et al. (J. Phys. Chem A 2009, 113, 10241) as kinf = 7.9 × 10-11 cm3 molecule-1 s-1 at 296 K. The individual Troe parameters were: He, k0 = 2.8 × 10-29 and Fcent = 0.47; Ne, k0 = 2.7 × 10-29 and Fcent = 0.34; Ar, k0 = 4.4 × 10-29 and Fcent = 0.41; N2, k0 = 5.7 × 10-29 and Fcent = 0.61, with units cm6 molecule-2 s-1 for k0. In the case of N 2 as the third body, it was possible to measure the recombination rate constant for the NH2 + H reaction near 20 Torr total pressure. The pure three-body recombination rate constant was (2.3 ± 0.55) × 10-30 cm6 molecule-2 s-1, where the uncertainty is the total experimental uncertainty including systematic errors at the 2σ level of confidence.
The multichannel reaction NH2+NH2 at ambient temperature and low pressures
Stothard, Nigel,Humpfer, Robert,Grotheer, Horst-Henning
, p. 474 - 480 (2008/10/08)
NH2 profiles were measured in a discharge flow reactor at ambient temperature by monitoring reactants and products with an electron impact massspectrometer. At the low pressures used (0.7 and 1.0 mbar) the gas-phase self-reaction is dominated by a 'bimolecular' H2-eliminating exit channel with a rate coefficient of k(3b)(300 K)=(1.3+/-0.5)E-12 cm**3 molecule**-1 s**-1 and leading to N2H2+H2 or NNH2+H2. Although the wall loss for NH2 radicals is relatively small (k(w)apprxeq.6-14 s**-1), the contribution to the overall NH2 decay is important due to the relatively slow gas-phase reaction. The heterogeneous reaction yields N2H4 molecules.
308 nm laser photodissociation of HN3 adsorbed on Si(111)-7×7
Bu, Y.,Lin, M. C.
, p. 118 - 128 (2008/10/08)
The photodissociation of HN3 adsorbed on Si(111)-7×7 at 308 nm was investigated using HREELS and XPS. Species such as NHx N2, and N3 were identified on the surface with comparable concentrations after the irradiation with 1×1020 photons of a 10 L HN3 dosed Si(111) surface. The N3 species showed two stretching modes at 178 and 255 meV, while that of the N2 appeared at 206 meV in HREELS. The formation of these products was also corroborated by the corresponding XPS results. Further laser irradiation caused the dissociation and partial desorption of the adsorbates with NHx left on the surface. Annealing the post-irradiated sample to 500 and 800 K resulted in the breaking of the NH bond and the desorption of the H-species, while the atomic N remained on the surface forming silicon nitride. The possibility of using HN3 for laser-induced chemical vapor deposition of Si3 N4 and group-III nitrides at low temperatures is suggested.
The Reaction of NH2 with O
Adamson, J. D.,Farhat, S. K.,Morter, C. L.,Glass, G. P.,Curl, R. F.,Phillips, L. F.
, p. 5665 - 5669 (2007/10/02)
The reaction between atomic oxygen and the amidogen radical, NH2, has been studied at 295 K by infrared kinetic spectroscopy.The NH2 radical was produced by excimer laser photolysis of NH3 at 193 nm and reacted with O atoms produced by a microwave discharge of dilute O2/He mixtures.IR transient absorptions of NH2, and of NH and OH radicals formed as reaction intermediates, were monitored using a tunable infrared colorcenter laser.The room-temperature rate constant for the overall reaction was measured as (6.5 +/- 1.3)E-11 cm3 molecule-1 s-1.The minor channel leading to NH + OH was observed but accounted for at most about 8percent of the NH2 reacting.The rate constant for the reaction NH + O was determined from fitting the NH time profile to be (6.6 +/- 1.5)E-11 cm3 molecule-1 s-1.
Photoinitiated H- and D-atom reactions with N2O in the gas phase and in N2O-HI and N2O-DI complexes
Boehmer, E.,Shin, S. K.,Chen, Y.,Wittig, C.
, p. 2536 - 2547 (2007/10/02)
Reactions of H atoms with N2O have two product channels yielding NH + NO and OH + N2.Both channels were observed via NH A3Π X3Σ and OH A2Σ X2Π laser-induced fluorescence spectra.Photoinitiated reactions with N2O-HI complexes yield a much lower / ratio than under the corresponding bulk conditions at the same photolysis wavelength.For hot D-atom reactions with N2O, this effect is somewhat more pronouced.These results can be interpreted in terms of entrance channel geometric specificity, namely, biasing hydrogen attack toward the oxygen.Another striking observation is that the OH and OD rotational level distributions (RLD) obtained under bulk conditions differ markedly from those obtained under complexed conditions, while the NH as well as the ND RLD are similar for the two environments.In addition, OH Doppler profiles change considerably in going from bulk to complexed conditions, while such an effect is not observed for NH.The changes observed with the OH RLD are most likely due to OH-halogen interactions and/or entrance channel specificity.Under bulk conditions, the Doppler shift measurements indicate a large amount of N2 internal excitation (i.e., ca. 25 000 cm-1) for the OH (Υ = 0) levels monitored.This is consistent with a reaction mechanism involving an HNNO intermediate.The hot hydrogen atom first attaches to the terminal nitrogen of N2O and forms an excited HNNO intermediate having a relatively elongated N-N bond compared with N2O.Then the H atom migrates from nitrogen to oxygen and exits to the N2 + OH product channel, leaving N2 vibrationally excited.A simple Franck-Condon model can reconcile quantitatively the large amount of N2 vibrational excitation.
Spectrokinetic Studies of the Gas Phase Reactions NH2 + NOx Initiated by Pulse Radiolysis
Pagsberg, Palle,Sztuba, Barbara,Ratajczak, Emil,Sillesen, Alfred
, p. 329 - 334 (2007/10/02)
NH2 radicals were produced by pulse radiolysis of Ar-SF6-NH3 mixtures to initiate the reaction F + NH3 -> HF + NH2.Decay rates of NH2 were studied by monitoring the transient absorption signals of NH2 at 597.6 nm in the presence of varying amounts of NO and NO2.Values of k(NH2 + NO) = (1.3 +/- 0.2) * 1010 M-1 s-1 and k(NH2 + NO2) = (1.1 +/- 0.3) * 1010 M-1 s-1 were obtained at 298 K.By monitoring the transient absorption of OH radicals at 309 nm we have determined a very low branching for the reaction channel NH2 + NO -> N2H + OH, suggesting that NH2 + NO -> N2 + H2O is the most important product channel at room temperature.The analysis of the experimental results was based on computer modelling of the observed radical yields and kinetics, taking into account various competing reactions which were shown to be important by the evaluation of branching ratios.
