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1.
The second-order rate constants of gas-phase Lu( 2D 3/2) with O 2, N 2O and CO 2 from 348 to 573 K are reported. In all cases, the reactions are relatively fast with small barriers. The disappearance rates are independent of total pressure indicating bimolecular abstraction processes. The bimolecular rate constants (in molecule −1 cm 3 s −1) are described in Arrhenius form by k(O 2)=(2.3±0.4)×10 −10exp(−3.1±0.7 kJmol −1/ RT), k(N 2O)=(2.2±0.4)×10 −10exp(−7.1±0.8 kJmol −1/ RT), k(CO 2)=(2.0±0.6)×10 −10exp(−7.6±1.3 kJmol −1/ RT), where the uncertainties are ±2σ. 相似文献
2.
Medium-resolution spectra of the N 2 b 1Π u-X 1Σ g+ band system were recorded by 1 + 1 multiphoton ionization. In the spectra we found different linewidths for transitions to different vibrational levels in the b 1Π u state: Δν 0 = 0.50 ± 0.05 cm −1, Δν 1 = 0.28 ± 0.02 cm −1, Δν 2 = 0.65 ± 0.06 cm −1, Δν 3 = 3.2 ± 0.5 cm −1, Δν 4 = 0.60 ± 0.07 cm −1, and Δν 5 = 0.28 ± 0.02 cm −1. From these linewidths, predissociation lifetimes τ ν were obtained: τ 0 = 16 ± 3 ps, τ 1 > 150 ps, τ 2 = 10 ± 2 ps, τ 3 = 1.6 ± 0.3 ps, τ 4 = 9 ± 2 ps, and τ 5 > 150 ps. Band origins and rotational constants for the b 1Π uν = 0 and 1 levels were determined for the 14N 2 and 14N 15N molecules. 相似文献
3.
The reaction: F + HCl→ HF ( v 3) + Cl (1), has been initiated by photolysing F 2 using the fourth-harmonic output at 266 nm from a repetitively pulsed Nd: YAG laser By analysing the time-dependence of the HF(3,0) vibrational chemiluminescence, rate constants have been determined at (296 ± 5) K for reaction (1), k1 = (7.0 ± 0.5) × 10 −12 cm 3 molecule −1 s −1, and for the relaxation of HF( v = 3) by HCl, CO 2, N 2O, CO, N 2 and O 2: kHCl = (1.18 ±0.14) × 10 −11 kCO2 = (1.04 ± 0. 13) × 10 −12, kN2O = (1.41 ± 0.13) × 10 −11 kCO = (2.9 ± 0.3) × (10 −12, kN2 = (7.1 ± 0.6) × 10 −14 and kO2 = (1.9 ± 0.6) × 10 −14 cm 3molecule −1s −1. 相似文献
4.
Rotational-state distributions of the CO + (A–X, B–X) and N 2+(B–X) emissions produced by the collisions of He(2 3S) with CO and N 2 were studied in the collision energy ( ER range 100–200 meV. The rotational populations of the emitting states can be fitte by single Boltzmann temperatures ( TR. The TR (320 ± 30 K) for the ν′ = 3 and 4 levels of the CO + (A 2Π) state are nearly independent of, or slightly increase with, ER, while TR for the CO +(B 2Σ +, ν′ = 0) state increases rapidly with ER.The TR (430 ± 20 K) for the N 2+(B 2Σ +, ν′ = 0) state is nearly independent or slightly decreases with increasing ER. Interactions providing these trends are discussed. 相似文献
5.
The state-selected reaction of CH(X 2Πν″ = 0, 1) with H 2 has been studied, in which CH was generated by IRMPD of a precursor gas, CH 3OH. The subsequent evolution of CH (ν″ = 0, 1) was monitored by the sensitive LIF technique. For the ground state and vibrationally excited state CH, the reaction with H 2 is found to depend on the total pressure in the sample cell at room temperature, which suggests that the reaction proceeds through an intermediate adduct, CH 3. The backward dissociation process is found to depend on the buffer pressure, which can be rationalized via a collision-induced backward dissociation. The decay rates of CH (ν″ = 0, 1) due to collisions with H 2 and Ar at a buffer pressure of 10 Torr are kH2 (ν″ = 1) = (2.3±0.1) × 10 −1 cm 3 molecule −1 s −1 and kAr (ν″ = 1) = (4.4±0.1) × 10 −13 cm 3 molecule −1 s −1. Possible effects of the vibrational excitation on the reaction rate of CH (ν″ = 1) are discussed. 相似文献
6.
Gaseous nitryl azide N 4O 2 is generated by the heterogeneous reaction of gaseous ClNO 2 with freshly prepared AgN 3 at −50 °C. The geometric and electronic structure of the molecule in the gas phase has been characterized by in situ photoelectron spectroscopy (PES) and quantum chemical calculations. The experimental first vertical ionization energy of N 4O 2 is 11.39 eV, corresponding to the ionization of an electron on the highest occupied molecular orbital (HOMO) {4a″(π nb(N4–N5–N6))} −1. An apparent vibrational spacing of 1600 ± 60 cm −1 (ν asO1N2O3) on the second band at 12.52 eV (π nb(O1–N2–O3)) further confirms the preference of energetically stable chain structure in the gas phase. To complement the experimental results, the potential-energy surface of this structurally novel transient molecule is discussed. Both calculations and spectroscopic results suggest that the molecule adopts a trans-planar chain structure, and a five-membered ring decomposition pathway is more favorable. 相似文献
7.
NH 2 profiles were measured in a discharge flow reactor at ambient temperature by monitoring reactants and products with an electron impact mass spectrometer. At the low pressures used (0.7 and 1.0 mbar) the gas-phase self-reaction is dominated by a ‘bimolecular’ H 2-eliminating exit channel with a rate coefficient of k3b(300 K) = (1.3 ± 0.5) × 10 −12 cm 3 molecule −1 s −1 and leading to N 2H 2 + H 2 or NNH 2 + H 2. Although the wall loss for NH 2 radicals is relatively small ( kw ≈ 6–14 s −1), the contribution to the overall NH 2 decay is important due to the relatively slow gas-phase reaction. The heterogeneous reaction yields N 2H 4 molecules. 相似文献
8.
A high-resolution emission spectrum of a low-pressure Ar-diluted CO + N 2O → CO 2 + N 2 flame catalyzed by Na metal vapor has been obtained and examined for vibrational disequilibrium. Emission in the 1900-2400 cm −1 spectral region, which includes the fundamental and “hot” bands of CO, CO 2(ν 3), and N 2O(ν 3), was recorded with high resolution and the CO emission was analyzed in detail to determine vibrational and rotational temperatures which were found to be unequal, Tv = 2050°K and TR = 1100°K. An examination of vib-vib and vib-trans energy transfer mechanisms results in the conclusion that an excess of 14% of the chemical energy is preferentially deposited in the resonantly-coupled N 2, CO, CO 2 (ν 3), and N 2O(ν 3) vibrational modes. It is further observed that CO vibrational levels for ν > 4 are excessively populated, presumably due to quenching of Na*(3p) by CO; the flame is accompanied by intense Na D-line chemiluminescence. 相似文献
9.
FTIR spectra of the four isotopically substituted 1:1 complexes of acetonitrile and boron trifluoride were recorded in Ar, N 2 and Xe matrices. In Ar, previously unreported three vibrational modes of the complex were clearly observed. Several significant vibrational bands were also observed in N 2 and Xe. The observed frequency shifts on complexation, Δ ν, were qualitatively in good agreement with the computational results, which were calculated at the B3LYP/6-311++G(d,p) level using the optimized geometry of the C3v eclipsed conformation. The observed magnitudes of Δ ν for most of the complex bands were larger than the calculated values. The BF 3 symmetric deformation mode is an exception. The observed frequency shits for this mode were smaller than the calculated values, especially in N 2. This suggests that even an inert matrix can significantly affect the vibrational spectrum of the complex. 相似文献
10.
The electric field gradients (EFG’s) at the nucleus are calculated as a function of internuclear separation in the X 2Σ g+ and B 2Σ u+ electronic states of the nitrogen molecule cation using the internally contracted multireference configuration interaction (icMRCI) method. The EFG’s and potential energy functions (PEF’s) are used to estimate the 14N nuclear quadrupole coupling constants (NQCC’s) in the two electronic states as functions of vibrational and end-over-end rotational quantum numbers. The dependences of the computed constants on the basis set and reference configuration space are investigated. Since no counterpart for comparison of the calculated NQCC’s exists, the N 2+ results are supported by analogous calculations on the X 1Σ g+ and A 3Σ u+ states of N 2, for which established data are available. The overall good quality of the icMRCI wave functions is further corroborated by a favorable agreement of spectroscopic constants derived from the corresponding PEF’s and experimental data. Variations of the EFG with internuclear separation are explained in terms of wave function composition, and used for gaining specific insight into the chemical bonding in N 2+ and N 2. 相似文献
11.
Thionitrosyl hexafluoroarsenate, [NS][AsF 6], reacted with caesium azide, [Cs][N 3], to form S 2N 2 which polymerized to give (SN) x. The structures of the following likely intermediate species were calculated at correlated MP2/6–31G(d,p) level of theory (relative energies in kcal mol −1): thionitrosyl azide, N 3---N=S (37.8), thiazyl azide, N 3---SN (39.2) and cyclic N 4S (0.0). ‡ 相似文献
12.
Absorption and fluorescent scattering of nitrogen laser radiation by a low-pressure RF laboratory plasma ( ne = 10 12 cm −3) has been observed for the first negative system of N 2+. A 67±1 ns lifetime of N 2+ (B 2Σ u+) was experimentally measured from the laser-induced fluorescence. In addition, enough collisionally excited N 2 (B 3Π g) was produced to observe laser-induced fluorescence for the second positive system of N 2. The lifetime of N 2 (C 3Π u) was found to be 41±2 ns. The measured lifetimes are in good agreement with published values calculated from theory. 相似文献
13.
This survey begins with the photochemistry at 254 nm and 298 K in the system H 2O 2COO 2RH, the primary objective of which is to determine the rate constants for the reaction OH + RH → H 2O + R relative to the well-known rate constant for the reaction OH + CO → CO 2 + H. Inherent in the scheme is that the reaction HO 2+CO→OH+CO 2 is negligible compared with the OH reaction, and a literature consensus gives kHO2 < 10 −19 cm 3 molecule −1 s −1, or some 10 6 less than kOH at 298 K. Theoretical calculations establish that the first stage in the HO 2 reaction is the formation of a free radical intermediate HO 2 + CO → HOOCO (perhydroxooxomethyl) which decomposes to yield the products, and that the rate of formation of the intermediate is equal to the rate of formation of the products. The structure of the intermediate and a reaction profile are shown. High temperature rate data reported subsequent to the data in the consensus and theoretical calculations lead here to a recommendation that, in the range 250–800 K, kHO2 = 3.45 × 10−12T1/2 exp(1.15 × 104/T) cm3 molecule−1 s−1, the hard-sphere-collision Arrhenius modification. This yields kHO2(298) = 1.0 × 10−27 cm3 molecule−1 s−1 or some 1014 slower than kOH(298). 相似文献
14.
The temperature dependence of the rate constants, for the reactions of hydrated electrons with H atoms, OH radicals and H 2O 2 has been determined. The reaction with H atoms, studied in the temperature range 20–250°C gives k(20°C) = 2.4 × 10 10M -1s 1 and the activation energy EA = 14.0 kJ mol -1 (3.3 kcal mol -1). For reaction with OH radicals the corresponding values are, k(20° C) = 3.1 × 10 10M -1s -1 and EA = 14.7 kJ mol -1 (3.5 kcal mol -1) determined in the temperature range 5–175°C. For reaction with H 2O 2 the values are, k(20° C) = 1.2 × 10 10M -1s -1 and EA = 15.6 kJ mol -1 (3.7 kcal mol -1) measured from 5–150°C. Thus, the activation energy for all three fast reactions is close to that expected for diffusion controlled reactions. As phosphates were used as buffer system, the rate constant and activation energy for the reaction of hydrated electron with H 2PO 4- was determined to k(20° C) = 1.5 × 10 7M -1s -1 and EA = 7.4 kJ mol -1 (1.8 kcal mol -1) in the temperature range 20–200°C. 相似文献
15.
Complexes with the formula CuX(L) (X=N 3 1, NCO 2 and NCS 3) and [Cu(NO 3)(HL)(H 2O)](NO 3) 4, where HL=C 7H 8N 4S, (pyridine-2-carbaldehyde thiosemicarbazone), have been characterised. Single-crystal X-ray diffraction studies on compounds 3 and 4 have been carried out. The structure of compound 4 consists of monomeric distorted square pyramidal copper(II) species. The copper(II) ions are coordinated to the NNS atoms from the tridentate thiosemicarbazone ligand and one oxygen atom of a nitrate group in the equatorial position. The oxygen atom of the water molecule occupies the apical position. The structure of compound 3 consists of non-centrosymmetric {Cu 2(μ-SR) 2} entities in which the copper(II) ions exhibit five-coordinate square–pyramidal geometry. The thiosemicarbazone ligand and one nitrogen atom from the thiocyanate ion are in a basal position. The sulfur atom of the tridentate ligand acts as a bridge occupying the apical position. Structural and spectroscopic results suggest the presence of relevant σ ligand-to-metal charge transfer and metal-to-ligand π-backdonation character in these compounds. The ESR spectra of compounds 3 and 4 show rhombic symmetry. For complexes 1 and 2 the ESR spectra exhibit axial signals. Magnetic measurements on compounds 1, 2 and 3 show antiferromagnetic couplings. The susceptibility data were fitted by the Bleaney–Bowers’ equation for copper(II) dimers. The obtained J/ k values are −4.22, −6.10 and −7.33 K for compounds 1, 2 and 3, respectively. 相似文献
16.
Complexed diimine in μ-N 2H 2[Cr(CO) 5] 2 undergoes a rapid H — D-exchange with deuterium ions, which is inhibited completely by acids; the rate of the H — D exchange is significantly larger for the diimine complex that for the corresponding hydrazine and ammonia complexes, which is explained by the acidic properties of the diimine protons. In the presence of catalytic amounts of strong base N 2H 2[Cr(CO) 5] 2 disproportionates fast and irreversibly to N 2[Cr(CO) 5] 2 and N 2H 4[Cr(CO) 5] 2; a mechanism is proposed for this reaction. The reactions of the complexed diimine are compared to those of the free diimine; their significance with respect to intermediated steps of the enzymatic N 2 fixation is discussed. 相似文献
17.
Determination of the ionic dissociation constants of nitrosyl chloride and dinitrogen tetroxide in sulpholane.A silver chloride—silver electrode is used to study electrochemical systems involving nitrosyl chloride and dinitrogen tetroxide in sulpholane: Ag↓ + NOCl AgCl↓ + NO+ + e- and Ag↓ + NOCl + NO-3 AgCl↓ + N2O4 + e- The dissociation constants of these two NO+ donors determined in this way are: K(NOCl) = 10-11.8 mol l-1 and K(N2O4) = 10-7.2 mol l-1. A titration of N2O4 solutions alone or in the presence of nitric acid is described. This titration is possible in mixtures which contain up to 90% (w/w) nitric acid. 相似文献
18.
The spectrum of CD 2HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm −1 fwhm) between 800 and 1200 cm −1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν 9: 912.2028 cm −1, ν 6:964.4994 cm −1, ν 5: 1050.5104 cm −1, ν 4: 1093.8632 cm −1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν 9 and ν 6 (ξ a= 1.069 cm −1, ξ c= −0.3535 cm −1) and between ν 5 and ν 4 (ξ b= −0.80606 cm −1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level. 相似文献
19.
A mixture of NF 3 and Ar is passed through an rf discharge in a flow-system to produce, among other species, F and NF 2. When H 2, D 2, or CH 4 are added downstream, reactions with F atoms produce vibrationally excited HF or DF together with H, D, or CH 3. The latter free radicals can react with NF 2, probably by an elimination reaction to produce electronically excited NF: NF 2( 2B 1) + H(D, CH 3) → HF *(DF * + NF(a 1Δ). A vibrational-to-electronic energy transfer process between the products of this reaction then produces the next higher state of NF: HF(ν 2) + NF(a 1Δ) → HF(ν−2) + NF(b 1Σ +). A similar transfer process has also been found between the electronically excited a 1Δ states of O 2 and NF: O 2(a 1Δ) + NF(a 1Δ) → O 2(X 3Σ −) + NF(b 1Σ +). The H or D atoms but not the CH 3 radicals are then found to react with either NF(a 1Δ) or NF(X 3Σ −) to produce electronically excited N( 2D) atoms, which in turn react with the NF(a 1Δ) molecules to produce N 2(B 3Π g). The observed nitrogen first positive radiation has been demonstrated to be produced entirely by this reaction mechanism rather than by the N( 4S) recombination that accounts for the Rayleigh afterglow. In addition, the occurrence of the reaction N( 2D) + N 2O → NO(B 2Π r) + N 2 (X 1Σ +g) has been verified. Finally we have observed emission at 3344 Å, which we attribute to the NF(A 3Π), which has not been previously reported. 相似文献
20.
This Letter reports the first kinetic study of 2-butoxy radicals to employ direct monitoring of the radical. The reactions of 2-butoxy with O 2 and NO are investigated using laser-induced fluorescence (LIF). The Arrhenius expressions for the reactions of 2-butoxy with NO ( k1) and O 2 ( k2) in the temperature range 223–311 K have been determined to be k1=(7.50±1.69)×10 −12×exp((2.98±0.47) kJmol −1/RT) cm 3 molecule −1 s −1 and k2=(1.33±0.43)×10 −15×exp((5.48±0.69) kJmol −1/RT) cm 3 molecule −1 s −1. No pressure dependence was found for the rate constants of the reaction of 2-butoxy with NO at 223 K between 50 and 175 Torr. 相似文献
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