On the additivity of atomic and molecular dipole properties and dispersion energies using H,N, O,H2, N2, O2, NO,N2O,NH3 and H2O as models

The zeroth-order theory of intermolecular forces is used to derive additivity relations for rotationally averaged molecular dipole properties and dispersion energy constants by assuming that a molecule is comprised of non-interacting atoms or molecules. Some of the additivity rules are new and others, for example the mixture rule for dipole oscillator strength distributions (DOSDs), Bragg's rule for stopping cross sections and Landolt's rule for molecular refractivities, are well known. The additivity rules are tested by using previously constructed DOSDs and reliable values for the dipole oscillator strength sums S_k , L_k and I_k , and dispersion energy constants C ₆, for H, N, O, H₂, N₂, O₂, NO, N₂O, NH₃ and H₂O as models. It is found that additivity is generally unreliable for estimating molecular properties corresponding to k < -2. Generally for k ≥ -2 and for C ₆, and if the hydrogen molecule is used to represent the hydrogen atom in the additivity rules, the additivity relations yield results that are reliable to within ?20 per cent and the estimates improve substantially as k increases. The effects of molecule formation on DOSDs is examined by comparing the various molecular DOSDs with the sum of the DOSDs for the atoms making up the molecules. Molecule formation results in a net decrease in the amount of dipole oscillator strength for low excitation energies and a compensating net increase for higher energies in a region extending from the absorption threshold to about 100 eV. This is shown to imply that estimates of the stopping average energy I ₀, obtained by using bona fide atomic I ₀ values, are lower bounds to the correct molecular I ₀ results.     

Dispersion energy constants C 6(A,B), dipole oscillator strength sums and refractivities for Li,N, O,H2, N2, O2, NH3, H2O,NO and N2O

Accurate values for the orientation-averaged long-range dipole-dipole dispersion energy coefficients, C ₆(A, B), have been determined for all possible pair interactions involving ground state H, Li, N, O, H₂, N₂, O₂, NH₃, H₂O, NO, and N₂O. The calculations have been carried out by employing dipole oscillator strength distributions for these species that have been constructed (except in the case of H) by using discrete oscillator strength, photo-absorption, and high energy inelastic scattering data and by requiring the distributions to reproduce the Thomas-Reiche-Kuhn sum rule and, in the case of the molecules, available accurate refractivity and dispersion measurements for the relevant dilute gases. These oscillator strength distributions were also used to evaluate the refractivity R(λ), as a function of wavelength λ in the visible and ultra-violet region below the ultra-violet absorption thresholds, and the dipole oscillator strength sums S _-2l , l = 1, 2, …, 7, for each atom and molecule. The calculated values of R(λ) provide refractivities for wavelengths, especially in the ultra-violet region, for which accurate experimental data are often not available. The accurate results for C ₆(A, B) and for various dipole oscillator strength sums are used to make self-consistent tests of the adequacy of (1) the C ₆(A, A) bounds provided by Padé approximant methods and (2) various semi-empirical formulae for C ₆(A, B). Some problems that can arise in using other procedures to evaluate the S _-2l and C ₆(A, B) are discussed briefly.     

Investigation of Absorption and Emission Spectra of Nitrogen Oxides NO,N2O,NO2, and N2O4

Russian Physics Journal - The absorption and emission spectra of NO, N2O, NO2, and N2O4 nitrogen oxides have been studied with high and intermediate spectral resolution in the range 0.25–25...     

FTIR-spectra of solid O2, N2 and CO

FTIR measurements of thin films of N₂, O₂ and CO at about 20 K contain a line due to the allowed or induced fundamental transition and a broad structure shifted to higher frequencies. This phonon sideband is explainable by coupling of lattice vibrations to the molecular fundamental vibration, and mirrors the weighted one phonon density-of-states. This IR-derived density-of-states can be compared with those from other experimental studies (neutron scattering, Raman) and from theoretical models.     

UV absorption cross section of the molecules O2, NO,N2O,CO2, H2O,and NO2

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 3, pp. 455–465, March, 1990.     

气相中2Ca＋介入N2O与CO, N2O与H2反应的计算研究

本文采用密度泛函理论DFT-UB3LYP方法, 在6-311+G(2d, p)的基组下, 计算研究了气相中Ca+离子介入N2O (1∑+)和CO (1∑+) 与N2O (1∑+) 和 H2 (1∑+g)反应的微观机理. 报道了二重态势能面上各反应物、中间体和过渡态的构型特征及能量, 并用频率分析和内禀反应坐标（IRC）方法对过渡态进行了验证. 计算结果表明,金属离子参与N2O和CO与N2O和H2的反应都分两步进行, 其中Ca+离子对反应N2O (X1∑+) + CO (1∑+)生成N2 (X1∑+g) + CO2 (1∑+g)比较Fe+, Ir+, Pt+等的金属离子有良好的催化作用, 而对反应N2O (X1∑+) + H2 (1∑+g) → N2 (1∑+g) + H2O (1A1) 催化作用不是很好,N2、CaOH+和H是该反应的主要产物,与实验观测结果相符, 并通过对金属离子亲氧性（OA）的计算, 从热力学方面进一步说明主题反应的可行性.     

Correction to: Investigation of Absorption and Emission Spectra of Nitrogen Oxides NO,N2O,NO2, and N2O4

Russian Physics Journal - To the article “Investigation of Absorption and Emission Spectra of Nitrogen Oxides NO, N2O, NO2, and N2O4,” by N. I. Moskalenko, O. R. Kluchnikov, S. N....     

气相中2Ca＋介入N2O与CO, N2O与H2反应的计算研究

本文采用密度泛函理论DFT-UB3LYP方法, 在6-311+G(2d, p)的基组下, 计算研究了气相中Ca+离子介入N2O (1∑+)和CO (1∑+) 与N2O (1∑+) 和 H2 (1∑+g)反应的微观机理. 报道了二重态势能面上各反应物、中间体和过渡态的构型特征及能量, 并用频率分析和内禀反应坐标（IRC）方法对过渡态进行了验证. 计算结果表明,金属离子参与N2O和CO与N2O和H2的反应都分两步进行, 其中Ca+离子对反应N2O (X1∑+) + CO (1∑+)生成N2 (X1∑+g) + CO2 (1∑+g)比较Fe+, Ir+, Pt+等的金属离子有良好的催化作用, 而对反应N2O (X1∑+) + H2 (1∑+g) → N2 (1∑+g) + H2O (1A1) 催化作用不是很好,N2、CaOH+和H是该反应的主要产物,与实验观测结果相符, 并通过对金属离子亲氧性（OA）的计算, 从热力学方面进一步说明主题反应的可行性.     

A quadratic configuration interaction study of N2O and N2O·−

The geometries and vibrational frequencies of both N₂O and N₂O^·– were calculated at the QCISD and QCISD(T) levels of theory using aug-cc-pVDZ and aug-cc-pVTZ basis sets. The electron affinity of N₂O was determined to be ?0.15 eV. This work corroborates an earlier G2 study and suggests that the currently accepted value for the electron affinity, 0.22eV, is in error. This study represents the best calculation to date for the geometry and vibrational frequencies of N₂O^·?     

Simultaneous determination of the ground level abundances of N2O,CO2, CO and H2O

The AFCRL atmospheric line-parameter listing has been used with a non-linear, least-squares method of analysis to obtain the abundances of N₂O and CO in a sample of ground level air with a precision of about 1%. Absorption coefficients calculated for N₂O agree satisfactory with laboratory measurements but an error of 0.0267 cm^-1 in the listed position of an H₂O line at 2205.250 cm^-1 has been corrected and errors in the positions and intensities of CO₂ lines between 2230 and 2250 cm^-1 have been observed.     

Foreign gas broadening of difluoromethane by N2, O2 and CO2

The linewidth parameters of difluoromethane broadened by N₂, O₂, and CO₂ have been measured at microwave frequencies and are compared with calculated values for dipole-quadrupole interactions by using the Murphy-Boggs theory. The observed linewidths yield reasonable values of molecular quadrupole moments.     

Angular distribution of the photoelectron spectrum of CO2, COS,CS2, N2O,H2O,and H2S

The photoelectron spectra of the triatomic molecules CO₂, COS, CS₂, N₂O, H₂O, and H₂S have been measured as a function of the angle θ between the direction of the incoming photon and outgoing photoelectron. The photoelectron spectra have been measured with a double-focusing electrostatic electron spectrometer to which has been attached a chamber containing a gas discharge lamp that can be freely rotated. (The photon source used was the 21.22 eV He I resonance line). From the dependence of intensity as a function of θ the angular parameter β was determined for each ionization band observed in the photoelectron spectra. A correlation was noted between the values of β and the molecular orbitals relative to the contributions of oxygen and sulfur atomic orbitals. Individual β values were also obtained for most of the vibrational bands seen in the photoelectron spectra. In most cases the vibrational structure showed little or no change in the angular parameter for a given electronic state. In certain cases, however, such as the fourth ionization band in CS₂, CO₂, and COS, rather sizeable changes in β were observed for the different vibrational bands.     

Real-gas properties of n-alkanes, O2, N2, H2O, CO, CO2, and H2 for diesel engine operation conditions

The objective of the research outlined in this paper was to develop the analytical approximations for calculating real-gas properties (p-v-T data, thermodynamic functions: internal energy, enthalpy, and entropy, and specific heats) of vapor-phase n-alkanes from C₁ (methane) to C₁₄ (normal tetradecane), O₂, N₂, H₂O, CO, CO₂, and H₂ within the range of pressure 0.05 MPa ≤ p ≤ 20 MPa and temperature 280 K ≤ T ≤ 3000 K aimed for implementation into computational fluid dynamics (CFD)-codes simulating the operation process in modern Diesel engines. The analytical approximations have been developed based on available literature data and on the new equation of state for moderately dense gases. The approximations reported are rather simple and therefore can be used directly in CFD codes. Approximations for mixing rules are also provided.     

Diode-laser absorption measurements of CO2, H2O, N2O, and NH3 near 2.0 μm

2 , H₂O, N₂O, and NH₃ concentrations in various flowfields using absorption spectroscopy and extractive sampling techniques. An external-cavity diode laser with a tuning range of 1.953–2.057 μm was used to record absorption lineshapes from measured transitions in the CO₂ 4ν₂ ⁰+ν₃, ν₁+2ν₂ ⁰+ν₃, and 2ν₁+ν₃ bands, H₂O ν₂+ν₃and ν₁+ν₂ bands, N₂O 2ν₁+4ν₂ ⁰, ν₂ ¹+2ν₃, 3ν₁+2ν₂ ⁰, and 4ν₁ bands, and NH₃ν₁+ν₄ and ν₃+ν₄ bands. Measured CO₂, H₂O, and N₂O survey spectra were compared to calculations to verify the HITRAN96 database and used to determine optimum transitions for species detection. Individual lineshape measurements were used to determine fundamental spectroscopic parameters including the line strength, line-center frequency, and self-broadening coefficient of the probed transition. The results represent the first measurements of CO₂, H₂O, N₂O, and NH₃ absorption near 2.0 μm using room-temperature near-IR diode lasers. Received: 12 March 1998/Revised version: 7 May 1998     

Sensors for the nitrogen oxides, NO2, NO and N2O, based on In2O3 and WO3 nanowires

Sensing characteristics of ZnO, In₂O₃ and WO₃ nanowires have been investigated for the three nitrogen oxides, NO₂, NO and N₂O. In₂O₃ nanowires of ∼20 nm diameter prepared by using porous alumina membranes are found to have a sensitivity (defined as the ratio of the sensor resistance in the gas concerned to that in air) of about 60 for 10 ppm of all the three gases at a relatively low temperature of 150 °C. The response and recovery times are around 20 s. The sensitivity of these In₂O₃ nanowires is around 40 for 0.1 ppm of NO₂ and N₂O at 150 °C. WO₃ nanowires of 5–15 nm diameter, prepared by the solvothermal process show a sensitivity of 20–25 for 10 ppm of the three nitrogen oxides at 250 °C. The response and recovery times are 10 s and 60 s, respectively. The sensitivity is around 10 for 0.1 ppm of NO₂ at 250 °C. The sensitivity of In₂O₃ and WO₃ nanowires is not affected by humidity even up to 90% relative humidity. The study also reveals that the sensing mechanism for the three nitrogen oxides have a commonality in that the desorption of oxygen is a crucial step in all the cases. PACS 07.07.Df; 85.35.-p; 82.35.Np     

Measurement of the Kerr constant of He,A, O2, N2, H2 and D2

Summary The Kerr electro-optic constant of helium, argon and of molecular oxygen, nitrogen, hydrogen and deuterium have been measured at room temperature and low pressure, by using a low-frequency-modulated electric field. In this paper the density is given in amagat,i.e. in moles per molar volume.     

Ionization energies of the N2, CO,CO2, N2O,C2H2 and SiH4 molecules calculated by universal model potential

Acta physica Academiae Scientiarum Hungaricae - A modified XαSW method with universal potential (MXαSWU) was used to calculate ionization energies of the N2, CO, CO2, N2O, C2H2 and SiH4...