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1.
刘安雯  胡水明  丁昀  朱清时 《中国物理》2005,14(10):1946-1953
Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model.The dipole moment surfaces of NH3 and SbH3 are calculated with the density functional theory and at the correlated MP2 level,respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH3, PH3,AsH3 and SbH3) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered. The intensity “borrowing” effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit.  相似文献
2.
The laser-induced fluorescence (LIF) spectrum of jet-cooled CoF has been obtained in the wavelength region of 260-290 nm for the first time. Seventeen vibronic bands were observed and assigned to three types of transition from the ground state to upper states Ω′ = 3, 4, 5 by rotational analysis. A new vibrational transition with the 0-0 band at 34697.22 cm−1 has been assigned as the [34.7]3Γ5-X3Φ4 transition and effective equilibrium molecular constants for the upper state have been determined. In addition, lifetime measurements have been carried out for most of the bands under collision-free conditions. On the basis of the spectroscopic data and lifetime measurements, the electronic structures of these possible high-lying electronic states are discussed.  相似文献
3.
Jun Fang 《Applied Surface Science》2007,253(22):8952-8961
We have investigated the geometric and electronic structures of the cerium oxide (CeO2)-titanium dioxide (TiO2) mixed oxides with various Ce/TiO2 weight ratios prepared by the sol-gel method in detail by means of X-ray diffraction (XRD), high-resolution X-ray photoelectron spectroscopy (XPS), Raman spectroscopy excited by 325 and 514.5 nm lasers, and scanning electron microscope (SEM). Existence of cerium effectively inhibits the phase transition of TiO2 from the anatase phase to the rutile phase. XRD peaks of TiO2 anatase attenuate continuously with the increasing amount of CeO2 in the mixed oxide, but the XRD peaks of cubic CeO2 appear only after the weight ratio of Ce/TiO2 reaches 0.50. The average crystalline sizes of TiO2 anatase and cubic CeO2 in CeO2-TiO2 mixed oxides are smaller than those in the corresponding individual TiO2 anatase and cubic CeO2. Raman spectroscopy excited by the 514.5 nm laser detects CeO2 after the weight ratio of Ce/TiO2 reaches 0.70 whereas Raman spectroscopy excited by the 325 nm laser detects CeO2 after the weight ratio of Ce/TiO2 reaches 0.90. XPS results demonstrate that Ti exists in the form of Ti4+ in the CeO2-TiO2 mixed oxide. Ce is completely in the form of Ce3+ in the mixed oxides with a 0.05 weight ratio of Ce/TiO2. With the increasing weight ratio of Ce/TiO2, Ce4+ dominates. On basis of these results, we proposed that CeO2 initially nucleates at the defects (oxygen vacancies) within TiO2 anatase, forming an interface bridged with oxygen between CeO2 and TiO2 anatase. At the interface, Ce species cannot substitute Ti4+ in the lattice of TiO2 anatase whereas Ti4+ can substitute Ce4+ in the lattice of cubic CeO2. The decreasing concentration of oxygen vacancies, the Ti-O-Ce interface, and the decreasing average crystalline size of TiO2 anatase act to inhibit the phase transformation of TiO2 anatase. With the increasing amounts of CeO2, the CeO2 clusters continuously grow and form cubic CeO2 nanocrystals. Spectroscopic results strongly demonstrate that the surface region of CeO2-TiO2 mixed oxide is enriched with TiO2.  相似文献
4.
The absorption spectrum of the natural sample of nitrous oxide has been recorded at Doppler limited resolution with a Fourier-transform spectrometer in the spectral range 5000-10 000 cm−1. Ten cold bands (8Σ − Σ and 2Σ − Π), thirteen hot bands (11Π − Π, Σ − Σ, and Δ − Δ) of 14N216O and the 3ν3 band of 14N15N16O have been newly detected. The uncertainty of the line position determination is estimated to be about 0.005 cm−1 for unblended lines. The assignment of the spectrum has been done with the help of the prediction performed within the framework of the polyad model of effective Hamiltonian. The spectroscopic parameters Gv, Bv, Dv, Hv, and qv have been determined for all newly detected bands. The line intensities of 13 weak bands have been measured. The uncertainty of the obtained line intensity values varies from 7 to 13%.  相似文献
5.
High resolution Fourier transform spectra of the HDS molecule were recorded and analyzed for the first time in the region of the bands ν1 + 2ν2 (3938.6 cm−1), ν1 + ν3 (4522.6 cm−1), 2ν2 + ν3 (4638.8 cm−1), 2ν1 + ν2 (4767.7 cm−1), ν1 + ν2 + ν3 (5525.2 cm−1), 3ν1 (5560.6 cm−1), ν1 + 2ν3 (7047.2 cm−1), and 2ν2 + 2ν3 (7123.9 cm−1). The ro-vibrational energies of the upper vibrational states of these bands together with the ro-vibrational energies of 12 other bands already studied at high resolution were used as inputs in a Global Fit analysis firstly described in [O.N. Ulenikov, G.A. Onopenko, H. Lin, J.-H. Zhang, Z.-Y. Zhou, Q.-S. Zhu, R.N. Tolchenov, J. Mol. Spectrosc. 189 (1998) 29-39]. In this case, the resonance interactions between the states (v1v2v3) and (v1 ± 2 v2 ? 1 v3 ? 1) were taken into account. The resulting set of 143 parameters reproduces all the experimental data (2984 vibration-rotation energies of 20 vibrational states which correspond to about 9700 ro-vibrational transitions with Jmax = 23) with accuracies comparable with the experimental uncertainties.  相似文献
6.
The laser-induced fluorescence excitation spectrum of jet-cooled CoO molecules has been studied in the range of 540-725 nm. Beside all the parallel-polarized and perpendicular bands observed previously by Barnes and co-workers [M. Barnes, D.J. Clouthier, P.G. Hajigeorgiou, G. Huang, C.T. Kingston, A.J. Merer, G.F. Metha, J.R.D. Peers, S.J. Rixon, J. Mol. Spectrosc. 186 (1997) 374-402], 59 new bands have been recorded. Rotational constants have been derived and three new vibrational progressions identified. These three new band systems have been designated [13.99]4Π5/2-X4Δ7/2, [14.20]4Π5/2-X4Δ7/2 and [15.85]4Π5/2-X4Δ7/2. In addition, lifetime measurements have been carried out for most of the bands under collision-free conditions.  相似文献
7.
The high-resolution absorption spectrum of the HDO molecule was recorded with a Fourier-transform interferometer in the region of 8900-9600 cm−1, where the strongly interacted bands 2ν1 + ν3, 3ν1 + ν2, ν1 + 2ν2 + ν3, 2ν1 + 3ν2, 4ν2 + ν3, ν1 + 5ν2, and 7ν2 are located. About 1000 transitions were assigned to these seven bands based on the ab initio predictions [J. Chem. Phys. 106 (1997) 4618]. Altogether, 375 upper energy levels were determined, including 24 energy levels of the highly excited bending (070) state. On that basis, the necessity of the “Effective Hamiltonian” concept in the spectroscopic analysis is discussed.  相似文献
8.
High-resolution Fourier transform spectrum of the HD32S molecule was studied in the region of 5000-9000 cm−1. More than 1600 observed transitions yielded 239, 264, 131, and 116 upper state ro-vibrational energies of the states (002), (012), (003), and (013), respectively. With a Watson-type effective Hamiltonian model, the ro-vibrational parameters of these four upper states were determined by a least-square fitting which can reproduce the ro-vibrational energies close to the experimental accuracy. The relative linestrengths are also discussed.  相似文献
9.
The absolute line intensities of the Fermi triad 2003i-00001 (i = 1, 2, 3) of 12C16O2 and 13C16O2 isotopic species of carbon dioxide were retrieved from Fourier-transform spectra recorded at Doppler limited resolution in the region 9200-9700 cm−1. The accuracy of the line intensity determination is estimated to be better than 15% for most lines. The vibrational transition dipole moments squared and Herman-Wallis coefficients have been determined. The global fittings of the observed line intensities within the framework of the effective operators method have been performed. The fitting results reproduce the data within experimental uncertainty.  相似文献
10.
The absolute line intensities of 13C16O2 were retrieved from Fourier-transform spectra recorded in the region 4200-8500 cm−1. The accuracy of the line intensity determination is estimated to be 5% or better for most lines and about 10% for weak ones. The vibrational transition dipole moments squared and Herman-Wallis coefficients have been determined. The global fittings of the observed line intensities within the framework of the effective operators approach have been performed. As the result of the fittings, most line intensities are reproduced within the experimental accuracy. The comparison between the new measured data and the HITRAN database are also carried out.  相似文献
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