Showing papers by "Vl.G. Tyuterev published in 1998"

Global fitting of 12c16o2 vibrational-rotational line positions using the effective hamiltonian approach

Abstract: About 13 000 experimental lines of the principal isotopic species of CO2 selected from the literature have been used to derive about 100 parameters of a reduced effective Hamiltonian built up to sixth order in the Amat–Nielsen ordering scheme. This Hamiltonian has been obtained from an effective Hamiltonian describing all vibrational–rotational energy levels in the ground electronic state and containing in explicit form all resonance interaction terms due to the approximate relations between harmonic frequencies ω1≈2ω2andω3≈ω1+ω2. An RMS deviation of 0.001 cm-1 has been achieved in the fitting. In order to test its predictive capabilities, the model has been used to calculate the line positions of six bands: 05511←05501, 1005(1, 2)←1004(1, 2), 1006(1, 2)←1005(1, 2), and 20033←00001, which are compared with experimental lines not included in the data set. The results are discussed and compared with the predictions of the Direct Numerical Diagonalization technique.

The GEISA system in 1996: Towards an operational tool for the second generation vertical sounders radiance simulation

Abstract: Since their creation, in 1974, the GEISA (Gestion et Etude des Informations Spectroscopiques Atmospheriques: Management and Study of Atmospheric Spectroscopic Information) database system (more than 730 000 entries between 0 and 22 656 cm−1, corresponding to 40 molecules and 86 isotopic species, in its 1992 edition) and the associated software have been widely used for forward atmospheric radiative transfer modelling, with the maximum reliability, tractability and efficiency. For the upcoming high spectral resolution sounders like IASI (Infrared Atmospheric Sounding Interferometer) and AIRS (Atmospheric InfraRed Sounder), more complete and accurate laboratory measurements of spectroscopic parameters, presently included in the databases, are required, and more sophisticated theoretical radiative transfer modelling should be developed. Consequently, it is intended to elaborate the GEISA database as an interactive tool, named GEISA/IASI, designed for providing spectroscopic information tailored to the IASI sounding radiative transfer modelling.

Analysis of high resolution measurements of the 2ν1 + 3ν3 band of ozone: Coriolis interaction with the ν1 + 3ν2 + 2ν3 band

Abstract: The 2ν1 + 3ν3 band of ozone, which occurs in the 5080 cm−1 region, has been observed for the first time using a Fourier transform spectrometer, operating at 0.008 cm−1 resolution and with a large pathlength x pressure product (3616 cm × 42.8 torr). Assignment of rotation-vibration transitions was done for J = 40 and Ka = 14. It was necessary to account for the Coriolis coupling between the levels of the (203) and (132) states to correctly reproduce the energy levels, particularly for states with Ka = 4. In this way, we have obtained a very satisfactory r.m.s. error of 1.8 × 10−3 cm−1, close to the experimental accuracy. In addition, line intensities of the 2ν1 + 3ν3 band were measured and calculated, and transition moment constants derived. Finally a complete list of line positions and intensities was calculated, leading to a total band intensity of Sv = 0.133 × 10−21 cm−1/mole cm−2 at 296 K.

Infrared high-resolution spectra of ozone in the range 5500-?: analysis of ? and ? bands

Abstract: The and bands of ozone, which occur in the region, have been observed for the first time using a Fourier transform spectrometer, operating at resolution and with a large pathlength pressure product . The assignment of rotation-vibration transitions has been done for J up to 35 and Ka up to 12, for the band and up to J = 40 and Ka = 2 for the band respectively. The effective Hamiltonian used in calculations accounts for the first-order Coriolis coupling between these two bands. In addition, as the levels corresponding to Ka = 5 are perturbed, it was necessary to account for anharmonic resonance with the (321) state. Also, to correctly reproduce the levels of (015) with Ka = 8,9,10 it has been necessary to include a Coriolis coupling with (080) state in the model. In this way, we have obtained a very satisfactory r.m.s. deviation of , near the experimental accuracy. Rovibrational line intensities of and bands were measured and the value of the principal transition moment constants have been recovered. Finally a complete list of line positions and intensities was calculated leading to the integrated band intensity of /molecule for the band and /molecule for the band at 296 K with a cut-off of .

Analysis of high resolution measurements of the v1 + 5v3 band of ozone: Coriolis interactions with the 6v3 and 3v1 + v2 + 2v3 bands

Abstract: The υ1 + 5υ3 band of ozone, which occurs in the 5780cm−1 region, has been observed for the first time using a Fourier transform spectrometer, operating at 0.008 cm-1 resolution and with a large pathlength pressure product (3216 cm × 28.3 Torr). The assignment of rotation vibration transitions has been made for J up to 39 and K a up to 12, respectively. As the levels corresponding to K a = 6 were perturbed, it has been necessary to account for the Coriolis coupling with the (312) state. It has also been necessary to include the Coriolis coupling with the (006) state. In this way, we have obtained a root-mean square deviation of 2.1 × 10−3cm−1, close to the experimental uncertainty. Rovibrational line intensities of the υ1 + 5υ3 band were measured and the value of the principal transition moment has been recovered. Finally, a complete list of line positions and intensities was calculated (with a cutoff of 3 × 10−26 cm−1 molecule−1 cm−2), leading to the integrated band intensity of s v = 4.581 × 10−23 cm−1 m...

Vibrational spectra of ternary ordered vacancy compounds

Abstract: We have studied the lattice dynamics of A2B23C45 crystals with the thiogallate structure using a nonpolarized ion model. We computed the interatomic interaction parameters for nine compounds. The calculated phonon spectra, density of vibrational states, and temperature dependence of the specific heats agree well with the available experimental data.