O.N. Ulenikov

Analysis of the SO2 absorption Fourier spectrum in regions 1055 to 2000 and 2200 to 2550 cm−1

Abstract High-resolution spectra of sulfur dioxide have been recorded between 1055 and 2550 cm −1 using infrared Fourier transform spectroscopy. More than 18 000 recorded lines have been assigned to nine cold and four hot vibration-rotation bands of SO 2 . Precise values of the band centers, rotational and centrifugal parameters, and anharmonic constants have been determined that allow one to reproduce and to predict the energy spectrum of SO 2 and its isotopic species with high accuracy.

On isotope effects in polyatomic molecules: Some comments on the method

Abstract The quantum mechanical expressions for the Hamiltonians of various isotope modifications of a polyatomic molecule are transformed to the coordinate systems connected with the molecules. Such coordinate transformations selected in the proper way permit all Hamiltonians His to be expressed as functions of the parameters rNα0, lNαλ, ζλμα, kλ⋯μ of one of them. Isotopic relations for the parameters of Watsons Hamiltonian (Mol. Phys. 15, 479–490 (1968)) of an arbitrary isotopic modification of a molecule are determined.

Analysis of the ν1 and ν3 absorption bands of 32S16O2

Abstract The spectrum of 32 S 16 O 2 between 1055 and 2000 cm −1 has been investigated under high resolution with a Fourier transform interferometer. Two fundamental bands have been analyzed; the A -type band ν 3 and the B -type band ν 1 . A careful analysis of these bands has led to the availability of an extended and more precise set of rotational levels belonging to the vibrational states (000), (100) and (001). From this set of improved vibrational energies, rotational and centrifugal constants for the states (000), (100), and (001) have been obtained.

On the displacements of centers of vibration-rotation bands under isotope substitution in polyatomic molecules

Abstract The effect of isotope substitution in polyatomic molecules on the displacements of absorption vibration-rotation band centers is considered. Formulas are obtained that allow the band-center displacements to be calculated in harmonic approximation and with anharmonicity. The effect of resonance interactions is also considered. The results obtained are illustrated by numerical calculation for a number of molecules.

Analysis of highly excited ‘hot’ bands in the SO2 molecule: ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2

We set up a variational procedure of assignments of transitions and we applied it to the analysis very weak ‘hot’ bands, ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2, of the SO2 molecule. As the first step of the study, the ‘cold’ bands, 3ν3 and 2ν1 + ν3, are re-analysed and transitions belonging to those bands are assigned up to the values of quantum numbers J max. = 60, , and J max. = 69, for the bands 3ν3 and 2ν1 + ν3, respectively. After ‘cleaning’ the experimental spectrum from transitions belonging to the 3ν3 and 2ν1 + ν3 bands, a variational procedure was used that allowed us to assign 230 and 115 transitions with the values of quantum numbers J max. = 35, , and J max. = 26, for the bands ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2, respectively. The sets of spectroscopic parameters obtained by fitting the assigned experimental transitions reproduce the initial experimental data with an accuracy close to experimental uncertainties.

On the transformation of the complete electron-nuclear Hamiltonian of a polyatomic molecule to the intramolecular coordinates☆

Abstract The transformation of the total electron-nuclear Hamiltonian of a polyatomic molecule, both for nonlinear and linear molecules, to the intramolecular vibrational and rotational coordinates has been made on the basis of the formulas for coordinate and impulse transformations from the space-fixed system of reference to the molecule-fixed one.

High resolution vibration-rotation spectrum of the D2O molecule in the region near the 2ν1 + ν2 + ν3 absorption band

The high resolution Fourier transform spectrum of the D20 (ν = ν1 + ν2/2 + ν3 = 3.5) polyad was analysed within the framework of the Hamiltonian model taking into account resonance interactions between the seven states (310), (211), (112), (013), (230), (131) and (032). Transitions belonging to the 2ν1 + ν2 + ν3, 3ν1 +ν2 and 3ν2 + 2ν3 bands were assigned in the experimentally recorded spectrum. This provided the possibility of obtaining spectroscopic parameters of the ‘visible’ states (211), (310) and (032) and of estimating the band centres, and the rotational and resonance interaction parameters of the ‘dark’ states (112) and (131).

High-resolution rovibrational analysis of vibrational states of A2 symmetry of the dideuterated methane CH2D2: the levels ν 5 and ν 7 + ν 9

The infrared spectrum of the CH2D2 molecule has been measured in the region 900–1500 cm−1 on a Bomem DA002 Fourier transform spectrometer with a resolution of 0.0024 cm−1 (FWHM, unapodized). Transitions belonging to the hot bands ν 7 + ν9−ν 7, ν7 + ν9− ν 9, ν5 + ν7−ν5, and ν5 + ν9−ν5 were extracted from the recorded spectra to determine the rovibrational energies of the A2 symmetry vibrational states (v 7 = v 9 = 1) at 2329.698 cm−1 and (v 5  = 1) at 1331.409 cm−1. Vibrational energies as well as rotational and centrifugal distortion parameters of the (v 7 = v 9=1) and (v 5 = 1) states were determined that reproduce the experimental rovibrational energy levels of the (v 7 = v 9 = 1) and (v 5 = 1) vibrational states with a d rms deviation of 0.0017 and 0.0006 cm−1, respectively. The results are discussed in relation to the equilibrium structure of methane, which is redetermined here from the experimental data, and in relation to its potential hypersurface and anharmonic vibrational dynamics.

Rotation-vibration spectra of deuterated water vapor in the 9160–9390-cm−1 region☆

Abstract The absorption spectrum of mixtures of H 2 O, HDO and D 2 O has been recorded in the region 9161.5 to 9392.5 cm −1 with an absorption sensitivity of 10 −7 cm −1 and a line-center determination accuracy of 0.08 cm −1 . An attempt to identify the absorption bands of the spectrum obtained experimentally was undertaken. The justification for attributing the observed lines to the HDO bands (3 ν 1 + ν 2 ), ( ν 1 + 2 ν 2 + ν 3 ) and D 2 O bands ( ν 2 + 3 ν 3 ), ( ν 1 + ν 2 + 2 ν 3 ) is given. In this study the bands centers have been found and the molecular rotational and centrifugal constants have been determined as well.

Water-vapor absorption spectrum in the 0.59-μm region☆

Abstract The paper gives the results of investigation of the water-vapor absorption spectrum in the range of 586.9–596.6 nm. In the given range, 282 water-vapor absorption lines were recorded and were identified as belonging to the bands 4 ν 1 + ν 3 , 3 ν 1 + 2 ν 2 + ν 3 , 3 ν 1 + 2 ν 3 . Theoretical justification of the technique for interpreting the observed spectrum was made. The values of more vibration-rotation levels of energy were determined: for state (401) up to J = 10, for state (321) up to J = 10, and for state (302) up to J = 8. The rotational and centrifugal constants of the reduced Watsons Hamiltonian for the vibrational states (401), (321), (302), and (222) and constants of Fermi resonance (401)-(321), (302)-(222), and Coriolis resonance between the states (401), (321), and (302), (222) were determined.