Analysis of the D2O absorption spectrum near 2.5 μm

The D2O absorption spectrum recorded with a selective modulation Girard spectrometer in the region of 3690-4190 cm-1 (resolution ∼0.07 cm-1) has been analyzed. Based on the fitting of experimental data the spectroscopic parameters of the vibrational state (011) have been determined and the parameters of the vibrational states (110) and (030) have been estimated. © 1987

Algebraic-matrix calculation of vibrational levels of triatomic molecules

We introduce an accurate and efficient algebraic technique for the computation of the vibrational spectra of triatomic molecules, of both linear and bent equilibrium geometry. The full three-dimensional potential energy surface (PES), which can be based on entirely {\it ab initio} data, is parameterized as a product Morse-cosine expansion, expressed in bond-angle internal coordinates, and includes explicit interactions among the local modes. We describe the stretching degrees of freedom in the framework of a Morse-type expansion on a suitable algebraic basis, which provides exact analytical expressions for the elements of a sparse Hamiltonian matrix. Likewise, we use a cosine power expansion on a spherical harmonics basis for the bending degree of freedom. The resulting matrix representation in the product space is very sparse and vibrational levels and eigenfunctions can be obtained by efficient diagonalization techniques. We apply this method to carbonyl sulfide OCS, hydrogen cyanide HCN, water H$_2$O, and nitrogen dioxide NO$_2$. When we base our calculations on high-quality PESs tuned to the experimental data, the computed spectra are in very good agreement with the observed band origins.Comment: 11 pages, 2 figures, containg additional supporting information in epaps.ps (results in tables, which are useful but not too important for the paper

SOME NEW ASPECTS IN THE LOCAL MODE AND NEAR LOCAL MODE APPROACHES IN MOLECULES

1. L. Halonen and A.G. Robiette, J. Chem. Phys., 84, 6861 (1986).Author Institution: Tomsk State University, Tomsk, 634050, RUSSIAEfficient in applications in molecular spectroscopy local mode method was modified on the base of careful analysis of transformation coefficients $l_{N\alpha \lambda}$ and properties of intramolecular potential function. Approach was applied to the $XY_{2} (C_{2v} symmetry), XY_{3} and ZXY_{3} (C_{3v}), XY_{4} (T_{d})$, and $X_{2}Y_{2} (D_{\infty h})$ molecules. It was shown, that even in the framework of strict local mode approach known in $literature^{1}$ relations between some spectroscopic parameters should be improved. New relations between centrifugal distortion coefficients and some other fourth order spectroscopic parameters were obtained. It was shown, that the knowledge of centrifugal distortion coefficients of the ground vibrational states of above mentioned molecules gives possibility to predict with high enough accuracy both the band centers, and vibration-rotation energy spectra of deformational bands even in conditions of total absence of any initial experimental information about these deformational bands. Recommendations on possibilities of prediction of vibration-rotation spectra in excited vibrational states on the base of experimental information about lowest vibrational states are made. This work was supported by the grant of Russian Foundation of Fundamental Researches N94-02-03081-a

METHODS AND SOME RESULTS OF STUDY FINE ROTATIONAL STRUCTURES OF EXCITED VIBRATIONAL STATES OF POLYATOMIC MOLECULES

Author Institution:The methods which have been derived especially for analysing complicated vibration-rotation high resolution spectra of different type polyatomic molecules are discussed. The efficiencies of those are methods are illustrated by the results of the first studies of some excited strongly interacting vibrational states of the $CH_{2}D_{2}, H_{2}Se, D_{2}S, HDS$, and some other polyatomic molecules. Possibility of using of obtained information in the problem of determination of fundamental molecular parameters is discussed

ON THE NEW PRECISE SPECTROSCOPIC STUDY OF THE CH3DCH_{3}D MOLECULE

$^{a}$ O.N. Ulenikov. S. Alanko. M. Koivusaari. and R. Anttila. Chem. Phys. Lett. 268, p242-248 (1997)Author Institution: Tomsk State UniversityOn the basis of recorded (Oulu, Finland) high resolution Fourier transform spectra ($\nu_{3}, \nu_{5}$, and $\nu_{6}$ bands) and of ``super-combination differences'' $method^{a} A_{1}-A_{2} (K=3)$ splittings were first time determined in the ground vibrational state of the $^{12}CH_{3}D$ molecule for the states with $10 < J < 22$. Problem of simultaneous determination of the $\bar{\epsilon}$ and $\bar{h}_{3}$ parameters which are responsible for such splittings is solved on the basis both of theoretical calculation and of analysis of resonance interactions in recorded experimental spectra. Numerous peculiarities in the spectra of the $\nu_{3}, \nu_{5}$, and $\nu_{6}$ bands (in particular $A_{1}-A_{2}$ splittings for the $K=1,2,3,4,5,6,7$, and othe effects) are discussed. Analogous problems for the $^{13}CH_{3}D$ molecule are considered