This work is a part of our systematic investigation of the very weak absorption spectra of 16O3 and 18O3 by high sensitivity Cavity Ring Down Spectroscopy between 5850 and 7920 cm-1. In total, 29 vibrational bands of 16O3 and 24 bands of 18O3 have been assigned in this range. Here we present the recent results of analyses of highly excited states of 18O3 ozone, located near the dissociation energy (D0~8560 cm-1). The comparison of the vibrational band centers obtained from the analysis with the predictions based on the potential energy surface (PES) suggests that the hypothesis of the “reef structure” at the ozone transition state towards the dissociation is not confirmed by spectroscopic observations. In this work, we focus on the comparison between theoretical and experimental values of the 18O3 vibrational levels near the dissociation limit.
This study is the continuation of our analysis of emission spectra of pure D20. The spectra have been recorded in the 320 - 860 and 1750 - 4300 cm-1 spectral regions at different pressures and temperatures. The measurements were performed
in an alumina cell with an effective length of hot gas of about 50 cm. All spectra have been recorded by using the Bruker
IFS 120 spectrometer at the Physikalisch-Chemisches-Institut, Justus-Liebig-Universitat Giessen (Germany). More than
5600 lines have been assigned to the second triad {(030), (110), (011)} of interacting states of the D2160 molecule. These
transitions were assigned to 24 vibration-rotation and rotational bands. An extended set of more than 1500 experimental
rovibrational levels for the (030), (110), and (011) interacting states has been obtained. The maximum values of
rotational quantum numbers are Jmax = 30 and Ka max = 21 with Emax = 10568 cm-1 for the (011) state; Jmax = 29 and
Ka max = 21 with Emax= 10540 cm-1 for the (030) state, and Jm 26 and Ka max 22 with Eniax 10488 cm1 for the (110)
state. A comparison of the observed energy levels with the best available values from literature and with the global
prediction is discussed.
Thanks to the record ofnew FTS spectra of O3 in the 4300 cm1 region, the 122-000 band is now observed. Assignments
of line transitions for following values of rotational quantum numbers J and Ka: 10 < J < 51 , Ka ≤ 8 were done. In the
linelist about 443 transitions of v1+2v2+2v3 band are presented. To correctly reproduce the obtained energy levels of
(122) state, the very weak "dark state" (400) was introduced. A data reduction has been done using effective Hamiltonian
for three interacting states {400, 122 023}, which are coupled through the usual Coriolis and high order rotational and
vibrational resonances. The final fit on the 589 energy levels is quite satisfactory. The root mean square deviation
between observed and calculated values is about O.0029cm-1. The fit of line intensities allows us to derived transition
moment parameters for 2v2+3v3 and v1+2v2+2v3 bands.
The work is aimed at building systematic links between accurate intra-molecular potential energy surfaces (PES) and effective rovibrational Hamiltonians for polyads of near degenerate vibrational states. A specialized computing package MOL_CT of formal rovibrational calculation developed for this purpose for a semi-rigid polyatomic molecule is presented. The general algorithm of high-order calculations, computer implementation and ordering issues are discussed. The package contains a suite of routines for PES and dipole moment surfaces (DMS) analysis, coordinate and axes transformations, change of operator representations, commutator calculations and term reductions. This allows a systematic computer assisted construction of effective rovibrational Hamiltonians for successive polyads starting with a PES for nuclear motion in a give electronic state. Some applications to asymmetric-top triatomic C2v and Cs molecules with examples using recent accurate PES of water and ozone are briefly discussed.
The potential energy function of the ozone molecule empirically optimised to the largest set of spectroscopical high-resolution data of nine isotopomers 16O3, 16O16O18O, 16O18O16O, 16O18O18O, 18O16O18O, 18O3, 16O16O17O, 16O17O16O, and 16O17O17O used for this purpose so far is reported. The average accuracy of vibrational calculations for about sixty measured bands for nine isotopic species up to 3800 cm-1 is about 0.02cm-1. Reported variational calculations of high-J rovibrational states show a comparable accuracy up to J=45 for fundamental bands. The related global predictions were found very useful for the band and isotopic assignments of dense and complicated 18O enriched spectra recorded in Reims University and containing overlapping bands of six 18O enriched ozone isotopomers simultaneously.
Various empirical and ab initio potential energy surfaces (PES) of ozone are compared with recent accurate PES obtained by a variational fit to spectroscopic data. The value of the dissociation energy De obtained from this PES agrees well with recent experimental values. Problems in the normal mode assignment of highly excited vibrational states are discussed.
This paper reviews main features of an IBM PC software package GEISA-PC designed for the use and managing large- scaled data bases of the atmospheric physics and spectroscopy interest. The current version of this program can process GEISA data bank on IR high resolution absorption spectra of 40 molecules and 86 isotopic species, a data base on IR absorption cross sections of commonly used chlorofluorocarbons. The N2O5, SF6, and ClONO2 molecules as well as six U.S. standard atmosphere models and those for altitude-frequency dependencies of the atmospheric aerosol extinction coefficient. The recent developments of the software and data in use have been discussed in detail. The free demo versions are available upon request.
Fourier transform spectra of water vapor have been recorded in the range 2500 - 4500 cm-1. This spectral range is important for accurate modeling of radiative transfer phenomena in the Earth's atmosphere and in other planetary atmospheres, and is frequently used for atmospheric remote sensing applications. The measurements were performed with the combination of a 4 m base length White-type multipass absorption cell and an FTIR Spectrometer, the Bruker IFS 120 HR.
The software designed to manage spectroscopical database GEISA-92 adapted for PC\AT compatible computers has been developed thanks to the cooperation between Lab. de Meteorologie Dynamique and Lab. of Theoretical Spectroscopy. The latest edition of GEISA contains 731,206 entries between 0 and 22,656 cm-1 corresponding to 40 molecules and 86 isotopic species.
The Pade-technique, developed before, along with the RKR-method is used for describing the absorption frequencies and energy levels of diatomic molecules. The inner wall of the potential energy curve is extrapolated from the force field adjusted in the fitting of low-laying energy levels, and a long-range part of the potential energy curve near dissociation is recovered by application of the RKR-method. The latter uses the extrapolated values of the vibrational energy levels. The similar calculations have been made through the adjusted spectroscopic parameters obtained by a phenomenological Pade-approach. Ab initio energies of the H2 molecule have been exploited to test the Pade-models.
Inverse problem which is a fit of a sample of experimental data to a multiparameter model of effective Hamiltonian H or an effective moment of transition M is an essential part of data reduction in molecular spectroscopy. In the present paper we describe a flexible inverse problem solver called GIP (General Inverse Problem) which, firstly, may be applied to a sufficiently large number of molecules, and secondly, enables one to overcome the major difficulties and limitations and provides a scientist with a useful tool to make studies in molecular spectroscopy.
The TDS project is concerned with high resolution spectroscopy of spherical top molecules. These molecules are known for the complexity of their spectra as well as their specific role in advanced fundamental and applied research in molecular physics and quantum chemistry. The prototype of the TDS computer package, which is the concrete result of a collaboration supported by CNRS and Russian Academy of Sciences, was presented at the Dijon Colloquium in September 1991. A brief documentation on this updated system runnable on IBM PC and compatible is presented here in the form of seven questions and answers and illustrated by selected screen copies. The electronic publication of an operating package (including sample data) via Spectrochimica Acta Electronica is envisaged.
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