Comprehensive high resolution study of the SiH(M=28,29,30) tetradecad stretching bands: Appearance and applications of the isotopic substitution effect in molecules of spherical symmetry.

A set of new relations between different spectroscopic parameters of the high symmetry XY spherical top molecules is derived on the basis of the general isotopic substitution theory, and a comprehensive high accurate analysis of the five stretching bands (the bands ν+ν(F), 2ν(F), 2ν(E), 2ν(A), and 2ν(A); the three latter ones are forbidden in absorption) of the tetradecad of the SiH molecule is made. The high resolution spectra of SiH(M=28,29,30) in their natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at the Technische Universität Braunschweig, Germany with an optical resolution of 0.003 cm and theoretically analyzed (in this case, for the first time both for all five bands of the SiH and SiH species, and for 2ν(E), 2ν(A) bands of the SiH one).

High resolution spectroscopy of asymmetric top molecules in nonsinglet electronic states: the ν fundamental of chlorine dioxide (OClO) free radical in the XB electronic ground state.

Highly resolved spectra of the OClO isotopologue of chlorine dioxide were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer in the region of the ν band. The analysis was made in the frame of the spin-rotational effective Hamiltonian (in A-reduction and I-representation) taking into account spin-rotational coupling operators up to the sixth order and the corresponding reduction of the Hamiltonian. The mathematical description of the ro-vibrational spectra was implemented to the specially created computer program ROVDES.

On the method and results of calculation of vibrational tetrahedral sub-level energies and resonance interactions in vibrational spectra of high symmetry molecules: CH and GeH as an application of the XY (T) molecule.

We report here the analytical description of one of the important problems in the study of XY (T) molecules, namely, description of vibrational tetrahedral sub-level structures and resonance interactions caused by the high symmetry of a molecule. The results obtained are applied to description of the vibrational energy spectrum of the CH and GeH molecules.

High-resolution spectroscopy of CHD: Line positions and energy structure of the strongly interacting ν,ν,ν,ν and ν bands.

High resolution infrared spectra of CHD were recorded in the region of 550-1950 cm with a Bruker IFS125 HR Fourier transform infrared spectrometers and rotational structures of the five lowest strongly interacting ν, ν,ν,ν and ν bands were analyzed. The number of about 28000 transitions (4200/6800/5600/5000/6400 for the bands ν,ν,ν,ν and ν) with J = 40 and K = 20 were assigned to these five bands. The weighted fit of 3990 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account resonance interactions between all studied bands as well as with the sixth ν band which was considered in this case as a "dark" one.

High resolution spectroscopy of the ν+ν band of the ClO free radical: Spin-rotation-vibration interactions.

The high resolution spectrum of the ν+ν band of the ClO free radical was recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and theoretically analysed with an improved theoretical basis including the reduced effective spin-rotation Hamiltonian (which takes into account sixth order operators describing spin-rotational interactions) and a newly created computer code ROVDES for the ro-vibrational spectra of open-shell free radicals. About 2600 spin-ro-vibrational transitions with the values N=59 and K=17 (being about 2.4 times higher in comparison with the number of assigned transitions known in the literature) were assigned to the ν+ν band of ClO and 1049 spin-ro-vibrational energies (produced only from unblended non-saturated and not very weak experimental lines) of the (101) upper vibrational state were obtained.

High resolution FTIR spectroscopy of germane: First study of GeH in the region of Tetrad of the strongly interacting ν+ν,ν+ν,ν+ν and ν+ν ro-vibrational bands.

The infrared spectra of germane, purified and enriched up to 88.1% of GeH, was measured at the temperature of (22.6±0.

High resolution ro-vibrational analysis of molecules in doublet electronic states: the fundamental of chlorine dioxide (OClO) in the electronic ground state.

We report the spectrum of the ν1 fundamental of chlorine dioxide centered in the infrared atmospheric window at 945.592 cm-1 measured with essentially Doppler limited resolution at an instrumental line width of 0.001 cm-1 using the Zürich prototype ZP2001 Bruker IFS 125 HR Fourier transform infrared spectrometer.

On the method of precise abundance determination of isotopologues in a gas mixture.

A method is presented which allows one to derive partial pressures of isotopologue molecules in a gaseous mixture under the conditions of rapid isotope exchange. For this purpose, isotopic relations between effective dipole moment parameters of a "parent" molecule and its related isotopically substituted species are derived on the basis of the general isotopic substitution theory. The efficiency of the method is illustrated.

Survey of the high resolution infrared spectrum of methane ((12)CH4 and (13)CH4): partial vibrational assignment extended towards 12,000 cm(-1.).

We have recorded the complete infrared spectrum of methane (12)CH4 and its second most abundant isotopomer (13)CH4 extending from the fundamental range starting at 1000 cm(-1) up to the overtone region near 12,000 cm(-1) in the near infrared at the limit towards the visible range, at temperatures of about 80 K and also at 298 K with Doppler limited resolution in the gas phase by means of interferometric Fourier transform spectroscopy using the Bruker IFS 125 HR prototype (ZP 2001) of the ETH Zürich laboratory. This provides the so far most complete data set on methane spectra in this range at high resolution. In the present work we report in particular those results, where the partial rovibrational analysis allows for the direct assignment of pure (J = 0) vibrational levels including high excitation.

High-resolution near infrared spectroscopy and vibrational dynamics of dideuteromethane (CH2D2).

We report the infrared spectrum of CH(2)D(2) measured in the range from 2800 to 6600 cm(-1) with the Zurich high-resolution Fourier transform interferometer Bruker IFS 125 prototype (ZP 2001, with instrumental bandwidth less than 10(-3) cm(-1)) at 78 K in a collisional enclosive flow cooling cell used in the static mode. Precise experimental values (with uncertainties between 0.0001 and 0.

High resolution Fourier transform spectroscopy of CH2D2 in the region 2350-2650 cm(-1): the bands nu5 + nu7, 2nu9, nu3 + nu4, nu3 + nu7 and nu5 + nu9.

The IR spectrum of the CH2D2 molecule has been measured in the region of 2350-2650 cm(-1) on a Bomem DA002 Fourier transform spectrometer with a resolution of 0.004 cm(-1) (FWHM, apodized) and analyzed with a Hamiltonian model which takes into account resonance interactions between all vibrational states in that region. More than 3000 transitions have been assigned to the bands 2nu9, nu3 + nu4, nu5 + nu9, nu5 + nu7 and nu3 + nu7 using ground state combination differences from the known ground state parameters.

Rotational Analysis of the Ground State and the Lowest Fundamentals nu(3), nu(5), and nu(6) of (13)CH(3)D.

The nu(3), nu(5), and nu(6) fundamental bands of the (13)CH(3)D molecule have been studied with Fourier transform infrared spectroscopy. The spectra and results for the parent species (12)CH(3)D (O. N.

High-Resolution Study of the (v(1) + 12v(2) + v(3) = 3) Polyad of Strongly Interacting Vibrational Bands of D(2)O.

Analysis of the high-resolution Fourier transform spectra of the D(2)O first decade was carried out in the framework of the Hamiltonian model which took into account resonance interactions between the seven states, (300), (201), (102), (003), (220), (121), and (022). Assigned from the experimentally recorded spectrum transitions belonged to the four bands, 2nu(1) + nu(3), 3nu(3), nu(1) + 2nu(2) + nu(3), and 3nu(1), gave the possibility both of obtaining rotational, centrifugal distortion, and resonance interaction parameters of "appeared" states, (201), (003), (121), and (300), and of estimating from the fit band centers, rotational, and resonance interaction parameters of the three "dark" states, (220), (022), and (102). Copyright 2000 Academic Press.

High-Resolution Study of the nnu(2), n = 1, 2, 3, Vib-Rotational Bands of D(2)Se.

High-resolution Fourier transform spectra of the D(2)(M)Se with M = 76, 77, 78, 80, and 82 in the regions of the first and second bending overtones 2nu(2) and 3nu(2) near 1480 and 2210 cm(-1), respectively, were recorded for the first time and assigned. On the basis of these experimental data, rotation-vibration energies were determined and fitted together with those of the (010) state reported earlier (W. Jerembeck, H.

High-Resolution Study of Strongly Interacting Vibrational Bands of HDO in the Region 7600-8100 cm(-1).

The high-resolution Fourier transform spectrum of the HDO molecule was recorded and analyzed in the region 7600-8100 cm(-1) where the weak vibration-rotation bands 3nu(1) and nu(1) + nu(2) + nu(3) are located. Because of the presence of strong local resonance interactions, transitions belonging to the 3nu(2) + nu(3) and 6nu(2) bands were assigned as well. Spectroscopic parameters of all four bands were estimated, which reproduce initial line positions with accuracy close to experimental uncertainties.

Analysis of the (0 0 v(3)), v(3) = 1, 2, 3 Vibrotational States of HDSe.

High-resolution Fourier transform spectra of HDSe in the region of the 2nu(3) and 3nu(3) bands were recorded and analyzed for five different (M)Se isotopic HDSe species. Energies obtained from rovibrational analyses of the (002) and (003) states, together with those taken of the (001) state from an earlier study [O. N.

High-Resolution Fourier Transform Spectra of HDSe: The Interacting States (v(1) v(2) v(3))/(v(1) +/- 1 v(2) -/+ 2 v(3)) with 2v(1) + v(2) = 1, 2, 3, and 4.

For the first time, high-resolution Fourier transform spectra of HDSe in the region of the three polyads, nu(1)/2nu(2), nu(1) + nu(2)/3nu(2), and 2nu(1)/nu(1) + 2nu(2)/nu(2) + nu(3), have been recorded and analyzed. Combined with an earlier investigation of the nu(2) band, and including estimates for the unobserved "dark" 4nu(2) band, these levels were subjected to a "Global Fit," which makes use of relations between parameters within the different polyads. Since there are five isotopic species present in natural HD(M)Se (M = 82, 80, 78, 77, 76), altogether 34 vibration-rotation bands have been studied in the present contribution.

High-Resolution Fourier Transform Spectrum of the D(2)O Molecule in the Region of the Second Triad of Interacting Vibrational States.

The high-resolution Fourier transform spectrum of the D(2)O molecule was recorded in the 3200-4200 cm(-1) region, where the bands of the second triad of interacting vibrational states are located. As a result of the theoretical analysis, both the rotational-vibrational structure of the (011) vibrational state was improved, and the rotational energies of the (110) and (030) vibrational states were determined for the first time up to rotational quantum numbers J(max.) = 15 and 14, respectively.

High-Resolution Study of the First Hexad of D(2)O.

The high-resolution Fourier transform spectra of the D(2)O molecule have been recorded and assigned in the 4200-5700 cm(-1) region where the vibration-rotation bands 2nu(1), 2nu(3), nu(1) + nu(3), nu(1) + 2nu(2), 2nu(2) + nu(3), and 4nu(2) are located. The presence of numerous and very strong accidental perturbations between the states of the hexad makes it necessary to take into account not only ordinary resonance interactions of the Fermi, Darling-Dennison, and/or Coriolis types, but interactions between the states (v(1)v(2)v(3)) and (v(1) -/+ 2v(2) +/- 2v(3) +/- 1) as well. Parameters of all six vibrational states of the hexad were obtained from the fit of experimental energy values.

Study on the Rovibrational Interactions and a(1)/a(2) Splittings in the nu(3)/nu(5)/nu(6) Triad of CH(3)D.

High-resolution Fourier transform infrared spectrum of CH(3)D has been recorded in the region of the fundamental bands nu(3), nu(5), and nu(6) between 900 and 1700 cm(-1). High sensitivity of the equipment used as well as high accuracy of the recorded line positions gave the possibility of assigning the first-time transitions with the upper state J quantum number up to 23. In the analysis the new ground vibrational state information [O.

Isotope Substitution in Near Local-Mode H(2)X Molecules: Stretching Fundamental Bands of HDSe.

The high-resolution FTIR spectrum of the HDSe molecule in the presence of H(2)Se and D(2)Se was recorded on (80)Se monoisotopic and natural samples in the 1500-2900 cm(-1) region and theoretically analyzed in the regions of the stretching fundamental bands nu(1) and nu(3) near 1692 and 2351 cm(-1), respectively. The analysis was performed starting from derived isotopic relations between vibration-rotation, anharmonic, centrifugal distortion, and other parameters which reveal high predictive power. Strong resonance interactions between the states (100) and (020) are taken into account, and sets of parameters which reproduce the experimental rotation-vibration energies of the (100) and (001) states with a mean accuracy of 0.

The Ground State of D(2)Se and HDSe.

Ground state rotational constants of D(M)(2)Se and HD(M)Se, M = 76, 77, 78, 80, and 82, have been determined up to octic centrifugal distortion terms from ground state combination differences. These were obtained from rotational analyses of the nu(2), nu(1), and nu(3) bands both of natural and (80)Se monoisotopic material recorded with a resolution of ca. 3 x 10(-3) cm(-1).

Isotope Substitution in Near Local Mode H(2)X Molecules: The nu(1) and nu(3) Bands of D(2)Se.

The high-resolution (0.0027 cm(-1)) Fourier transform spectra of the D(2)Se molecule as (80)Se monoisotopic and natural material were recorded for the first time in the 1500-1900 cm(-1) region where the nu(1) and nu(3) vibration-rotation bands are located. Because accurate information about the rotational structures of different vibrational states was still lacking, the isotopic relations between rotational, centrifugal distortion, resonance interaction, etc.

On the Rotational Analysis of the Ground Vibrational State of CH3D Molecule.

The rotational analysis in the ground vibrational state has been carried out for CH3D by using the ground state combination differences. More than 1500 allowed and 2500 forbidden transitions from the fundamental bands nu3, nu5, and nu6 were used to determine 12 rotational parameters, which reproduce the observed combination differences within an accuracy of 1.0 x 10(-4) cm-1.

Isotope Substitution in near Local Mode Molecules: Bending Overtones nnu2 (n = 2, 3) of the HDS Molecule.

There are two main goals in the present study: (a) to record and analyze the weak overtones nnu2 (n = 2, 3) of the bending fundamental nu2 of the HDS molecule and (b) to derive new isotopic relations for spectroscopic parameters applicable to predict, at least qualitatively, the structures of the excited bending states of HDX-type molecules. Copyright 1998 Academic Press.