ABSTRACT
The infrared spectrum in the range 900-1230 cm(-1) including the fundamental bands nu(3) and nu(6) of CD(3)CN has been studied. The resolution attained was 0.0025 cm(-1) in the measurement on the Bruker 120 HR Fourier spectrometer in Oulu. About 4000 lines were assigned in the nu(6) band. For the weak nu(3) band, which has not been observed earlier directly, we were able to assign 206 lines in three subbands K=8-10. These lines become detectable due to the strong nu(3)/nu(6) Coriolis resonance. There is also an l(1,-2) resonance between nu(3) and nu(6), which made it possible to obtain a value 2.647721(50) cm(-1) for the axial rotational constant A(0), when D(0)(K) from force field calculations was applied. Different types of resonances with the overtone 3nu(8) and the combinations nu(4)+nu(8) and nu(7)+nu(8) were observed. A fit with a standard deviation of 0.0019 cm(-1) was attained by using a model of 10 different resonances. Copyright 2001 Academic Press.
ABSTRACT
Four vibrational levels in the energy region around 1000 cm(-1) were studied. These were the v(5)=1 and v(8)=1 fundamental levels, both components of the v(9)=v(10)=1 combination level (l(9)=l(10)=+/-1 and l(9)=-l(10)=+/-1), and both components of the v(10)=3 overtone level (l(10)=+/-1 and +/-3). New FTIR spectra with a synchrotron radiation source were recorded in the region of the "superhot" v(10)=3<--2 bands, which made possible the first assignment of levels of the v(10)=3(+/-1) sublevel. More than 330 new rotational transitions in the combination and overtone levels were measured by millimeter-wave spectroscopy betwen 50 and 360 GHz. The new data were analyzed simultaneously together with the previously assigned rovibrational data for the fundamental and combination levels and rotational data for the fundamental levels using a global model with all anharmonic, Coriolis, l-type, and alpha-resonances. Significant improvement of data reproduction and very good consistency with the Hamiltonian parameters of the lower vibrational levels v(9)=1 and v(10)=1, 2 were achieved. A strong dependence of the A(v) constant on the l(10) quantum number is found for propyne: this is shown to be characteristic of skeleton C-C identical withC or C-C identical withN bending modes in H(3)CCCH, H(3)CCN, and their fully deuterated species. Copyright 2001 Academic Press.
ABSTRACT
The Fourier transform gas-phase infrared spectra of the Coriolis-perturbed nu(6) and nu(8) bands of deuterated formic acid DCOOH were measured with a resolution of ca. 0.003 cm(-1). Combined analysis of the 8977 IR transitions and all the available rotational data (from literature) in the ground state, as well as in the excited vibrational states v(6) = 1 and v(8) = 1 was carried out. The Coriolis coupling terms were determined and improved sets of rotational and centrifugal distortion parameters for the ground and excited vibrational states were obtained. The determined band centers are nu(0) (nu(8)) = 873.385046(12) cm(-1) and nu(0) (nu(6)) = 970.8889551(46) cm(-1). Copyright 1999 Academic Press.
ABSTRACT
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.
ABSTRACT
The rotational structure in three fundamental bands nu3, nu5, and nu6 of 13CHD3 has been analyzed. As this study evidently is the first high-resolution investigation on the spectrum of this molecule, the determination of the ground state rotational constants was the necessary first step. The nu5 band (1290.536 cm-1) could be treated as an isolated band whereas it was necessary to analyze the bands nu3 (994.713 cm-1) and nu6 (1030.243 cm-1) simultaneously because of very strong interactions. The total number of assigned lines was 1116. The spectral region 850-1530 cm-1 was measured on a Fourier transform spectrometer and the 13C species was in natural abundance in CHD3. Copyright 1998 Academic Press.
ABSTRACT
High-resolution spectrum of the HDS molecule was recorded with the Bruker Fourier spectrometer in Oulu in the regions of the nu1 and 2nu1/nu2 + nu3 absorption bands. Fine rotational structure of the nu1 band was analyzed with the model of an isolated vibrational state, while in the analysis of the 2nu1 and nu2 + nu3 bands it was necessary to take into account the resonance interactions between these two bands. Comparison of the experimentally determined parameters is made with the deductions of the expanded local mode approach. Copyright 1998 Academic Press.
ABSTRACT
The high-resolution infrared spectra of the lowest fundamental bands nu3 and nu6 of 12CD3I and 13CD3I have been measured using a Fourier transform spectrometer. The bands are analyzed on one hand by taking into account the Coriolis resonance nu3/nu6 and on the other hand without this Coriolis effect. The molecular constants obtained for the two vibration modes are introduced and a discussion of the influence of the Coriolis interaction to the parameter set is shortly outlined. Copyright 1997 Academic Press. Copyright 1997Academic Press
ABSTRACT
A careful rotational analysis of the ground vibrational state of the CHD3 molecule is made on the basis of the ground state combination differences method using, as the initial information, transitions from 12 infrared absorption bands: nu3(A1), nu6(E), nu5(E), 2nu3(A1), 2nu6(A1), 2nu6(E), nu3 + nu6(E), 2nu5(A1), 2nu5(E), nu3 + nu5(E), nu5 + nu6(A1 + A2), and nu5 + nu6(E). More than 2500 "forbidden" transitions were used to determine the parameters C, DK, and HK. a1 - a2 (K = 3) splittings in the ground vibrational state were found and analyzed. Copyright 1997 Academic Press. Copyright 1997Academic Press
ABSTRACT
The high-resolution absorption spectrum of the CHD3 molecule has been measured on a Fourier transform spectrometer in the region of the nu5 and nu3/nu6 bands and analyzed for the first time by taking into account a1 - a2 (K = 3) splittings of the ground vibrational state. The problem of ambiguity in determining the corresponding epsilon; parameter of the ground vibrational state was solved on the basis of the analysis of the rotational structure of the nu5 band. Numerous a1-a2 splittings for the states with Kupper = 1, 2, 4, 5, 7 in the nu5 and nu6 bands are described. Copyright 1997 Academic Press. Copyright 1997Academic Press
ABSTRACT
The infrared spectrum of doubly deuterated methane CH2D2 has been recorded in the region from 1900 to 2400 cm-1 at almost Doppler-limited resolution by using two high-resolution Fourier transform spectrometers. The vibrational bands observed include 2nu4, nu4 + nu7, 2nu7, nu2, nu8, nu4 + nu9, and nu7 + nu9, which were analyzed by taking into account Coriolis and Fermi interactions among them and also those with nu4 + nu5, nu3 + nu7, and nu5 + nu7. Most of the centrifugal distortion constants were constrained to appropriate values, while the vibrational term value and three rotational constants in each of the seven excited states were adjusted along with Coriolis and Fermi interaction parameters by the least-squares analysis of the observed spectrum. The vibration-rotation interaction constants alphas thus determined for the nu2 and nu8 states were combined with those of other fundamental states already published to calculate the equilibrium C-H distance.
