RESUMEN
The first stretching overtone region of short-lived, formerly inaccessible BiH3 near 3405 cm(-1) has been measured by Fourier-transform infrared spectroscopy with a resolution of 0.0066 cm(-1). Only the 2nu1(A1)/nu1+nu3(E) band system has been observed. Rotational analysis, with transitions reaching J'max=14, has revealed almost perfect local-mode behavior for the upper states denoted as (200A1/E) in the local-mode notation. Ratios of vibration-rotation interaction parameters q(eff)/alpha(eff)(BB) and r(eff)/alpha(eff)(BC), and the appropriate rotational constant differences, are in good agreement with theoretical local-mode limit values. A simple stretching vibrational model reproduces the observed vibrational term values well, and the potential parameters obtained are close to true values.
RESUMEN
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. Ulenov, G. A. Onopenko, N. E. Tyabaeva, H. Bürger, and W. Jerzembeck, J. Mol. Spectrosc. 198, 27-39 (1999)], were used as input information for a "Global Fit" procedure. This fit provided 34 spectroscopic parameters for the HD(80)Se species which reproduced rotational-vibrational transitions of the (001), (002), and (003) states within experimental accuracy. Corresponding analyses were performed for the other (M)Se (M = 82, 78, 77, and 76) species. Copyright 2000 Academic Press.
RESUMEN
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. The parameters determined by the Global Fit reproduce upper vibrational-rotational energies of all these bands with accuracies close to experimental precision. Copyright 2000 Academic Press.
RESUMEN
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. Bürger, J.-M. Flaud, and Ph. Arcas, J. Mol. Spectrosc. 197, 215-221 (1999)) by using the "Global Fit" procedure. The obtained set of 43 fitted parameters for these three vibrational states of the D(2)(80)Se species (altogether 86 fitted parameters for 12 states of five M species) reproduces the rotation-vibration energies of all studied states with accuracies close to experimental uncertainties. Copyright 2000 Academic Press.
RESUMEN
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., parameters of the H(2)Se and D(2)Se species were derived and successfully used for the construction of a synthetic spectrum for the nu(1) and nu(3) bands. As a result, lines of the recorded spectrum were assigned, and band centers, rotational, centrifugal distortion, and resonance interaction parameters for the (100) and (001) states of the species D(2)(M)Se, M = 76, 77, 78, 80, and 82, were determined. The obtained sets of parameters reproduce values of the vibration-rotation energies with a "mean" accuracy of 0.00007 cm(-1) for the D(2)(80)Se, and a slightly worse accuracy for other Se isotopic species. Copyright 1999 Academic Press.
RESUMEN
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). While the full set of rotational parameters of the (80)Se species was determined with significance, some of the centrifugal distortion terms of the less abundant species were either constrained to those of the (80)Se species or extrapolated. Copyright 1999 Academic Press.
RESUMEN
For the first time D(2)Se and HDSe as (80)Se monoisotopic and natural material were studied in the region of the nu(2) fundamental vibration by high-resolution (0.0033 cm(-1)) Fourier transform infrared spectroscopy. For D(2)Se which is an asymmetric rotor with C(2v) symmetry the nu(2) band is of B type while for HDSe (C(s) symmetry) it is a hybrid band, and both A- and B-type transitions were observed. Depending on the isotopic abundances, 300-1000 lines were assigned for each of the isotopic (M)Se species (M = 76, 77, 78, 80, and 82). The corresponding (010) experimental rotational levels, obtained by adding the observed line positions to the ground state levels derived from J.-M. Flaud, Ph. Arcas, O. N. Ulenikov, G. A. Onopenko, N. E. Tyabaeva, W. Jerzembeck, and H. Bürger, (J. Mol. Spectrosc., in press) were fitted satisfactorily using a Watson-type Hamiltonian in A reduction and I(r)-representation: the rms deviations are ranging from 1.5 to 4.3 x 10(-4) cm(-1) depending on the isotopic species. Hamiltonian constants up to high order (octic terms) were determined for each isotopic species. For the most abundant Se isotopic species, namely (80)Se, the band centers are nu(0) (D(2)(80)Se) = 741.67503 cm(-1) and nu(0) (HD(80)Se) = 900.43820 cm(-1). Copyright 1999 Academic Press.
RESUMEN
The infrared spectrum of SCF(2) was recorded in the 1000-1400 cm(-1) region with a resolution of 2.5 x 10(-3) cm(-1). The rotationally resolved nu(1) and nu(4) band systems were studied for the first time, and altogether 11 500 transitions were assigned. Both fundamentals are involved in strong anharmonic (Fermi) resonances. Effective centers (J = K(a) = K(c) = 0) of the interacting bands are nu(1) 1366.7117 cm(-1), nu(3) + 2nu(5) 1365.4257 cm(-1), nu(2) + nu(3) 1311.1491 cm(-1) (a(1) species), and nu(4) 1190.0839 cm(-1), nu(2) + nu(5) 1217.8191 cm(-1) (b(1) species). The strong K(a) dependence of the nu(1)/nu(3) + 2nu(5) level mixing enabled a numerical determination of the interaction constants while the other anharmonic interactions were accounted for by consideration of relative intensities. Deperturbed band centers, anharmonicity constants, and equilibrium and excited state rotational and centrifugal distortion constants were determined. Copyright 1999 Academic Press.
RESUMEN
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 0.00008 and 0.00009 cm(-1), respectively, for the HD(80)Se species, were obtained. For the less abundant species, for which some higher order terms were constrained, slightly worse agreement was achieved. The refined spectroscopic parameters are very close to their predicted values. Copyright 1999 Academic Press.
RESUMEN
The Fourier transform gas-phase infrared spectra of the two lowest Coriolis-perturbed nu7 and nu9 bands of deuterated formic acid HCOOD and DCOOD have been measured with a resolution of ca. 0.003 cm-1. Combined analysis of the assigned IR transitions and all the available rotational data have allowed the determination of the band centers, rotational and centrifugal distortion parameters, and Coriolis coupling terms. Standard deviations of the IR transitions are 0.000246 cm-1 for HCOOD and 0.000209 cm-1 for DCOOD. Determined band centers are nu0(nu7) = 558.2723 cm-1, nu0(nu9) = 508.1321 cm-1 for HCOOD and nu0(nu7) = 554.4397 cm-1, nu0(nu9) = 492.2254 cm-1 for DCOOD. Copyright 1999 Academic Press.
RESUMEN
The ground state rotational spectra of SiH3CN and its 29Si, 30Si, 13C, 15N, d1, d2, and d3 isotopic species have been measured by Fourier transform microwave spectroscopy and by millimeterwave spectroscopy. Accurate rotational, centrifugal distortion, and 14N and D nuclear quadrupole coupling constants have been derived. The dipole moment of the parent species has also been measured, µ = 3.4400(42) D. The structure, force field, dipole moment, and nuclear quadrupole coupling constants have been calculated ab initio at the SCF, MP2, and B3LYP levels using triple zeta polarized basis sets. The experimental ro, rs, and rz structures have been determined. An approximate equilibrium structure has been obtained by combining the experimental results and the ab initio calculations: re(C&tbond;N) = 1.159 Å, re(Si&sbond;C) = 1.848 Å, re(Si&sbond;H) = 1.470 Å, and angle(HSiC) = 107.4 degrees. Copyright 1998 Academic Press.
RESUMEN
High resolution Fourier Transform spectra of HSiD3 and monoisotopic H120SnD3 have been recorded in the region of the nu5 fundamental at 850.68 and 646.90 cm-1 with a resolution of 3.3 and 2.8 x 10(-3) cm-1, respectively. About 2000 rovibrational transitions of each species have been assigned and fitted to two different reductions of the effective Hamiltonian, with sigma(Fit) = 1.2 x 10(-4) (HSiD3) and 1.4 x 10(-4) cm-1 (H120SnD3). The two sets of parameters were shown to be equivalent, and relations between parameters belonging to different reductions are perfectly fulfilled. Furthermore the ground state constants C0 and DK0 have been determined for the first time. For consistency the previously measured data belonging to the nu5 band of H70GeD3 have been refitted, sigma(Fit) = 1.6 x 10(-4) cm-1, on the basis of improved ground state parameters including the h'3 term accounting for the splitting of the K = 3 level. Copyright 1998 Academic Press.
RESUMEN
High-resolution ( approximately 3 x 10(-3) cm-1) FTIR spectra of the planar SCF2 molecule have been recorded in the range of the four lowest-lying fundamentals nu2 (789.535 cm-1), nu3 (526.697 cm-1), nu5 (419.546 cm-1), and nu6 (623.187 cm-1). For each band 4500-7500 transitions have been assigned and fitted to a standard Watson-type Hamiltonian up to quartic terms, sigma(Fit) approximately 3.5 x 10(-4) cm-1. No indication of rovibrational perturbations was found, excited state rotational and centrifugal distortion constants being close to their ground state values. Ground state parameters previously determined from microwave spectra were, in part, improved by a merge of the appropriately weighted microwave data and approximately 10 000 ground state combination differences that were obtained from the nu4 band and spanning J and Ka values of 88 and 49, respectively. Copyright 1998 Academic Press.