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1.
The high resolution infrared spectrum of mono-isotopic F37Cl16O3 has been studied in the regions of ν1, ν2, ν4 and ν2 + ν5 bands, centered at 1060.20, 707.16, 1301.71 and 1292.15 cm−1, respectively. The ν1 and ν2 parallel bands are unperturbed so their analysis was straightforward and 3355 and 2433 transitions were assigned, respectively. The band origins, the rotational and centrifugal molecular constants in the v1 = 1 and v2 = 1 states have been determined, with standard deviation of the fits σ = 0.00019 and 0.00018 cm−1. The ν4 fundamental is affected by an anharmonic resonance with the ν2 + ν5 combination band. The kl > 0 sublevels cross at kl ? 27 because of the opposite values of and . The anharmonic resonance constant cm−1 has been derived. The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances have been found to be effective in ν4, while in ν2 + ν5 only the Δl = Δk = ±2 one was active. A total of 5721 transitions have been assigned, 25% of them belonging to ν2 + ν5. The rovibrational parameters and the interaction constants of F37Cl16O3 have been obtained. The standard deviation of the fit is 0.0006 cm−1, six times the estimated data precision. The equilibrium geometry of perchloryl fluoride has been determined from the Ae and Be constants of F35Cl16O3 and F37Cl16O3. Using the A0 and B0 constants of all the symmetric species the r0 geometry has also been derived. 相似文献
2.
The high-resolution (0.0030 cm−1) Fourier transform infrared spectrum of CH279BrF has been studied in part of the atmospheric window between 910 and 980 cm−1, the region of the ν9 (935.847 cm−1) and ν5 + ν6 (961.239 cm−1) bands. The ν9 fundamental consists of a pseudo a-type band induced by Coriolis coupling with ν5 + ν6, in turn exhibiting a predominant a-type structure. Several interactions connecting these levels and the dark state 3ν6 have been assessed. The whole data set is treated using Watson’s A-reduced Hamiltonian in the Ir representation implemented with first order a- and b- and c-type Coriolis terms. A detailed analysis of the rotational structure yields a set of accurate upper-state parameters up to quartic distortion terms for ν9 and ν5 + ν6. In addition, spectroscopic information about the dark ternary overtone of ν6 has been obtained. 相似文献
3.
4.
O.N. Ulenikov E.S. Bekhtereva O.L. Petrunina H. Bürger 《Journal of Molecular Spectroscopy》2003,219(1):13-29
The P-H stretching bands ν1/ν5 and 2ν1/ν1+ν5 were recorded using a Bruker 120 HR interferometer with a resolution of 0.0042 and 0.0088 cm−1, respectively, and analyzed. From the fits 33 and 50, respectively, vibrational, rotational, centrifugal distortion, and resonance interaction parameters were obtained. These reproduce 668 and 497 rovibrational energies of the pairs of states ν1/ν5 and 2ν1/ν1+ν5 with experimental accuracies, rms=0.00016 and , respectively. “Local mode” behavior of the PH2 fragment is established and discussed in detail. 相似文献
5.
The vibration-torsion-rotation spectrum of CH3SiH3 has been measured from 470 to 725 cm−1 at near-Doppler resolution. The full-width at half - maximum of the lines observed near 600 cm−1 was 0.0011 cm−1. The spectra were obtained using a Bruker IFS 125 HR Fourier transform spectrometer with the broadband source radiation being supplied from the synchrotron emission of the storage ring at the Canadian Light Source. Three vibrational bands were investigated: the lowest lying perpendicular fundamental ν12 centred near 524 cm−1, the lowest lying parallel fundamental ν5 near 703 cm−1, and the torsional hot band ν12 + ν6 − ν6 near 534 cm−1. For ν12 and ν5, the resolution and sensitivity are much improved over those in earlier studies, with many of the torsional multiplets now being resolved even in the cases where the upper levels are unperturbed. The primary motivation for the present work was the hot band, here reported for the first time, where the dependence of the silyl rock in ν12 on the torsional motion is much more pronounced. In addition, for the vibrational ground state (gs), two “forbidden” high torsional overtones v6 = 3 ← 0 and 5 ← 0 have been observed that become allowed through resonant mixing of the upper states with ν12 and ν5, respectively. In each case, two (K, σ) series have been measured where the mixing is largest. Here σ = 0, 1, −1 labels the torsional sub-levels. Using the Fourier transform waveguide spectrometer at E. T. H., the three σ-components of the (J = 1 ← 0) transition in ν12 + ν6 were observed, and a series of direct l-doubling transitions in ν12 + ν6 were measured for σ = 0. In a global fit, all the new data have been analysed along with the frequencies for other transitions obtained in earlier investigations. The analysis takes into account the relevant interactions among the torsional stacks of levels in the gs, ν12, and ν5. These include the previously known (gs, ν12) Coriolis-like and (gs, ν5) Fermi-like interactions along with a higher order (ν12, ν5) Coriolis-like coupling introduced here. This last is responsible for the strong perturbation of the ν5 series with K = 10, 11, and 12, and of the corresponding hot band series. A good fit to 9282 frequencies including 7942 new measurements was obtained both with the Free Rotor model in which the torsion is classified as a rotation, and with the High Barrier model in which the torsion is classified as a vibration. The Hamiltonian is discussed with emphasis on the new terms required for treating ν12 + ν6 − ν6. 相似文献
6.
The Fourier transform gas-phase IR spectrum of 1,2,3-thiadiazole, C2H2N2S, has been recorded with a resolution of ca. 0.003 cm−1 in the 700-1100 cm−1 spectral region. Four fundamental bands ν6(A/; 1101.8 cm−1), ν7(A/; 1038.8 cm−1), ν9(A/, 858.9 cm−1), and ν13(A//; 746.2 cm−1) have been analyzed using the Watson model in A-reduction. Two additional bands, ν8 (A/; 894.6 cm−1) and ν12(A//; 881.2 cm−1) were assigned by their weak Q-branches. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. A number of weak global and local interactions are present in the bands. The resonances identified were qualitatively explained by Coriolis type perturbations with neighboring levels. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement. 相似文献
7.
The Fourier transform gas-phase IR spectrum of 1,3,4-thiadiazole, C2H2N2S, has been recorded with a resolution of ca. 0.003 cm−1 in the 800-1500 cm−1 spectral region. Five fundamental bands ν2(A1; 1391.9 cm−1), ν4(A1; 964.4 cm−1), ν5(A1; 894.6 cm−1), ν9(B1; 821.5 cm−1), and ν14(B2; 898.4 cm−1) have been analysed using the Watson model. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. The ν4 and ν9 bands are unperturbed while a strong c-Coriolis resonance perturbs the close-lying ν5 and ν14 bands. This dyad system has been analysed by a model including first and second order c-Coriolis resonance using the theoretically predicted Coriolis coupling constant . The ν2 band is strongly perturbed by a local resonance, and we obtain a set of spectroscopic parameters using a model including second order a-Coriolis resonance with the inactive ν10 + ν14 band. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement. 相似文献
8.
The high-resolution infrared spectrum of deuterated fluoroform (DCF3) was studied in the 700 and 1200 cm−1 regions, with the aim of assigning and analyzing the ν4 CF3 asymmetric stretching vibration. The Fermi-type anharmonic coupling between the ν4 = 1 and ν3 = ν6 = 1 rovibrational levels, already mentioned in an early work of Ruoff et al. [Spectrochimica Acta Part A 31A (1975) 1099-1100], was studied here for the first time under high resolution. Assignments in the ν3 + ν6/ν4 band system were confirmed and extended by the identification of the ν3 + ν6 − ν6 and ν4-ν6 bands in the 700 cm−1 region, the latter being enhanced near the Fermi crossings of the studied levels. Data from both the hot and difference bands were included in the analysis. The close separation of the studied vibrational levels of about 14.8 cm−1 produces a large variety of resonance crossings which involve levels with . Besides the Fermi () and Coriolis () resonances, they were accounted for by inclusion of additional higher-order ( and ) interaction terms between the vibrational states. The least-squares fit of more that 16,000 vibration-rotation transitions provides a quantitative reproduction of data in all bands. 相似文献
9.
J.-M Flaud J Orphal P.-M Flaud C Piccolo 《Journal of Quantitative Spectroscopy & Radiative Transfer》2003,77(4):355-364
Nitric acid which is an important NOx atmospheric reservoir molecule exhibits a strong absorption in the spectral region. Since this region, which corresponds to an atmospheric window, is one of the most commonly used for the retrieval of HNO3 in the atmosphere it is essential to have the best possible corresponding spectral parameters. Updates of these spectral line parameters were recently performed in the last versions of the atmospheric databases. They concern the line positions and intensities not only of the two interfering cold bands ν5 and 2ν9 but also of the ν5+ν9−ν9 hot band. This hot band exhibits indeed a sharp and strong Q branch at which is clearly observable in atmospheric spectra and is used for the retrievals. However, in spite of these recent updates, it proved that the spectral parameters of the hot band are not accurate enough to reproduce accurately the observed atmospheric HNO3 absorption in ATMOS spectra. The present paper is dedicated to a more accurate analysis of this hot band using new laboratory high-resolution (0.002-) Fourier transform spectra. As a consequence, new and more precise line positions and line intensities (about 35% weaker than in HITRAN2K) were derived leading to a significant improvement in the simulation of atmospheric spectra. 相似文献
10.
C Betrencourt-Stirnemann G Graner D.E Jennings W.E Blass 《Journal of Molecular Spectroscopy》1978,69(2):179-198
Previous studies of the parallel bands 2ν2 and of CH3Br by the two first authors have been completed by the analysis of the weaker perpendicular band ν2 + ν5, centered near 2745 cm?1. It is well known that the v2 = 1 and v5 = 1 states of methylbromide are linked by an x-y-type Coriolis interaction. Therefore, in the 2500–2900-cm?1 range, the levels are linked by a similar interaction. Least-squares and prediction programs have been written to treat this kind of problems and they have been satisfactorily applied to both isotopic species, CH379Br and CH381Br. A localized resonance in the K = 0 subband of ν2 + ν5 has been shown to be due to the 3ν3 + ν6 band. No evidence for a strong Fermi resonance between ν1 and has been found. 相似文献
11.
The 71 and 91 vibrational states of deuterated species of formic acid molecule DCOOH have been recorded by a FTIR spectrometer in the region 450- at a resolution of and a millimeter wave spectrometer. In the analysis microwave transitions from literature were used in addition to 14 835 assigned IR and 114 millimeter wave lines in the 71 and 91 vibrational states. The analysis resulted in band origins, rotational, centrifugal distortion, and eight interaction parameters of the Coriolis coupled 71 and 91 vibrational states. RMS deviation of the fit was for the IR data and the maximum values of J and Ka quantum numbers in the fit were 64, 28 and 64, 30 for 71 and 91 states, respectively. 相似文献
12.
The infrared spectra of the 2ν1, 2ν2 and 2ν3 overtones of perchloryl fluoride, FClO3, have been recorded at high resolution using monoisotopic pure samples. Four symmetric top species have been investigated: F35Cl16O3, F37Cl16O3, F35Cl18O3 and F37Cl18O3. The vi = 2, i = 1, 2, 3 vibrationally excited states are totally symmetric, so these overtones correspond to parallel bands of medium/weak intensity, centered from 2010 to 2120 cm−1 (2ν1), from 1390 to 1430 cm−1 (2ν2) and from 1070 to 1100 cm−1 (2ν3). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v1 = 2, v2 = 2 and v3 = 2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067 cm−1. The 2ν1 overtones of F35Cl16O3 and F37Cl16O3 are perturbed by an A1/E Coriolis resonance between the v1 = 2 state and one E component of the v4 = 1, v6 = 2 manifold. The 2ν2 of F37Cl18O3 is perturbed by the same kind of interaction involving the v1 = v6 = 1 (E) state, at about 1396 cm−1. In these bands the resonance is localized on rotational levels with specific J and K values. As a consequence, a few transitions of the perpendicular bands involving the interacting levels could be identified in the spectra. A simultaneous fit of the transitions assigned to the dyads has been performed and the parameters of the excited states have been determined, including the high order Coriolis interaction coefficient . The anharmonic constants x11, x22, x33 of all the studied isotopologues of FClO3, x46 of F35Cl16O3, x46 + g46 of F37Cl16O3 and x16 of F37Cl18O3, have been derived. 相似文献
13.
The high resolution infrared spectra of monoisotopic F35Cl18O3 and F37Cl18O3 have been studied in the region of the ν4 fundamentals, centered at 1278.3 and 1263.3 cm−1, respectively. Large perturbations are observed in both bands due to a Fermi type anharmonic resonance with the ν2 + ν5 combination bands, centered at 1270.7 cm−1 in F35Cl18O3 and 1257.3 cm−1 in F37Cl18O3. In particular, they affect the kl > 0 levels of the v4 = 1 and v2 = v5 = 1 states which cross at kl ? 18 in F35Cl18O3 and kl ? 3 in F37Cl18O3, due to the opposite values of and . The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances are also effective in the excited states of the dyad in F35Cl18O3, while in F37Cl18O3 only the Δl = Δk = ±2 one is active. In the spectrum of F35Cl18O3 3423 transitions have been assigned, 10% of them belonging to ν2 + ν5. The rovibrational parameters and the interaction constants between the v4 = 1 and v2 = v5 = 1 levels have been obtained. The depertubed band origins of ν4 and ν2 + ν5 are 1277.310567(165) and 1271.753733(195) cm−1, respectively, and the anharmonic resonance constant is 2.804416(153) cm−1. For F37Cl18O3, 3022 transitions have been assigned, 38% belonging to the ν2 + ν5 combination band. The depertubed band origins are 1260.856338(123) and 1259.872338(134) cm−1, for ν4and ν2 + ν5 and the constant is 2.9350669(405) cm−1. The equilibrium geometry of perchloryl fluoride, re (ClO) = 139.7(3) pm, re (ClF) = 161.0(5) pm, and αe (OClO) = 115.7(4) degree, has been determined using the Ae and Be equilibrium constants of the four symmetric isotopologues of perchloryl fluoride, F35/37Cl16O3 and F35/37Cl18O3. 相似文献
14.
Vibration-rotation transitions of diacetylene between the first excited states of the ν6 (CCH symmetric bending) and the ν8 (CCH antisymmetric bending) vibrations were observed with a Stark modulation microwave spectrometer. The rotational, centrifugal distortion and l-type doubling constants of the two vibrational states were determined as follows with 2.5 σ uncertainties in parentheses.
4391.3230(84) | 0.582(154) | 2.4830(32) | |
4391.1921(94) | 0.594(179) | 2.4073(37) |