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1.
The Fourier transform infrared (FTIR) absorption spectrum of the ν12 fundamental band of ethylene-d4 (C2D4) was recorded in the 1017-1137 cm−1 region with an unapodized resolution of 0.0063 cm−1. Upper state (v12 = 1) rovibrational constants consisting of three rotational and five quartic constants were improved by assigning and fitting 2103 infrared transitions using Watson’s A-reduced Hamiltonian in the Ir representation. The band centre of the A-type ν12 band is found to be 1076.98480 ± 0.00002 cm−1. The present analysis covering a wider wavenumber range and higher J and Kc values yielded upper state constants including the band centre which are more accurate than previously reported. The rms deviation of the upper state fit is 0.00045 cm−1. Improved ground state rovibrational constants were also determined from the fit of 1247 ground state combination differences (GSCD) from the presently-assigned infrared transitions of the ν12 band of C2D4. The rms deviation of the GSCD fit is 0.00049 cm−1. In the rovibrational analysis, local frequency perturbations were not detected even at high J and Ka values. The calculated inertial defect Δ12 is 0.32551 ± 0.00001 μÅ2. The line intensities of the individual transitions in the ν12 band were measured and the band strength of 39.8 ± 2.0 cm−2 atm−1 was derived for the ν12 band of C2D4. 相似文献
2.
The far infrared and infrared spectra of formamide (HCONH2) have been recorded at high resolution (0.00125 cm−1) in the region of 90-1060 cm−1. Over 20,000 transitions from the out-of-plane NH2 wagging motion (n12 = 1 ← 0 fundamental, n12 = 2 ← 0 overtone, n12 = 2 ← 1 difference bands), torsion (n11 = 1 ← 0 bands), and out-of-phase NCO/NH2 bend (n9 = 1 ← 0 bands) have been assigned. Molecular parameters have been obtained for the ground state and the unperturbed n12 = 1 state. The least-squares fit calculations were completed with the microwave data available in the literature. The complicated resonance system between the n12 = 2, n11 = 1, and n9 = 1 states has been investigated carefully. Thus, we have been able to verify almost all resonances (avoided crossing) existing in the region J, K investigated. In the coupled Hamiltonian used for the fit, all Watson’s reduced parameters, including the octic ones and 16 Coriolis coupling parameters were taken into account. The rms deviation obtained from the fit was 0.000247 cm−1. 相似文献
3.
F. Kwabia Tchana W.J. Lafferty L. Manceron 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(9):1277-1281
The ν9 fundamental band (C-C-C deformation) of propane (C3H8) at 369 cm−1 has been studied at high-resolution (0.0011 cm−1) with spectra recorded using the synchrotron radiation from the French light source facility at SOLEIL coupled to a Bruker IFS 125HR Fourier transform spectrometer. A 2.526 m base multipass cell with optical paths from 10.296 to 151.78 m was used. In addition, a spectrum was also recorded using a conventional globar source. Comparison of these experimental spectra shows clearly the gain obtained on the signal-to-noise ratios with the synchrotron radiation. The spectra have been thoroughly analyzed and transitions up to J=65 and Ka=33 have been assigned. The upper-state rotational levels were fitted using an A-type Watson Hamiltonian written in the Ir representation. An accurate band center ν0 (ν9)=369.228080(25) cm−1 as well as accurate rotational and centrifugal distortion constants have been obtained and used to simulate a synthetic spectrum. These parameters should be useful to simulate hot bands of propane involving the 91 vibrational level as their lower state. 相似文献
4.
The ν3 fundamental band (CO stretch) of HDCO at 1724 cm?1 has been studied using both conventional infrared absorption and CO laser Stark spectroscopy. In addition to the excited-state (v3 = 1) rotational constants, improved constants for the ground state of HDCO have been obtained by combining previous microwave data with some infrared combination differences. The following constants were determined:
Constant | Ground state | state | Units |
1724.267 | cm?1 | ||
198 119.75 | 198 210.4 | MHz | |
34 910.646 | 34 676.6 | MHz | |
29 561.488 | 29 331.3 | MHz | |
2.3302 | 2.3486 | D | |
0.195 | 0.190 | D |
4391.3230(84) | 0.582(154) | 2.4830(32) | |
4391.1921(94) | 0.594(179) | 2.4073(37) |
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