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1.
High resolution infrared spectra (0.001 cm−1 FWHM) have been measured for mixtures of 1-chloro-1,1-difluoroethane in Ne, expanded in a supersonic planar jet. The ν6 fundamental, infrared active with a dominant parallel transition moment, exhibits a remarkable splitting of about 0.035 cm−1 for both 35Cl and 37Cl isotopomers. Several mechanisms of interaction of ν6 with states with high torsional excitation are critically examined to explain the observed effect. It is concluded that the observed torsional splitting patterns can be explained in terms of a torsional Coriolis interaction between ν6 and a highly excited torsional mode, 6ν18. A full numerical analysis, performed including a torsional Coriolis term in the Hamiltonian, shows that the interaction mechanism requires a torsional barrier height of about 1270 cm−1. 相似文献
2.
The absorption spectrum of the ν2 fundamental band of the cis-conformer of the transient molecule HOPO, namely the terminal PO stretching mode, has been detected and measured using diode laser spectroscopy. The molecule was generated in a discharge flow system containing hydrogen and white phosphorus vapour (P4) and a trace of oxygen. The spectrum has the appearance of an a-type band of a near prolate asymmetric top. Above Ka = 5 the spectrum is perturbed and transitions terminating on these higher Ka levels were excluded from the fit. The vibrational frequency and rotational constants derived from the unperturbed parts of the spectrum are compatible with new high precision ab initio calculations reported here. A combined fit of the ν2 band and the ν4 band data, measured earlier, was carried out. The ν2 band origin was determined to be 1258.539525(32) cm−1, approximately 5.5 cm−1 higher than the matrix value. 相似文献
3.
Taras Zaporozan 《Journal of Molecular Spectroscopy》2010,264(2):105-110
Rotationally resolved vibrational spectra of the three lowest frequency bands of the four-membered heterocycle azetidine (c-C3H6NH) have been collected with a resolution of 0.00096 cm−1 using the far infrared beamline at the Canadian Light Source synchrotron. The modes observed correspond principally to motions best described as: β-CH2 rock (ν14) at 736.701310(7) cm−1, ring deformation (ν15) at 648.116041(8) cm−1, and the ring puckering mode (ν16) at 207.727053(9) cm−1. A global fit of 14 276 rovibrational transitions from the three bands provided an accurate set of ground state spectroscopic constants as well as excited state parameters for each of the three vibrational modes. The ground state structure was determined to be that of the puckered conformer having the NH bond in an equatorial arrangement. 相似文献
4.
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
5.
The ν4 and the ν9 bands of CF2CH2 have been studied using coincidences with the 10.4 μm band of the CO2 laser and the 10.9 μm band of the N2O laser. These resonances have been analyzed, together with recent microwave results, to give the following vibration-rotation parameters and dipole moments in the ν4 and ν9 states
CF2CH2 | CF2CH2 | ||
925.7692 (2) | 953.8057 (2) | cm?1 | |
10 971.99 (2) | 11 026.918 (6) | MHz | |
10 414.98 (2) | 10 436.381 (6) | MHz | |
5328.48 (2) | 5346.100 (6) | MHz | |
μ | 1.382 (1) | 1.382 (1) | D |
0.014 (2) | 0.004 (1) | D |
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 |
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