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1.
Vibration-rotation spectra of the ν2 and ν4 bands of CH4 have been analysed by a simultaneous diagonalization of the hamiltonian matrices for the v 2=1 and v 4=1 states coupled by the Bξ2,4 Coriolis interaction term. The effective hamiltonians used extend to sextic centrifugal distortion terms. The results are a significant improvement on any previous analysis; 438 assigned transitions up to J′=16 have been fitted with an overall standard deviation of 0·016 cm-1. The method used is compared with an alternative theoretical approach given by Berger. 相似文献
2.
MARCEL SNELS HANS HOLLENSTEIN MARTIN QUACK ELISABETTA CANÉ ANDREA MIANI AGOSTINO TROMBETTI 《Molecular physics》2013,111(7):981-1001
We report results from measurements of the high resolution FTIR spectrum for the fully deuterated benzene molecule C6D6 in the range 450–3500 cm?1. Accurate spectroscopic constants have been obtained for the fundamental vibration ν11 at 496.208 cm?1 and improved ground state constants have been deduced from a fit of ground state combination differences. The J structure of the combination parallel bands ν2 + ν11 (at 2798.1 cm?1), ν5 + ν12 (1802.5 cm?1) and ν7, + ν16 (2619.3 cm?1) of C6D6 has been analysed as well, from which improved values of the band origin and of the B and D j constants of the excited states have been obtained. The strongest hot bands accompanying these parallel transitions have been assigned by means of the anharmonic force field calculated by Maslen et al. [1992, J. chem. Phys., 97, 4233]. In particular (ν11 + ν16) ? ν16 is assigned to the band at 492.4 cm?1 even though its shape is typical of a perpendicular transition (PAPE). New values for the ν5, ν12 and ν16 band origins are determined from the band origins of combination bands and from calculated anharmonic constants. Numerous anharmonic constants are derived from the assignment of hot band and combination transitions. 相似文献
3.
J.-M. Flaud W.J. Lafferty F. Kwabia Tchana A. Perrin X. Landsheere 《Journal of Molecular Spectroscopy》2012,271(1):38-43
Fourier transform spectra of oxirane (ethylene oxide, c-C2H4O) have been recorded in the 730–1560 cm?1 (6.4–13.7 μm) spectral region using a Bruker IFS125HR spectrometer at a resolution of 0.0019 cm?1. A total of six vibration bands, ν15, ν12, ν5, ν3, ν10 and ν2, have been observed and analyzed. The corresponding upper state ro-vibrational levels were fit using Hamiltonian matrices accounting for various interactions. Satisfactory fits were obtained using the following polyads {151, 121, 51} and {101, 21} of interacting states. As a result, an accurate and extended set of Hamiltonian constants were obtained. The following band centers were derived: ν0 (ν15) = 808.13518(60) cm?1, ν0 (ν12) = 822.27955(37) cm?1, ν0 (ν5) = 876.72592(15), ν0 (ν3) = 1270.37032(10) cm?1, ν0 (ν10) = 1471.35580(50) cm?1 and ν0 (ν2) = 1497.83309(15) cm?1 where the uncertainties are one standard deviation. 相似文献
4.
The vibration-rotation spectra of the ν1 and ν8 fundamental bands of 32SF4 have been observed using Fourier-transform infrared spectroscopy. The band centre of the c-type ν1 symmetric sulphur-equatorial-fluorine stretching vibration was observed at 891.6 cm?1 and that for the b-type ν8 asymmetric sulphur-equatorial-fluorine stretching vibration at 864.6 cm?1. In total, 2044 rovibrational transitions have been assigned. Analysis of the spectra showed that the rotational states of the ν1 = 1 and ν8 = 1 upper vibrational levels are coupled by an a-type Coriolis interaction. This coupling has been treated both using perturbation theory and by the explicit inclusion of an appropriate Hamiltonian matrix element in a combined fit of the data for both bands. Spectroscopic parameters have been determined for the ground, ν1 = 1 and ν8 = 1 vibrational levels. Weaker transitions resulting from difference bands and the fundamental bands of the 34SF4 isotopomer have been identified but could not be assigned, because of the density of lines in the room-temperature spectrum. The possibility that discrepancies between the observed and predicted spectra of the ν1 fundamental may result from either a Coriolis interaction with the states of another vibrational level, or the effects of intramolecular exchange of axial and equatorial fluorine atoms is considered. The discussion is supported by theoretical calculations which show that the likely path for intramolecular exchange is via a C 4v transition state. 相似文献
5.
The strong infrared absorption in the ν3 S–F stretching region of sulphur hexafluoride (SF6) near 948 cm?1 makes it a powerful greenhouse gas. Although its present concentration in the atmosphere is very low, it is increasing rapidly, due to industrial pollution. The ground state population of this heavy species is only 32% at room temperature and thus many hot bands are present. Consequently, a reliable remote-sensing spectroscopic detection and monitoring of this species require an accurate modelling of these hot bands. We used two experimental set-ups at the SOLEIL French synchrotron facility to record some difference and combination bands of SF6: (1) a new cryogenic multiple pass cell with 93 m optical path length and regulated at 163 ± 2 K temperature and (2) the Jet-AILES supersonic expansion set-up. With this, we could obtain high-resolution absorption spectra of the ν3 ? ν1, ν3 ? ν2, ν1 + ν3 and ν2 + ν3 bands at low temperature. These spectra could be assigned and analysed, thanks to the SPVIEW and XTDS computer programs developed in Dijon. We performed two global fits of effective Hamiltonian parameters. The first one is a global fit of the ground state, ν2, ν3, ν3 ? ν2, ν2 + ν3, 2ν3 and 2ν3 ? ν3 rovibrational parameters, using the present spectra and previous infrared, Raman and two-photon absorption data. This allows a consistent refinement of the effective Hamiltonian parameters for all the implied vibrational levels and a new simulation of the 2ν3 + ν2 ? ν2 hot band. The second global fit involves the present ν3 ? ν1 and ν1 + ν3 lines, together with previous ν1 Raman data, in order to obtain refined ν1 parameters and also ν1 + ν3 parameters in a consistent way. This allows to simulate the ν3 + ν1 ? ν1 hot band. 相似文献
6.
The high-resolution Fourier transform infrared spectrum of CH2D79Br has been recorded and analysed in the region of the ν4 and ν8 fundamentals located in the range 1125?1360 cm?1. The strong ν4 band, centred at 1225 cm?1, shows an a/b-hybrid structure with predominant a-type character, whereas ν8, at 1253 cm?1, generates a c-type contour comparable in intensity to the b-type component of ν4. The upper states of these fundamentals are coupled through a- and b-type Coriolis resonances; further complications in this band system arise from perturbations due to the ν6 = 2 (1183 cm?1) and ν5 = ν6 = 1 (1359 cm?1) dark states. The former interacts with ν8 = 1 by b-type Coriolis coupling, whereas the latter perturbs the ν4 = 1 and ν8 = 1 levels by anharmonic and a-type Coriolis resonances, respectively. Accurate upper state parameters and interaction terms have been determined for the tetrad system ν4/ν8/2ν6/ν5+ν6 by also including in the dataset the assigned transitions of the 2ν6?ν6 and ν5+ν6?ν6 hot bands obtained from previous analysis. 相似文献
7.
T. M. Petrova A. M. Solodov A. A. Solodov V. M. Deichuli V. I. Starikov 《Molecular physics》2018,116(10):1409-1420
The water vapour line broadening and shifting for 97 lines in the ν1 + ν2 + ν3 band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm?1 and in a wide pressure range of H2. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν2, ν1, and ν3 vibrational bands are presented. 相似文献
8.
The ν2 and ν3 fundamentals of FNO have been recorded with a Fourier transform spectrophotometer at an apodized resolution of approximately 0.004 cm?1. The Fourier infrared data have been analyzed together with previous microwave data to yield improved molecular parameters for the (000) and (010) vibrational states and the first set of constants for the (001) state. The main results (in cm?1) are
Ground state | |||
A | 3.1751882 (17) | 3.1861249 (12) | 3.1958722 (15) |
B | 0.39508266 (12) | 0.39407878 (14) | 0.39211484 (14) |
C | 0.35051504 (11) | 0.34899779 (16) | 0.34747411 (14) |
0 | 765.3551 (4) | 519.5980 (4) |