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1.
The absorption spectrum of ozone, 16O3, has been recorded in the 5903-5960 cm−1 region by high sensitivity CW-cavity ring down spectroscopy (αmin ∼ 5 × 10−10 cm−1). The ν1 + 3ν2 + 3ν3 and 4ν1 + ν2 + ν3 A-type bands centred at 5919.15 and 5947.07 cm−1 were newly observed. A set of 173 and 168 energy levels could be experimentally determined for the (1 3 3) and (4 1 1) states, respectively. Except for a few Ka = 5 levels of the (4 1 1) state, the rotational structure of the two states was found mostly unperturbed. The spectroscopic parameters were determined from a fit of the corresponding line positions by considering the (1 3 3) and (4 1 1) states as isolated. The determined effective Hamiltonian and transition moment operators were used to generate a list of 785 transitions given as Supplementary Material.  相似文献   

2.
A high-resolution Fourier transform spectrum of the D2MSe species (M = 82, 80, 78, 77, and 76) in the region 2300-2500 cm−1 was recorded for the first time and assigned. On the basis of these experimental data, rotation-vibration energies of the (1 1 0) and (0 1 1) vibrational states were fitted, and band centers, and rotational, centrifugal distortion, and resonance interaction parameters were determined for the main D280Se species. The obtained set of 32 fitted parameters reproduces the 647 rotation-vibration energies with a rms deviation of 0.00024 cm−1. The ν1 + ν2 and ν2 + ν3 bands of the other four isotopic species are analyzed as well.  相似文献   

3.
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 (Kσ) 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 (gsν12) Coriolis-like and (gsν5) Fermi-like interactions along with a higher order (ν12ν5) 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   

4.
This study provides the first direct experimental measurements of the off-diagonal relaxation matrix element coefficients for line mixing in air-broadened methane spectra for any vibrational band and the first off diagonal relaxation matrix elements associated with line mixing for pure methane in the ν2 + ν3 band of 12CH4. The speed-dependent Voigt profile with line mixing is used with a multispectrum nonlinear least squares curve fitting technique to retrieve the various line parameters from 11 self-broadened and 10 air-broadened spectra simultaneously. The room temperature spectra analyzed in this work are recorded at 0.011 cm−1 resolution with the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory, Kitt Peak, Arizona. The off-diagonal relaxation matrix element coefficients of ν2 + ν3 transitions between 4410 and 4629 cm−1 are reported for eighteen pairs with upper state J values between 2 and 11. The observed line mixing coefficients for self broadening vary from 0.0019 to 0.0390 cm−1 atm−1 at 296 K. The measured line mixing coefficients for air broadening vary from 0.0005 to 0.0205 cm−1 atm−1 at 296 K.  相似文献   

5.
The ν18 fundamental band (∼158 cm−1) of acrolein is studied at high resolution (0.0015 cm−1) using synchrotron radiation from the Canadian Light Source facility and a Bruker IFS 125HR Fourier transform spectrometer. By fitting this band, together with some pure rotational transitions, molecular parameters are obtained to accurately determine the energies of the ν18 = 1 state levels for values of (JKa) up to at least (45, 24). These parameters should be useful for future high resolution studies of acrolein hot bands. This is demonstrated here by a detailed analysis of the (ν17 + ν18) − ν18 hot band at ∼589 cm−1. The upper state (ν17 + ν18) of this band is found to be perturbed by Coriolis interactions analogous to those affecting the ν17 state.  相似文献   

6.
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   

7.
The ammonia ν1 + 2ν4 perpendicular stretch-bend combination band has been investigated in spectra of 14NH3 and 15NH3 recorded in the 6400-6800 cm−1 region with an external cavity tunable diode laser (ECTDL) spectrometer. For 14NH3, new assignments were determined initially by extrapolating from published low-J jet-cooled beam results up to transitions of higher J and K. Corresponding ν1 + 2ν4 transitions for the 15NH3 species were then found by identifying similar patterns of lines with a characteristic downshift of approximately 9.7 cm−1. Assignments were confirmed employing ground-state combination differences. Term values, a-s inversion splittings, l-doubling energies and parameter estimates from simple single-state fits are reported for the two ammonia species.  相似文献   

8.
The ν1(A1), Si-H stretching, ν2(A1) and ν4(E), Si-D stretchings, fundamental bands of HSiD3 have been recorded at an effective resolution of ca. 0.003 cm−1 between 2080 and 2280 cm−1 and between 1480 and 1720 cm−1, respectively. Ro-vibrational transitions of the H28SiD3 isotopologue have been assigned in the two spectral ranges, about 700 belonging to ν1, with J′ up to 25 and K up to 21, and about 1600 to the ν2/ν4 dyad, with J′ up to 24 and K′ up to 19. The spectra of all the bands evidence the existence of several perturbations. The transitions of ν1 have been analyzed either neglecting or including in the model A1/E Coriolis-type interactions with nearby dark states. The υ2 = 1 and υ4 = 1 states have been fitted simultaneously taking into account several ro-vibrational interactions between them and, in addition, with the υ5 = 2, l = 0 component, and with few other close dark states. The standard deviation of the fit for both ν1 and the ν2/ν4 dyad is, however, more than one order of magnitude larger than the estimated experimental precision and is independent on the adopted model.  相似文献   

9.
We report measurements of self- and nitrogen-pressure broadening of the P(11) line in the ν1 + ν3 combination band of acetylene at 195 739.649 5135(80) GHz by absorption of radiation emitted by an extended cavity diode laser referenced to a femtosecond frequency comb. Broadening, shift and narrowing parameters were determined at 296 K. For the most appropriate, hard collision, model in units of cm−1/atm, we find 0.146317(27), 0.047271(104) and −0.0070819(22) for the acetylene self-broadening, narrowing and shift, and 0.081129(35), 0.022940(74) and −0.0088913(25) respectively, for the nitrogen-broadening parameters. The uncertainties are expressed as one standard deviation (in parenthesis) in units of the last digit reported. These parameters are 2-3 orders of magnitude more precise than those reported in previous measurements. Similar analyses of the experimental data using soft collision and simple Voigt lineshape models were made for comparison.  相似文献   

10.
The high-resolution Fourier transform absorption spectrum of an isotopic sample of nitrogen dioxide, 15N16O2, was recorded in the 3.4 μm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242 (1991) 367-377] a new analysis of the ν1 + ν3 band located at 2858.7077 cm−1 has been performed. This new assignment concerns (1 0 1) energy levels involving rotational quantum numbers up to Ka = 10 and N = 54. Using a theoretical model which accounts for both the electron spin-rotation resonances within each vibrational state and the Coriolis interactions between the (1 2 0) and (1 0 1) vibrational states, the spin-rotation energy levels of the (1 0 1) vibrational state could be reproduced within their experimental uncertainty. In this way, the precise vibrational energy, rotational, spin-rotation, and coupling constants were achieved for the {(1 2 0), (1 0 1)} interacting states of 15N16O2. Using these parameters and the transition moment operator which was obtained for the main isotopic species, 14N16O2, a comprehensive list of the line positions and intensities was generated for the ν1 + ν3 band of 15N16O2.  相似文献   

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