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1.
The method of radiofrequency spectroscopy inside a CO2N2O laser cavity has been applied to the observation of pure nuclear quadrupole resonance, A1-A2 transitions and two-photon transitions of AsH3. From the assignment of these transitions some coincidences between laser lines and Δk = 3 transitions in the ν2 band and Δ|k ? l|; = 3 transitions in the ν4 band have been assigned. The quadrupole coupling constant eqQ and its rotational dependence χJ, χK and χd, and the spin-rotation constants CN and CK for the As nucleus have been determined for the ground state. The effective values of eqQ has been determined for the ν2 and the ν4 states. 相似文献
2.
The J = 0 ← 1 transitions in CH379Br (I), CH381Br (II), CD379Br (III), and CD381Br (IV) were measured using a Stark-cell spectrometer constructed from C-band waveguide. High-resolution spectra yielded precise values for the bromine quadrupole coupling strength. Values obtained were eqQ(I) = ?577.08 ± 0.15 MHz, eqQ(II) = ?482.18 ± 0.15 MHz, eqQ(III) = ?575.66 ± 0.15 MHz, and eqQ(IV) = ?480.89 ± 0.15 MHz. The observed center frequencies for the J = 0 ← 1 transitions are ν0(I) = 19136.35 ± 0.03 MHz, ν0(II) = 19063.62 ± 0.03 MHz, ν0(III) = 15429.23 ± 0.03 MHz, and ν0(IV) = 15362.41 ± 0.03 MHz. A 0.26 ± 0.02% decrease in bromine quadrupole coupling is observed when the methyl group is fully deuterated. This is in agreement with, and supports interpretations given for, previous results on methyl chloride. 相似文献
3.
Pure quadrupole resonances of methyl chloride have been observed using the highly sensitive method of infrared-radiofrequency double resonance inside a laser cavity. Quadrupole resonances have been observed for the ground and ν6 states for both the CH3Cl35 and CH3Cl37 isotopes using the direct double-resonance as well as collisionally induced satellites. Most of the six hyperfine constants: the quadrupole coupling constant, eqQ; its rotational dependence, χJ and χK; Hougen's coefficient, χD; and the spin-rotation constants, CN and CK, have been determined for the two states for both isotopes. 相似文献
4.
The infrared absorption of arsine, AsH3, between 750 and 1200 cm?1 has been recorded at a resolution of 0.006 cm?1. Altogether 2419 transitions, including nearly 700 “perturbation allowed” transitions with Δ∥k ? l∥ = ±3, ±6, and ±9, have been assigned to the ν2(A1) and ν4(E) bands. Splitting of the transitions for K″ = 3, 6, and 9 was also observed. To fit the rotational pattern of the v2 = 1 and v4 = 1 vibrational states up to J = 21, all the experimental data were analyzed simultaneously on the basis of a rovibrational Hamiltonian which took into account the Coriolis interaction between ν2 and ν4 and also included several essential resonances within them. The derived set of 38 significant spectroscopic parameters reproduced the 2328 transition wavenumbers retained in the final fit within the accuracy of the experimental measurements. 相似文献
5.
The infrared bands ν2 and ν5 of CH3Br have been measured at a resolution of 0.015 cm?1. The lines due to the isotopic species CH379Br and CH381Br were resolved and altogether about 3000 lines were assigned. The bands were analyzed simultaneously by taking into account the xy-Coriolis resonance between the states v2 = 1 and v5 = 1. A local perturbation observed in ν5 could be explained in terms of a (1,?2) resonance between v2 = 1 and v5 = 1. Some perturbation allowed transitions could be assigned and they give an equation between A0 and D0K. 相似文献
6.
Lary W. Pinkley K. Narahari Rao G. Tarrago G. Poussigue M. Dang-Nhu 《Journal of Molecular Spectroscopy》1977,68(2):195-222
The ν6(E) fundamental vibration-rotation band of monodeuteromethane (12CH3D) has been recorded in the spectral range 1033–1270 cm?1 with a resolution of approximately 0.04 cm?1. Of the 669 transitions with J′ ≤ 17 identified, 633 have been retained for the determination of the rotational levels in the upper state v6 = 1. The Coriolis interaction between the v6 = 1(E) and v3 = 1 (A1) vibrational states of 12CH3D results in large A1A2 splittings of levels with v6 = 1 and |K ? l6| = 0 or 3; the mixing in K and l6 also gives rise to some ten forbidden transitions observed in the spectra. These effects have been very well explained within the formulation based on the contact transformation method. Values of 15 molecular structure constants of the v6 = 1 state have been determined from a least-squares analysis of the 633 retained transitions. These constants can be used to estimate values of the upper-state energies up to fourth order, and through them the spectral positions of the 633 retained transitions are reproduced with an overall standard deviation of 0.013 cm?1, which is within experimental uncertainties. 相似文献
7.
A. Baldacci A. Pietropolli Charmet G. Cazzoli C. Puzzarini 《Journal of Molecular Spectroscopy》2007,246(1):126-132
The enriched 81Br isotopic species of bromofluoromethane has been investigated in the infrared and microwave regions. The rovibrational spectrum of the ν5 fundamental has been studied by high resolution FTIR spectroscopy, while the rotational spectra of the ground and v6 = 1 states have been observed by means of microwave spectroscopy. More than 2700 transitions have been assigned in the ν5 band and the analysis of the rovibrational structure reveals a first-order c-type Coriolis resonance with the v6 = 2 state. The present study improves the ground state constants available in the literature and enables the determination of further centrifugal distortion parameters together with the full bromine quadrupole coupling tensor. A set of spectroscopic parameters up to the sextic distortion terms for the vibrational excited states has been accurately evaluated for the first time. 相似文献
8.
The J → J + 1 transitions (J = 4, 5, 6, 7, 8) in the microwave spectra of methyl isocyanide and its 15N derivative have been obtained and analyzed in the 4ν8 degenerate vibrational state. Theoretical analytical expressions are given for the rotational frequencies in a 4νE state, separately for the l = 0, ±2, ±4 values. These formulas could only be used as a starting point for the assignment and analysis, because of the complexity of the spectrum and the number of accidental resonances appearing in many l = 0 and ±2 lines for low K values. A detailed analysis was obtained through a diagonalization of the energy matrix. Many types of A1A2 doublings could be localized; in particular for CH315NC the K, l = ±1, ±4 doubling allowed the calculation of the g6 coefficient of the 〈K, l|H|, l ± 6〉 term. As in the 3ν8 state, some lines seem to undergo the effects of a vibrational resonance. A set of constants is given for both species, and a comparison is made with the other states. 相似文献
9.
The microwave spectrum of CD3F in the v2 = 1, v3 = 1, v5 = 1, and v6 = 1 states was observed, including the direct l-doubling transitions in the v5 = 1 and v6 = 1 states. The Coriolis interaction between the v2 = 1 and v5 = 1 states was analyzed in detail. An anomaly in the Stark effect was noticed in some of the direct l-doubling transitions in the v6 = 1 states, and was explained in terms of accidental degeneracy between the Kl5 = 1 and the Kl5 = ? 2 levels. Molecular constants associated with the vibrational and rotational motions were determined through an analysis of these spectra.The J = 1 ← 0 transitions of 12CH3F in the v2 = 1, v3 = 1, v5 = 1, and v6 = 1 states and of 13CH3F in the v3 = 1 and v6 = 1 states were observed, as well as the direct l-doubling transitions of 12CH3F in the v5 = 1 state. A preliminary analysis was carried out on the strong Coriolis interaction between the v2 = 1 and v5 = 1 states. 相似文献
10.
C Betrencourt-Stirnemann G Graner G Guelachvili 《Journal of Molecular Spectroscopy》1974,51(2):216-237
A Fourier transform spectrum (resolution 0.005 cm?1) of the ν4 band of methyl bromide has been analyzed. More than one thousand lines have been assigned for each isotopic species CH379Br and CH381Br. A perturbation is apparent mainly near KΔK = 5. It was interpreted as due to a Coriolis interaction with ν3 + ν5 + ν6. The whole spectrum is reproduced with a standard deviation smaller than 10?3 cm?1. Finally, the “hot” band ν4 + ν3 ? ν3 has been assigned and analyzed. 相似文献
11.
About 940 Stark resonances for CD335Cl and 610 resonances for CD337Cl have been measured by using a CO2 laser with the 9- and 10-μm regions. They were assigned to 59 rovibrational transitions of ν2 (J′ ≤ 37, K ≤ 14) and 200 of ν5 (J′ ≤ 47, ?14 ≤ k′l′ ≤ +10) for 35Cl, and 31 of ν2 (J′ ≤ 12, K ≤ 10) and 175 of ν5 (J′ ≤ 46, ?14 ≤ k′l′ ≤ +9) for 37Cl. These data, combined with the microwave and FIR data in the ν2 and ν5 states, were analyzed by taking account of the Coriolis interaction between ν2 and ν5, and the (2, 2) and (2, ?1) interactions in ν5. Several ΔK = +2 transitions of the ν5 band were observed in the Stark spectra, and the ground state constants, A0 and DK0, were determined precisely for both 35Cl and 37Cl species. Also, the vibrationally induced dipole moments were obtained. The molecular constants and the zero-field transition frequencies of the ν2 and ν5 bands were determined. 相似文献
12.
Georges Graner 《Journal of Molecular Spectroscopy》1974,51(2):238-260
This band was studied on a Fourier Transform spectrum (resolving power of the apparatus: 0.005 cm?1). For each isotopic species CH379Br and CH381Br, about 800 lines were assigned. The band is well explained by a x-y type Coriolis interaction with ν2 + ν5. Several local resonances occur for low K values as well as a doubling of the K = 3 levels. Their study provides interesting information on neighboring bands, especially 3ν6(E), ν2 + ν3 + ν6, and 2ν5(E). 相似文献
13.
A value of A0 = 5.1800 ± 0.0010 cm?1 for CH3Br has been determined from an analysis of the ν4 Raman band, based both on a direct fit of Q-branch frequencies and on ground state combination differences. The constants ν4, (Aζ)4, η44, and Ae = 5.2442 ± 0.0015 cm?1 were also determined. The equilibrium distance of the H atoms from the figure axis is calculated as 0.32077 ± 0.00005 Å. All the fundamental Raman bands of CH3Br were observed, and experimental results for the ν1, ν2 and ν5 bands are included. 相似文献
14.
About 900 Stark transitions from 70 vibration-rotation transitions in CH335Cl and about 400 transitions from 38 transitions in CH335Cl in the ν6 band have been assigned. These data were analyzed simultaneously with previously published microwave data on the ν6 = 1 state. The fit has a standard deviation of about 2 MHz for the data for both isotopes. The isoptopic shift ν635 ? ν637 = 0.3766(6) cm?1. Rotational dependence of the dipole moment was also just apparent at about μJ = μK = 1 × 10?5 D, and a complete set of molecular constants is given. 相似文献
15.
The infrared spectrum of gaseous cyclopropane has been measured in the regions 980–1080 and 1400–1500 cm?1, containing the ν10 and ν9E′ fundamental bands, respectively, using a high-resolution Fourier transform instrument. Deconvolution was used to enhance the resolution in the crowded parts of the spectrum to ~0.0020–0.0025 cm?1. Apart from the rotational l-resonance affecting mainly the low-K subbands, the ν9 band is strongly perturbed by Fermi resonance with the 2ν142 state lying ~41 cm?1 above. The effects of the Fermi resonance are most pronounced in the high-KΔK = +1 subbands as the 2ν14?2 levels would cross the ν9+ levels near K = 30. rR lines of 2ν14?2 for K = 24 to 36, enhanced by the resonance, have been identified in the region 1469–1475 cm?1 of the spectrum. Two extra perturbation-enhanced subbands are found adjacent to the K = 16?17 and K = 17?16 subbands of ν9: these have been ascribed to the K = 18?17 transitions in 2ν14?2 and to the K = 19?16 transitions in , respectively, as their upper states coincide with the corresponding levels ν9?(K = 16) and ν9+(K = 17). A combination of l-resonance and Fermi resonance is mainly responsible for the interactions causing the perturbations and appearance of the extra subbands, but a direct rotational interaction 〈ν9?(K)|h3|2ν14?2(K + 2)〉 also had to be introduced to accurately account for the observations. In contrast, the ν10 band is not appreciably perturbed by other states and merely exhibits effects of strong l-resonance in the low-K subbands, and K-doubling of the high-J lines of the K = 2–3 subband. A detailed analysis of the spectrum and of the perturbations is described and sets of accurate spectroscopic constants are reported for ν10 and ν9 as well as for the perturbing state 2ν142, which reproduce 3020 observed lines of the ν10 band with a standard deviation of 0.0008 cm?1 and 1810 lines of ν9 with a standard deviation of 0.0010 cm?1. 相似文献
16.
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
17.
H.-J. Clar M. Reich R. Schieder G. Winnewisser Koichi M.T. Yamada 《Journal of Molecular Spectroscopy》1985,112(2):447-458
The ΔK = Δl = +1 transitions of the ν6 band of the CH3I molecule were measured by a tunable diode laser spectrometer. A newly designed Fabry-Perot étalon with a free spectral range of 0.00945 cm?1 was used to calibrate the line position very precisely. The present data were analyzed together with the previously reported transition wavenumbers, and precise molecular constants have been obtained. 相似文献
18.
Laurie's theory on the coupling between internal rotation and a degenerate vibration in a symmetric-top molecule is examined by investigating the microwave spectra of methyl silane and methyl silane-d3 in the ν12 and ν6 + ν12 states. Two sets of l-type doublets are observed in the J = 2 ← 1, K = 1 transitions; however, the observed frequencies as well as the Stark effects of the l-type doublets indicate definitely that Laurie's expressions for the l-type doublets are to be revised. It is shown theoretically that Coriolis couplings remove discrepancy between theory and experiment; when A1 and A2 denote the rotational constants of CH3 and SiH3 about the symmetry axes and ζ1 and ζ2 measure the magnitudes of angular momenta induced by the ν12 vibration in the two tops, experimental results require that (−A1ζ1 + A2ζ2) is 104 950-107 048 MHz and 45 214-47 626 MHz for CH3SiH3 and CH3SiD3, respectively. 相似文献
19.
The and fundamental bands of CH379Br and CH381Br have been studied by Fourier transform infrared spectroscopy with an unapodized resolution of 0.004 cm−1, corresponding to an improvement of one order of magnitude compared to previous studies. For both isotopomers, some 2427 (2239) lines were newly assigned for the parallel and the perpendicular bands and, in addition, 80 perturbation-allowed transitions were also added. The ground-state axial rotational constants A0 were redetermined from allowed and perturbation-allowed infrared transitions observed in the v2 and v5 bands around the local crossing. The A0 values obtained for both isotopomers are more accurate but fully compatible with those obtained previously. Using those results, and the variation of the rotational constants with vibration, new accurate equilibrium constants Ae and Be have been also determined for CH379Br and CH381Br. The excited states v2=1 and v5=1 are coupled by Coriolis-type interactions (Δl=±1,ΔK=±1) and (Δl=?1,ΔK=±2), while the l5=±1 levels of v5 interact also through “l(2,2)”-type interaction (Δl=±2,ΔK=±2). The Coriolis coupling term was determined to be for CH379Br and for CH381Br. All interaction parameters have been determined with higher accuracy, compared to previous studies. A total of 4213 (3704) line positions with J?68(64) and K?16(11) including all available data was fitted using 20 (18) parameters with a root-mean-square deviation of 0.0007 (0.0006) cm−1 for CH379Br and CH381Br, respectively. Two different but equivalent forms of reduced Hamiltonians with two different sets of constrained constants were successfully applied according to Lobodenko's reduction [J. Mol. Spectrosc. 126 (1987) 159]. The ratio of the transition moments, |d2/d5|=1.65, and a positive sign of the Coriolis intensity perturbation d2×ζ25×d5 were determined. Therefore, it has been possible to generate an accurate prediction of the whole spectrum between 1200 and 1650 cm−1, including Q branches. 相似文献
20.
Isao Suzuki 《Journal of Molecular Spectroscopy》1976,61(2):289-298
The ν2 band of CH3CD3 has been measured under an effective resolution of 0.04 cm?1. About 400 transitions observed in the region from 2130 to 2060 cm?1 have been identified as due to the ν2 fundamental band. The least-squares analysis of these transitions yields the band constants: ν0 = 2089.957, B′ = 0.548937, DJ′ = 6.97 × 10?7, DJK′ = 1.92 × 10?6, A′ - A″ = ?0.01158, and DK′ - DK″ = 1.30 × 10?6 cm?1. The ground-state constants B″, DJ″, and DJK″ are fixed to the values obtained from microwave spectroscopy. 相似文献