Line intensities for the ν1, ν3 and ν1+ν3 bands of 34SO2

Using both high resolution (0.0018 cm^?1) and medium resolution (0.112 cm^?1) Fourier transform spectra of an enriched ³⁴S (95.3%) sample of sulfur dioxide, it has been possible to accurately measure a large number of individual line intensities for some of the strongest of the SO₂ bands, i.e. ν₁, ν₃ and ν₁₊ν₃. These intensities were least-squares fitted using a theoretical model which takes into account the vibration–rotation interactions linking the upper energy levels where needed, and, in this way, expansions of the various transition moment operators were determined. The Hamiltonian parameters determined in previous analyses together with these moments were then used to generate synthetic spectra for the bands studied and their corresponding hot bands providing one with an extensive picture of the absorption spectrum of ³⁴SO₂ in the spectral domains, 8.7, 7.4, and 4 μm.     

First high-resolution analysis of the ν15, ν12, ν5, ν10 and ν2 bands of oxirane

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.     

High-resolution spectroscopy of difference and combination bands of SF6 to elucidate the ν3 + ν1 − ν1 and ν3 + ν2 − ν2 hot band structures in the ν3 region

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.     

First high-resolution analysis of the ν1, ν3 and ν1 + ν3 bands of sulphur dioxide 33S16O2

• High-resolution spectra of ³³S¹⁶O₂ have been recorded for the first time in the 8 and 4 µm spectral regions.

• The ν₁, ν₃ and ν₁ + ν₃ bands of the ³³S¹⁶O₂ have been analysed up to very high quantum numbers.

• Accurate ro-vibrational upper states constants have been determined.

     

High-resolution Fourier transform spectroscopy of the ν2 and ν3 fundamentals of nitrosyl fluoride,FNO

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

     

7.

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule     

Zhabina  E. A.  Onopenko  G. A.  Ulenikov  O. N.  Burger  G.  Jerzembeck  W. 《Russian Physics Journal》2002,45(5):483-487

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

8.

Line broadening,shifting and mixing parameters for the ν1 + ν3 band of OCS perturbed by N2 and O2     

C. Jellali  S. Galalou  F. KwabiaTchana  H. Aroui 《Molecular physics》2014,112(8):1189-1200

In this paper, we report measured Rosenkranz N₂- and O₂-broadening, induced pressure-shift and mixing coefficients for OCS in the ν₁ + ν₃ band, using a multi-pressure fitting technique applied to the measured shapes of the lines, including the interference effects caused by the line overlaps. These measurements were made by analysing six laboratory absorption spectra recorded at 0.004 cm^?1 resolution using the Fourier transform spectrometer Bruker IFS125HR located at the Laboratoire Interuniversitaire des Systèmes Atmosphériques, in Créteil. The spectra have been recorded in the 1850–3000 cm^?1 wave number range at 295 K, using a multipass absorption cell with an optical path of 3.249 m. The total sample pressures ranged from 5.97 to 83.28 Torr with OCS volume mixing ratios between 0.001 and 0.013 in nitrogen or oxygen. We have been able to determine the N₂- and O₂-pressure-broadening coefficients of 81 ν₁ + ν₃ transitions with rotational quantum number J up to 50. The measured N₂- and O₂-broadening coefficients range from 0.0815 ± 0.0698 to 0.1169 ± 0.1027 cm^?1 atm^?1 at 295 K, respectively. Most of the measured pressure shifts are positive. The reported N₂- and O₂-induced pressure-shift coefficients vary from about ?0.0103 ± 0.0092 to 0.0097 ± 0.0092 cm^?1 atm^?1, respectively. We have examined the dependence of the measured broadening parameters on the quantum number m (m = ?J for the P branch and m = J + 1 for the R branch) and also developed an empirical expression to describe the broadening coefficients in terms of |m|. On average, this empirical expression reproduces the measured broadening coefficients to within 2%. Using a semi-classical Robert and Bonamy formalism, the theoretical broadening coefficients have been calculated at room temperature and compared with the experimental results. The theoretical results of the broadening coefficients are in very good overall agreement with the experimental data (2%).     

9.

High resolution FTIR spectra and analysis of the ν11 fundamental and of the ν2 + ν11, ν5 + ν12 and ν7 + ν16 combination bands of 12C6D6     

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.     

10.

Measurements and calculations of H2-broadening and shift parameters of water vapour transitions of the ν1 + ν2 + ν3 band     

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.     

11.

The ν1 and ν3 bands of 16O3: Line positions and intensities     

《Journal of Molecular Spectroscopy》1987,124(1):209-217

Using 0.005 cm⁻¹ resolution Fourier transform spectra of samples of ozone, the ν₁ and ν₃ bands of ¹⁶O₃ have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K_a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the ν₁ and ν₃ states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the ν₁ and ν₃ bands of ¹⁶O₃ has been generated.     

12.

H2-broadening,shifting and mixing coefficients of the doublets in the ν2 and ν4 bands of PH3 at room temperature     

Jamel Salem  Ghislain Blanquet  Muriel Lepère  Rached ben Younes 《Molecular physics》2018,116(10):1280-1289

The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν₂ and ν₄ bands of PH₃ perturbed by H₂ have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH₃), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν₂ and ν₄ bands of PH₃ perturbed by hydrogen (H₂) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A₁ and A₂ doublet lines with quantum numbers K = 3n,?(n = 1,?2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.     

13.

Study of the ν3 and 2ν3 ← ν3 bands of 12CH3F by infrared laser sideband and submillimeter-wave spectroscopy     

《Journal of Molecular Spectroscopy》1987,123(1):145-160

An infrared laser sideband spectrometer operating in the CO₂ laser region with 8- to 18-GHz sidebands has been used to record 266 transitions in the ν₃ band and 84 transitions in the 2ν₃ ← ν₃ band of ¹²CH₃F. The accuracy of the measured frequencies is estimated to be 1–3 MHz. A millimeter/submillimeter-wave spectrometer has been used to record the spectra of 48 pure rotational transitions in the ground vibrational state and 55 transitions in the v₃ = 1 vibrational state with an accuracy of 20–90 kHz. The new measurements have been combined with previous radio frequency and infrared laser results to derive sets of constants for the ground, v₃ = 1, and v₃ = 2 states for this molecule. Tables of the vibrational dependence of the parameters and of the near coincidences of the ν₃ and 2ν₃ ← ν₃ band transitions with CO₂ laser frequencies are given.     

14.

Simultaneous analysis of the ν2 and ν4 bands of methane     

D.L. Gray  A.G. Robiette 《Molecular physics》2013,111(6):1609-1625

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 Bξ_2,4 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.     

15.

Absorption of 12CH3D at 6–10 μm: Triad ν3, ν5, ν6     

《Journal of Molecular Spectroscopy》1987,126(1):149-158

The absorption of ¹²CH₃D at 6–10 μm was recorded under vacuum with a resolution of 0.0054 cm⁻¹. For the first time the ν₅ band was assigned extensively, allowing the analysis of ν₃, ν₅, and ν₆ together within a “triad model,” including a rigorous treatment of all the Coriolis couplings involved. The assignments in the spectral range were anlarged from the original 1000 to the present 3500. The newly assigned lines essentially concerned the ν₅ band and a great number of perturbation-allowed transitions (about 30% of all observations). Ground state energy parameters were refined from 2641 combination differences involving J up to 19 and |ΔK| up to 6; the standard deviation of the fit was 0.0003 cm⁻¹. A set of 35 triad upper state energy parameters was derived, reproducing all observations with a standard deviation of 0.0076 cm⁻¹. The three dipole moment derivatives involved in the intensity calculations were estimated theoretically, by taking advantage of the recent accurate determination of the band strengths S₃ and S₄ of ¹²CH₄. Finally, about 6000 triad transitions predicted with linestrengths at least equal to 4 × 10⁻²⁵ cm·molecule⁻¹ were tabulated with assignments, wavenumbers, linestrengths, and lower and upper energy levels.     

16.

Measurements of the line strengths,N2− and O2-broadened half-widths in the ν3, ν1+2ν2 and 2ν1 bands of 14N2 16O at room temperature     

Masashi Fukabori  Tadao Aoki  Takeshi Watanabe 《Molecular physics》2013,111(8):811-818

The line strengths, N₂? and O₂-broadened half-widths in the ν₃, ν₁+2ν₂ and 2ν₁ bands of ¹⁴N₂ ¹⁶O were determined from spectra obtained by a high-resolution Fourier transform spectrometer at room temperature. The squared vibrational transition dipole moments and the coefficients of the Herman–Wallis factor were also determined for these bands. The squared vibrational transition dipole moments for these bands agreed with the values of HITRAN and high-resolution experiments within 6%. The N₂? and O₂-broadened half-widths were in agreement with the results of recent high-resolution experiments. The air-broadened half-widths were calculated using the smoothed N₂? and O₂-broadened half-widths and compared with the compiled values in the HITRAN database.     

17.

High-resolution rovibrational spectroscopy of fluorobenzene,C6H5F: analysis of the B1 fundamentals ν4, ν10b, ν17b,the B2 fundamental ν15 and assignment of the A1 levels ν12, 2ν16a and 2ν18b†     

Sieghard Albert  Karen Keppler 《Molecular physics》2015,113(15-16):2267-2289

     

18.

The 2ν1 + ν3 and 3ν3 bands of 14N16O2     

《Journal of Molecular Spectroscopy》1987,122(2):365-370

The spectra of the 2ν₁ + ν₃ and 3ν₃ bands of ¹⁴N¹⁶O₂ have been recorded by means of high-resolution Fourier transform spectroscopy and have been extensively analyzed. The (2 0 1) and (0 0 3) rotational levels deduced from the analysis have been reproduced within the experimental uncertainty using a Hamiltonian which takes into account the Coriolis interaction coupling the vibrational states of the diads {(2 2 0), (2 0 1)} and {(0 2 2), (0 0 3)}. Finally, precise sets of vibrational energies, and spin-rotation, rotational, and coupling constants have been derived for these vibrational states.     

19.

Analysis of FTIR spectra of CH2 79Br35Cl; the ν3 and ν9 fundamentals     

Marcel Snels  El Bachir Mkadmi 《Molecular physics》2013,111(13):1469-1473

The infrared spectrum of isotopically pure CH₂ ⁷⁹BrCl has been recorded at a resolution of 0.0025?cm^?1 and 0.0023?cm^?1 (FWHM) in the range 600–1600?cm^?1 with a Bruker IFS 120 HR Fourier transform spectrometer in Wuppertal. Here we report the full rotational analysis of the ν₃ and ν₉ fundamentals of the most abundant species CH₂ ⁷⁹Br³⁵Cl . Improved ground state constants, up to quartic terms, have been obtained from ground state combination differences (GSCD) involving transitions of the fundamentals ν₃, ν₄, ν₅ and ν₉. Both ν₃ and ν₉ transitions were fitted to a Watson-type Hamiltonian in the S-reduction, yielding accurate molecular constants for the ν₃ and ν₉ excited states. Small local perturbations were observed in both bands. Prominent features in the spectra were assigned to the ν₃ and ν₉ fundamentals of the CH₂ ⁷⁹Br³⁷Cl isotopic species and the hot-bands ν₃+ν₆???ν₆ and ν₉+ν₆???ν₆ of CH₂ ⁷⁹Br³⁵Cl.     

20.

The 3ν1+ ν2Combination Band of HOCl: Assignments,Perturbations, and Line Intensities     

《Journal of Molecular Spectroscopy》1997,185(2):336-346

The high-resolution spectra (0.012 cm⁻¹) of the 3ν₁+ ν₂combination band of hypochlorous acid HO³⁵⁽³⁷⁾Cl in the near infrared (∼11 478 cm⁻¹) have been measured using a titanium:sapphire intracavity laser absorption (ICLA) spectrometer. Line assignments, absolute intensities, and the total band intensity for both isotopomers are reported. In the course of the band analysis twoK_abranches (K_a= 2,3) were found to be perturbed via low-order Fermi-type (anharmonic) resonances by a dark perturber which has been identified to be the 2ν₁+ 2ν₂+ 3ν₃state. The data are compared with intensity predictions from simple empirical models and discussed with regard to detection limits for this molecule in the near infrared spectral region of the atmosphere.     

	Ground state	$\text{ν}{}_2$	$\text{ν}{}_3$
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)
$\text{ν}{}_0$	0	765.3551 (4)	519.5980 (4)

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

Line broadening,shifting and mixing parameters for the ν1 + ν3 band of OCS perturbed by N2 and O2

In this paper, we report measured Rosenkranz N₂- and O₂-broadening, induced pressure-shift and mixing coefficients for OCS in the ν₁ + ν₃ band, using a multi-pressure fitting technique applied to the measured shapes of the lines, including the interference effects caused by the line overlaps. These measurements were made by analysing six laboratory absorption spectra recorded at 0.004 cm^?1 resolution using the Fourier transform spectrometer Bruker IFS125HR located at the Laboratoire Interuniversitaire des Systèmes Atmosphériques, in Créteil. The spectra have been recorded in the 1850–3000 cm^?1 wave number range at 295 K, using a multipass absorption cell with an optical path of 3.249 m. The total sample pressures ranged from 5.97 to 83.28 Torr with OCS volume mixing ratios between 0.001 and 0.013 in nitrogen or oxygen. We have been able to determine the N₂- and O₂-pressure-broadening coefficients of 81 ν₁ + ν₃ transitions with rotational quantum number J up to 50. The measured N₂- and O₂-broadening coefficients range from 0.0815 ± 0.0698 to 0.1169 ± 0.1027 cm^?1 atm^?1 at 295 K, respectively. Most of the measured pressure shifts are positive. The reported N₂- and O₂-induced pressure-shift coefficients vary from about ?0.0103 ± 0.0092 to 0.0097 ± 0.0092 cm^?1 atm^?1, respectively. We have examined the dependence of the measured broadening parameters on the quantum number m (m = ?J for the P branch and m = J + 1 for the R branch) and also developed an empirical expression to describe the broadening coefficients in terms of |m|. On average, this empirical expression reproduces the measured broadening coefficients to within 2%. Using a semi-classical Robert and Bonamy formalism, the theoretical broadening coefficients have been calculated at room temperature and compared with the experimental results. The theoretical results of the broadening coefficients are in very good overall agreement with the experimental data (2%).     

High resolution FTIR spectra and analysis of the ν11 fundamental and of the ν2 + ν11, ν5 + ν12 and ν7 + ν16 combination bands of 12C6D6

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.     

Measurements and calculations of H2-broadening and shift parameters of water vapour transitions of the ν1 + ν2 + ν3 band

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.     

The ν1 and ν3 bands of 16O3: Line positions and intensities

Using 0.005 cm⁻¹ resolution Fourier transform spectra of samples of ozone, the ν₁ and ν₃ bands of ¹⁶O₃ have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K_a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the ν₁ and ν₃ states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the ν₁ and ν₃ bands of ¹⁶O₃ has been generated.     

H2-broadening,shifting and mixing coefficients of the doublets in the ν2 and ν4 bands of PH3 at room temperature

The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν₂ and ν₄ bands of PH₃ perturbed by H₂ have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH₃), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν₂ and ν₄ bands of PH₃ perturbed by hydrogen (H₂) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A₁ and A₂ doublet lines with quantum numbers K = 3n,?(n = 1,?2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.     

Study of the ν3 and 2ν3 ← ν3 bands of 12CH3F by infrared laser sideband and submillimeter-wave spectroscopy

An infrared laser sideband spectrometer operating in the CO₂ laser region with 8- to 18-GHz sidebands has been used to record 266 transitions in the ν₃ band and 84 transitions in the 2ν₃ ← ν₃ band of ¹²CH₃F. The accuracy of the measured frequencies is estimated to be 1–3 MHz. A millimeter/submillimeter-wave spectrometer has been used to record the spectra of 48 pure rotational transitions in the ground vibrational state and 55 transitions in the v₃ = 1 vibrational state with an accuracy of 20–90 kHz. The new measurements have been combined with previous radio frequency and infrared laser results to derive sets of constants for the ground, v₃ = 1, and v₃ = 2 states for this molecule. Tables of the vibrational dependence of the parameters and of the near coincidences of the ν₃ and 2ν₃ ← ν₃ band transitions with CO₂ laser frequencies are given.     

Simultaneous analysis of the ν2 and ν4 bands of methane

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 Bξ_2,4 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.     

Absorption of 12CH3D at 6–10 μm: Triad ν3, ν5, ν6

The absorption of ¹²CH₃D at 6–10 μm was recorded under vacuum with a resolution of 0.0054 cm⁻¹. For the first time the ν₅ band was assigned extensively, allowing the analysis of ν₃, ν₅, and ν₆ together within a “triad model,” including a rigorous treatment of all the Coriolis couplings involved. The assignments in the spectral range were anlarged from the original 1000 to the present 3500. The newly assigned lines essentially concerned the ν₅ band and a great number of perturbation-allowed transitions (about 30% of all observations). Ground state energy parameters were refined from 2641 combination differences involving J up to 19 and |ΔK| up to 6; the standard deviation of the fit was 0.0003 cm⁻¹. A set of 35 triad upper state energy parameters was derived, reproducing all observations with a standard deviation of 0.0076 cm⁻¹. The three dipole moment derivatives involved in the intensity calculations were estimated theoretically, by taking advantage of the recent accurate determination of the band strengths S₃ and S₄ of ¹²CH₄. Finally, about 6000 triad transitions predicted with linestrengths at least equal to 4 × 10⁻²⁵ cm·molecule⁻¹ were tabulated with assignments, wavenumbers, linestrengths, and lower and upper energy levels.     

Measurements of the line strengths,N2− and O2-broadened half-widths in the ν3, ν1+2ν2 and 2ν1 bands of 14N2 16O at room temperature

The line strengths, N₂? and O₂-broadened half-widths in the ν₃, ν₁+2ν₂ and 2ν₁ bands of ¹⁴N₂ ¹⁶O were determined from spectra obtained by a high-resolution Fourier transform spectrometer at room temperature. The squared vibrational transition dipole moments and the coefficients of the Herman–Wallis factor were also determined for these bands. The squared vibrational transition dipole moments for these bands agreed with the values of HITRAN and high-resolution experiments within 6%. The N₂? and O₂-broadened half-widths were in agreement with the results of recent high-resolution experiments. The air-broadened half-widths were calculated using the smoothed N₂? and O₂-broadened half-widths and compared with the compiled values in the HITRAN database.     

The 2ν1 + ν3 and 3ν3 bands of 14N16O2

The spectra of the 2ν₁ + ν₃ and 3ν₃ bands of ¹⁴N¹⁶O₂ have been recorded by means of high-resolution Fourier transform spectroscopy and have been extensively analyzed. The (2 0 1) and (0 0 3) rotational levels deduced from the analysis have been reproduced within the experimental uncertainty using a Hamiltonian which takes into account the Coriolis interaction coupling the vibrational states of the diads {(2 2 0), (2 0 1)} and {(0 2 2), (0 0 3)}. Finally, precise sets of vibrational energies, and spin-rotation, rotational, and coupling constants have been derived for these vibrational states.     

Analysis of FTIR spectra of CH2 79Br35Cl; the ν3 and ν9 fundamentals

The infrared spectrum of isotopically pure CH₂ ⁷⁹BrCl has been recorded at a resolution of 0.0025?cm^?1 and 0.0023?cm^?1 (FWHM) in the range 600–1600?cm^?1 with a Bruker IFS 120 HR Fourier transform spectrometer in Wuppertal. Here we report the full rotational analysis of the ν₃ and ν₉ fundamentals of the most abundant species CH₂ ⁷⁹Br³⁵Cl . Improved ground state constants, up to quartic terms, have been obtained from ground state combination differences (GSCD) involving transitions of the fundamentals ν₃, ν₄, ν₅ and ν₉. Both ν₃ and ν₉ transitions were fitted to a Watson-type Hamiltonian in the S-reduction, yielding accurate molecular constants for the ν₃ and ν₉ excited states. Small local perturbations were observed in both bands. Prominent features in the spectra were assigned to the ν₃ and ν₉ fundamentals of the CH₂ ⁷⁹Br³⁷Cl isotopic species and the hot-bands ν₃+ν₆???ν₆ and ν₉+ν₆???ν₆ of CH₂ ⁷⁹Br³⁵Cl.     

The 3ν1+ ν2Combination Band of HOCl: Assignments,Perturbations, and Line Intensities

The high-resolution spectra (0.012 cm⁻¹) of the 3ν₁+ ν₂combination band of hypochlorous acid HO³⁵⁽³⁷⁾Cl in the near infrared (∼11 478 cm⁻¹) have been measured using a titanium:sapphire intracavity laser absorption (ICLA) spectrometer. Line assignments, absolute intensities, and the total band intensity for both isotopomers are reported. In the course of the band analysis twoK_abranches (K_a= 2,3) were found to be perturbed via low-order Fermi-type (anharmonic) resonances by a dark perturber which has been identified to be the 2ν₁+ 2ν₂+ 3ν₃state. The data are compared with intensity predictions from simple empirical models and discussed with regard to detection limits for this molecule in the near infrared spectral region of the atmosphere.