Spectra of carbon disulphide in the 3400–4400 cm−1 region by Fourier transform spectroscopy

Fourier transform spectra have been recorded for carbon disulphide (CS₂) in the region between 3400 cm^?1 and 4400 cm^?1. A data analysis has determined new molecular constants: 14 bands were observed for the main isotopic form ¹²C³²S₂, two bands for the isotopomer ¹²C³²S³⁴S and one each for ¹²C³²S³³S and ¹³C³²S₂.     

High resolution vibration-rotation spectrum of the D2O molecule in the region near the 2ν1 + ν2 + ν3 absorption band

The high resolution Fourier transform spectrum of the D₂0 (ν = ν₁ + ν₂/2 + ν₃ = 3.5) polyad was analysed within the framework of the Hamiltonian model taking into account resonance interactions between the seven states (310), (211), (112), (013), (230), (131) and (032). Transitions belonging to the 2ν₁ + ν₂ + ν₃, 3ν₁ +ν₂ and 3ν₂ + 2ν₃ bands were assigned in the experimentally recorded spectrum. This provided the possibility of obtaining spectroscopic parameters of the ‘visible’ states (211), (310) and (032) and of estimating the band centres, and the rotational and resonance interaction parameters of the ‘dark’ states (112) and (131).     

Line intensities in the ν1 + 2ν2, 2ν2 + ν3, 2ν1, ν1 + ν3, 2ν3, and ν1 + ν2 + ν3 − ν2 bands of H216O,between 6300 and 7900 cm−1

Using Fourier transform spectra, the intensities of 428 weak lines belonging to the ν₁ + 2ν₂, 2ν₂ + ν₃, 2ν₁, ν₁ + ν₃, 2ν₃, and ν₁ + ν₂ + ν₃ − ν₂ bands of the H₂¹⁶O molecule have been measured, between 6300 and 7900 cm⁻¹, with an average uncertainty of 7%.     

The high-resolution infrared spectrum of HBF2: The 201 band near 1164 cm−1

The type-B totally symmetric stretching fundamental ν₂ (near 1164 cm⁻¹) of difluoroborane has been recorded. Rotational and centrifugal distortion constants have been evaluated for the two isotopic species H¹⁰BF₂ and H¹¹BF₂, in both the ground and 2¹ levels. The spectrum has been found to be regular, with no perturbations and no new information on the position of the missing fundamental ν₆.     

The high-resolution infrared spectrum of HBF2: The 401 band near 926 cm−1

The type-C out-of-plane bending fundamental ν₄ (near 926 cm⁻¹) in the infrared spectrum of gaseous difluoroborane, HBF₂, has been recorded at high resolution. Rotational and centrifugal distortion constants have been obtained for the two isotopic species H¹⁰BF₂ and H¹¹BF₂ in both the ground and 4¹ levels. A small rotational perturbation in the 4¹ level of H¹¹BF₂ has allowed an estimate of the position of the ν₆ fundamental, which so far has not been observed directly.     

The near infrared overtone spectrum of propyne taken by diode laser in the 12700 cm−1region

Detailed regions of the near infrared spectrum of propyne between 12737 cm-¹ and 12778cm-¹ have been measured using a simple and inexpensive home-made laser diode spectrometer. This part of the spectrum covers the overlapping 3v₁ + v₃ + v₅ and 3v₁ + v₃ + v₅ + v₁₀—v₁₀ bands. Combining a global fit and an individual profile analysis made possible the determination of the vibrational and rotational constants in each band and in some cases the resolution of the individual K structure in each transition cluster.     

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.     

Absolute line intensities in the ν1 + 3ν3 band of 12C2H2 by laser photoacoustic spectroscopy and Fourier transform spectroscopy

Line intensities and self-broadening coefficients in the ν₁ + 3ν₃ band of ¹²C₂H₂ near 0.8 μm at room temperature were measured by means of both laser photoacoustic and Fourier transform spectroscopy. An experimental protocol has been developed to obtain absolute intensities from the photoacoustic measurements. Namely, the spectrometer was calibrated using water vapour line intensities available in Hitran 1996 [L. S. Rothman et al. (1998) J. quant. Spectrosc. Radiat. Transfer, 60, 665–710]. These photoacoustic line intensities were found to be on average 5% higher than corresponding measurements performed using Fourier transform spectroscopy, the accuracy of the latter being estimated to better than 4%. The accuracy of the photoacoustic intensities is discussed. Previous results from the literature [F. Herregodts, D. Hurtmans, J. Vander Auwera, and M. Herman (1999) J. chem. Phys., 111, 7954—7960] are revised.     

Low-temperature high-resolution absorption spectrum of 14NH3 in the ν1+ν3 band region (1.51 μm)

Jet-cooled spectra of ¹⁴NH₃ and ¹⁵NH₃ in natural abundance were recorded using cavity ring-down (CRDS, 6584–6670 cm^?1) and cavity enhanced absorption (CEAS, 6530–6700 cm^?1) spectroscopy. Line broadening effects in the CRDS spectrum allowed lines with J ^″-values between 0 and 3 to be identified. Intensity ratios in ¹⁴NH₃ between the jet-cooled CRDS and literature room-temperature data from Sung et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012 K. Sung , L.R. Brown , X. Huang , D.W. Schwenke , T.J. Lee , S.L. Coy , and K.K. Lehmann , J. Quant. Spectrosc. Radiat. Transfer 113 , 1066 (2012).[Crossref], [Web of Science ®] , [Google Scholar]), 1066) further assisted the line assignments. Ground state combination differences were extensively used to support the assignments, providing reliable values for J, K and inversion symmetry of the ground state vibrational levels. CEAS data helped in this respect for the lowest J lines, some of which are saturated in the CRDS spectrum. Further information on a/s doublets arose from the observed spectral structures. Thirty-two transitions of ¹⁴NH₃ were assigned in this way and a limited but significant number (19) of changes in the assignments results, compared to Sung et al. or to Cacciani et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012 P. Cacciani , P. Cermak , J. Cosleou , M. Khelkhal , P. Jeseck , and X. Michaut , J. Quant. Spectrosc. Radiat. Transfer 113 , 1084 (2012).[Crossref], [Web of Science ®] , [Google Scholar]), 1084). Sixteen known and 25 new low-J transitions were identified for ¹⁵NH₃ in the CRDS spectrum but the much scarcer literature information did not allow for any more refined assignment. The present line position measurements improve on literature values published for ¹⁵NH₃ and on some line positions for ¹⁴NH₃.     

High-resolution Fourier transform study of the ν3 fundamental band of trans-formic acid

Using high-resolution Fourier transform spectra of trans-HCOOH recorded at 5.6 μm, we carried out an extensive analysis of the strong ν₃ fundamental band (carbonyl stretching mode) at 1776.83 cm^?1, starting from results of a previous analysis [Weber WH, Maker PD, Johns JWC, Weinberger E. J Mol Spectrosc 1987; 121: 243–60]. As pointed out in the literature, the ν₃ band is significantly perturbed by resonances due to numerous dark bands. We were able to assign series belonging to the ν₅+ν₇, ν₅+ν₉, ν₆+ν₇ and ν₆+ν₉ dark bands, located at 1843.48, 1792.63, 1737.96 and 1726.40 cm^?1, respectively. The model used to calculate energy levels accounts partly for the observed resonances, and enabled us to reproduce most of the observed line positions, within their experimental uncertainties. We also determined absolute line intensities with an accuracy estimated to 15%. Finally, we generated, for the first time, a list of line parameters for the 5.6 μm region of trans-formic acid.     

The high-resolution infrared spectrum of ethylene in the 1800–2350 cm−1 spectral region

Fourier transform spectra of ethylene (C₂H₄) have been recorded in the 1800–2350?cm^?1 (4.3–5.6?µm) spectral region using a Bruker IFS125HR spectrometer at a resolution of 0.004?cm^?1 leading to the observation of six vibrational bands, ν ₇?+?ν ₈, ν ₄?+?ν ₈, ν ₆?+?ν ₁₀, ν ₆?+?ν ₇, ν ₄?+?ν ₆ and ν ₃?+?ν ₁₀. The corresponding upper state ro-vibrational levels were fit using a Hamiltonian matrix accounting for numerous interactions. A satisfactory fit could be obtained using a polyad of nine interacting states {8¹10¹,?7¹8¹,?4¹8¹,?8¹12¹,?6¹10¹,?6¹7¹,?4¹6¹,?3¹10¹,?3¹7¹} of which three (8¹10¹, 8¹12¹ and 3¹7¹) are unobserved dark states. As a result a much more accurate and extended set of Hamiltonian constants were obtained than previously derived. The following band centers were determined: ν ₀(ν ₇?+?ν ₈)?=?1888.9783(20)?cm^?1, ν ₀(ν ₄?+?ν ₈)?=?1958.2850(20)?cm^?1, ν ₀(ν ₆?+?ν ₁₀)?=?2047.7589(20)?cm^?1, ν ₀(ν ₆?+?ν ₇)?=?2178.011(60)?cm^?1, ν ₀(ν ₄?+?ν ₆)?=?2252.8026(24)?cm^?1 and ν ₀(ν ₃?+?ν ₁₀)?=?2171.2397(20)?cm^?1. Finally, a synthetic spectrum that could be useful for ethylene detection in planetary atmospheres was generated.     

The Raman spectrum of C2D4 near 1000 cm−1: The Coriolis coupled ν3 and ν6 bands

The Raman spectrum of deuterated ethylene C₂D₄ has been investigated in the 1000-cm⁻¹ regions. The close-lying (16 cm⁻¹ apart) ν₃ and ν₆ bands are perturbed by a Coriolis interaction around the c axis with |ζ₃₆^c| = 0.39. This interaction distorts both the anisotropy and the trace spectra, which are presented as recorded in Aarhus and Madrid, showing also computer simulation of the contours. A least-squares refinement of around 300 transitions allows the determination of the ν₃ and ν₆ band origins and rotational constants.     

Fourier transform spectra of the 3300 cm−1 bands of HCN

The 3300-cm⁻¹ bands of various isotopes of HCN have been measured with a resolution of about 0.01 cm⁻¹ using the Fourier transform spectrometer constructed by J. Brault and co-workers at the National Solar Observatory. The frequencies of 910 HCN lines obtained from absorption spectra of three different isotopic species are reported with an accuracy of approximately 0.0001 cm⁻¹. Six bands of HCN, four bands of H¹³CN, and two bands of HC¹⁵N were analyzed to obtain band origins, rotational constants, and l-doubling constants. The first (11¹0 ← 01¹0) and second (12⁰0 ← 02⁰0 and 12²0 ← 02²0) hot bands of H¹³CN are measured at high resolution for the first time. The fine structures of the Q branches of (110 ← 010), (12²0 ← 02²0), and (13³0 ← 03³0) “hot bands” of HCN have been completely resolved and measured. The accuracies of the calculated band origins are better than 0.0001 cm⁻¹ for most bands, and the upper state rotational constants (B′) have accuracies which range from 1 × 10⁻⁷ to 5 × 10⁻⁶ cm⁻¹ (0.003 to 0.015 MHz).     

Analysis of the Fourier transform infrared spectrum of the stannane species 116SnH4 in the region 1270–1600 cm-1

Monoisotopic stannane 116SnH4 has been investigated at room temperature in the 600–850 cm-1 and 1270–1600 cm-1 regions by FTIR spectroscopy with an effective resolution of 2.1 ×10-3 cm-1 and 2.0 ×10-3 cm-1 respectively. The simultaneous analysis of infrared transitions of both the bending triad and the hot band {bending triad} minus {bending dyad}, enabled us to determine 26 parameters for the (22) band and the combination band (2+4). The standard deviation of the fit was about 1.5×10-3 cm-1. In this analysis, we have used, for the bending triad, a Hamiltonian developed to the fourth order of approximation. 163 observed transitions for the hot band and most observed transitions for the bending triad spectrum, were assigned to the two bands 22 and (2+4), up to J=9. In the fit of the Hamiltonian parameters, we have used for the ground state and for the fundamentals 2 and 4, the parameters determined by Brunet, Pierre, and Bürger [J. Mol. Spectrosc. 140, 237 (1990)].