HDO absorption spectrum above 11 500 cm: Assignment and dynamics

Assignment of an HDO line list extracted from a recently measured H₂O/HDO/D₂O Fourier transform absorption spectrum recorded in the 11 600-23 000 cm⁻¹ region by Bach et al. (M. Bach, S. Fally, P.-F. Coheur, M. Carleer, A. Jenouvrier, A.C. Vandaele, J. Mol. Spectrosc. 232 (2005) 341-350.) is presented. More than 94% of the 3256 lines are given quantum number assignments and ascribed to line absorption by HDO; most of the remaining lines are actually due to D₂O. High accuracy variational predictions of line positions and intensities are used for the spectral assignment process. Assignments to the ν₁ + 5ν₃, 2ν₂ + 5ν₃, ν₁ + ν₂ + 3ν₃ and ν₁ + 6ν₃ bands are presented for the first time. Comparisons are made with published ICLAS spectra covering the same spectral region and suggestions made for its recalibration. The results are used to illustrate the dynamical behaviour of highly excited vibrational states of HDO and to discuss previous vibrational assignments to high lying rotation-vibration states of this system.     

Fourier transform measurements of water vapor line parameters in the 4200-6600 cm region

New high-resolution water vapor absorption spectra were obtained at room temperature in the 4200-6600 cm⁻¹ spectral region by combining Fourier transform spectrometers (FTS) with single and multiple reflection cells. With absorption paths from 0.3 to 1800 m in pure and air diluted water vapor, accurate measurements of about 10400 lines in an intensity range from 10⁻²⁹ to 10⁻¹⁹ cm/molecule have been performed. Positions, intensities, self- and air-broadening coefficients and air-induced shifts were determined for the H₂¹⁶O, H₂¹⁷O, H₂¹⁸O and HDO isotopologues. The rovibrational assignment of the observed lines was performed with the use of global variational predictions and allowed the identification of several new energy levels. One major contribution of this work consists of the identification of 3280 new weak lines. A very close agreement between the new measured parameters and those listed in the database is reported as well as between the observations and the most recent variational calculations for the positions and the intensities. The present parameters provide an extended and homogeneous data set for water vapor, which is shown to significantly improve the databases for atmospheric applications, especially in the transmission windows on both sides of the band centered at 5400 cm⁻¹.     

High resolution Fourier transform spectrum of HDO in the 7500-8200 cm region: revisited

The HDO absorption FT spectrum is recorded and analyzed in the 7500-8200 cm⁻¹ spectral region. The high accuracy ab initio calculation of Schwenke and Partridge was successfully applied for spectrum assignment that resulted in derivation of 508 precise rovibrational energy levels for the (3 0 0), (0 3 1), (1 1 1), (0 6 0), (2 2 0), and (0 0 2) states, with 295 of them being reported for the first time. In particular, eight new energy levels, including the band center at 7914.3170 cm⁻¹, were derived for the highly excited bending (0 6 0) state from transitions borrowing their intensities through local high-order resonance coupling with the (3 0 0) and (0 3 1) states.     

Intracavity laser absorption spectroscopy of HDO between 11 645 and 12 330 cm

The weak absorption spectrum of monodeuterated water, HDO, has been recorded by intracavity laser absorption spectroscopy (ICLAS) between 11 645 and 12 330 cm⁻¹. This spectrum is dominated by the ν₂ + 3ν₃ band of HDO at 11969.76 cm⁻¹. A total of 497 energy levels belonging to 12 vibrational states were determined while only 140 levels were previously reported from a recent investigation by Fourier transform spectroscopy in the same spectral region. The rovibrational identification process of the 1378 lines assigned to the HDO isotopologue was mostly based on the results of the accurate variational calculations of Schwenke and Partridge. The overall agreement between these calculations and the observed spectrum is very good. However, strong discrepancies in the calculated line intensities were evidenced in a few cases corresponding to an intensity transfer to a dark state through local resonance interaction.     

High-resolution ro-vibrational spectroscopy of HDO in the region of 8900-9600 cm

The high-resolution absorption spectrum of the HDO molecule was recorded with a Fourier-transform interferometer in the region of 8900-9600 cm⁻¹, where the strongly interacted bands 2ν₁ + ν₃, 3ν₁ + ν₂, ν₁ + 2ν₂ + ν₃, 2ν₁ + 3ν₂, 4ν₂ + ν₃, ν₁ + 5ν₂, and 7ν₂ are located. About 1000 transitions were assigned to these seven bands based on the ab initio predictions [J. Chem. Phys. 106 (1997) 4618]. Altogether, 375 upper energy levels were determined, including 24 energy levels of the highly excited bending (070) state. On that basis, the necessity of the “Effective Hamiltonian” concept in the spectroscopic analysis is discussed.     

Fourier transform spectroscopy of N2O weak overtone transitions in the 1-2 μm region

The absorption spectrum of the natural sample of nitrous oxide has been recorded at Doppler limited resolution with a Fourier-transform spectrometer in the spectral range 5000-10 000 cm⁻¹. Ten cold bands (8Σ − Σ and 2Σ − Π), thirteen hot bands (11Π − Π, Σ − Σ, and Δ − Δ) of ¹⁴N₂¹⁶O and the 3ν₃ band of ¹⁴N¹⁵N¹⁶O have been newly detected. The uncertainty of the line position determination is estimated to be about 0.005 cm⁻¹ for unblended lines. The assignment of the spectrum has been done with the help of the prediction performed within the framework of the polyad model of effective Hamiltonian. The spectroscopic parameters G_v, B_v, D_v, H_v, and q_v have been determined for all newly detected bands. The line intensities of 13 weak bands have been measured. The uncertainty of the obtained line intensity values varies from 7 to 13%.     

Fourier-transform spectroscopy of NNO in the 3500-9000 cm region

The Fourier-transform absorption spectrum of ¹⁵N¹⁴N¹⁶O-enriched nitrous oxide has been recorded at the Doppler limited resolution in the spectral range 3500-9000 cm⁻¹. More than 15 000 transitions of ¹⁵N¹⁴N¹⁶O were observed and assigned based on the global effective Hamiltonian model. The band-by-band analysis led to the determination of the ro-vibrational parameters of a total of 133 bands. Among these bands, 103 were newly observed, and the rotational analysis of 30 others were significantly extended and improved.     

Self-broadened line parameters for water vapour in the spectral region 5000-5600 cm

The self-broadening coefficients and intensities of approximately 460 of the strongest water vapour lines (intensity S ? 1.5 × 10⁻²³ cm molec⁻¹) in the spectral region 5000-5600 cm⁻¹ have been derived from new laboratory measurements. The derived line intensities are on average in a good agreement with those in HITRAN-2001 (v.11.0) (within 0.5% for total band intensity). Self-broadening coefficients are compared with values estimated from the HITRAN-2001 foreign-broadening coefficients. Comparison has been also made with the recent HITRAN-2004 (v.12.0) compilation, which revealed marked systematic differences in the self-broadening coefficients (up to 20%) and in the line intensities (up to 5%). The possible reasons for these deviations are discussed.     

Fourier transform spectroscopy of CO2 and OCO in the 3800-8500 cm region and the global modeling of the absorption spectrum of CO2

The absorption spectrum of the ¹⁸O enriched carbon dioxide has been recorded at Doppler limited resolution with a Fourier transform spectrometer in the spectral range 3800-8500 cm⁻¹. Seventeen cold bands (14Σ-Σ and 3Σ-Π) and nine hot bands (9Π-Π) of ¹²C¹⁸O₂, nineteen cold bands (18Σ-Σ and 1Σ-Π) and eighteen hot bands (6Σ-Σ, 9Π-Π and 3Δ-Δ) of ¹⁶O¹²C¹⁸O have been observed. Among them, 14 ¹²C¹⁸O₂ bands and 12 ¹⁶O¹²C¹⁸O bands are observed for the first time. The spectroscopic parameters G_v, B_v, and centrifugal distortion constants, have been determined for all observed bands. Effective Hamiltonian parameters for the ¹²C¹⁸O₂ isotopic species are retrieved from the global fitting of the observed line positions presented in this paper and collected from the literature. As the result, 65 obtained effective Hamiltonian parameters reproduce 5443 observed line positions of 73 ¹²C¹⁸O₂ bands with RMS = 0.00145 cm⁻¹.     

Intracavity laser absorption spectroscopy of HDO between 12 145 and 13 160 cm

The high resolution absorption spectrum of monodeuterated water, HDO, has been recorded by Intracavity Laser Absorption Spectroscopy (ICLAS) in the 12 145-13 160 cm⁻¹ region. The achieved sensitivity (noise equivalent absorption on the order of α_min ∼ 10⁻⁹ cm⁻¹) allowed detecting transitions with line strengths as weak as 10⁻²⁷ cm/molecule which is about 50 times lower than the weakest line intensities previously detected in the considered region.The rovibrational assignment of the 1179 lines attributed to the HDO isotopologue was based on the results of the variational calculations of Schwenke and Partridge as well as the recent calculations based on a new HDO potential energy surface refined from the fitting to the available experimental data. The overall agreement between these new calculations and the observed spectrum is very good, the rms deviation of the differences between the calculated and observed energy values being 0.05 cm⁻¹. A set of 304 new experimental HDO energy levels was obtained. In particular, band origins for the (1 2 2), (2 0 2), and (3 1 1) vibrational states, at 12 568.190, 12 644.652, and 12 919.938 cm⁻¹, respectively, and their rotational sublevels are derived for the first time. A detailed HDO database of 1337 transitions was constructed and is provided as Supplementary Material.     

Line intensity measurements in N2O and their treatment using the effective dipole moment approach.II. The 5400-11 000 cm region

The absorption spectrum of N₂O, at room temperature, was recorded in the 5400-11 000 cm^-1 region at resolutions ranging from 0.008 cm^-1 near 5400 to 0.023 cm^-1 near 11 000 cm^-1 using a Bruker IFS120HR Fourier transform spectrometer. Sample pressure/absorption path length products ranging from 200 to 4700 mbar×m were used. More than 6000 absolute line intensities have been measured in 64 different bands of ¹⁴N₂¹⁶O. Using wavefunctions previously determined from a global fit of an effective Hamiltonian to more than 18 000 line positions [Tashkun SA, Perevalov VI, and Teffo JL, to be published], the experimental intensities measured in this work and by Toth [J Mol Spectrosc 1999;197:158-87] were fit using 62 parameters of a corresponding effective dipole moment, with residuals very close to the experimental uncertainty.     

High sensitivity absorption spectroscopy of HDO by ICLAS-VeCSEL between 9100 and 9640 cm

The absorption spectrum of monodeuterated water has been recorded between 9100 and 9640 cm⁻¹ using intracavity laser absorption spectroscopy (ICLAS) based on a vertical external cavity system emitting laser (VeCSEL). Overall 1706 lines were attributed to the HDO species. The spectrum assignment was performed on the basis of the ab initio calculations by Schwenke and Partridge. A set of 746 energy levels was derived from transitions assigned to 13 upper vibrational states, 300 of them being reported for the first time. Resonance interactions leading to an important strengthening and observations of the very weak 7ν₂ and ν₁ + 5ν₂ bands are discussed. A detailed line list has been generated.     

Vibrational spectroscopy of perfluoropropionic acid in the region between 1000 and 11 000 cm

Fully fluorinated compounds, known as perfluorinated compounds, are widely used in industrial applications. Recently, some perfluorinated acids have been detected in the atmosphere and the tissues of animals. Some perfluorocarboxylic acids are emitted to the atmosphere from the thermolysis of fluoropolymers and the degradation of fluorotelomer alcohols. The gas phase vibrational spectrum of a representative perfluorocarboxylic acid in the region between 1000 and 11 000 cm⁻¹ has been investigated, with emphasis on the vibrational overtone spectrum in the near-IR region. The most intense transition in the fundamental spectrum is the CF₃ stretch while in the overtone region, the O-H stretch carries most of the intensity. A comparison of the perfluorocarboxylic acid vibrational spectrum with the hydrocarbon analog acid is discussed.     

Fourier transform absorption spectra of H2O and H2O in the 8000-9400 cm spectral region

Fourier transform spectra of water vapor enriched in ¹⁸O and ¹⁷O were recorded between 8012 and 9336 cm⁻¹ and analyzed for the first time. High accuracy ab initio predictions of line positions and intensities by Partridge and Schwenke [J. Chem. Phys. 106 (1997) 4618-4639; 113 (2000) 6592-6597] were used in the process of spectrum assignment. Transitions involving the (031), (111), (130), (210), and (012) upper vibrational states were identified in the recorded spectra. As a result, 514 and 244 precise ro-vibrational energy levels were derived for the H₂¹⁸O and H₂¹⁷O molecules, respectively. High-order resonance perturbations between levels of the vibrational states involved were evidenced leading to the identification of a number of rotational levels of the (050) and (060) highly excited bending states.     

Water line parameters for weak lines in the range 9000-12 700 cm

A total of 7923 transitions previously derived from long pathlength, Fourier transform spectra of pure water vapor (Schermaul et al., J. Mol. Spectrosc. 211 (2002) 169) have been refitted and reanalyzed using a newly calculated variational linelist. Of these, 6600 lines are weaker than 1 × 10⁻²⁴ cm/molecule, for which reliable intensities are obtained. These weak lines include 1082 lines, largely due to H₂¹⁶O, which have not been previously observed. A total of 7156 lines were assigned resulting in 329 new energy levels for H₂¹⁶O spread over 32 vibrational levels. Estimates are also given for the band origins of the (022), (140), and (051) vibrational states.     

Fourier-transform spectroscopy of NNO in the 3800-9000 cm region and global modeling of its absorption spectrum

The absorption spectrum of ¹⁴N¹⁵N¹⁶O-enriched sample of nitrous oxide has been recorded at Doppler limited resolution with a Fourier-transform spectrometer in the spectral range 3500-9000 cm⁻¹. More than 12 000 transitions of ¹⁴N¹⁵N¹⁶O were observed and ro-vibrationally assigned on the basis of the global effective Hamiltonian model. The band-by-band analysis led to the determination of the ro-vibrational parameters of a total of 107 bands. Among the 107 bands, 80 are newly observed, for 27 others the rotational analysis is significantly extended and improved. The effective Hamiltonian parameters are determined from global fitting to the observed line positions presented in this paper and collected from the literature. As a result, a set of 117 obtained effective Hamiltonian parameters reproduces 16 134 observed line positions of 148 bands with RMS of 0.0014 cm⁻¹.     

Water vapor absorption line intensities in the 1900-6600 cm region

Water vapor infrared spectra have been measured using the Bruker IFS 120 HR Fourier transform spectrometer at the Physikalisch-Chemisches Institut of the Justus-Liebig-Universität Giessen. Spectra were recorded at pressure-broadening-limited resolution and at room temperature in the range of 1900-6600 cm⁻¹. The use of fully evacuated transfer optics and a White-type multireflection cell made it possible to obtain pressure×pathlength products up to 31.27 mbar×288.5 m. These spectra have previously been used to determine experimental values of rovibrational line positions and upper energy levels of the 2ν₂, ν₁, and ν₃ bands [Mikhailenko SN, Tyuterev VlG, Keppler KA, Winnewisser BP, Winnewisser M, Mellau G, et. al. The 2ν₂ band of water: analysis of new FTS measurements and high-K_a transitions and energy levels. J Mol Spectrosc 1997;184: 330-49] and of the 3ν₂, ν₁+ν₂, and ν₂+ν₃ bands [Mikhailenko SN, Tyuterev VlG, Starikov VI, Albert KK, Winnewisser BP, Winnewisser M, et al. Water spectra in the region 4200-6250 cm⁻¹, extended analysis of ν₁+ν₂, ν₂+ν₃, and 3ν₂ bands and confirmation of highly excited states from flame spectra and from atmospheric long-path observations. J. Mol. Spectrosc. 2002; 213: 91-121].This work presents the intensities of 3769 lines for the weak and medium transitions in the spectral range indicated. These data provide an independent source of experimental information which is complementary to intensity data available in the literature and can thus help to evaluate experimental errors and the reliability of these spectral line parameters.     

Water line parameters for weak lines in the range 7400-9600 cm

A long pathlength, Fourier transform spectrum of pure water vapour [J. Mol. Spectrosc. 211 (2002) 169] has been fitted and analysed. Line centres, intensities, and self-broadening parameters have been obtained for about 3900 lines with intensities less then 1 × 10⁻²⁴ cm/molecule. Transitions to 240 newly observed energy levels of H₂O have been identified. 855 lines have been assigned to three other major isotopologues of water. It is pointed out that a new intensity measurements are needed for the stronger lines in this region.     

High-resolution Fourier-transform spectroscopy of O-enriched water molecule in the 1080-7800 cm region

Fourier-transform absorption spectrum of ¹⁸O enriched water sample was recorded in the 1080-7800 cm⁻¹ region. The transitions of H₂¹⁸O were assigned on the base of the high accuracy ab initio calculations by Partridge and Schwenke (PS). One thousand two hundred and forty-six ro-vibrational energy levels were retrieved, which belong to the , 1, and 1.5 polyads: (0 1 0), (1 0 0), (0 2 0), (0 0 1), (1 1 0), (0 1 1), and (0 3 0) states. Four hundred and thirty-two of them are reported for the first time. The results are also investigated comparing with the PS calculations and the available literature data in the considered spectral range. HD¹⁸O as a small concentration in the sample, more than 4900 transitions were also observed. These transitions yield 1066 ro-vibrational energies of nine vibrational states, 504 energy levels were obtained for the first time.     

Fourier transform spectroscopy of new emission systems of NbN in the visible region

The emission spectrum of NbN has been reinvestigated in the 8000-35 000  cm⁻¹ region using a Fourier transform spectrometer and two groups of new bands were observed. The bands observed in the 18 000-20 000 cm⁻¹ region have been assigned to a new ³Π-X³Δ transition. Three bands with R heads near 19 463.8, 19 659.0 and 19 757.0 cm⁻¹ have been assigned as 0-0 bands of the ³Π₂-X³Δ₃, ³Π₁-X³Δ₂ and ³Π_0±-X³Δ₁ subbands, respectively, of this new transition. Three additional ΔΩ = 0 bands have been observed in the 24 000-26 000  cm⁻¹ region. A 0-0 band with an R head near 25 409.9 cm⁻¹ has been assigned as a ΔΩ = 0 transition having X³Δ₂ as its lower state while two additional bands with heads near 25 518.7 and 25 534.8 cm⁻¹ were found to be ΔΩ = 0 bands having X³Δ₁ as the common lower state. Two of these three bands are perhaps subbands of a ³Δ-X³Δ transition. Most of the excited levels are affected by perturbations.