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A continuous-wave cavity ring-down spectrometer was employed to record the spectrum of the acetylene molecule spanning the 12350 - 12790 cm−1 region. A total of 747 lines from the principal isotopologue and 68 lines from 12C13CH 2 were identified, with nearly all line intensities retrieved from the spectra. These lines belong to eighteen vibrational bands of 12C 2 H 2 and two vibrational bands of 12C13CH 2 , among which five vibrational bands are reported here for the first time. Spectroscopic constants were deduced for all the identified bands, and the vibrational dipole moment squared along with Herman–Wallis coefficients were determined for the majority of these bands. Additionally, several resonance interactions were thoroughly explored. [Display omitted] • CRDS spectrum of acetylene in the 800 nm region. • Eighteen observed bands of 12C 2 H 2 and two observed bands of 12C13CH 2 • Five newly observed bands. • The experimental line intensities for nineteen bands of acetylene in the 800 nm region. [ABSTRACT FROM AUTHOR]

• Fourier transform spectroscopy with high absorption path length. • Line intensities for bands of 12C13CH 2 and 12C 2 HD. • 12C13CH 2 and 12C 2 HD line lists near 3.8 μ m for the databases. The intensities of minor acetylene isotopologues 12C13CH 2 and 12C 2 HD have been studied from Fourier transform spectra of acetylene in natural abundance using high optical path length. This study completes the work performed in the two first paper of the series (JQSRT 2023;295:108,413 and JQSRT 2023;311:108,771) where 71 bands of 12C 2 H 2 were studied in the Δ P = 4 spectral region (∼2400–2900 cm−1). In this work, 692 measured line intensities allowed to derive vibrational transition dipole moment squared (and sometimes Herman-Wallis coefficients) for 11 bands of 12C13CH 2 and 6 bands of 12C 2 HD. Using line positions and broadening parameters from literature, a line list has been generated for atmospheric and astrophysical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Fourier transform spectroscopy with high absorption path length. • Line positions and intensities for 51 newly observed bands of 12C 2 H 2. • Comparisons with HITRAN2020 for 5 bands. • Spectroscopic constants for vibrational levels. • 12C 2 H 2 acetylene line list near 3.8- μ m for the databases. The investigation of the 3.8 µm spectral region of acetylene 12C 2 H 2 main isotopologue has been completed from spectra recorded with Fourier Transform Spectrometer (FTS) using high optical path length. This work is the second of a series dedicated to the Δ P = 4 spectral region. In the first paper of the series (JQSRT 2023;295:108413) 14 bands of 12C 2 H 2 were studied in the beginning of the region. In the present work the whole Δ P = 4 spectral region was investigated. 52 newly observed vibrational bands have been studied as well as the 5 intense bands present in the HITRAN and GEISA databases. The band centers and the upper level spectroscopic constants were retrieved for all bands. The comparison with the data from HITRAN and GEISA databases revealed important deviations from the measurements due to wrong extrapolations (especially line positions). The effective dipole moment operator parameters describing intensities of all transitions observed in the Δ P = 4 spectra region were refined. A complete list of calculated line parameters for 7515 transitions has been generated for 71 bands between 2389 cm−1 and 2890 cm−1. [ABSTRACT FROM AUTHOR]

• CRDS spectrum of acetylene in the 760 nm region. • Five newly observed acetylene bands. • First publication of the acetylene line intensities in the 760 nm region. • Spectroscopic constants for ten acetylene bands. • Vibrational transition moments squared and Herman-Wallis parameters for ten acetylene bands. The Cavity Ring-Down Spectra (CRDS) of acetylene were recorded in the 13,087–13,300 cm−1 range with the sensitivity of 3.4 × 10−11 cm−1. Four cold and six hot bands of 12C 2 H 2 were assigned in these spectra. Only five of them were observed before. The ν 1 + 3 ν 3 + ν 4 1 band is the strongest one lying in this region. The line positions and intensities were recovered from the recorded spectra. The line intensities in this region are reported for the first time. The line positions were modeled using the traditional power series expression in terms of the angular momentum quantum number for an isolated band. The line intensities were modeled using the vibrational transition dipole moment squared and the Herman-Wallis parameters. [ABSTRACT FROM AUTHOR]

In a companion paper, rovibrational assignments of acetylene in the 9280–10,740 cm –1 region were extended on the basis of a long path absorption spectrum recorded by Fourier-transform spectroscopy. Thirty-three and seven bands of 12 C 2 H 2 and 12 C 13 CH 2 were assigned, respectively, twelve 12 C 2 H 2 bands being newly assigned. In the present work, the vibrational transition dipole moments squared and Herman–Wallis coefficients of the bands are derived from a fit of the measured intensity values. An empirical recommended line list is provided with positions calculated using empirical spectroscopic band parameters and intensities calculated using the derived Herman–Wallis coefficients. As a result the constructed line list in the 9450–10,740 cm -1 region includes a total of 2774 lines belonging to 32 bands of 12 C 2 H 2 and seven bands of 12 C 13 CH 2 . For comparison the HITRAN database in the same region includes 305 lines of 4 bands, all belonging to 12 C 2 H 2 . The recommended acetylene line list is compared to the HITRAN line list and to the Acetylene Spectroscopic Database (ASD) constructed using the global effective operator approach. The measured bands belong to the ΔP  = 15 and 16 series of bands where P  = 5 V 1  + 3 V 2  + 5 V 3  +  V 4  +  V 5 is the polyad quantum number. An improved set of ΔP  = 15 effective dipole moment (EDM) parameters is derived from a fit of the measured intensity values. The ΔP  = 16 EDM parameters are derived for the first time. The derived sets of EDM will allow extending the Acetylene Spectroscopic Database at higher energy. [ABSTRACT FROM AUTHOR]

• The 2005 i - 00001 (i = 1,2) absorption bands of 12C16O 2 revisited. • First observation of the 20053 – 00001absorption band of 12C16O 2. • The first measurements of the line intensities of the 2005 i - 00001 (i = 1,2,3) bands of 12C16O 2. • The HITRAN2020 line parameters for the studied bands should be updated. The absorption spectra of carbon dioxide were recorded in the region from 13,500 to 14,200 cm−1, using a Bruker IFS 125 HR Fourier transform spectrometer and a 30 m multipass cell with the White type optical system. The recording was performed at spectral resolution of 0.03–0.04 cm−1, room temperature, path length of 1057.95 m and at three pressures of 252, 403 and 582 mbar. The achieved sensitivity (noise equivalent absorption) at the level of k ν = 6 × 10−10 cm−1 allowed detection of a number of lines of three 2005 i - 00001 (i = 1,2,3) bands of 12C16O 2 with the intensity values down to 10−29 cm−1/(molecule cm−2) at 296 K. The 20053–00001 band was observed for the first time. The line intensities for all bands were measured for the first time. The uncertainty of the line position measurements was estimated to be about 0.007 cm−1 for the unblended lines with a high value of the signal-to-noise ratio. The uncertainties of the retrieved line intensities for the strongest unblended lines are on the level of 10%. The spectroscopic constants for the three observed bands were fitted to the observed line positions. The vibrational transition dipole moments squared of these bands were fitted to the observed line intensities. A comparison of the measured line positions to those from the HITRAN2020 database was done. Finally a comparison of the measured line intensities to those contained in the HITRAN2020 database as well as in the new version of the Ames line list was also given. [ABSTRACT FROM AUTHOR]

• Fourier transform spectroscopy with high absorption path length. • Measured and calculated line positions and intensities for 14 newly observed bands of 12C 2 H 2. • Acetylene line list for the databases near 3.8- μ m. Two acetylene spectra were recorded between 2350 and 2750 cm−1 with Fourier Transform Spectrometer (FTS) using high optical path length. 14 bands were observed for the first time including one cold band. The positions and the intensities of the lines have been measured for 824 transitions of the 12C 2 H 2 isotopologue. The band centers, the band strengths, the upper level spectroscopic constants and the Herman-Wallis parameters were retrieved for all bands. The effective dipole moment parameters of the Δ P = 4 region were refined, P being the polyad number defined as P = 5 V 1 + 3 V 2 + 5 V 3 + V 4 + V 5 , where V i are the vibrational normal mode principal quantum numbers, with i = 1 − 5. An updated line list for the ∆P = 4 series of transitions is proposed as supplementary data in order to improve the spectroscopic databases such as HITRAN or GEISA. [ABSTRACT FROM AUTHOR]

• CRDS spectrum of acetylene in the 770 nm region. • First publication of the acetylene line intensities in the 770 nm region. • Spectroscopic constants for seven bands. • Vibrational transition moments squared and Herman-Wallis parameters for seven bands. • Recommended line list of acetylene for the 12887–13084 cm−1 region. The Cavity Ring-Down Spectra (CRDS) of acetylene were recorded in the 12933–13087 cm−1 region with sensitivity of 2 × 10−11 cm−1. Six bands of 12C 2 H 2 and one band of 12C13CH 2 were assigned in these spectra. The 3ν 1 +ν 3 band is the strongest one lying in this region. The line positions and intensities were recovered from the recorded spectra. The line intensities in this region are reported for the first time. The line positions were modeled using the traditional power series expression in terms of the angular momentum quantum number for an isolated band. The line intensities were modeled using the vibrational transition dipole moment squared and the Herman-Wallis parameters. The recommended line list of acetylene was prepared for the 12887–13084 cm−1 region. It is based on the calculated line parameters. But in the case of the perturbations, the calculated line parameters are substituted by the observed ones. The harmonic basis state compositions of the upper states of the two bands at 12991.08 and 12988.75 cm−1 were considered in detail. [ABSTRACT FROM AUTHOR]

Abstract: Based on new line intensity measurements collected from the literature, the effective dipole moment parameters of acetylene have been found for the 100, 7.7, 1.4, 1.3, 1.2 and 1μm spectral regions by least-squares fittings. On average, the experimental uncertainty was obtained in all fits. The new sets of the effective dipole moment parameters combined with those that were previously published allow for the calculation of the line intensities for the majority of the acetylene bands in the spectral range from 100 to 1μm. [Copyright &y& Elsevier]

Abstract: Using FT spectra (unapodized resolution ~0.0056cm−1) of the nitrous oxide isotopologue , the line positions and intensities have been measured for 511 lines of 8 cold bands and one hot band lying between 5800 and 7600cm−1. A multispectrum fitting procedure has been used to retrieve line parameters from 5 experimental spectra recorded at different pressures. An absolute wavenumber calibration has been performed using acetylene line positions around 6500cm−1 and water line positions in the 7100–7300cm−1 region. The average absolute accuracy of the line parameters obtained in this work has been estimated to be ±0.0005cm−1 for the line positions, 2–5% for the line intensities depending on the transitions. For each studied band, the vibrational transition dipole moment squared value and the empirical Herman–Wallis coefficients have been determined. Moreover, the line positions measured in this work and those collected from the literature allowed the global fitting of the effective Hamiltonian parameters for this isotopologue. [Copyright &y& Elsevier]

Abstract: Using the Fourier transform spectra of the acetylene molecule recorded near 1.5-μm, the intensities of 111 lines belonging to seven hot bands of the main isotopologue 12C2H2 have been retrieved by means of a multispectrum fitting procedure. Considering the density of lines in the spectra, and the fact that the measured bands are the weakest observed, the accuracy of the measurements is around 10%. At first stage, an empirical treatment of these data has been performed, leading to the vibrational transition dipole moment squared and some Herman–Wallis coefficients. Then the measured line intensities of this work and collected ones from the literature have been treated simultaneously within the framework of the effective operator approach. [Copyright &y& Elsevier]

Abstract: More than 440 line positions and intensities of 8 bands of acetylene are measured in the 2.2-μm spectral region. A multispectrum fitting procedure has been applied to retrieve line parameters. The average absolute accuracy of the line parameters obtained in this work is estimated to be ±0.0005cm−1 for the line positions, and ±5% for the line intensities. Vibrational transition dipole moment and Herman–Wallis coefficients are determined for two of the studied bands. An unusual rotational dependence of the vibrational–rotational transition dipole moment of remaining bands has been found. All measured line intensities are treated simultaneously within the framework of the effective operators approach. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental uncertainty. [Copyright &y& Elsevier]

Abstract: More than 670 line intensities of nine perpendicular bands of acetylene are measured in the 2.5-μm spectral region using a step-by-step interferometer. Absolute values of line intensities are obtained with an average accuracy of 5%. Vibrational transition dipole moment and Herman–Wallis coefficients are determined for each studied band. These measured line intensities, and those previously measured in the 3.8-μm region [Jacquemart D, Lacome N, Mandin JY, Dana V, Lyulin OM, Perevalov VI. Multispectrum fitting of line parameters for 12C2H2 in the 3.8-μm spectral region. JQSRT, submitted for publication], are treated simultaneously within the framework of the effective operators approach. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental uncertainty. The good predictive ability of the modele is demonstrated. [Copyright &y& Elsevier]

Abstract: About 170 line intensities of 14 weak parallel hot bands of acetylene have been measured in the 3-m region. Absolute values of line intensities are obtained with a mean uncertainty of 10%, except for a few lines of 3 very weak bands (uncertainty up to 20%). Vibrational transition dipole moment and Herman–Wallis coefficients have been determined for each measured band. These measured line intensities together with previously published ones (JQSRT 2005;92:239–60) have been treated simultaneously within the framework of the effective operators approach. Using only 6 effective dipole moment parameters, it was possible to reproduce the 591 measured line intensities of the 20 bands with a root mean square of the residuals equal to 4.2%. [Copyright &y& Elsevier]

Abstract: The line positions and intensities of carbon dioxide isotopologues have been retrieved in 3200–4700cm−1 region from Fourier transform spectra of carbon dioxide recorded in LADIR (Paris, France) with the Bruker IFS 125-HR [Jacquemart D et al. J Quant Spectrosc Radiat Trans 2012;113:961–75]. In total 11318 line positions and intensities of 151 bands of 12 isotopologues 16O12C16O, 16O13C16O, 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 18O12C18O, 17O12C18O, 18O13C18O, 17O12C17O, 17O13C18O, and 17O13C17O have been retrieved. 53 bands were newly assigned. All studied bands belong to the ΔP=5 and ΔP=6 series of transitions, where is the polyad number (V i are the vibrational quantum numbers). The accuracy of the line position measurement is about 0.3×10−3 cm−1 for the unblended and not very weak lines. The accuracy of the line intensities varies from 4% to 15% depending on the isotopologue, on the intensity of the line and on the extent of the line overlapping. The spectroscopic constants for the majority of the observed bands have been derived. The observed line positions together with those collected from the literature were used to fit the effective Hamiltonian parameters for the 16O12C17O and 17O12C17O isotopologues. In both cases the fitted models were capable of reproducing the measured line positions with accuracy compatible with the measurement uncertainties (rms are 0.0011cm−1 and 0.0009cm−1 for 16O12C17O and 17O12C17O, respectively). The observed intensities were used to fit the effective dipole moment parameters for the ΔP=5 and ΔP=6 series of transitions of 16O12C17O, 17O12C17O and 16O12C18O isotopologues of carbon dioxide. [Copyright &y& Elsevier]

Three bands 4003 i –00001 ( i =2, 3, 4) of the Fermi pentad of 12 C 16 O 2 near 830 nm have been recorded with a continuous-wave cavity ring down spectrometer. A sensitivity at the 5×10 –11 cm −1 level allowed us to obtain line positions and intensities of these very weak bands. The measured line intensities of these three bands together with those published for the 10051–00001 and 10052–00001 bands were used to obtain the effective dipole moment parameters of 12 C 16 O 2 for the Δ P =17 series of transitions, where P =2 V 1 + V 2 +3 V 3 is a polyad number ( V i ( i =1, 2, 3) are vibrational quantum numbers). Comparisons of the measured line positions and intensities of the 4003 i –00001 ( i =2, 3, 4) bands to those from the AMES and GEISA line lists are given. [ABSTRACT FROM AUTHOR]

Abstract: Using FT spectra (Bruker IFS 120, unapodized FWHM resolution ≈ 0.001cm−1) of acetylene 12C2H2, absolute positions and intensities have been measured for about 250 lines between 2600 and 2800cm−1 in the and cold bands, and in the and hot bands. These measurements improve the accuracy of wavenumbers previously available and lead to individual line intensities for the first time in this spectral region. A multispectrum fitting procedure has been used to retrieve line parameters from five experimental spectra recorded at different pressures. The frequencies of the ν 3 band of 12C16O2 allowed to perform an absolute wavenumber calibration. The accuracy of the amount of 12C2H2 in the sample has been checked using the cold band around 2100cm−1, and has been estimated to be around ±2%. The average absolute accuracy of the line parameters obtained in this work has then been estimated to be ±0.0002cm−1 for line positions, and ±5% for line intensities. For each studied band, the vibrational transition dipole moment squared value has been determined, as also empirical Herman–Wallis coefficients. A complete line list containing positions and intensities for the five strongest bands around 3.8μm has been set up for atmospheric applications. [Copyright &y& Elsevier]