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Positions and intensities for transitions in the 1←0 bands of the four CO isotopologues (12C16O, 13C16O, 12C18O and 13C18O) were retrieved from analyses of spectra of different low-pressure pure samples and high-pressure air-broadened mixtures (1940–2260 cm−1) in two different multispectrum fittings involving selected groups of 21 (for 13C16O) and 20 (for 12C18O) spectra. Air-broadened half-width and air-shift coefficients, their temperature dependences, line mixing via off-diagonal relaxation matrix element coefficients for CO-air collision systems, and quadratic speed dependence parameters were measured for 13C16O and 12C18O transitions. In both the fittings, two low-pressure room-temperature spectra of a high purity natural sample of CO recorded with the Kitt Peak FTS were included to retrieve the positions and intensities of 12C16O transitions. All other spectra in the fittings were obtained with either 13C-enriched or 18O-enriched samples using the JPL Bruker IFS-125HR FTS. Four absorption cells with path lengths between 0.5131(5) and 20.38(2) cm were used to record the data. The cells are temperature controlled, except for the shortest cell. Positions and intensities for the 1←0 band transitions were determined from the retrieved ro-vibrational constants (G, B, D and H), band intensity and Herman-Wallis parameters by applying the theoretical quantum mechanical expressions. The band strengths of 12C16O, 12C18O and 13C18O are very close (∼0.3%) to HITRAN2012 values but for 13C16O the band strength is ∼4.8% larger than the HITRAN2012 and 2.6% larger than the HITRAN2016 value.

We report experimental measurements of spectral line shape parameters (air-broadened width, shift, and line mixing coefficients) for several transitions in the ν3 Q branch of methane in the 3000–3023 cm−1 region. 13 high-resolution, room temperature laboratory spectra of pure methane and air-broadened methane recorded with two different Fourier transform spectrometers are fitted. 12 of these spectra were acquired at 0.01 cm−1 resolution with the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak, and one higher-resolution (∼0.0011 cm−1) low pressure methane spectrum was obtained with the Bruker IFS-120HR FTS at the Pacific Northwest National Laboratory, in Richland, Washington. All the spectra were obtained using high purity natural samples of CH4 and lean mixtures of the same natural CH4 in dry air. For the 12 spectra recorded at Kitt Peak, three different absorption cells (L = 5, 25 and 150 cm) were used while the methane spectrum at PNNL was obtained using a 19.95 cm long absorption cell. For the analysis, an interactive multispectrum nonlinear least squares fitting software was employed where all the 13 spectra were fitted simultaneously. An accurate and self-consistent set of line parameters were determined by constraining a few of those for severely blended transitions. Line mixing was measured for 14 transition pairs for the CH4-air collision system. A constant speed dependence parameter, consistent with measured speed dependence values obtained in other methane bands, was applied to all the transitions included in the fitted region. The present measurements are compared to values reported in the literature.

Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν 2 0 +ν3) band of 12C16O2 at 6228 cm−1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004–0.011 cm−1), absorption path lengths (2.46–121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured. Results from previous works and new calculations are compared to present measurements, where appropriate.

In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν 3 Q branch manifolds, Q(11)–Q(1) of methane ( 12 CH 4 ), in the 5996.5–6007-cm −1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12 C-enriched 12 CH 4 and dilute mixtures of 12 CH 4 in dry air in the 130–296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH 4 –CH 4 and CH 4 –air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q( J ) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database.

We have made the measurements of H2-broadened line shape parameters of CH4 transitions in the v2+v3 band located at 2.2 µm. These measurements support atmospheric opacity calculations of cold giant planets, hot Jupiters, and low mass brown dwarfs, for which H2 is the dominant atmospheric constituent. For this reason, a series of spectra of pure CH4 and CH4 H2 mixtures were obtained in the Octad (4100–4600 cm−1) region for a wide temperature range between 80 and 370 K using a Bruker 125HR high-resolution Fourier transform spectrometer (FTS) at Jet Propulsion Laboratory (JPL). Three custom-designed gas absorption cells vacuum-coupled to the FTS were used to obtain the spectra. All spectra were fit simultaneously using a multispectrum non-linear least-squares fitting software, which adopts a speed-dependent Voigt line shape using full line mixing taken into account through a relaxation matrix operation. H2 pressure broadened half-widths, and H2 pressure-induced shift coefficients were determined in 11 J-manifolds covering P(4) – R(6) plus the Q-branch. The temperature dependences of the width and shift coefficients were determined based upon the power law and the linear models. Collisional line mixing coefficients for CH4 H2 were retrieved for ten transition pairs. For the same transitions, speed dependence parameters for the CH4 H2 transitions were found to be smaller than for CH4-air-broadening. We have compiled the retrieved line parameters in an electronic format and reported as supplemental document. This will facilitate the analyses of planetary and exoplanetary atmospheres using ground-, air- and space-based observations (e.g., Keck I and II, SOFIA, JWST).

In this paper we report line shape parameters of 12 CH 4 for several hundred 2ν 3 transitions in the spectral regions 5891–5996 cm −1 (P branch) and 6015–6115 cm −1 (R branch). Air- and self-broadening coefficients were measured as a function of temperature; line mixing via off-diagonal relaxation matrix element coefficients was also obtained for 47 transition pairs. In total, nearly 1517 positions and intensities were retrieved, but many transitions were too weak for the line shape study. For this analysis, we used 25 high-resolution (0.0056 and 0.0067 cm −1 ) and high signal-to-noise (S/N) spectra of high-purity 12 CH 4 and the same high-purity 12 CH 4 broadened by dry air recorded at different sample temperatures between 130 K and 295 K with the Bruker IFS 125HR Fourier transform spectrometer at JPL. Three different absorption cells were used (1) a White cell set to a path length of 13.09 m for room temperature data, (2) a single-pass 0.2038 m long coolable cell (for self-broadening) and (3) a multipass cell with 20.941 m total path coolable Herriott cell (for air-broadening). In total there were 13 spectra with pure 12 CH 4 (0.27–599 Torr) and 12 air-broadened spectra with total sample pressures of 80–805 Torr and volume mixing ratios (VMR) of methane between 0.18 and 1.0. An interactive multispectrum nonlinear least-squares technique was employed to fit the individual P10–P1 and R0–R10 manifolds in all the spectra simultaneously. Results obtained from the present analysis are compared to other recent measurements.

Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. In this paper, we report the self- and air-broadened Lorentz half-widths, pressure-induced shifts and line mixing coefficients (via off-diagonal relaxation matrix elements) along with their temperature dependences for methane ν2+ν3 absorption lines in the 4500–4630 cm−1 region of the Octad. For this, we recorded 14 high-resolution, high signal to noise ratio (S/N) spectra of high-purity (99.95% 12C-enriched) samples of pure methane and its dilute mixtures in dry air between 298 K and 148 K. A Bruker IFS 125HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California, was used to obtain the experimental data. The absorption cell used for this study was a specially built 20.38 cm long coolable cell installed in its sample compartment. The sample pressures for the pure 12CH4 spectra were 4.5−385 Torr; for the air-broadened spectra the total pressures ranged between 95 and 300 Torr with the methane volume mixing ratios between 0.04 and 0.097. All 14 spectra were fitted simultaneously using an interactive multispectrum nonlinear least-squares curve fitting technique. The results are compared to values reported in the literature.

We review efforts to experimentally determine absolute line intensities for ozone transitions in the 9–11 μm spectral region over the last several decades. Much of this work has been driven by the requirements for remote sensing of terrestrial atmospheric ozone. While significant progress has been achieved, discrepancies persist among various infrared measurements, and the relation between infrared and ultraviolet standards is not clearly resolved.

The first air broadening line shape parameters were determined for the 2 ← 0 bands of 13C16O near 4166.8 cm−1 and 12C18O near 4159.0 cm−1. Air-broadened Lorentz half-width coefficients, their temperature dependence exponents; air-induced pressure shift coefficients, their temperature dependences; and air line mixing coefficients were measured. Additionally, speed-dependent line shapes with line mixing employing the off-diagonal relaxation matrix element coefficients were applied to minimize the fit residuals. Finally, individual line positions and line intensities of the two isotopologues were constrained to the well-known theoretical quantum mechanical expressions in order to obtain the rovibrational (G, B, D and H) and band intensity parameters (including Herman–Wallis coefficients). For this, laboratory spectra were recorded at 0.005 cm−1 resolution using a temperature-controlled coolable absorption cell configured inside a Bruker IFS 125HR Fourier transform spectrometer. Gas temperatures and pressures for the spectra varied from 150 to 298 K and 20 to 700 Torr, respectively. Results were obtained from broad-band multispectrum least-squares fitting of the 4000–4360 cm−1 spectral region. Four isotope-enriched pure sample spectra and twelve spectra with air + CO samples (13C16O or 12C18O, as appropriate) were fitted simultaneously. The results obtained for 13C16O and 12C18O are compared and discussed.

Accurate individual line intensities have been measured for the five interacting bands ν 10 , ν 8 , ν 7 , ν 4 and ν 6 of ethylene-1- 13 C using a multispectrum nonlinear least squares fitting technique. The measured intensities have been very satisfactorily fit leading to the determination of precise vibrational transition moments. A calculated spectrum accounting for the various rovibrational interactions has been generated. Such a spectrum should be useful for the planetary atmosphere modeling-community. Lorentz self-broadened half-width coefficients have also been measured for nearly 300 transitions in the strongest ν 7 band.

Line positions, Lorentz air-broadened half width and air pressure-induced shift coefficients have been measured for nearly 200 transitions in the ν 4 band of 13 CH 4 from high-resolution spectra recorded with the McMath-Pierce Fourier transform spectrometer. Three room temperature spectra of 13 CH 4 used in the previous study of Malathy Devi et al. (Air-broadened Lorentz halfwidths and pressure-induced line shifts in the ν 4 band of 13 CH 4 . Appl. Opt. 1988; 27: 2296–2308) were analyzed together with a large number of additional spectra of self- and air-broadened CH 4 recorded at 210–314 K and one room-temperature spectrum of self-broadened 13 CH 4 . Analyses applying the multispectrum nonlinear least squares fitting technique were performed to retrieve the spectral line parameters. In addition to air-broadened half width and shift coefficients, self-broadened half width and shift coefficients were determined for at least 56 13 CH 4 ν 4 transitions. Off-diagonal relaxation matrix element coefficients for air-broadened line mixing were also determined for 28 pairs of P and R transitions in a number of J manifolds, and mixing parameters for self-broadening were also determined for some of these pairs. Temperature-dependences of the pressure-induced shift and mixing parameters for the 13 CH 4 lines could not be determined from the spectra used in the present analysis, but temperature dependences of the half width coefficients were determined for the strongest transitions. The results of this study are compared with other studies of air- and self-broadened 13 CH 4 and 12 CH 4 .

The McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (NSO) on Kitt Peak, Arizona, was used to record infrared high resolution absorption spectra of CO 2 spectra broadened by O 2 . These spectra were analyzed to measure O 2 -broadened half-width coefficients, O 2 -induced pressure-shift coefficients and speed dependent parameters for transitions in the 30013←00001 and 30012←00001 bands of 16 O 12 C 16 O located near 6227 and 6348 cm −1 , respectively. All spectra were obtained at room temperature using the long path, 6 m base path White cell available at NSO. A multispectrum nonlinear least-squares fitting algorithm employing Voigt line shapes modified to include line mixing and speed dependence was used to fit simultaneously a total of 19 spectra in the 6120–6280 cm −1 (30013←00001) and 6280–6395 cm −1 (30012←00001) spectral regions. 16 of the 19 spectra analyzed in this work were self broadened and three spectra were lean mixtures of CO 2 in O 2 . The volume mixing ratios of CO 2 in the three spectra varied between 0.06 and 0.1. Lorentz half-width and pressure-induced shift coefficients were measured for all transitions in the P(50)–R(50) range in both vibrational bands. The results obtained from present analysis have been compared with measurements available in the literature for self-, air-, oxygen- and argon-broadening. No significant differences were observed between the broadening and shift coefficients of the two bands. The N 2 -broadened half-width and pressure-shift coefficients were computed from measured air- and O 2 -broadened width and shift coefficients.

Ethane is a prominent contributor to the spectrum of Titan, particularly in the ν 9 region centered near 822 cm −1 . To improve the spectroscopic line parameters at 12 μm, 41 high-resolution (0.0016–0.005 cm −1 ) absorption spectra of C 2 H 6 were obtained at sample temperatures between 211 and 298 K with the Bruker IFS 120HR at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Two additional spectra were later recorded at ∼150 K using a new temperature-stabilized cryogenic cell designed for the sample compartment of the Bruker IFS 125HR at the Jet Propulsion Laboratory (JPL) in Pasadena, California. A multispectrum nonlinear least-squares fitting program was applied simultaneously to all 43 spectra to measure the line positions, intensities, N 2 - and self-broadened half-width coefficients and their temperature dependences. Reliable pressure-induced shift coefficients could not be obtained, however, because of the high congestion of spectral lines (due to torsional-split components, hot-band transitions as well as blends). Existing theoretical modeling of this very complicated ν 9 region permitted effective control of the multispectrum fitting technique; some constraints were applied using predicted intensity ratios, doublet separations, half-width coefficients and their temperature dependence exponents in order to determine reliable parameters for each of the two torsional-split components. For 12 C 2 H 6 , the resulting retrievals included 17 p Q and r Q sub-bands of ν 9 (as well as some p P, r R sub-bands). Positions and intensities were measured for 3771 transitions, and a puzzling difference between previously measured ν 9 intensities was clarified. In addition, line positions and intensities were obtained for two 12 C 2 H 6 hot bands (ν 9 +ν 4 −ν 4 , ν 9 +2ν 4 −2ν 4 ) and the ν 9 band of 13 C 12 CH 6 , as well as several hundred presently unidentified transitions. N 2 - and self-broadened half-width coefficients were determined for over 1700 transitions, along with 1350 corresponding temperature dependence exponents. Similar to N 2 - and self-broadened half-width coefficients, their temperature dependence exponents were also found to follow distinctively different patterns. However, while the self- and N 2 -broaded widths differed by 40%, the temperature dependence exponents of the two broadening gases were similar. The variations of the observed half-width coefficients and their temperature dependences with respect to J , K quantum numbers were modeled with a set of linear equations for each K . The present broadening coefficients compared well with some of the prior measurements.

Line positions, intensities, Lorentz self- and N2-broadened half-width coefficients have been measured for PQ3, PQ2, PQ1, RQ0, RQ1, RQ2, and RQ3 sub-band transitions in the ν9 fundamental band of 12C2H6. A multispectrum nonlinear least-squares fitting technique was used to fit up to 17 high-resolution (∼0.00156 cm−1), room temperature absorption spectra of pure (99.99% chemical purity) natural sample of ethane and lean mixtures of the high-purity ethane diluted with N2. A Bruker IFS 120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington was used to record the data. A standard Voigt line shape was assumed to fit all the data since no line mixing or other non Voigt line shapes were required to fit any of the spectra used in the analysis. Short spectral intervals (∼2–2.5 cm−1) of all 17 spectra covering a specific PQ or RQ sub-band were fit simultaneously. For the first time in an ethane band, pressure-broadened half-width coefficients were determined for the torsional-split components. However, for better reliability of the retrieved coefficients for the weaker components (transitions with large intensity ratios of 4:1 or 3:1 for most K levels between the strong and weak components), constraints were used such that the half-width coefficients of both torsional-split components for a given J were identical for a specific broadening gas. No pressure-induced shift coefficients were necessary to fit the spectra to their noise level. The present study revealed for the first time the dependence of self- and N2-broadened half-width coefficients upon the J, K quantum numbers of the transitions in ethane. A number of transitions belonging to the ν9+ν4−ν4 and the ν9+2ν4−2ν4 hot bands were also observed in the fitted regions and measurements were made when possible.

Line positions and strengths of 16O13C16O (636), 16O13C18O (638) and 16O13C17O (637), and 18O13C18O (838) bands were measured using natural and 13C- and 18O-enriched samples of CO2 at room temperature. Twenty-five near infrared (NIR) absorption spectra were recorded at 0.01–0.013 cm−1 resolution with the McMath–Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak, Arizona. Absorption cells with optical path lengths ranging from 0.347 m to 385 m were used with pressures ranging between 0.5 and 147 torr. Line strengths were obtained for 17 bands of (636) between 4697 and 6797 cm−1, 13 bands of (638) between 2192 and 4954 cm−1, 4 bands of (637) between 3437 and 4981 cm−1 and 7 bands of (838) between 2182 and 4888 cm−1. Band strengths and Herman–Wallis-like F-factor coefficients were determined from least-squares fits to over 2000 measured transition intensities involving 41 different bands. The observed line positions of several bands were analyzed to obtain the upper state term values and rotational constants. Five of the 18O13C18O bands and two of the 16O13C18O bands were modeled for the first time.

Half-width and pressure-induced shift coefficients; the temperature-dependence exponents of the half-widths and the temperature-dependence coefficients of pressure-induced shifts have been measured for N2-broadened transitions in the ν2 band of HCN. Line positions and intensities were also determined. A total of 34 laboratory absorption spectra, recorded at 0.002–0.005 cm−1 resolution with two different Fourier transform spectrometers, were used in the determination of the spectral line parameters. The total pressures of the HCN–N2 samples ranged from less than 1 torr up to nearly 1 atm, and temperatures were between 211 and 300 K. A multispectrum nonlinear least-squares fitting technique employing a modified Voigt line profile, including speed dependence and line mixing via the off-diagonal relaxation matrix formulation, was used in the analysis. Speed-dependence parameters were determined in the P and R branches of the ν2 band of H12C14N, and in the ν2 Q branches of H12C14N and H13C14N the off-diagonal relaxation matrix elements that characterize line mixing were included in the analysis to fit the data. Present results are compared with previous measurements reported in the literature.

A new spectroscopic database for carbon dioxide in the near infrared is presented to support remote sensing of the terrestrial planets (Mars, Venus and the Earth). The compilation contains over 28,500 transitions of 210 bands from 4300 to 7000 cm−1 and involves nine isotopologues: 16O12C16O (626), 16O13C16O (636), 16O12C18O (628), 16O12C17O (627), 16O13C18O (638), 16O13C17O (637), 18O12C18O (828), 17O12C18O (728) and 18O13C18O (838). Calculated line positions, line intensities, Lorentz half-width and pressure-induced shift coefficients for self- and air-broadening are taken from our recent measurements and are presented for the Voigt molecular line shape. The database includes line intensities for 108 bands measured using the McMath–Pierce Fourier transform spectrometer located on Kitt Peak, Arizona. The available broadening parameters (half-widths and pressure-induced shifts) of 16O12C16O are applied to all isotopologues. Broadening coefficients are computed using empirical expressions that have been fitted to the experimental data. There are limited data for the temperature dependence of widths and so no improvement has been made for those parameters. The line intensities included in the catalog vary from 4×10−30 to 1.29×10−21 cm−1/(molecule cm−2) at 296 K. The total integrated intensity for this spectral interval is 5.9559×10−20 cm−1/(molecule cm−2) at 296 K.

This study provides the first direct experimental measurements of the off-diagonal relaxation matrix element coefficients for line mixing in air-broadened methane spectra for any vibrational band and the first off diagonal relaxation matrix elements associated with line mixing for pure methane in the ν 2 + ν 3 band of 12 CH 4 . The speed-dependent Voigt profile with line mixing is used with a multispectrum nonlinear least squares curve fitting technique to retrieve the various line parameters from 11 self-broadened and 10 air-broadened spectra simultaneously. The room temperature spectra analyzed in this work are recorded at 0.011 cm −1 resolution with the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory, Kitt Peak, Arizona. The off-diagonal relaxation matrix element coefficients of ν 2 + ν 3 transitions between 4410 and 4629 cm −1 are reported for eighteen pairs with upper state J values between 2 and 11. The observed line mixing coefficients for self broadening vary from 0.0019 to 0.0390 cm −1 atm −1 at 296 K. The measured line mixing coefficients for air broadening vary from 0.0005 to 0.0205 cm −1 atm −1 at 296 K.

Line position, intensity and line shape parameters (Lorentz widths, pressure shifts, line mixing, speed dependence) are reported for transitions of the 30013 ← 00001 band of 16O12C16O (ν0 = 6227.9 cm−1). The results are determined from 26 high-resolution, high signal-to-noise ratio spectra recorded at room temperature with the McMath-Pierce Fourier transform spectrometer. To minimize the systematic errors of the retrieved parameters, we constrained the multispectrum nonlinear least squares retrieval technique to use quantum mechanical expressions for the rovibrational energies and intensities rather than retrieving the individual positions and intensities line by line. Self- and air-broadened Lorentz width and pressure-induced shift, speed dependence and line mixing (off-diagonal relaxation matrix elements) coefficients were adjusted individually. Errors were further reduced by simultaneously fitting the interfering absorptions from the weak 30012 ← 00001 band of 16O13C16O as well as the weak hot bands 31113 ← 01101, 32213 ← 02201, 40014 ← 10002 and 40013 ← 10001 of 16O12C16O in this spectral window. This study complements our previous work on line mixing and speed dependence in the 30012 ← 00001 band (ν0 = 6347.8 cm−1) [V.M. Devi, D.C. Benner, L.R. Brown, C.E. Miller, R.A. Toth, J. Mol. Spectrosc. 242 (2007) 90-117] and provides key data needed to improve atmospheric remote sensing of CO2.

Line positions and strengths of 16O12C18O (628), 18O12C18O (828) and 17O12C18O (728) were measured between 2200 and 7000 cm−1 using 22 near infrared (NIR) absorption spectra recorded at 0.01–0.013 cm−1 resolution with the McMath–Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak, Arizona. These data were obtained at room temperature using absorption cells with optical path lengths ranging from 2.4 to 385 m; the cells were filled with natural and 18O-enriched samples of CO2 at pressures ranging from 0.54 to 252 torr. The observed line positions were analyzed to obtain the upper state band centers and rotational constants for 17 bands of 16O12C18O, 19 bands of 18O12C18O and 8 bands of 17O12C18O. The majority of the 18O12C18O and 17O12C18O bands were measured for the first time. In addition, the rotational constants for the lower states 00001, 01101e and 01101f were derived for all three species using the method of combination differences in which the averaged values obtained from the line positions of two or more bands were least-squares-fitted. Rovibrational parameters were also obtained for the 02201e, 02201f, 10002 and 10001 states of 18O12C18O. The line position analysis revealed that transitions of the levels 38 ⩽ J′ ⩽ 46 of the 11111f ← 01101f band of 18O12C18O are perturbed. Perturbed transitions were also observed for the 12212 ← 02201 band and in the high-J transitions (J′ ⩾ 49) of the 20012 ← 00001 band of 18O12C18O. Band strengths and Herman–Wallis-like F-factor coefficients were determined for 21 bands of 16O12C18O, 25 bands of 18O12C18O and 8 bands of 17O12C18O from least-squares fits to more than 3700 measured transition intensities; band strengths and line positions for 34 of these bands were obtained for the first time.

Intensity and line shape parameters which predict spectral lines with absolute accuracies better than 0.3% have been determined for transitions of the 30012 ← 00001 band of 16 O 12 C 16 O centered near 6348 cm −1 from 26 high resolution, high signal-to-noise ratio spectra recorded at room temperature with the McMath–Pierce Fourier transform spectrometer. To maximize the accuracies of the retrieved parameters, the multispectrum non-linear least squares retrieval technique was modified to adjust the rovibrational constants ( G , B , D , etc.) and intensity parameters, including Herman–Wallis terms, rather than retrieving the individual positions and intensities. Speed-dependent Voigt line shapes with line mixing were required to remove systematic errors in the fit residuals. Self- and air-broadening (widths and pressure-induced shifts, speed dependence parameters) and line mixing (off-diagonal relaxation matrix elements) coefficients were thus obtained in the multispectrum fit. Remaining errors were minimized by fitting the weak 30011 ← 00001 band of 16 O 13 C 16 O as well as the weak hot bands 31112 ← 01101, 32212 ← 02201, 40012 ← 10001, and 40013 ← 10002 of 16 O 12 C 16 O that contribute interfering absorptions in this spectral window. This study presents the most extensive set of measurements to date for self- and air-broadening and self- and air-shift coefficients of a near infrared band of CO 2 . This is also the first study where line mixing parameters have been experimentally determined for any parallel CO 2 band.

The temperature-dependences of line broadening and shift parameters for many 12CH3D transitions have been determined using six high-resolution, high signal-to-noise ratio, room-temperature CH3D (98% purity) and CH3D-N2 spectra recorded with 25 cm path length ( at 0.01 cm−1 unapodized resolution) using the McMath−Pierce FTS located on Kitt Peak, Arizona, and 17 additional high quality, pure CH3D (99% purity) and CH3D-N2 spectra recorded between 79 and 296 K with the 20.38 cm path coolable cell (at 0.0056 cm−1 unapodized resolution) with the Bruker 125HR FTS at the Jet Propulsion Laboratory (JPL), Pasadena, California. The spectra have been fitted simultaneously applying a multispectrum nonlinear least-squares technique. In the analysis, the Lorentzian N2-broadened half-width coefficients and the corresponding pressure-shift coefficients as well as their temperature dependences are extracted for about 400 transitions (0≤J″≤19, K″≤16) in the perpendicular (ΔK=±1) ν6 band. At 296 K, the measured N2-broadened half-width coefficients range from 0.0209 to 0.0782 cm−1 atm−1 whereas the majority of the associated N2-induced shift coefficients are negative, and the values are between -0.016 and 0.005 cm−1 atm−1. The temperature dependence exponents for N2-broadened half-widths range between 0.264 and 0.924, whereas the temperature dependence coefficients for N2-induced shifts are between 0 and 0.00011 cm−1 atm−1 K−1. The N2-broadened half-width coefficients have been also calculated using a semi-classical approach based on a rigorous treatment of the active molecule as a symmetric top, a model intermolecular potential comprising both short- and long-range interactions, and exact classical trajectories. The role of the various high-order multipoles in the line-broadening at low, middle and high values of the rotational quantum number J″ has been investigated and the main features of the K-dependences analyzed. The calculations performed for 296, 240 and 190 K have allowed to deduce the half-width temperature-dependence exponents, completing the general comparison of our new experimental results with those which are available in the literature.

Line positions and strengths of 12 C 16 O 2 were measured between 4550 and 7000 cm −1 using near infrared absorption spectra recorded at 0.01–0.013 cm −1 resolution with the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory at Kitt Peak, Arizona. These were retrieved from 42 laboratory spectra obtained at room temperature with five absorption cells having various optical path lengths (from 0.1 to 409 m) filled with natural and enriched samples of CO 2 at pressures ranging from 2 to 581 Torr. In all, band strengths and Herman–Wallis-like F -factor coefficients were determined for 58 vibration–rotation bands from the least-squares fits of over 2100 unblended line strengths; strengths of 34 of these bands had not been previously reported. Band strengths in natural abundance generally ranged from 3.30 × 10 −20 to 2.8 × 10 −25 cm −1 /molecule cm −2 at 296 K. It was found that the high J transitions ( J ′ ⩾ 61) of the 20012 ← 00001 band centered at 4977.8347 cm −1 are perturbed, affecting both measured positions and strengths. Two other interacting bands, 21113e ← 01101e and 40002e ← 01101e, were also analyzed using degenerate perturbation theory. Comparisons with corresponding values from the literature indicate that absolute accuracies better than 1% and precisions of 0.5% were achieved for the strongest bands.

Line mixing has been measured for two pairs of transitions in the ν 2 band of H 2 16 O. The rotational assignments of the four lines (in terms of the rotational quantum numbers J , K a and K c ) are (a) two P branch lines: (1 0 1)←(2 1 2) mixing with (2 1 2)←(3 0 3) at 1539.061 and 1540.300 cm −1 , respectively; and (b) two R branch lines: (3 0 3)←(2 1 2) mixing with (2 1 2) ←(1 0 1) at 1652.400 and 1653.267 cm −1 , respectively. Pressure broadening coefficients of H 2 O (halfwidths, pressure shifts and off-diagonal relaxation matrix elements) are reported for seven broadeners (self, H 2 , He, CO 2 , N 2 , O 2 and air) from retrievals performed by multispectrum fitting implemented with line mixing. The effect is largest for self- and H 2 -broadening.

Absolute intensities, self- and air-broadening coefficients, self- and air-induced shift coefficients and their temperature dependences have been determined for lines belonging to the P- and R-branches of the m2 band of H 12 C 14 N centered near 712 cm � 1 . Infrared spectra of HCN in the 14-lm region were obtained at high resolution (0.002–0.008 cm � 1 ) using two different Fourier transform spectrometers (FTS), the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak and the Bruker IFS 120HR FTS at the Pacific Northwest National Laboratory. Spectra were recorded with 99.8% pure HCN as well as lean mixtures of HCN in air at various temperatures ranging between +26 and � 60 � C. A multispectrum nonlinear least squares technique was used to fit selected intervals of 36 spectra simultaneously to obtain the line positions, intensities, broadening, and shift parameters. The measured line intensities were analyzed to determine the vibrational band intensity and the Herman–Wallis coefficients. The measured self-broadening coefficients vary between 0.2 and 1.2 cm � 1 atm � 1 at 296 K, and the air-broadening coefficients range from 0.08 to 0.14 cm � 1 atm � 1 at 296 K. The temperature dependence exponents of self-broadening range from 1.46 to � 0.12 while the corresponding exponents for air broadening vary between 0.58 and 0.86. The present measurements are the first known determination of negative values for the temperature dependence exponents of HCN-broadening coefficients. We were able to support our selfbroadening measurements with appropriate theoretical calculations. Our present measurements are compared, where possible, with previous measurements for this and other HCN bands, as well as the parameters that are included in the 2000 and 2004 editions of the high-resolution transmission (HITRAN) database.

Air-broadened linewidths, pressure-induced shift coefficients and their temperature dependences were retrieved for over 1000 transitions in the ν 3 band of 14 N 16 O 2 at 6 μm. In addition, precise line center positions and relative intensities were also determined. The results were obtained by fitting simultaneously 27 spectra recorded at high resolution (0.002–0.006 cm −1 ) with two Fourier transform spectrometers and gas sample temperatures ranging from 206 to 298 K. It was necessary to modify the multispectrum fitting software to accommodate constraints on the retrieved parameters of closely spaced spin–split doublets in order to successfully determine their broadening and shift parameters. The variations of the widths, shifts and their temperature dependences with the quantum numbers were investigated. Subsets of the observed linewidths were reproduced to within 3% using an empirical smoothing function.

Line intensities of the three lowest fundamentals of the 12CH3D Triad are modeled with an RMS of 3.2% using over 2100 observed values retrieved by multispectrum fitting of enriched sample spectra recorded with two Fourier transform spectrometers. The band strengths of the Triad in units of 10−18 cm−1/(molecule cm−2) at 296 K are, respectively, 2.33 for ν6 (E) at 1161 cm−1, 1.75 for ν3 (A1) at 1307 cm−1 and 0.571 for ν5 (E) at 1472 cm−1. The total calculated absorption arising from 12CH3D Triad fundamentals is 4.65×10−18 cm−1/(molecule cm−2) at 296 K. In addition, some 740 intensities of nine hotbands are fitted to 8.1%; most of the hotband measurements belong to 2ν6−ν6 and ν3+ν6−ν3 near 1160 cm−1, 2ν3−ν3 near 1290 cm−1 and ν3+ν6−ν6 near 1304 cm−1. The other observed hotbands are ν5+ν6−ν6, 2ν5−ν5, ν5+ν6−ν5, ν3+ν5−ν3, and ν3+ν5−ν5.

Two editions of the methane line parameters (line positions, intensities and broadening coefficients) available from HITRAN in 2000 and 2001 are described. In both versions, the spectral interval covered was the same (from 0.01 to 6184.5 cm −1 ), but the database increased from 48,033 transitions in 2000 to 211,465 lines in 2001 because weaker transitions of 12 CH 4 and new bands of 13 CH 4 and CH3D were included. The newer list became available in 2001 in the “Update” section of HITRAN. The sources of information are described, and the prospects for future improvements are discussed.

Air- and N2-broadening, air- and N2-pressure-induced shift coefficients and the temperature dependence exponent of the broadening coefficients and the temperature dependent coefficient of pressure-induced shifts have been determined for transitions of the ν1 band of H12C14N from 39 laboratory absorption spectra recorded at 0.005 and 0.008 cm −1 resolutions with two different Fourier transform spectrometers. The parameters were retrieved from the multispectrum nonlinear least-squares fits to the 3200– 3400 cm −1 region of spectra recorded at temperatures between +26°C and −60°C. Pure samples of HCN in a 19.95 cell and a 0.958 cm cell at room temperature as well as lean mixtures of HCN in N2 or dry air in a coolable cell with a 50 cm absorption path were used in the experiments. Line parameters for N2 broadening were determined by fitting 27 spectra simultaneously while air-broadening parameters were quantified from simultaneous fits to 22 spectra. The average ratio and the standard deviation of the room-temperature air- to N2-broadening coefficient of lines with assignments between P(29) and R(28) are 0.904±0.001. Pressure-induced shift coefficients at 296 K are all negative with values between 0 and ∼−0.006 cm −1 atm −1 and different rotational dependences in the P- and R-branches. Differences between our results, previous measurements and the parameters that are reported in the 2000 edition of HITRAN (HIgh-resolution TRANsmission) database are quantified and discussed.

Line intensities of the two 12 C 16 O 2 laser bands (ν3–ν1 and ν3–2ν20) centered near 960.9 and 1063.7 cm −1 , respectively, were obtained from analysis of 30 room temperature long path laboratory absorption spectra recorded at 0.0028 and 0.0053 cm −1 resolution with the McMath–Pierce Fourier transform spectrometer at the National Solar Observatory (located on Kitt Peak). The spectra were analyzed simultaneously with the multispectrum nonlinear least-squares fitting procedure. The measured line intensities were further analyzed to derive the vibrational band intensities and Herman–Wallis coefficients.

Extensive high-resolution experimental determination is provided for air- and N2-broadening and pressure shift coefficients for the two 13 C 16 O 2 laser bands (located at 913.4 and 1017.6 cm −1 , respectively), in addition to new measurements of self-broadening and self-shift coefficients for the 12 C 16 O 2 laser bands. These parameters were determined from analysis of spectra recorded with the McMath–Pierce Fourier transform spectrometer (FTS) of the National Solar Observatory on Kitt Peak, Arizona. We used a multispectrum nonlinear least-squares fitting technique to analyze 30 long path, room temperature absorption spectra. By combining the spectra of 12 CO 2 and 13 CO 2 in the same fit we were able to obtain a consistent set of line parameters for both molecules. The results obtained for the 12 CO 2 and 13 CO 2 laser bands were compared with each other, with values in the HITRAN database, and with values reported in the literature for CO2 bands. Comparisons revealed no significant differences in the broadening or shift coefficients between the two laser bands. The coefficients determined for the two isotopomers agreed closely.

Self- and hydrogen-broadening coefficients and pressure-shift coefficients for the first overtone band transitions of 12 C 16 O at room temperature have been determined through analysis of nine high-resolution (0.0055 cm −1 ) absorption spectra. These spectra were recorded using the 1-m Fourier transform spectrometer (FTS) at the McMath-Pierce facility of the National Solar Observatory on Kitt Peak, Arizona. Because of the short path length of the sample cell (10.0 cm ) , the volume mixing ratios of CO in hydrogen were relatively high, ∼18–22%, to achieve measurable absorption. These large volume-mixing ratios necessitated the simultaneous determination of the CO self-broadening and self-shift coefficients along with the hydrogen-broadening and hydrogen-induced shift coefficients. We have determined these coefficients at room temperature, along with line positions and absolute intensities, for the P(27) through R(27) 12 C 16 O 2-0 transitions by fitting the entire spectral interval from 4130 to 4345 cm −1 in all nine spectra simultaneously using our multispectrum nonlinear least-squares procedure. Our intensity measurements are consistently low (1–6%) compared with the HITRAN values but the majority of the intensities are within 4% of the HITRAN values. The values of self-broadening coefficients vary from 0.0452 to 0.0862 cm −1 atm −1 at 296 K and those of hydrogen-broadening coefficient range between 0.0475 and 0.0795 cm −1 atm −1 at 296 K . All of our measured self- and hydrogen-shift coefficients are negative and range from −0.002 to −0.008 cm −1 atm −1 . With the pressure and path length used in our study we did not find evidence of significant line mixing in either the self- or hydrogen-broadened spectra. This study represents the first high-resolution experimental determination of hydrogen-induced pressure broadening and pressure-shift coefficients in the 2-0 band of 12 C 16 O at room temperature.

We report the first measured Lorentz self- and nitrogen-broadening and the corresponding pressure-shift coefficients in the ν5(E) perpendicular band of 12CH3D between 1275 and 1600 cm −1 . The multispectrum fitting technique allowed us to analyze simultaneously both self-broadened and N2-broadened spectra recorded at 0.005 to 0.006-cm−1 resolution with a Fourier transform spectrometer located at Kitt Peak. Self-broadening coefficients for over 550 transitions and self-shift coefficients for more than 480 transitions with rotational quantum numbers up to J″=17 and K″=14 were determined. Nitrogen-broadening and nitrogen pressure-induced shift coefficients were determined for more than 300 of those transitions. The measured broadening coefficients vary from 0.020 to about 0.091 cm −1 atm −1 at 296 K . The measured pressure-shift coefficients had values extending from about −0.014 to +0.005 cm −1 atm −1 . Very few of the pressure-shift coefficients were positive, and the positive pressure-shift coefficients were mostly associated with the J″=K″ transitions in the PQ sub-bands. The J″=K″ transitions in the PP and RR sub-bands were associated with the smallest broadening coefficients. Our measurements also included 46 forbidden lines with Δ K=±2 (10 O P , 9 O Q ,3 Q P , 7 Q Q , 1 Q R , 13 S Q and 3 SR). The off-diagonal relaxation matrix element coefficients, Wij, in cm −1 atm −1 at 296 K which are associated with line mixing were determined for a few transitions with K″=3 (A+A−splitting) in the P P , P Q and RP sub-bands. We have examined the dependence of the measured parameters on J,K quantum numbers and also developed empirical expressions to describe the broadening coefficients in terms of J and K.

Lorentz self- and nitrogen-broadening coefficients as well as self- and nitrogen-pressure induced shift coefficients were measured at room temperature for more than 440 transitions in the QP, QQ and QR branches of the ν3(A1) parallel band of 12CH3D. The simultaneous multispectrum nonlinear least-squares fitting analysis was performed in the 1140– 1440 cm −1 region using 14 spectra of room temperature gas recorded with the McMath–Pierce Fourier transform spectrometer ( 0.005 cm −1 unapodized resolution) of the National Solar Observatory (NSO) on Kitt Peak. The measured self-broadening coefficients varied from about 0.025 cm −1 atm −1 at 296 K for high J, K transitions to about 0.09 cm −1 atm −1 at 296 K for low J, K transitions. In the case of nitrogen broadening these values ranged from about 0.023 to 0.073 cm −1 atm −1 at 296 K . The majority (>90%) of the self-pressure induced shift coefficients as well as nitrogen-pressure-induced shift coefficients was negative with values varying between approximately 0 and −0.012 cm −1 atm −1 . However, similar to air-induced pressure-shift coefficients determined in an earlier study, the measured self- and nitrogen-induced pressure-shift coefficients were positive for the QR-branch transitions with J″=K″, varying from 0 to about +0.009 cm −1 atm −1 . Weak line mixing effects were observed in several high-J lines with K″=3 splitting and approximate values for the off-diagonal relaxation matrix-element coefficients were determined for a few A 1 A 2 (A + A − ) split components. Comparisons are made between the measured self- and nitrogen-broadening and shift coefficients, and the results are also compared with measurements in other bands.

A multispectrum nonlinear least-squares fitting technique has been applied to determine accurate zero-pressure line center positions, Lorentz self- and N2-broadening coefficients and self- and N2-induced pressure shift coefficients of transitions in the ν6 (E) perpendicular band of 12CH3D between 1035 and 1270 cm −1 . Seventeen high-resolution (0.002– 0.006 cm −1 ) room temperature absorption spectra recorded with two Fourier transform spectrometers (FTS) were analyzed together. Self-broadening coefficients for over 700 transitions and self-shift coefficients for more than 600 transitions were determined. Measurements of nitrogen-broadening coefficients for more than 480 transitions and nitrogen pressure induced shift coefficients for nearly 430 transitions were also made. The measurements include transitions with rotational quantum numbers as high as J″=18 and K″=15 and several forbidden transitions. The measurements were made in all six sub-bands ( P P , P Q , P R , R P , R Q and RR). The measured self-broadening coefficients vary from 0.025– 0.096 cm −1 atm −1 at 296 K and the N2-broadening coefficients from 0.02 to 0.08 cm −1 atm −1 at 296 K . Self-induced-shift coefficients range from −0.014 to +0.004 cm −1 atm −1 while the nitrogen-induced-shift coefficients vary from −0.013 to +0.008 cm −1 atm −1 . Very few of the measured pressure-shift coefficients were positive, and the positive shift coefficients were mostly associated with the J″=K″ transitions in the PQ sub-bands. The off-diagonal relaxation matrix element coefficients of a number of transitions with K″=3 doublets for both self- and N2-broadening were also obtained. The results obtained with the two different broadening gases are compared and discussed. Comparisons with previous values from the literature are also made.

High-resolution, high signal-to-noise spectra of a high-purity (99%) mono-substituted 13C-enriched ethane (13C12CH6) in the ν12 fundamental band near 12.2 μm region were recorded with a Bruker IFS 125HR Fourier transform spectrometer. The data were obtained for four sample pressures at three different temperatures (130–208 K) using a 20.38-cm long coolable absorption cell. The spectra were fitted simultaneously to retrieve individual line positions and absolute line intensities for 1660 absorption features. A multispectrum nonlinear least squares spectrum fitting technique was employed in the analysis. Constraints were used to fit each pair of doublet components arising from torsional Coriolis interaction of the excited ν12 = 1 state with the nearby excited torsional ν6 = 3 state. Line positions and absolute line intensities were retrieved by simultaneously fitting the four experimental spectra recorded at three low sample temperatures (130 K, 178 K and 208 K). The measured positions and intensities were determined for the standard reference temperature of 296 K and compared with the predicted values listed in the HITRAN database. Calculated line intensities at each of the measured spectrum temperatures are also provided as supplemental data. Integrated intensities are also reported.

Air-broadening and shift coefficients for more than 680 transitions in the 1040– 1410 cm −1 spectral region of the ν6 perpendicular band of 12CH3D have been measured. Values have been obtained from analysis of 11 room temperature absorption spectra recorded at 0.005 cm−1 resolution with the McMath–Pierce Fourier transform spectrometer located on Kitt Peak National Solar Observatory and retrieved using a multispectrum nonlinear least-squares fitting technique. The measured broadening coefficients range from 0.016 to 0.077 cm −1 atm −1 at 296 K for transitions up to J″=17 and K″=15, including 34 forbidden lines with 2≤ΔK≤4. The corresponding pressure-induced shift coefficients vary from −0.012 to +0.008 cm −1 atm −1 , and the majority of these are negative. Within each J series in the PP and RR sub-bands, the J″=K″ (and J′=K′) transition exhibited the smallest broadening coefficient. In the PQ sub-band, the J″=K″ transition in each J series of lines had the largest positive pressure-shift coefficient while the largest negative pressure-shift coefficients were associated with the J′=K′ lines in the RQ sub-band. Subsets of the air-broadened width coefficients vary somewhat smoothly as a function of the rotational quanta, and this behavior has been modeled to ±8% using empirical expressions. Finally, Line mixing effects were observed for the first time in several of the K″=3 ( A + A − ) split components in the P P, P Q, P R, R P, R Q and RR sub-band transitions, and values for off-diagonal relaxation matrix coefficients were determined.

We have measured the room temperature, widths, pressure shifts, and line asymmetry coefficients for many transitions of the first overtone band of CO and CO perturbed by N2. The broadening coefficients were obtained with an accuracy of about 1%. The pure CO profiles have been fitted by a Voigt profile while the CO–N2 spectral profiles have been fitted with a Lorentz and an empirical line shape model (HCv) that blends together a hard collision model and a speed-dependent Lorentz profile. In addition to the Voigt, Lorentz, and HCv models, we have added a dispersion profile to account for weak line mixing. The line broadening and shift coefficients are compared to semiclassical calculations employing a variety of intermolecular interactions. The line asymmetry results are compared to line mixing calculations based on the energy corrected sudden (ECS) model. The results indicate that effects other than line mixing also contribute to the measured line asymmetry.

We describe atmospheric validation of View the MathML source and View the MathML source CO_2 absorption coefficient databases for use by the Orbiting Carbon Observatory (OCO-2). The OCO-2 mission will collect the measurements needed to estimate column-averaged CO_2 dry air mole fraction within 1 ppm accuracy without the region- or airmass-dependent biases that would significantly degrade efforts to understand carbon sources and sinks on a global scale. To accomplish this, the forward radiative transfer model used to generate synthetic atmospheric spectra for retrievals must achieve unprecedented spectroscopic fidelity within the short wave infrared CO_2 bands sampled by the sensors. The failure of Voigt line shapes and conventional line mixing formulations for such objectives has motivated significant revisions to line shape models used to generate the gas absorption cross sections for the OCO-2 forward model. In this paper, we test line mixing and speed dependent line shapes combined with improved experimental line parameters. We evaluate pre-computed absorption coefficients in the two spectral regions of CO_2 absorbtion using high resolution FT-IR laboratory spectra, atmospheric spectra from the Total Carbon Column Observing Network (TCCON), and medium resolution soundings from the space-based Greenhouse Gases Observing Satellite (GOSAT).

We present a detailed spectroscopic study of carbon dioxide in support of atmospheric remote sensing. We have studied two weak absorption bands near the strong ν2 band that is used to derive atmospheric temperature profiles. We have analyzed our laboratory spectra recorded with the synchrotron and globar sources with spectral line profiles that reproduce the absorption features with high accuracy. The Q‐branch transitions exhibited asymmetric line shape due to weak line‐mixing. For these weak transitions, we have retrieved accurate experimental line strengths, self‐ and air‐broadening, self‐ and air‐induced shift coefficients and weak line mixing parameters. The experimental precision is sufficient to reveal inherent variations of the width and shift coefficients according to transition quantum numbers.

Ethane is a prominent contributor to the spectrum of Titan, particularly in the region of the ν9 band at 12 μm. A multispectrum nonlinear least squares fitting program was applied to laboratory spectra of ethane to measure accurate positions, absolute intensities, N2‐ and self‐broadened half‐width coefficients and their temperature dependences for a large number transitions. These measurements include several pQ and rQ sub‐bands (and other sub‐bands such as pP, rR) in the ν9 fundamental band of 12C2H6 centered near 822 cm−1. Positions and intensities were measured for 3771 transitions. N2‐ and self‐broadened half‐width coefficients were determined for over 1700 transitions while temperature dependence exponents were retrieved for over 1350 of those transitions. Of these, many measurements (mostly line positions and intensities) belong to the 12C2H6ν9+ν4−ν4 and the ν9+2ν4−2ν4 hot bands, 13C12CH6 ν9 band and unidentified transitions. Forty‐three high resolution (0.0016–0.005 cm−1) infrared laboratory absorp...

We have recorded high-resolution absorption spectra of methane broadened by dry air and by N 2 at temperatures from −63 to 41°C using a Fourier transform spectrometer. These spectra have been analyzed to determine pressure broadening and line-shift coefficients, along with their temperature dependences, for 148 lines in the ν 4 fundamental band of 12 CH 4 . The experimental uncertainties for lines with J ″≤10 are generally b 0 L , 6–12% for its temperature dependence exponent n , 6–20% for the line-shift coefficient δ 0 , and 20–40% for its temperature dependence coefficient δ′; for J ″> 10 the experimental uncertainties are somewhat larger. These results, especially for N 2 -broadening, are in excellent agreement with other recent measurements. Since the present results cover a wide range of rotational quantum numbers ( J ″ up to 14), the variation of the temperature dependence of the half-widths and shifts from line to line within the ν 4 band is also examined.

Lorentz-broadening and pressure-induced line-shift coefficients are determined experimentally for 126 transitions in the nu2 band of D2(O-16) from laboratory spectra with a Fourier-transform spectrometer. A nonlinear least-squares fitting procedure is employed to measure transitions up to J double-prime = 12 in the buffer gases air, nitrogen, and oxygen. The N2-broadening/O2-broadening coefficient ratio is correlated with the magnitude of the O2-broadening coefficient, and the pressure coefficients are not correlated with line widths.

A multispectrum fitting algorithm has been used to identify line mixing and determine mixing parameters for infrared transitions of H2O and CH4 in the 5-9 micrometer region. Line mixing parameters at room temperature were determined for two pairs of transitions in the v2 fundamental band of H2O-16, for self-broadening and for broadening by H2, He, CO2, N2, O2 and air. Line mixing parameters have been determined from air-broadened CH4 spectra, recorded at temperatures between 210 K and 314 K, in selected R-branch manifolds of the v4 band. For both H2O and CH4, the inclusion of line mixing was seen to have a greater effect on the retrieved values of the line shifts than on the retrieved values of other parameters

Erratum to ‘‘Spectral line parameters including temperature dependences of selfand air-broadening in the 2’0 band of CO at 2.3 mm’’ [J Quant Spectrosc Radiat Transfer 2012;113:1013–33] V. Malathy Devi , D. Chris Benner , M.A.H. Smith , A.W. Mantz , K. Sung , L.R. Brown , A. Predoi-Cross e a Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187, USA b Science Directorate, NASA Langley Research Center, Hampton, VA 23681, USA c Department of Physics, Astronomy and Geophysics, Connecticut College, 270 Mohegan Avenue, New London, CT 06320, USA d Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA e Department of Physics and Astronomy, The University of Lethbridge, 4401 University Drive, Lethbridge, AB, Canada TIK 3M4

The primary objective of this project is to enhance our spectroscopic knowledge of methane in the crowded "octade region" containing eight overtone and combination bands.

Other terms in Eq. (2) were defined in Ref. [1] but are included here for the convenience of the reader: mi = wavenumber (in cm ) of a transition; v0 = band center (in cm , equal to G0 G00); E00 = the lower state energy (in cm ); T0 = the temperature of the absorbing gas, which in the present case is the reference temperature of 296 K; Sv = the vibrational band strength in cm/molecule at 296 K; Si = line intensity (in cm/ molecule at 296 K); Li = the Honl-London factors; C2 = the second radiation constant = 1.4387 when line positions and lower state energies are in cm , T in Kelvin and the molecular mass is in amu. Qr = lower state rotational quantum partition function at temperature T0 (296 K), (224.074297 for CO and 112.464588 for CO). The F factors have already been given by Eq. (3) in Ref. [1]. Please note that all of the intensity values reported in tables and figures of Ref. [1] were generated using the correct form of Eq. (2) including the statistical weight. The authors especially thank Gang Li and Iouli Gordon at the Harvard-Smithsonian Center for Astrophysics, Cambridge MA for pointing out this omission.

Absolute line intensities have been determined at room temperature for a total of 22 transitions belonging to rP and pP subbands in the ν6(E) perpendicular band of 12CH3D between 1062 and 1114 cm−1 under Doppler-limited resolution using a tunable diode-laser spectrometer system. Although the line intensities were determined with good precision (≈3%), the squared vibrational transition dipole matrix element derived from each line intensity showed large variations (≈500%) indicating intensity perturbations, possibly caused by Coriolis interactions between the ν3, ν5, and ν6 fundamentals. The “Herman-Wallis” F-factor coefficients derived from the rP and pP subband transitions were significantly different from each other, but compared well with those reported in a recent study by M. Delaveau (Ph.D. thesis, Universite de Paris-Sud, Orsay, 1985) using a Fourier transform spectrometer. Room temperature air- and nitrogen-broadened halfwidths have also been determined for 24 lines. The average of the ratios of nitrogen- to air-broadened halfwidths was 1.01 with a standard deviation of 0.01, giving almost equal broadening efficiencies for nitrogen and air. Room temperature self-broadened halfwidths were derived for two transitions with a mean value of 0.081 ± 0.001 cm−1 atm−1 at 296 K.