AGW Observer

Observations of anthropogenic global warming

Papers on laboratory measurements of other GHGs

Posted by Ari Jokimäki on April 27, 2010

This is a list of papers on laboratory measurements of absorption properties of other GHGs than carbon dioxide (carbon dioxide has its own list). The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

Studies of several gases and other general papers

The infrared absorption cross-section and refractive-index data in HITRAN – Massie & Goldman (2003) “The cross-sections and indices of refraction on the HIgh-resolution TRANsmission (HITRAN) database are summarized. HITRAN contains a tabulation of cross-sections of atmospheric chemical reservoir and source species, chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons, and indices of refraction of liquid and solid compounds. The temperature and pressure dependences of the cross-sections and the temperature dependence of the indices of refraction are illustrated. Data uncertainties and applications are discussed, and some future needs of the remote-sensing community are identified.”

Cw cavity ring-down infrared absorption spectroscopy in pulsed supersonic jets: nitrous oxide and methane – Hippler & Quack (1999) “We introduce cw cavity ring-down spectroscopy (cw-CRDS) in pulsed supersonic jet expansions employing a tuneable near-infrared cw diode laser and a solenoid slit nozzle. The cavity is mode-matched to the laser wavelength during the gas pulses to achieve highest resolution and lowest noise level. The new technique is characterised by observing very weak rovibrational lines of the ν1+3ν3 combination band of nitrous oxide near 7780 cm−1 and the ν2+2ν3 combination band of methane near 7510 cm−1. We demonstrate the increased spectral resolution due to the reduced Doppler width of rovibrational transitions and the spectral simplification afforded by the rotational cooling.”

Water vapour

New studies of the visible and near‐infrared absorption by water vapour and some problems with the HITRAN database – Belmiloud et al. (2000) “New laboratory measurements and theoretical calculations of integrated line intensities for water vapour bands in the near‐infrared and visible (8500–15800 cm−1) are summarised. Band intensities derived from the new measured data show a systematic 6 to 26% increase compared to calculations using the HITRAN‐96 database. The recent corrections to the HITRAN database [Giver et al., J. Quant. Spectrosc. Radiat. Transfer, 66, 101–105, 2000] do not remove these discrepancies and the differences change to 6 to 38%. The new data is expected to substantially increase the calculated absorption of solar energy due to water vapour in climate models based on the HITRAN database.” [Full text]

Measurements of absorption coefficients of water vapor by means of an H2O laser in the far-infrared – Kempkens et al. (1979) “Absorption coefficients of water vapor were investigated for the frequency of a water vapor laser in the far-infrared (λ = 118.6 μm). The theoretical treatment of these coefficients was carried out assuming self-broadening of H2O and D2O rotational transitions as well as foreign gas broadening of these vapors by nitrogen. Comparing these theoretical values with the corresponding experimentally determined data it turns out that there must be an additional absorption mechanism due to HDO molecules, which in low concentration are contained in natural water and in the D2O available. Taking into account the absorption by HDO, the theoretical and experimental values show a good agreement. In addition, the absorption coefficients of H2O and D2O were measured for foreign gas broadening by hydrogen and argon.”

Total Absorptance of Water Vapor in the Near Infrared – Burch et al. (1963) “The total absorptance ∫ A{v)dv of water vapor in the vicinity of its vibration-rotation bands near 5332, 3700, and 1595 cm−1 has been determined as a function of absorber concentration w and equivalent pressure Pe for pure water vapor samples and samples of water vapor mixed with nitrogen. The present results, together with previously published results of Howard, Burch, and Williams, are presented in graphical form; logarithmic plots give ∫ A(v)dv for various values of Pe as a function of absorber concentration w. These plots may be used in estimating total absorptance of water vapor in any sample for which w and Pe are known, and they may be applied in atmospheric studies.”

Methane

The Intensities of Methane in the 3–5 μm Region Revisited – Féjard et al. (2000) “The analysis of the linestrengths of the infrared spectrum of methane (12 and 13) in the 3–5 μm region has been revisited on the basis of new measurements from Fourier transform spectra recorded at Kitt Peak under various optical densities. A simultaneous fit of these new data with previously reported tunable difference-frequency laser data has been done. An effective transition moment model in tensorial form up to the third order of approximation within the Pentad scheme has been used. The standard deviations achieved are very close to the experimental precision: 3 and 1.5%, respectively, for the two sets of data for the 12CH4 molecule, representing a substantial improvement with respect to earlier studies. The integrated bandstrengths obtained in the present work differ from previously reported values by factors ranging from −5 to +6%.” [Full text]

Quasi-Random Narrow-Band Model Fits to Near-Infrared Low-Temperature Laboratory Methane Spectra and Derived Exponential-Sum Absorption Coefficients – Baines et al. (1993) “Near-infrared 10-cm−1 resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112 K, 188 K, and 295 K), and 20 pressures from 0.0001 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 μm. … The validity of exponential-sum coefficients derived from broadband (10 cm−1) transmission data is demonstrated via direct comparison with line-by-line calculations.”

Determination of the ν4 band strength of 12CH4 from diode laser line strength measurements – Jennings & Robiette (1982) “The strengths of over 50 lines in the ν4 region of 12CH4 were measured using a diode laser spectrometer. Forty-nine lines were assigned to transitions of the ν4 band. Analysis of the strengths of these 49 lines leads to a value of the integrated band strength S40 = 127 ± 4 cm-2 atm-1 at 295.7 K; this value is compared to other recent band strength determinations. The Herman-Wallis factor, expressing the dependence of the transition moment on rotational quantum number, is also discussed.”

Line positions and strengths of methane in the 2862 to 3000 cm−1 region – Toth et al. (1977) “Measurements of line center positions and strengths of 1591 absorptions of CH4 in the 2862 to 3000 cm−1 region have been made at high resolution. New assignments have been determined for several components in the P14 and P15 manifolds of the ν3 band of 12CH4. The strength data of the allowed transitions in the ν3 band have been analyzed to determine the band strength and the coefficients of the F factor. The strength data given by Pine (1976) were also included in the analysis. For the ν3 band, a strength of 259.5 cm−2 atm−1 at 296 K was obtained. Many forbidden lines in the ν3 band were also observed in the spectra Line strengths in the ν3 band of 13CH4 were determined from the spectra.”

Total Absorptance of Carbon Monoxide and Methane in the Infrared – Burch & Williams (1962) “The total absorptance ∫ A(v)dv of the major infrared bands of carbon monoxide and methane has been measured as functions of absorber concentration w and equivalent pressure Pe over wide ranges of these variables. The experimental results are presented graphically, and empirical equations relating ∫ A(v)dv, w, and Pe are presented. By employing small values of w and large values of Pe, it has been possible to determine the band strengths or intensities ∫ k(v)dv for the fundamental band of carbon monoxide and for v2, v3, and v4 fundamentals of methane; the values obtained are compared with results of other investigators.”

Ozone

The infrared spectrum of ozone – McCaa & Shaw (1968) “Fourteen bands of ozone between 500 and 3300 cm−1 have been identifiedand values of the vibrational anharmonic constants determined. The integrated band absorptances of many of these bands have been measured from spectra of a 32-m path of ozone-oxygen mixtures containing up to 30 atm cm O3 near 25°C. The dependences of the band absorptances on O3 concentration and total pressure are described and the strengths of nine of the bands are given. It is shown that the statistical band model describes the behavior of the bands reasonably well for the ranges of experimental variables used.”

Nitrous oxide

Total Absorptance by Nitrous Oxide Bands in the Infrared – Burch & Williams (1962) “The total absorptances of the 2563, 2461, 2224, 1285, 1167, 692, and 589 cm−1 bands of pure N2O and N2O mixed with N2 have been determined as a function of absorber concentration w and equivalent pressure Pe which involves the partial pressures of the two gases. The results are given in graphical form. In general, it is found that in situations in which existing theory predicts absorptance proportional to the square roots of pressure and absorber concentration, the total absorptance is indeed nearly proportional to the square root of absorber concentration but not to the square root of the pressure; for the 2224 cm−1 band, ∫ A(ν)dν α Pe0.37. In addition to graphical presentation of results, it is possible to express ∫ A{ν)dν in terms of w and Pe by means of empirical equations applicable to certain definite ranges of the variables; the validity and the limitations of such empirical equations are discussed. For samples for which the product of the absorption coefficient k(ν) and the absorber concentration is much less than unity for all frequencies in an absorption band, it is possible to measure the band intensity or band strength ∫ k(ν)dν. Values of band intensity for the 2563, 2461, 2224, 1167, and 589 cm−1 N2O bands are listed and compared with values previously reported by others.”

CFC’s, HCFC’s, and HFC’s

Thermal infrared cross-sections of C2F6 at atmospheric temperatures – Zou et al. (2004) “Spectral absorption cross-sections, kν (cm-1 atm-1), have been measured in the 8.0 and 8.95 μm bands of C2F6. Temperature and total (N2-broadening) pressure have been varied to represent the conditions specified in various models of the terrestrial atmosphere so that the absorption cross-sections can be applied directly to the optical remote-sensing of C2F6 in the atmosphere. The measured absolute intensities of the 8.0 and the 8.95 μm bands are (1.636±0.003)×10-16 and (0.467±0.0018)×10-16 cmmolecule-1, respectively.”

Absorption cross-sections of HFC-134a in the spectral region between 7 and 12 μm – Nemtchinov & Varanasi (2004) “Spectral absorption cross-sections kν (cm2 molecule-1) were measured in the 7.07, 8.08, 9.24, 10.3, and 11.9 μm bands of HFC-134a at temperatures between 190 and 296 K and pressures between 10 and 1013 hPa with a high-resolution Fourier-transform spectrometer. Our data were obtained at pressures and temperatures that characterise several of the commonly adapted model atmospheres, represent tangent heights in solar-occultation-type remote-sensing observations of the atmosphere, and the conditions recorded in atmospheric observations at Arctic latitudes. The integrated cross-sections (or integrated intensities) of the absorption bands in the 7.07, 8.08, 9.24, 10.3, and 11.9 μm regions are, in the unit of 10-17 cmmolecule-1, 0.4674, 9.711, 1.508, 0.8753, and 0.2527, respectively.”

Thermal infrared absorption cross-sections of CF4 for atmospheric applications – Nemtchinov & Varanasi (2003) “Spectral absorption cross-sections, kν (cm2 molecule−1), have been measured in the 7.8 μm band of CF4 at temperatures between 180 and 296 K and pressures between 10 and 1013 mb (hPa) with a high-resolution Fourier-transform spectrometer. Our data were obtained at pressures and temperatures that parameterize several of the commonly adapted model atmospheres, represent tangent heights in solar-occultation type remote-sensing observations of the atmosphere, and the conditions recorded in atmospheric observations at polar latitudes. The combined absolute intensity of all of the bands contributing to the absorption around 7.8 μm is (1.926±0.012)×10−16 cmmolecule−1.”

Laboratory technique for the measurement of thermal-emission spectra of greenhouse gases: CFC-12 – Evans & Puckrin (1996) “A new technique has been developed to make possible the laboratory study of the infrared-emission spectra of gases of atmospheric interest. The thermal-emission spectra are in local thermodynamic equilibrium, just as they are in the atmosphere, and are not chemiluminescent. Demonstration results obtained by the use of this new technique are presented for dichlorodifluoromethane (CFC-12) at a pressure of 0.5 Torr in a cell with a path length of 5 cm. The measured cell spectra have been compared with simulations with the FASCD3P radiation code. The measurements of the emission spectra of radiatively active gases may be important for the atmospheric greenhouse effect and global warming.”

Thermal infrared absorption coefficients of CFC-12 at atmospheric conditions – Varanasi & Nemtchinov (1994) “Spectral absorption coefficients kν (cm-1 atm-1) have been measured in the 9 and 11 μm bands of CFC-12 (CF2Cl2) using a high-resolution Fourier transform spectrometer. Temperature and total (broadening) pressure have been varied to obtain results at conditions representative of tropospheric and stratospheric layers of the atmosphere. The measured absolute intensities (in units of 10-17 cm.molecule-1) of the 9 and 11 μm bands are 7.595 ±0.070 and 5.750 ±0.068, respectively.”

Other greenhouse gases

Thermal infrared absorption cross-sections of CCl4 needed for atmospheric remote sensing – Nemtchinov & Varanasi (2003) “Highly accurate spectral absorption cross-sections kν (cm2 molecule−1) were in the 12.7 μm band of CCl4 at temperatures between 208 and 296 K and pressures between 10 and 1013 mb with a high-resolution Fourier-transform spectrometer. Our data were obtained at pressures p and temperatures T that characterize the atmospheric layers in the commonly adapted models of the atmosphere. The selected (p,T) combinations also represent tangent heights in solar-occultation-type remote sensing observations and actual conditions recorded by balloon-borne instruments in the Arctic. The combined absolute intensity (or integrated cross-section) of the bands contributing to the absorption around 12.7 μm is 6.295±0.102×10−17 cmmolecule−1.”

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