References for the GEISA 2011 sub-database on absorption cross-sections : IR
Molecules list : SF5CF3, C6H6, CH3CN, C2H3NO5, (CH3)2CO
SF5CF3 (Trifluoromethyl sulphur pentafluoride)
SF5CF3 IR absorption cross-sections from M. Hurley were implemented in GEISA 2003. The absorption cross-sections measured by Rinsland et al. [1], at five temperatures between 213 and 323 K in the infrared bands of SF5CF3 are newly added to GEISA 2011. The spectra were recorded at a resolution of 0.112 cm-1 using a commercial Fourier transform infrared spectrometer and a 20 cm temperature-controlled sample cell. The full spectral range of the measurements was 520–6500 cm-1, with only weak bands observed beyond 1400 cm-1. Absorption of thermal radiation in the 8–12 μm atmospheric window region being important for climate change, the measured integrated cross-sections of the significant absorption bands in that spectral region have been added to the GEISA archive. It has to be noted that the SF5CF3 atmospheric growth has closely paralleled the rise of SF6 during the past three decades, with an estimated radiative forcing of 0.57 W m-2 ppb-1, slightly higher than for SF6 [2].
References :
[1] Rinsland CP, Sharpe SW, Sams RL. Temperature-dependent cross-sections in the thermal infrared bands of SF5CF3. JQSRT 2003;82:483–90.
[2] Scientific assessment of ozone depletion, 1988. Global ozone research and monitoring project, report 44, World Meteorological Organization, Geneva, 1999.
C6H6 (Benzene)
Integrated band intensities of benzene at temperatures of 278, 298, and 323 K, in the spectral range 600-6500 cm-1 by Rinsland et al. [1], have been added to GEISA 2011 IR cross-sections archive. These data derived from pressure broadened (1 atm N2) laboratory spectra of benzene vapor (in natural abundance) recorded at PNNL with a 0.112 cm-1 resolution Bruker-66 V Fourier transform spectrometer configured to operate in the mid-infrared. Using very high precision capacitance nanometers, over nine sample pressures were recorded for each of the three temperatures. Hard-mounted into the spectrometer, a temperature-stabilized static cell (19.94(1) cm path-length), was used for support of the samples introduced into it. Two- hundred fifty-six interferograms were averaged for each sample spectrum. A composite spectrum was calculated for each cell temperature from the individual absorbance spectra recorded at that temperature. The average uncertainty (NIST type-A) is respectively: 0.40%, 0.38% and 0.54% for the 278 K, 298 K, and 323 K spectra. The number density for the three composite spectra was normalized to 296 K. The spectra give the absorption IR cross-sections (cm2 molecule-1, naperian units) of benzene as a function of wavenumber
Reference :
[1] Rinsland CP, Devi VM, Blake TA, Sams RL, Sharpe S, Chiou LS. Quantitative measurement of integrated band intensities of benzene vapor in the mid-infrared at 278, 298, and 323 K. JQSRT 2008;109:2511-22.
CH3CN (Acetonitrile, -Methyl cyanide)
Infrared cross sections were measured at the Pacific Northwest National Laboratory by Rinsland et al. [1]. These 29 spectra covered 600 and 6500 cm-1 with a resolution of 0.1125 cm-1 and were measured at three different temperatures (276 K, 299 K, and 324 K). They were recorded with different CH3CN volume mixing ratios at 1 atm pressure using N2 as pressure broadening gas. The CH3CN cross-sections of Ref. [2] have been derived at three temperatures: 276.1 K, 298.7 K and 324.1 K, in six spectral ranges from 635 to 4574 cm-1 and 1 atm N2 pressure broadened vapour.
References :
[1] Rinsland CP, Devi VM., Benner DC, Blake TA, Sams RL, Brown LR, et al. Multispectrum analysis of the ν4 band of CH3CN: Positions, intensities, self- and N2-broadening and pressure-induced shifts. JQSRT 2008;109:974-94.
[2] Rinsland CP, Sharpe SW, Sams RL. Temperature-dependent infrared absorption cross sections of methyl cyanide (acetonitrile). JQSRT 2005;96:271-80.
C2H3NO5 (PeroxyAcetyl Nitrate, -PAN)
New spectroscopic data for PAN, in the form of cross-sections, have therefore been included in the GEISA database for the first time, based on the measurements of Allen et al. [1,2]. The cross-sections cover the spectral range between 560 cm-1 and 1400 cm-1 at three temperature (295 K, 273 K, 250 K), and between 1686 cm-1 and 2000 cm-1 at two temperatures (295 K and 250 K). The data include all bands from ν4 to ν19, except for ν16 centred at 1653 cm-1 which is detected in the original measurements at 295 K but is not included here because of weakness of the band and residual water vapour contamination. The band assignments are based on those reported in Gaffney et al. [3] and Bruckmann and Wilner [4]. The five main bands are ν4, ν5, ν9, ν10 and ν16 centred at 1842, 1741, 1302, 1161.5 and 791.5 cm-1 respectively; a small shift of 1 cm-1 was observed in the peak of the ν4 band at 1842 cm-1 with temperature [2]. Uncertainties in the cross-sections were estimated to be 5% at 250 K [2] rising to 7% at 295 K [1].
References :
[1] Allen G, Remedios JJ, Newnham DA, Smith KM, Monks PS. Improved mid-infrared cross-sections for peroxyacetylnitrate (PAN) vapour. Atmos Chem Phys 2005;5:47–56.
[2] Allen G, Remedios JJ, Smith KM. Low temperature mid-infrared cross-sections for peroxyacetyl nitrate (PAN) vapour. Atmos Chem Phys 2005;5:3153–8.
[3] Gaffney JS, Fajer R, Senum GI. An improved procedure for high purity gaseous peroxyacetyl nitrate production: Use of heavy lipid solvents. Atmos. Envir 1984;18:215–8.
[4] Bruckmann PW, Willner H. Infrared spectroscopic study of peroxyacetyl nitrate (PAN) and its decomposition products. Envir Sci Tech 1983;17:352–7.
(CH3)2CO (Acetone)
New spectroscopic data for acetone, in the form of cross-sections, have been included in the GEISA database for the first time, based on the measurements of Waterfall [1]. The cross-sections at spectral resolution of 0.03 cm-1 cover the spectral range between 600 cm-1 and 1800 cm-1 around six temperature series (214, 223, 233, 253, 272, 297 K); see Table 10 for precise details. The data include the ν18 band centred at 830 cm-1, the ν17 at 1218 cm-1, the ν16/ν5 bands close to 1360 cm-1 overlapping with the unresolved bands of ν15, ν4 and ν21 centred between 1430 and 1460 cm-1, and the ν3 band centred at 1738 cm-1; band assignments are taken from Wang et al. [2]. The ν7 band, centred at 777 cm-1, and the ν22/ν6 near 1093 cm-1 are only very weakly present in the measured cross-sections. The main cross-section influence is for the strongest bands observed between 1200 and 1800 cm-1 for which uncertainties range from 5% (7% for the centre of the ν3, 1738 cm-1 band) at the strongest parts of the band to 10% towards the edges. For the 830 cm-1 band, errors are approximately 12% at band centre rising to greater than 20% at the band edges.
References :
[1] Waterfall A. Measurement of organic compounds in the upper troposphere. Ph. D. Thesis, University of Oxford, 2003.
[2] Wang WF, Stevenson A, Reuter DC, Sirota JM. Absolute band intensities in of acetone (CH3)2CO in the infrared region of 830-3200 cm-1 at low and room temperatures. Spectrochim Acta Part A 2001;57:1603-10.
