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References for GEISA-2015 Thermal and Near-InfraRed absorption cross-sections sub-database UpdateA: GEISA-2015 THERMAL INFRARED (TIR) ABSORPTION CROSS-SECTIONS Thirty-nine molecules were represented by cross sections in GEISA-2011. The GEISA-2015 compilation has been updated with additional cross-section datasets, consisting of multiple temperature–pressure combinations, for new and existing molecules. This represents more than about 50% increase in information volume, with the introduction of 41 new molecular species. This update stems mainly from two sources: 1. CROSS-SECTION SET FROM THE University of Oslo [1,2] AND THE UNIVERSITY OF CASTILLA-LA MANCHA [ 3,4,5]. These compounds (halocarbons, bromocarbons, bromofluorocarbons, bromochlorofluorocarbons, halogenated alcohols, halogenated, fluorinated ethers and perfluorinated compounds) contribute to the global warming; Updated IR absorption cross-sections for CFC-12 and 31 fluorinated compounds, included in a recent review of Hodnebrog et al. [1] were added to GEISA-2015 and are listed in Table 1, which provides for each compounds: its chemical formula, common name, spectral information, i.e.: spectral range, gas bath, foreign broadening pressure (Pa), and references. These compounds (halocarbons, bromocarbons, bromofluorocarbons, bromochlorofluorocarbons, halogenated alcohols, halogenated, fluorinated ethers and perfluorinated compounds) contribute to the global warming. References [1] Ø. Hodnebrog, M. Etminan, J.S. Fuglestvedt, G. Marston, G. Myhre, C.J. Nielsen, K.P. Shine, T.J. Wallington, Global warming potentials and radiative efficiencies of halocarbons and related compounds: A comprehensive review, Reviews of Geophysics. 51 (2013) 300-378. [2] C.J. Nielsen, Private communication, 2014 [3] E. Jiménez, M. Antinolo, B. Ballesteros, E. Martinez, J. Albaladejo, Atmospheric Lifetimes and Global Warming Potentials of CF3CH2CH2OH and CF3(CH 2)2CH2OH, Phys. Chem. Chem. Phys. 11 (2010) 4079-4087. [4] M. Antiñolo, S. González, B. Ballesteros, J. Albaladejo, E. Jiménez, Laboratory Studies of CHF2CF2CH 2OH and CF3CF2CH2OH: UV and IR Absorption Cross Sections and OH Rate Coefficients between 263 and 358 K, J. Phys. Chem. A. 116 (2012) 6041-6050. [5] M. Antiñolo, Fluoroalcohols and Fluoroaldehydes in the Troposphere: Kinetics and Photochemistry in the Gas Phase sutdied by Pulsed Laser Techniques, PhD Thesis, University of Castilla-La Mancha. 2011. [6] G. Myhre, F. Stordal, I. Gausemel, C.J. Nielsen, E. Mahieu, Line-by-line calculations of thermal infrared radiation representative for global condition: CFC-12 as an example, J. Quant. Spectrosc. Radiat. Transfer 97 (2006) 317-331. [7] G. Acerboni, J.A. Beukes, N.R. Jensen, J. Hjorth, G. Myhre, C.J. Nielsen, J.K. Sundet, Atmospheric degradation and global warming potentials of three perfluoroalkenes, Atmos. Environ. 35 (2001) 4113-4123. [8] G. Myhre, C.J. Nielsen, D.L. Powell, F. Stordal, Infrared absorption cross section, radiative forcing, and GWP of four hydrofluoro(poly)ethers, Atmos. Environ. 93 (1999) 4447-4458. [9] S.M. Ryan, C.J. Nielsen, Global Warming Potential of Inhaled Anesthetics: Application to Clinical Use, Anesth. Analg. 111 (2010) 92-98. [10] B. D'Anna, S.R. Sellevag, K. Wirtz, C.J. Nielsen, Photolysis study of perfluoro-2-methyl-3-pentanone under natural sunlight conditions, Environ. Sci. Technol. 39 (2005) 8708-8711. [11] N. Oyaro, S.R. Sellevag, C.J. Nielsen, Study of the OH and Cl-initiated oxidation, IR absorption cross-section, radiative forcing, and global warming potential of four C-4-hydrofluoroethers, Environ. Sci. Technol. 38 (2004) 5567-5576. [12] N. Oyaro, S.R. Sellevag, C.J. Nielsen, Atmospheric chemistry of hydrofluoroethers: Reaction of a series of hydrofluoro ethers with OH radicals and Cl atoms, atmospheric lifetimes, and global warming potentials, J. Phys. Chem. A. 109 (2005) 337-346. [13] S.R. Sellevag, C.J. Nielsen, O.A. Sovde, G. Myhre, J.K. Sundet, F. Stordal, I.S.A. Isaksen, Atmospheric gas-phase degradation and global warming potentials of 2-fluoro ethanol, 2,2-difluoroethanol, and 2,2,2-trifluoroethanol, Atmos. Environ. 38 (2004) 6725-6735. [14] S.R. Sellevåg, B. D'Anna, C.J. Nielsen, Infrared Absorption Cross-Sections and Estimated Global Warming Potentials of CF3CH2CH2OH, CHF2CF2CH2OH, CF3CF2CH2OH, CF3CHFCF2CH2OH, and CF3CF2CF2CH2OH, Asian Chemistry Letters. (2007) 33-40. [15] S.R. Sellevåg, T. Kelly, H. Sidebottom, C.J. Nielsen, A study of the IR and UV-Vis absorption cross-sections, photolysis and OH-initiated oxidation of CF3CHO and CF3CH 2CHO, Phys. Chem. Chem. Phys. 6 (2004) 1243-1252. Table 1: Summary of GEISA-2015 infrared absorption cross-sections update. Data from University of Oslo [1,2] and the University of Castilla-La Mancha [3,4,5] at room temperature and spectral resolution of 1 cm-1.
a Each reference corresponds to a single T/P dataset. b Experiments performed with diluted compound in He provide the same infrared absorption cross-sections. 2. CROSS-SECTIONS SET FROM THE University of York [1,2]. This set includes complementary data for 4 molecular species already present in GEISA-2011, i.e.: C2H6, C3H8, CH 3CN, C3H6O, as well as added 3 new added molecular species, i.e.: methanol: (CH3OH) , trifluoromethane (CHF3) and acetaldehyde (CH3CHO). References [1] J.J. Harrison, P.F. Bernath, Mid- and long-wave infrared absorption cross sections for acetonitrile, J. Quant. Spectrosc. Radiat. Transfer 113 (2012) 221-225. [2] J.J. Harrison, Private communication, 2013.
--> Complementary data for species already implemented in GEISA-2011 Ethane ( C2H6) Infrared absorption cross sections for ethane over the spectral range 2545–3315 cm-1 [1] have been included in GEISA-2015. These cross sections provide a higher degree of accuracy for tropospheric sounding than can currently be obtained using the line list. Spectra of ethane / dry synthetic air mixtures inside a 26-cm cell were recorded at fourteen pressure–temperature combinations using a high-resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm-1 resolution (using the Bruker definition of 0.9/MOPD). Reference [1] J.J. Harrison, N.D.C Allen, P.F. Bernath, Infrared absorption cross sections for ethane (C2H6) in the 3 mm region, J. Quant. Spectrosc. Radiat. Transfer 111 (2010) 357-363.
Propane CH3CH2CH3 (C3H8) Absorption cross sections have been included in GEISA-2015 for the first time over the spectral range 2540–3300 cm-1 [1]. They cover the spectral region where propane has its strongest-intensity absorbance features (C-H stretch). Spectra of propane / dry synthetic air mixtures inside a 26-cm cell were recorded at twelve pressure–temperature combinations using a high-resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm-1 resolution (=0.9/MOPD). Reference [1] J.J. Harrison, P.F. Bernath, Infrared absorption cross sections for propane (C3H8) in the 3 mm region, J. Quant. Spectrosc. Radiat. Transfer 111 (2010) 1282-1288.
Acetone ((CH3)2CO) Two new datasets have been added in GEISA-2015; these cover the spectral ranges 830–1950 cm-1 [1] and 2615–3300 cm -1 [2]; the new mid-IR cross sections have been combined with a renormalized subset of those in GEISA-2011 to create a more optimised dataset for this spectral region. For the new measurements, spectra of acetone / dry synthetic air at a number of pressure–temperature combinations were recorded by a high spectral resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm -1 resolution (=0.9/MOPD) using a cooleable White cell with a maximum path length of 19.32 m. References [1] J.J. Harrison, N. Humpage, N.D.C. Allen, A.M. Waterfall, P.F. Bernath, J.J. Remedios, Mid-infrared absorption cross sections for acetone (propanone), J. Quant. Spectrosc. Radiat. Transfer 112 (2011a) 457-464. [2] J.J. Harrison, N.D.C. Allen, P.F. Bernath, Infrared absorption cross sections for acetone (propanone) in the 3 mm region, J. Quant. Spectrosc. Radiat. Transfer 112 (2011b) 53-58. Acetonitrile (CH3CN) GEISA-2015 contains additional new infrared absorption cross sections, covering the spectral ranges 880–1700 cm-1 [1] and 2550–3300 cm-1 [2]. Spectra of acetonitrile / dry synthetic air at a number of pressure–temperature combinations were recorded by a high-resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm -1 resolution (=0.9/MOPD) using a cooleable White cell with a maximum path length of 19.32 m. References [1] J.J. Harrison, P.F. Bernath, Mid- and long-wave infrared absorption cross sections for acetonitrile, J. Quant. Spectrosc. Radiat. Transfer 113 (2012) 221-225. [2] N.D.C. Allen, J.J. Harrison, P.F. Bernath, Acetonitrile (CH 3CN) infrared absorption cross sections in the 3 μm region, J. Quant. Spectrosc. Radiat. Transfer 112 (2011) 1961-1966. --> Molecular species added since the GEISA-2011 edition Methanol (CH3OH ) Two new infrared absorption cross section datasets have been added to the database, covering the spectral ranges 877-1167 cm-1 and 2600-3250 cm-1 [1]. Spectra of methanol/dry synthetic air at a number of pressure–temperature combinations were recorded by a high-resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm-1 resolution (=0.9/MOPD) using a cooleable White cell with a maximum path length of 19.32 m. Reference [1] J.J. Harrison, N.D.C. Allen, P.F. Bernath, Infrared absorption cross sections for methanol, J. Quant Spectrosc Radiat Transfer 113 (2012) 2189-2196.
Trifluoromethane ( CHF3, HFC-23) New infrared absorption cross sections for trifluoromethane over the spectral range 950–1500 cm-1 [1] have recently been made available; these are included in GEISA for the first time. Spectra of trifluoromethane / dry synthetic air mixtures inside a 26-cm cell were recorded at twenty-seven pressure–temperature combinations using a high-resolution FTIR spectrometer (Bruker IFS 125 HR) at 0.015 cm -1 resolution (=0.9/MOPD). Reference [1] J.J. Harrison, Infrared absorption cross sections for trifluoromethane, J. Quant. Spectrosc. Radiat. Transfer 130 (2013) 359-364. Acetaldehyde (CH3CHO) Acetaldehyde, a trace molecular species, found in the Earth’s atmosphere, plays an important role as a source of ozone (O3 ), PAN and HOx radicals. Infrared absorption cross-sections have been measured by Tereszchuk et al. [1] in the 3 µm region (2400–3400 cm -1) from spectra obtained using a FTIR spectrometer at a resolution of 0.005 cm-1. See Ref. [1] for details. Reference [1] K.A. Tereszchuk, P.F. Bernath, Infrared absorption cross-sections for acetaldehyde (CH3CHO) in the 3 µm region, J. Quant. Spectrosc. Radiat. Transfer 112 (2011) 990-993 The absorption cross section (in units of cm2 molecule -1) provided by York University for GEISA-2015 update are summarized in Table 2. Table 2: Absorption cross-sections provided by the University of York for GEISA-2015 update. For each molecular species listed are given: the temperature (T) range (K), the pressure (P) range (Torr), the number of T/P sets, and the spectral range (cm -1).
B: GEISA-2015 NEAR INFRARED (NIR) ABSORPTION CROSS-SECTIONS The 1-3 µm near-infrared spectral region is of great interest for atmospheric remote-sensing and planetary science. The sections below present and document a first set of seven high-resolution absorption cross-sections as reference data in the near-infrared region, for molecules and bands where no theoretical prediction is available. An overview of its contents is given in Table 3. The common names of the molecules and their formula are listed in the two first columns. The spectral regions covered (cm-1), the spectral resolution (cm-1), the maximal uncertainties of the spectral position (cm -1) and absorption cross-sections (%), are given in columns two to five, and references in the final column. Table 3: Summary of the molecules whose experimental absorption cross-sections in the NIR are newly implemented provided in GEISA-2015 database.
Acetonitrile (CH3CN) Absorption cross-sections of Acetonitrile between 6814 and 7067 cm-1 were measured, by O’Leary et al. [1 ], with off-axis CW-CEAS at 5 mbar with a resolution of about 0.001 cm-1. There are about 4630 absorption lines in this spectrum. Absorption features of H2O in this region have been removed from the spectrum. Approximately 200 individual overlapping spectral segments have been concatenated to cover the entire spectral range. Reference [1] D.M. O’Leary, A.A. Ruth, S. Dixneuf, J. Orphal, R. Varma, The near infrared cavity-enhanced absorption spectrum of methylcyanide, J. Quant. Spectrosc. Radiat. Transfer 113 (2012) 1138-1147. Methyl iodide , also called iodomethane (CH3I)
Measurements, by Farag¢ et al. [2], of methyl iodide were made using CW-CRDS in the wavenumber range 7473–7497 cm-1 at a total pressure of 50 Torr and a resolution of 0.001 cm-1. CH 3I was prepared as a diluted mixture in helium, and its concentration was determined from calibrated flowmeters. The spectrum was measured in several small portions in order to minimize a shift in the baseline between measurement of the spectrum with and without CH 3I. There are small gaps in the spectrum at wavelength ranges corresponding to absorption lines of water where data have been erased because water was present in the cell. Reference [2] E.P. Faragó, B. Viskolcz, C. Schoemaecker, C. Fittschen, Measurement of the absorption spectrum and of absolute absorption cross-sections of CH 3O2 Radicals and CH3I in the near IR Region, J. Phys. Chem. A 117 (2013) 12802-12811. Methyldioxidanyl (CH3O2) Measurements, by Farag¢ et al. [2], of methyldioxidanyl were made using CW-CRDS coupled to laser photolysis. The wavenumber range 7474–7493 cm-1 was scanned at a resolution of 0.025 cm-1. CH3O2 was generated by pulsed photolysis of CH3I in the presence of O2. Absolute CH3O 2 concentrations have been deduced by measuring the time-resolved absorbance following the photolysis pulse and adjusting the decay rate to the well-known rate constant of the self-reaction of CH3O2 radicals [2]. Calibration of CH3O 2 concentration was obtained by measuring the time-resolved evolution of the CH3O2 concentration and fitting the kinetic decay traces of CH3O2 to a bimolecular reaction. Using the well-known rate constant of the self-reaction allows retrieval of the initial CH3O2 concentrations. A generally broad absorption spectrum was obtained containing three striking absorption features located at 7748.18, 7489.16 and 7493.33 cm-1 . For these three characteristic lines absolute absorption cross-sections of 3.41x10-20, 3.40x10-20 and 2.11x10-20 cm2 were established, respectively. The remainder of the broad spectrum was scaled according to these cross-sections. Within the error limit of the measurement the cross-sections were not affected by changes of the pressure between 50 and 100 Torr. The error is estimated to be 30%, mostly due to uncertainty in the rate constant for the self-reaction. Reference [2] E.P. Faragó, B. Viskolcz, C. Schoemaecker, C. Fittschen, Measurement of the absorption spectrum and of absolute absorption cross-sections of CH 3O2 Radicals and CH3I in the near IR Region, J. Phys. Chem. A 117 (2013) 12802-12811. Formaldehyde (H2CO) Absorption cross-sections for formaldehyde were measured, by Staak et al. [3], with CW-CEAS at 2 mbar in the range 6547–7051 cm-1 with a resolution of about 0.001 cm-1. The absorption cross-sections were evaluated by comparison with the known measured line-intensities of CO 2 and H2O. H2CO was prepared by pyrolysis of paraformaldehyde under vacuum. The gaseous H2CO was first passed through a cooling trap below 200 K to remove water vapor and polymerization products of H2CO. The monomeric H2CO was trapped and stored at 77 K under vacuum. H2CO gas was introduced into the cavity by slowly heating the solid H2CO from the cooling trap; the temperature of the system was 291 ± 2 K. It was found that the absorption cross-sections from Staak et al. [3] were systematically a factor of 2 too large. A summary is given in Ruth et al. [4] together with new absorption data on H2CO between 6804 and 7051 cm-1. GEISA-2015 contains the data from Ruth et al. [4] and those of Staak et al. [3] corrected by a factor of 2 in the spectral range 6547–7051 cm-1. References [3] M. Staak, E.W. Gash, D.S. Venables, A.A. Ruth, The rotationally-resolved absorption spectrum of formaldehyde from 6547 to 6804 cm-1, J. Molec. Spectrosc. 229 (2005) 115-121. [4] A.A. Ruth, U. Heitmann, E. Heinecke, C. Fittschen, The rotationally-resolved absorption spectrum of formaldehyde from 6550 to 7050 cm–1, Z. Phys. Chem. 229 (2015) 1609-1624. Hydroperoxy radical (HO2) Measurements of the HO2 radical were made by Thiebaud et al. [5] and Ibrahim et al. [6] at a total pressure of 50 Torr. HO2 radicals were generated by reaction of Cl-atoms with CH 3OH in the presence of O2. Cl-atoms were generated either by photolysis of SOCl2 at 248 nm or by photolysis of Cl2 at 351 nm. The spectrum was measured in the 6604-6696 cm-1 wavenumber range with a resolution of better than 0.003 cm -1. A few selected lines were calibrated by determining the absolute, initial HO2 concentration in the same way as CH3O 2: time resolved HO2 absorption decays were measured following their pulsed photolysis. As the decay is governed by a bimolecular reaction, the initial HO2 radical concentration can be deduced from the shape of the decay . More details on the pressure broadening in HO2 can be found in [7]. References [5] J. Thiebaud, S. Crunaire, C. Fittschen, Measurements of line strengths in the 2n1 band of the HO2 radical using laser photolysis/continuous wave cavity ring-down spectroscopy (cw-CRDS), J. Phys. Chem. A 111 (2007) 6959-6966. [6] N. Ibrahim, J. Thiebaud, J. Orphal, C. Fittschen, Air-broadening coefficients of the HO2 radical in the 2n1 band measured using cw-CRDS, J. Mol. Spectrosc. 242 (2007) 64-69. [7] H. Bouzidi, M. Djehiche, T. Gierczak, P. Morajkar, C. Fittschen, P. Coddeville, A. Tomas, Low pressure photolysis of 2,3-pentanedione: quantum yields and reaction mechanism, J. Phys. Chem. A 119 (2015) 12781-12789. Nitrous Acid (HONO) Measurements of nitrous acid were made, by Jain et al. [8], in the range 6623.6–6645.6 cm-1 with a resolution of 0.005 cm -1, using CW-CRDS coupled to laser photolysis. HONO was generated in situ by photolysis of H2O2 in the presence of NO. Calibration of the HONO concentration (and hence the cross-sections) was achieved through modelling the kinetics of the time resolved concentrations of the OH and HO2 radicals, which are generated in the H2O2 photolysis. Reference [8] C. Jain, P. Morajkar, C. Schoemaecker, B. Viskolcz, C. Fittschen, Measurement of absolute absorption cross-sections for nitrous acid (HONO) in the near-infrared region by the continuous wave cavity ring-down spectroscopy (cw-CRDS) technique coupled to laser photolysis, J. Phys. Chem. A 115 (2011) 10720-10728. Ammonia (NH3) Absorption cross-sections, as a function of wavelength for NH3 were measured by O'Leary et al. [9], with off-axis CW-CEAS at 0.2 mbar (6883–6997 cm-1) and at 11.5 mbar (6850–6997 cm-1). A total of 1117 NH3 lines are contained in the spectrum. It should be noted that 262 lines of the NH3 line-by-line sub-database are present in this cross-sections spectral region. Among these lines, only 49 have been assigned. We retain the unassigned lines, which are useful for many purposes, and we have implemented the cross-sections, in addition, to provide the total absorption in that region. Reference [9] D.M. O'Leary, J. Orphal, A.A. Ruth, U. Heitmann, P. Chelin, C.E. Fellows, The cavity-enhanced absorption spectrum of NH3 in the near-infrared region between 6850 and 7000 cm-1, J. Quant. Spectrosc. Radiat. Transfer 109 (2008) 1004-1015. |