Self- in addition to air-broadened line shape parameters in the n2+n3 b in addition to of 12CH4: 4500-4

Self- in addition to air-broadened line shape parameters in the n2+n3 b in addition to of 12CH4: 4500-4 www.phwiki.com

Self- in addition to air-broadened line shape parameters in the n2+n3 b in addition to of 12CH4: 4500-4

Weeks, John, Features Editor & Writer has reference to this Academic Journal, PHwiki organized this Journal Self- in addition to air-broadened line shape parameters in the n2+n3 b in addition to of 12CH4: 4500-4630 cm-1 V. Malathy Devi Department of Physics The College of William in addition to Mary Williamsburg, VirginiaInternational Symposium on Molecular Spectroscopy69th Meeting – June 16-20, 2014 – Champaign-Urbana, IllinoisACKNOWLEDGMENTThe research per as long as med at the College of William in addition to Mary, Connecticut College in addition to NASA Langley Research Center was supported by NASA’s ASCENDS program. Part of the research conducted at the Jet Propulsion Laboratory was per as long as med under contract with National Aeronautics in addition to Space Administration. A. Predoi-Cross was funded by the Natural Sciences in addition to Engineering Research Council of Canada.D. Chris BennerDepartment of Physics, The College of William in addition to Mary, Williamsburg, Virginia, USA Mary Ann H. SmithScience Directorate, NASA Langley Research center, Hampton, VA, USA Arlan W. Mantz Department of Physics, Astronomy in addition to geophysics, Connecticut College, Connecticut, USAKeeyoon Sung, Linda R. Brown, Timothy J. Craw as long as dJet Propulsion Laboratory, Cali as long as nia Institute of Technology,Pasadena, Cali as long as nia,USAAdriana Predoi-CrossDepartment of Physics in addition to Astronomy, The University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada co-authors are:ObjectivePrior studies of the b in addition to investigated in this workExperimental detailsSample SpectraInstrumental line shape effectsAnalysis techniqueSample multispectrum fits Results9. Off-diagonal Relaxation Matrix Element Coefficients10. Summary in addition to Future plansThe following topics will be briefly discussed

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ObjectivesThe methane b in addition to system in the 2.3-mm region (Octad) is of interest not only as long as measurements of CH4 atmospheric profiles, but also because it overlaps the spectra of other atmospheric molecules such as CO in addition to HF The level of accuracy as long as line shape parameters in the Octad region of both 12CH4 in addition to 12CH4 is less compared to those as long as the lower polyads, Dyad in addition to PentadIn as long as mation on line shapes as long as b in addition to s in this spectral region do not meet the desired accuracy requirements to support remote sensing applications such as ASCENDS (Active Sensing of CO2 Emissions over Nights, Days in addition to Seasons) retrievalsOne of the major goals of this study was to measure the temperature dependences of Lorentz self- in addition to air-broadened halfwidth, pressure-shift in addition to line mixing (off-diagonal relaxation matrix elements) coefficients as long as transitions in the n2+n3 b in addition to of 12CH4A multispectrum fitting technique to include speed dependent Voigt profile in addition to full line mixing is applied to fit several spectra (room in addition to cold) simultaneouslyPrior line shape studies include the following: Multispectrum analysis of 12CH4 in the 4100-4635 cm-1(room temperature air-broadening) A. Predoi-Cross et al. J. Mol. Spectrosc 236 (2006) 201-215.Multispectrum analysis of 12CH4 in the 4100-4635 cm-1(room temperature self-broadening) A. Predoi-Cross et al. J. Mol. Spectrosc 232 (2005) 231-246.Line mixing effects in the n2+n3 b in addition to (room temperature air-broadening). A. Predoi-Cross et al. J. Mol. Spectrosc. 246 (2007) 65-76. Air-broadening in addition to pressure shifts in the 2.3 mm region (room temperature air-broadening) V. Malathy Devi et al. J. Mol. Spectrosc 157 (1993) 95-111.Temperature dependences of Lorentz air-broadening in addition to pressure shifts in the 2.3 mm region. V. Malathy Devi et al. J. Quant Spectrosc Radiat Transfer 51 (1994) 439-465. Other research groups are investigating N2-broadened line shape parameters as long as the Octad b in addition to s Experimental setup in addition to gas conditions a Relative calibration of wavenumber scaleswith respect to n3 H2O lines [HITRAN12]b Absolute calibration with respect to CH4 lines [Predoi-Cross et al. J. Mol. Spectrosc. 232 (2005) 231-246]

Summary of Experimental Conditions of Spectra Analyzed760 Torr = 1 atm =101.325 kPa = 1.01325 barThe 12CH4 sample was 99.95% enriched in 12CAdditional spectra as long as background in addition to calibration were recorded but not listed hereThree of the 14 spectra analyzed in this studyCell path length = 20.38 cm (a) Self-broadened 12CH4 spectrum with 385 Torr at 298.4 K (b) Self-broadened 12CH4 spectrum with 169 Torr at 200 K (c) 12CH4+air with 225 Torr total pressure in addition to methane volume mixing ratio of 0.04 Equations used to retrieve: Lorentz self- in addition to air-broadened widths, shifts in addition to their temperature variations

Multispectrum fit of the P(4) manifold in n2+n3Path length = 20.38 cm(a) Weighted (obs-calc) fit residuals(b) Multispectrum fit of 14 spectra on an exp in addition to ed (0.8-1.0) vertical scale(c) Same as in the above panel (b), but on a (0-1) vertical scaleThe short vertical lines are positions of transitions included in the fitMultispectrum fit of the R(6) manifold in n2+n3(a) Weighted (obs-calc) fit residuals; Voigt with speed dependence(b) Weighted (obs-calc) fit residuals; Voigt, with speed dependence in addition to full line mixing(c) Multispectrum fit (on an exp in addition to ed vertical scale: top 10%)(d) Same as in panel (c), plotted on a 0.4-1.0 vertical scaleThe short vertical lines are positions of transitions included in the fitMultispectrum fit of the “allowed” Q branch transitions in the n2+n3 b in addition to (a) Weighted (obs-calc) fit residuals with speed dependence in addition to full line mixing(b) Weighted (obs-calc) fit residuals using the HITRAN12 line parameters(c) Final fit of all 14 experimental spectraThe short vertical lines are positions of transitions included in the fit

Comparisons of line positions in addition to Ratios of line IntensitiesLine intensities in addition to Lorentz width in addition to shift coefficientsComparisons of self- in addition to air- widths in addition to pressure-shifts coefficientsComparisons of temperature dependences ofwidths in addition to pressure-shifts CoefficientsSample of measured line parameters

Sample of measured off-diagonal relaxation matrix element coefficientsa Predoi-Cross et al. (n2+n3)J. Mol. Spectrosc. 246 (2007) 65-76b Smith et al. (n4) self-broad.J. Quant. Spectrosc. Radiat Transfer 111 (2010) 1152-1166c Smith et al. (n4) air-broad.J. Quant. Spectrosc. Radiat Transfer 110 (2009) 639-653d Smith et al. (n2) self- in addition to air- broad.J. Quant. Spectrosc. Radiat Transfer 153 (2014) 217-234e Devi et al. (2n3)Self- in addition to air-broad.(Ongoing analysis)f HaTran (2n3) air-broad.Predicted values (Private communication)SUMMARY:I14 spectra (self- in addition to air-broadened) recorded between 150-298 K were fitted simultaneously to retrieve widths, shifts, relaxation matrix elements in addition to speed dependence by employing a non-Voigt line shape modelOff-diagonal relaxation matrix elements were measured as long as 10 pairs of line-mixed transitionsThe mean ratio in addition to st in addition to ard deviation of the Lorentz self- to air-widths coefficients =1.29(8)For the 22 comparisons made as long as the strong CH4 line positions, HITRAN12 values are lower by -0.0008(3) cm-1 compared to HITRAN08Comparisons of positions in HITRAN08 with our earlier study [Predoi-Cross et al. JMS 232 (2005) 231-246] agree within 0.00003(8) cm-1Present measurements agree with HITRAN08 values within 0.00001(2) cm-1 in addition to 0.00002(1) cm-1 with our earlier studySUMMARY (cont.)First measurements of temperature dependence exponents as long as self-broadening in addition to a combined analysis of both self- in addition to air-broadened spectra as long as the n2+n3 transitions Line positions, absolute line intensities, Lorentz self- in addition to air-broadened widths, shifts, line mixing coefficients as well as their temperature dependences are determinedSpeed dependence parameter was determined as long as several transitionsIn most cases, temperature dependence exponents as long as air-broadened width coefficients were slightly larger compared to self-broadened width coefficients as long as same transitionsOverall, as long as a given transition, temperature dependence as long as self-shift coefficient was larger compared to that as long as air-shift coefficientEven with data taken in the 150 K-298 K range, temperature dependence exponents of line mixing was determinable only as long as a few casesFuture plans include similar analyses in the 4100-4500 cm-1 region where the stronger Octad b in addition to s n1+n4 in addition to n3+n4 occur

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