1. 1 70 th Symp. Mol. Spectrosc. 2015 MJ14 13 CH 4 in the Octad Measurement and modeling of cold 13 CH 4 spectra from 2.1 to 2.7 µm Linda R. Brown 1, Andrei V. Nikitin 2,3, Keeyoon Sung 1, Michael Rey 4, Sergey A. Tashkun 2,3, Vladimir G. Tyuterev 4, Timothy J. Crawford 1, Mary Ann H. Smith 5, Arlan W. Mantz 6 1 Jet Propulsion Laboratory, California Institute of Technology, Drive, Pasadena, CA 91109, USA 2 Laboratory of Theoretical Spectroscopy, V.E. Zuev Institute of Atmospheric Optics, Tomsk, Russia 3 Tomsk State University, Tomsk, Russian Federation 4 Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, Université de Reims, Reims Cedex 2, France 5 Science Directorate, NASA Langley Research Center, Hampton, VA, USA 6 Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT, USA

2. 2 70 th Symp. Mol. Spectrosc. 2015 MJ14 Methane Polyads Polyads, P n and name Range (cm -1 ) # vib levels # sub- levels P0P0 GS < 20011 P1P1 Dyad 1200 – 170022 P2P2 Pentad 2400 – 320059 P3P3 Octad 3700 – 4700824 P4P4 Tetradecad 5000 – 62001460 P5P5 Icosad 6500 – 770020134  Vibrational States  Octad vibrational states for 13 CH 4  Some characteristics Eight different vibrational bands Most have multiple components of vib. sym.species. (i.e., A, E, F) Only F 2 is inherently IR active. All others borrow intensities through interactions. A tends to borrow less while F 1 and E borrows more.

3. 3 70 th Symp. Mol. Spectrosc. 2015 MJ14 Overview of 13 CH 4 Polyads Pentad 2400-3300 cm -1 Octad 3700-4700 cm -1 Tetradecad 5000-6300 cm -1 Icosad 6700-7800 cm -1 H2OH2O L = 10 cm; P = 207 Torr; T = 299 K; resln. = 0.007 cm -1 H2OH2O

4. 4 70 th Symp. Mol. Spectrosc. 2015 MJ14 4 Line intensities (log scale) vs cm -1 ~ 290000 lines ~ 468000 lines CH 4 HITRAN 2012 updates (Brown et al. 2013) Octad Only 793 13 CH 4 Octad lines were added because many predicted line intensities were wrong!

5. 5 70 th Symp. Mol. Spectrosc. 2015 MJ14 ConfigurationsKitt Peak McMathJPL Bruker-125HR Light Source Beam Splitter Detector Band pass (cm -1 ) Resolution (cm -1 ) Scanning time (hours) Signal to Noise Quartz-halogen CaF 2 InSb 1850 – 5500 0.012 1.1 800:1 Tungsten lamp CaF 2 InSb 3750 – 5000 0.0028, 0.0033, 0.005 ~ 5 1000:1 ◄ McMath-Pierce FT-IR, Kitt Peak Obs., AZ Bruker 125HR ► JPL, Pasadena Data acquisition with two FT-IR spectrometers ( Kitt-Peak and JPL)

6. 6 70 th Symp. Mol. Spectrosc. 2015 MJ14 State-of-art cryogenic cells for JPL-FTS Temps = 80 – 296 K ΔT = 0.01 K/day Temp. sensor ZnSe windows Shroud box Cold finger Heaters ◄ 20.94 m path long Herriott cell; Also designed/ Developed by Arlan Mantz

7. 7 70 th Symp. Mol. Spectrosc. 2015 MJ14 13 CH 4 : Measurement of line intensities Spectro- meter Temp (K) Pres (Torr) Path (m) Res. (cm -1 ) Calibration factor Kitt Peak McMath FTS 295.95.9300.2500.01170.999999952 296.38.8301.500.01170.999999965 291.47.8802.400.01171.000000087 JPL Bruker 125HR IFS 296.89.9560.2038 0.00560.9999995326 299.42.24020.941 0.00281.0000001220 225.06.0660.2038 0.00500.99999987099 148.47.3140.2037 0.00500.99999988911 140.27.07020.941 0.00330.99999989069 80.01.1440.2038 0.00500.99999989033 79.81.10720.941 0.00280.99999984842 JPL Kitt Peak JPL  Data acquisition: Experiment conditions  Intensity measurements  Derivation of Empirical lower state energies  Quantum assignments  Analysis and modeling  Line predictions – positions and intensities

8. 8 70 th Symp. Mol. Spectrosc. 2015 MJ14 Non-linear least squares retrievals Voigt profile assumed (no line mixing used) Nominal sinc function with FOV corrected used Fitting residuals < 1 % Fit spectrum by spectrum Line position, intensity, self- pressure broadening, simultaneously retrieved Separate quality controlled Averaged and compiled  Residuals = Observed - Calculated  Spectrum fitting ~ 15,000 line intensities retrieved (3750-4700 cm -1 ) 4362 cm -1 4362.8

9. 9 70 th Symp. Mol. Spectrosc. 2015 MJ14 Determination of empirical E″  Population shift with T (from Lyulin et al, 2010)

10. 10 70 th Symp. Mol. Spectrosc. 2015 MJ14 Nikitin’s graphic tool to assign 13 CH 4 Observed at 80 K Observed at 140 K 20.94 m: 80 K 20.94 m: 140 K Predicted 12 CH 4 Assigned

11. 11 70 th Symp. Mol. Spectrosc. 2015 MJ14 Vibrational sublevels and ranking number Effective band center (cm -1 ) Number of fitted line positions RMS (10 -3 cm -1 ) Number of fitted line intensities RMS (%) 3ν 2 (A 1 ) 4595.989 43.0 25.3 3ν 2 (A 2 ) 4595.755 112.5 85.7 3ν 2 (E) 4592.507 401.7 264.4 ν 2 +ν 3 (F 2 ) 4534.0563652.72718.0 ν 2 +ν 3 (F 1 ) 4527.8913902.52735.4 ν 1 +ν 2 (E) 4434.1641483.81035.2 2ν 2 +ν 4 (F 2 ) 2 4371.1791444.11015.4 2ν 2 +ν 4 (F 1 ) 4355.849 784.3 467.9 2ν 2 +ν 4 (F 2 ) 1 4340.9091194.2 846.2 ν 3 +ν 4 (A 1 ) 4304.8502054.81408.0 ν 3 +ν 4 (F 1 ) 4304.7254624.23547.7 ν 3 +ν 4 (E) 4304.6252725.52087.3 ν 3 +ν 4 (F 2 ) 4301.2934023.13159.6 ν 1 +ν 4 (F 2 ) 4213.8273094.01968.6 ν 2 +2ν 4 (A 2 ) 4146.023 895.3 605.6 ν 2 +2ν 4 (E) 2 4135.5381842.31266.9 ν 2 +2ν 4 (F 2 ) 4127.3632524.21864.5 ν 2 +2ν 4 (A 1 ) 4116.963 675.6 457.0 ν 2 +2ν 4 (F 1 ) 4113.1742035.31376.6 ν 2 +2ν 4 (E) 1 4086.5411713.11115.3 3ν 4 (F2) 1 3907.4982245.11504.9 3ν 4 (F 1 ) 3897.3632733.41564.3 3ν 4 (A 1 ) 3886.345 823.1 432.7 3ν 4 (F 2 ) 2 3848.3832394.01464.0 All 47524.03301 6.9

12. 12 70 th Symp. Mol. Spectrosc. 2015 MJ14 13 CH 4 Band Intensities Band This work ab initio variational calculation Intensity Ratio TW/calc 3ν 2 2.71e-222.61e-221.038 ν 2 +ν 3 6.66e-205.81e-201.146 ν 1 +ν 2 6.69e-227.42e-220.901 2ν 2 +ν 4 2.46e-203.18e-200.773 ν 3 +ν 4 5.00e-19 1.000 ν 1 +ν 4 2.84e-192.80e-191.014 ν 2 +2ν 4 1.72e-201.86e-200.924 3ν 4 3.12e-203.23e-200.965 All 9.25e-199.22e-191.003  This work  Two strong bands (ν 3 +ν 4 and ν 1 +ν 4 ) account for 80% of the opacity in this region.  The next four strongest bands (ν 2 +ν 3, 2ν 2 +ν 4, ν 2 +2ν 4 and 3ν 4 ) contribute most of the remaining intensity.  3v 2 borrows very little intensity.  Band intensities (cm -1 /(molecule.cm -2 ))  Further analysis is needed, esp., for ν 2 +ν 3, ν 1 +ν 2, 2ν 2 +ν 4

13. 13 70 th Symp. Mol. Spectrosc. 2015 MJ14 2016 database improvement Predicted 13 CH 4 from this work 3301 13 CH 4 intensities fitted in the model HITRAN2012

14. 14 70 th Symp. Mol. Spectrosc. 2015 MJ14  Summary  13 CH 4 line intensities have been measured in the Octad region.  Empirical lower states energies and assignments have been determined.  The Hamiltonian modeling of the Octad is in progress (Nikitin et al.).  Significance  Supports atmospheric remote sensing of 13 CH 4.  Advances the corresponding analysis of the main isotopologue, 12 CH 4.  Future work is needed; This work - one important step toward the ultimate goal. Acknowledgements This study was supported by The Tomsk State University Academic D.I. Mendeleev Fund Program grant. The support of the Laboratoire International Associé SAMIA between CNRS (France) and RFBR (Russia), from IDRIS / CINES computer centres of France and of the computer centre Reims-Champagne-Ardenne is acknowledged. A.N. thanks computer centres of SKIF Siberia (Tomsk). Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, Connecticut College and the NASA Langley Research Center under contracts with the National Aeronautics and Space Administration, including NASA’s Atmospheric Composition Laboratory (ACLAB) program.). 2016 database improvement Conclusion and Further work JPL