1. THz Spectroscopy of 1d-ethane: Assignment of v 18 ADAM M. DALY, BRIAN J. DROUIN, LINDA BROWN Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 PETER GRONER Department of chemistry, University of Missouri, Kansas City, MO. 18-Jun14 ISMS FE07

2. Motivation 18-Jun14ISMS FE07 A window in the ethane spectrum? Avoiding q-branch ethane Astronomy http://universe-review.ca/F07-planets06.htm

3. Motivation 18-Jun14ISMS FE07 Assign v 11 = 715 cm -1 and v 17 = 805 cm -1 in C 2 H 5 D and fit transitions to within the resolution of the measurement Data taken with the Bruker 125 HR with 20.8 m path length. Resolution 0.0028 cm -1 Temperature = 130 K Spectroscopy v 11 = 715 cm -1 v 17 = 805 cm -1 4v 18 = 726 cm -1 ?

4. 18-Jun14ISMS FE07 Motivation v 11 = 715 cm -1 (A’) and v 17 =805 cm -1 (A”) Dark state, 3 v 18 at 726 cm -1 (A”)

5. Motivation 18-Jun14ISMS FE07 Spectroscopy Assign v 11 = 715 and v 17 = 805 in C 2 H 5 D and fit transitions to within the resolution of the measurement Data taken with the Bruker 125 HR with 20.8 m path length. Resolution 0.0028 cm -1 Temperature = 130 K v 11 = 715v 17 = 805

6. Motivation 18-Jun14ISMS FE07 v 17 = 715 in C 2 H 5 D High K c R-branch v 11 = 715 Q-branch K a upper and Lower zero Spectroscopy J 1,J-1 ← J 0,J J 0,J ← J 1,J-1

7. Motivation 18-Jun14ISMS FE07 Spectroscopy A E A E A E A E A E A E A E J 1,J-1 <- J 0,J 1 2 3 4 5 6 7 3 0,2 <- 2 0,1 J= 6 1,6 <- 5 2,3 v 11 = 715 Q-branch K a lower zero

8. Motivation 18-Jun14ISMS FE07 Spectroscopy v 11 = 715v 17 = 805

9. Motivation 18-Jun14ISMS FE07 Spectroscopy 4←35←46←57←68←79←8K a ”←K a ’ v 17 = 805 Q-branch K a -> K a+1

10. Motivation 18-Jun14ISMS FE07 Clearly split by internal rotation Spectroscopy 15 2,13 ←14 1,13 16 1,15 ←15 0,15 v 17 = 805 Q-branch K a = 7 ← K a = 6 111 8 J21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

11. Background 18-Jun14ISMS FE07 D H H H H H Microwave spectra of deuterated ethanes: Internal rotation potential function and r z structure E. Hirota, Y. Endo, S. Saito, J.L. Duncan, J. Mol. Spectrosc. 89 (1981) 285–295. Pure a-dipole 12 pairs A/E 2 R-branch (J=3 and 4) b-dipole 15 pairs A/E that 2 R-branch (J=2 and 3) and 13 Q-branch (K a 2<- 1) TB03 OSU Conference 2013 BRIAN J. DROUIN, SHANSHAN YU, JOHN C. PEARSON, LINDA R. BROWN, KEEYOON SUNG, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; PETER GRONER, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. The data set contains two Q-branch measurements (K = 5-6 and K = 9,10, the first with J up to 30) and a smattering of R-branch measurements up to J = 28 and K’s in the teens. There are 475 unique assignments, but many of these are for blended features.

12. Methods 18-Jun14ISMS FE07 Ground state results

13. 18-Jun14ISMS FE07 Experimental Setups 520-605, 680-800, 960-1240 GHz, 6 meter path, 1.2 K Silicon Bolometer, Static cell with amorphous quartz windows Multiplier Inlet Port Vacuum Port Glass Cell 3m Rooftop Reflector Bolometer Polarized Grid Stanford Research Lock-in Amplifier Preamp 16.78888 Ghz Synthesizer GPIB

14. 18-Jun14ISMS FE07 Initial scans

15. 18-Jun14ISMS FE07 Initial scans

16. 18-Jun14ISMS FE07 Initial scans

17. 18-Jun14ISMS FE07 Initial scans

18. 18-Jun14ISMS FE07 Initial Scans

19. 18-Jun14ISMS FE07 Initial Scans

20. 18-Jun14 ISMS FE07 ERHAMSPFIT Pure Rotation A /MHz69633.185(10)69633.176(17) B /MHz18774.4219(20)18774.4207(21) C /MHz18164.4825(20)18164.4812(19) D J /kHz26.6122(24)26.6099(10) D JK /kHz68.538(33)68.469(46) D K /kHz241.69(12)241.35(28) d 1 /kHz-0.92184(67)-0.92106(81) d 2 /kHz0.12141(55)0.12285(46) H J /Hz-0.0055(28)- H JK /Hz0.175(30)0.158(27) H KJ /Hz1.53(25)0.31(28) H K /Hz--8.76(134) Tunneling termsERHAM SPFIT  10 /MHz 2253.10(22)2252.62(24)  20 /MHz 0.471(16)1.509(58)  0.4343990(81)[ 0.434401021]  / deg 0.873(75) -402.3(76)-640.2(85) 45.3(64)-21.99(94) -30.9(31)-116.98(51) 0.569(46)-33.4(16) -1.48(37)- 2.83(19)- 0.00283(19)0.00346(36) -0.00231(37) --0.00151(21).305(34)0.286(81) --58(20) -0.00134(49)-0.00154(27) -0.0333(57)0.080(31) -7.5(35) --0.00154(27) --0.000309(26) -- D ab / kHz1693.(202)- Final fit of v 18 TORSIONAL ENERGY DIFFERENCES (MHz) v18 (A-E) = -3381.8516 +/- 0.2667 v18 fit State 00: 163 lines MICROWAVE RMS = 0.268358 RMS ERROR = 1.130830 State 10: 164 lines MICROWAVE RMS = 0.349844 RMS ERROR = 1.344719

21. 18-Jun14 ISMS FE07 ERHAMSPFIT Pure Rotation A /MHz69633.185(10)69633.176(17) B /MHz18774.4219(20)18774.4207(21) C /MHz18164.4825(20)18164.4812(19) D J /kHz26.6122(24)26.6099(10) D JK /kHz68.538(33)68.469(46) D K /kHz241.69(12)241.35(28) d 1 /kHz-0.92184(67)-0.92106(81) d 2 /kHz0.12141(55)0.12285(46) H J /Hz-0.0055(28)- H JK /Hz0.175(30)0.158(27) H KJ /Hz1.53(25)0.31(28) H K /Hz--8.76(134) Tunneling termsERHAM SPFIT  10 /MHz 2253.10(22)2252.62(24)  20 /MHz 0.471(16)1.509(58)  0.4343990(81)[ 0.434401021]  / deg 0.873(75) -402.3(76)-640.2(85) 45.3(64)-21.99(94) -30.9(31)-116.98(51) 0.569(46)-33.4(16) -1.48(37)- 2.83(19)- 0.00283(19)0.00346(36) -0.00231(37) --0.00151(21).305(34)0.286(81) --58(20) -0.00134(49)-0.00154(27) -0.0333(57)0.080(31) -7.5(35) --0.00154(27) --0.000309(26) -- D ab / kHz1693.(202)- Final fit of v 18 Ground state State 00: 298 lines MICROWAVE RMS = 0.214684 RMS ERROR = 0.900575 State 10: 469 lines MICROWAVE RMS = 0.334478 RMS ERROR = 0.952100 TORSIONAL ENERGY DIFFERENCES (MHz) ground state (A-E) = 74.1616 +/- 0.0366 MHz v18 (A-E) -3381.8516 +/- 0.2667 MHz v18 fit State 00: 163 lines MICROWAVE RMS = 0.268358 RMS ERROR = 1.130830 State 10: 164 lines MICROWAVE RMS = 0.349844 RMS ERROR = 1.344719

22. 18-Jun14ISMS FE07 Using the ground state, v 18 and Raman data E. Hirota, Y. Endo, S. Saito, J.L. Duncan, Microwave spectra of deuterated ethanes: Internal rotation potential function and rz structure, J. Mol. Spectrosc. 89 (1981) 285–295. doi:10.1016/0022-2852(81)90024-2. J,M. Fernandez and S. Montero, J. Chem. Phys. 94, 7788 (1991)

23. Potential Fit 18-Jun14ISMS FE07

24. Conclusions: Future directions from TB03 (2013) 18-Jun14ISMS FE07 Retrieved positions and intensities up to 860 cm -1 (done) – Challenging spectrum 9000 features 700-850 cm -1 Complete assignments IR spectrum in 700 - 860 cm -1 range to v 11, v 17 and perhaps 3vt (overtone) (in progress) Develop Effective Hamiltonian and model observed positions and intensities (in progress) Create a linelist to enable the first detection of this species in outer planets. (in progress)

25. 18-Jun14ISMS FE07 Acknowledgements Brian Drouin Linda Brown John Pearson Peter Groner