1. High Precision Infrared Spectroscopy of OH + Charles R. Markus, Adam J. Perry, James N. Hodges, G. Stephen Kocheril, Paul A. Jenkins II, Benjamin J. McCall 70 th International Symposium on Molecular Spectroscopy University of Illinois at Urbana-Champaign 22 June, 2015 MF06

2. OH + background NICE-OHVMS technique Updated OH + values Conclusions and future directions Overview

3. OH + Background Sgr B2 Molecular cloud https://www.eso.org/public/usa/images/eso0924e/ Rodebush et al, J. Chem. Phys. 1933, 1696-702. Dossin, Sky Telesc. 1970, 39, 152-153. Wyrowski et al, Astron. Astrophys.,2010, 518, A26. Indriolo et al, Astrophys. J.,2015, 800, 40. Loomis and Brandt, Phys. Rev. 1935, 49, 55-67.

4. OH + Structure NotationJ F1F1 N+1 F2F2 N F3F3 N-1 N v= 1 v= 0 F1F1 F3F3 F1F1 F2F2 2 F3F3 F1F1 F2F2 F1F1 F3F3 F1F1 F2F2 2 F3F3 F1F1 F2F2

5. O 2 :H 2 :He 2:3:100 1.0 Torr total pressure Water cooled discharge T rot ~500 K OH + Generation

6. NICE-OHVMS Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy B. M. Siller, et al. Opt. Express 19, 24822-7, (2011)

7. NICE-OHVMS Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy B. M. Siller, et al. Opt. Express 19, 24822-7, (2011)

8. NICE-OHVMS Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy B. M. Siller, et al. Opt. Express 19, 24822-7, (2011)

9. NICE-OHVMS Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy B. M. Siller, et al. Opt. Express 19, 24822-7, (2011)

10. NICE-OHVMS Spectrometer YDFL EOM Lock-In Amplifier X & Y Channels Lock-In Amplifier X & Y Channels 80 MHz 90 o Phase Shift f = 100 kHz idler  pump  signal 50 kHz AOMAOM AOMAOM OPO Wavemeter Frequency Comb Lock Box PZT Slow Fast to PZT ~3 MHz ν 3.2-3.9 µm

11. F rr = 100 MHz Comb Calibration Frequency Bandpass Regions

12. Comb Calibration Frequency Bandpass Regions

13. Comb Calibration Frequency AOM Bandpass Regions

14. Comb Calibration Frequency AOM

15. Comb Calibration Frequency AOM

16. OH + Spectrum

18. Measured Transitions Transition Previous (MHz) This Work (MHz) 92125083(90)92125161.53(75) 92117348(90)92117389.9(12) 92112612(90)92112646.1(22) 91327875(90)91327963.4(14) 91315284(90)91315349.6(20) 91309648(90)91309739.3(19) 90514538(90)90514685.3(33) 90465732(90)90465759.8(16) 90458387(90)90458440.4(18) Rehfuss et al, J. Mol. Spec. 1992, 151, 59-70. Transition Previous (MHz) This Work (MHz) 89618548(90)89618552.1(18) 89557720(90)89557728.7(29) 87657606(90)87657543.8(19) 86693323(90)86693192.5(31) 86626260(90)86626361.3(14) 86617866(90)86617894.6(28) 86569719(90)86569701.7(69) 85557380(90)85557445.76(95) 85550275(90)85550367.0(24) 85537863(90)85537889.59(46)

19. Measured Transitions

21. Spectroscopic Constants ParameterRehfuss et alCurrent Work B 0 (cm -1 )16.42286(7) 16.4229183(98) D 0 x10 3 (cm -1 )1.9218(8) 1.9217(4) H 0 x10 6 (cm -1 )0.1355(29) 0.1339(23) 2.1434(6) 2.1346(4) -0.15108(17) -0.151302(37) 0.0264(50) 0.0273(16) 2956.3698(10)2956.35841(5) B 1 (cm -1 )15.69526(6) 15.695269(12) D 1 x10 3 (cm -1 )1.8732(8) 1.8729(5) H 1 x10 6 (cm -1 )0.1324(27) 0.13077(29) 2.1331(5) 2.1346(6) -0.14657(15) -0.14660(6) 0.0271(16) 0.0263(15) Rehfuss et al, J. Mol. Spec. 1992, 151, 59-70.

22. Calculated THz Transitions SOFIA - GREAT Herschel - PACS

23. Conclusions and Future Directions

24. Acknowledgments Advisor: Ben McCall Special thanks to: James Hodges Adam Perry G. Stephen Kocheril