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Fourier Transform Spectroscopy of the A 3 Π -X 3 Σ - Transition of OH +

This study investigates the Fourier Transform Spectroscopy of the A3Π-X3Σ- transition of OH+, a key intermediate in the interstellar medium. The study explores the formation of H2O+, H3O+, and OH, as well as the reactions of OH with carbon and carbon ions to initiate carbon chemistry. The observations, first made in 2010 using submillimeter and near-UV detection techniques, provide valuable insights into the cosmic ray ionization rate. The experiment employed a 1.m FT spectrometer at Kitt Peak and calibrated the data with OH. The study examined various OH+ transitions, including A-X and c-b transitions.

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Fourier Transform Spectroscopy of the A 3 Π -X 3 Σ - Transition of OH +

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  1. Fourier Transform Spectroscopy of the A3Π-X3Σ- Transition of OH+ James N. Hodges and Peter F. Bernath Old Dominion University Norfolk, VA June 21, 2017 - WA08

  2. Introduction - Astrochemistry • OH+ is a key intermediate in interstellar medium • Formation of H2O+, H3O+, & OH • OH reacts with C and C+ to initiate carbon chemistry Federman, S. R., Weber, J., & Lambert, D. L. 1996, ApJ, 463, 181 Hollenbach, D., Kaufman, M. J., Neufeld, D., Wolfire, M., & Goicoechea, J. R. 2012, ApJ, 754, 105 Porras, A. J., Federman, S. R., Welty, D. E., & Ritchey, A. M. 2014, ApJL, 781, L8 Indriolo, N., Neufeld, D. A., Gerin, M., et al. 2015, ApJ, 800, 40

  3. Introduction - Astrochemistry • OH+ is a key intermediate in interstellar medium • Ratio of column densities of OH+ and H used to estimate cosmic ray ionization rate Federman, S. R., Weber, J., & Lambert, D. L. 1996, ApJ, 463, 181 Hollenbach, D., Kaufman, M. J., Neufeld, D., Wolfire, M., & Goicoechea, J. R. 2012, ApJ, 754, 105 Porras, A. J., Federman, S. R., Welty, D. E., & Ritchey, A. M. 2014, ApJL, 781, L8 Indriolo, N., Neufeld, D. A., Gerin, M., et al. 2015, ApJ, 800, 40

  4. Introduction - Observations • First detections in 2010 • Submillimeter • APEX 12m George J. Bendo: http://www.jb.man.ac.uk N = 1 – 0 , J = 0 – 1 Wyrowski, F., Menten, K. M., Güsten, R., & Belloche, A. 2010, A&A, 518, A26 Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., et al. 2010, A&A, 521, L10 Krełowski, J., Beletsky, Y., & Galazutdinov, G. A. 2010, ApJL, 719, L20 Porras, A. J., Federman, S. R., Welty, D. E., & Ritchey, A. M. 2014, ApJL, 781, L8 Indriolo, N., Neufeld, D. A., Gerin, M., et al. 2015, ApJ, 800, 40 Bhatt, N. H., & Cami, J. 2015, ApJS, 216, 22 Zhao, D., Galazutdinov, G. A., Linnartz, H., & Krełowski, J. 2015, ApJL, 805, L12 www.eso.org

  5. Introduction - Observations • First detections in 2010 • Submillimeter • APEX 12m • Herschel HIFI U of Waterloo Herschel HIFI Group: http://astro.uwaterloo.ca/HIFI/ N = 1 – 0 , J = 2 – 1 Wyrowski, F., Menten, K. M., Güsten, R., & Belloche, A. 2010, A&A, 518, A26 Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., et al. 2010, A&A, 521, L10 Krełowski, J., Beletsky, Y., & Galazutdinov, G. A. 2010, ApJL, 719, L20 Porras, A. J., Federman, S. R., Welty, D. E., & Ritchey, A. M. 2014, ApJL, 781, L8 Indriolo, N., Neufeld, D. A., Gerin, M., et al. 2015, ApJ, 800, 40 Bhatt, N. H., & Cami, J. 2015, ApJS, 216, 22 Zhao, D., Galazutdinov, G. A., Linnartz, H., & Krełowski, J. 2015, ApJL, 805, L12

  6. Introduction - Observations • First detections in 2010 • Submillimeter • APEX 12m • Herschel HIFI • Near-UV Detection • VLT UVES www.eso.org R11(0) Wyrowski, F., Menten, K. M., Güsten, R., & Belloche, A. 2010, A&A, 518, A26 Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., et al. 2010, A&A, 521, L10 Krełowski, J., Beletsky, Y., & Galazutdinov, G. A. 2010, ApJL, 719, L20 Porras, A. J., Federman, S. R., Welty, D. E., & Ritchey, A. M. 2014, ApJL, 781, L8 Indriolo, N., Neufeld, D. A., Gerin, M., et al. 2015, ApJ, 800, 40 Bhatt, N. H., & Cami, J. 2015, ApJS, 216, 22 Zhao, D., Galazutdinov, G. A., Linnartz, H., & Krełowski, J. 2015, ApJL, 805, L12

  7. Introduction - Experiment Near-UV – Rodebush & Wahl 1933 1936 Near-UV – Loomis & Brandt 1975 Near-UV – Merer et al. Submillimeter – Bekooy et al. Laser Magnetic Resonance – Gruebele et al. Submillimeter – Liu et al. Laser IR – Crofton et al. 1985 Laser IR – Rehfuss et al. 1992 2016 Laser IR – Markus et al. Rodebush, W. H., & Wahl, M. H. 1933, JChPh, 1, 696 Loomis, F. W., & Brandt, W. H. 1936, PhRv, 49, 55 Merer, A. J., Malm, D. N., Martin, R. W., Horani, M., & Rostas, J. 1975, CaJPh, 53, 251 Bekooy, J. P., Verhoeve, P., Meerts, W. L., & Dymanus, A. 1985, JChPh, 82, 3868 Gruebele, M. H. W., Müller, R. P., & Saykally, R. J. 1986, JChPh, 84, 2489 Liu, D.-J., Ho, W.-C., & Oka, T. 1987, JChPh, 87, 2442 Crofton, M. W., Altman, R. S., Jagod, M.-F., & Oka, T. 1985, JPhCh, 89, 3614 Rehfuss, B. D., Jagod, M.-F., Xu, L.-W., & Oka, T. 1992, JMoSp, 151, 59 Markus, C. R., Hodges, J. N., Perry, A. J., et al. 2016, ApJ, 817, 138

  8. Fourier Transform Spectrum • 1 m FT spectrometer at Kitt Peak • Sum of 8 scans at 0.05 cm-1 • 8mm aperture • 280-540 nm bandpass • Calibrated with OH • Data acquired in 1989 by J.W. Brault and R. Engleman • Hollow cathode discharge • 10 mTorr H2O • 2.2 Torr He • 235 V at 300 mA Stark, G., Brault, J. W., & Abrams, M. C. 1994, JOSAB, 11, 3 Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  9. OH+ Transitions • A-X • (0,0) • (1,0) • (0,1) • (1,1) Rodgers, D. J., Batey, A. D., & Sarre, P. J. 2007, MolPh, 105, 849 Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  10. OH+Transitions • A-X • (0,0) • (1,0) • (0,1) • (1,1) • c-b • (2,0) • (3,0) • c-a • (2,4) • (3,4) Rodgers, D. J., Batey, A. D., & Sarre, P. J. 2007, MolPh, 105, 849 Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  11. Data Sources a) Bekooy, J. P., Verhoeve, P., Meerts, W. L., & Dymanus, A. 1985, JChPh, 82, 3868 b) Liu, D.-J., Ho, W.-C., & Oka, T. 1987, JChPh, 87, 2442 c) Markus, C. R., Hodges, J. N., Perry, A. J., et al. 2016, ApJ, 817, 138 d) Rehfuss, B. D., Jagod, M.-F., Xu, L.-W., & Oka, T. 1992, JMoSp, 151, 59 e) Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81 f) Rodgers, D. J., Batey, A. D., & Sarre, P. J. 2007, MolPh, 105, 849 Endres, C. P., Schlemmer, S., Schilke, P., Stutzki, J., & Müller, H. S. P. 2016, JMoSp, 327, 95 Pickett, H. M. 1991, JMoSp, 148, 371

  12. Effective Hamiltonian • Standard N2 Hamiltonian for a linear molecule in PGOPHER • A v =1 / b v = 0 perturbation is spin-orbit type: Western, C. M. 2017, JQSRT, 186, 221

  13. Fit Residuals Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  14. Effective Hamiltonian Fit X state parameters Added centrifugal distortion terms for v = 0 Discarded v = 5 data from Rehfuss Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81 Rehfuss, B. D., Jagod, M.-F., Xu, L.-W., & Oka, T. 1992, JMoSp, 151, 59

  15. Effective Hamiltonian Fit A state parameters Added centrifugal distortion term Merer fit treats Ω components and Λ-doubling differently First modern N2 linear molecule Hamiltonian fit for A state Distortion term for perturbation Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  16. Effective Hamiltonian Fit Singlet state parameters Added centrifugal distortion terms Added Λ-doubling terms Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  17. Equilibrium Molecular Constants Vibrational and Rotational equilibrium constants were calculated Equilibrium Bond Lengths calculated from Be The reduced mass was calculated by subtracting the e- mass from the atom that is ionized in the dissociation channel Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81 Cho, Y.-S., & Le Roy, R. J. 2016, JChPh, 144, 024311

  18. Astrophysical Implications Observed 12 33.33% Two Orders Improved One Order Improved 25.00% Minor Improvement 41.67% Hodges, J.N. & Bernath,P.F. 2017, ApJ, 840, 81

  19. Conclusions and Future Directions • New improved molecular parameters for A and X states. • The wavelength uncertainties for common astronomical lines are improved by two orders of magnitude – improved velocities for interstellar clouds • The most accurate treatment of the A-b perturbation to date • First inclusion of centrifugal distortion term for perturbation • Line intensities are to be calculated

  20. Acknowledgements Bernath Group at Old Dominion Especially Dr. Andy Wong J.W. Brault and R. Engelman in conjunction with National Solar Observatory for original acquisition of data.

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