A New Line List for A2Σ+-X2П Electronic Transition of OH Mahdi Yousefi and Dr. Peter F. Bernath June 20, 2017

Importance of OH Radical OH in astronomy Interstellar medium Comets Dark interstellar clouds OH in combustion Flames OH also has atmospheric importance Most important oxidizer in the atmosphere The source of airglow (Meinel bands) P. Felenbok and E. Roueff, OH in the line of sight to HD 27778 and ζ Persei, AJ, 465, 57–60, (1996)

Some Previous Studies on OH Stark et al., Fourier-transform spectra of the A2Σ+-X2П Δv=0 of OH and OD, J. Opt. Soc. Am. B 11, 3-32 (1994) J. A. Coxon, Optimum molecular constants and term values for the X2П(v≤ 5) and A2Σ+ (v≤3) states of OH, Can. J. Phys. 58, 933 (1980) J. S. A. Brooke et al., Line strengths of rovibrational and rotational transitions in the X2П ground state of OH, JQSRT 168, 142-157 (2016) J. Luque et al., Transition probabilities in the A2Σ+-X2П electronic system of OH, JCP 109, 439 (1998) C. W. Bauschlicher Jr. and S. R. Langhoff, Theoretical determination of the radiative lifetime of the A2Σ+-X2П state of OH, JCP 87, 4665 (1987) A. C. P. Bittencourt et al., The fitting of potential energy and transition moment functions using neural networks: transition probabilities in OH (A2Σ+−X2П), CP 297, 153– 161 (2004)

Main Goal of Current Study Calculating an extensive linelist for OH A-X electronic transition Improve the line intensities by 1. calculating new transition dipole moment function and 2. including Herman-Wallis effect (J dependent line intensities) A2Σ+ : v=0-4 X2П : v=0-13 E.L. Derro et al., Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A2Σ+ (v=4) radicals, JCP 122, 244313 (2005)

Sources Used for The Main Observed Lines Stark et al. (1994): A2Σ+- X2П v′-v″=(0,0), (1,1), (2,2) J. A. Coxon (1980) and (1994): A2Σ+-X2П v′-v″=(3,2), (3,3), (4,2); E.L. Derro et al. (2005) A2Σ+- A2Σ+ v′-v″=(4,2) J. S. A. Brooke et al. (2016): X2П-X2П v′-v″=(0,0), (1,0), (1,1), (2,0), (2,1), (2,2), (3,0), (3,1), (3,2), (3,3), (4,1), (4,2), (4,3), (4,4), (5,3), (5,4), (6,4), (6,5), (7,4), (7,5), (7,6), (8,5), (8,6), (8,7), (8,8), (9,6), (9,7), (9,8), (10,8), (10,9), (11,9)

Overall Method for The Production of Line Lists R.J. Le Roy, RKR1: A computer program implementing the first-order RKR method for determining diatomic molecule potential, JQSRT 186, 158–166 (2017) R.J. Le Roy, A computer program for solving the radial Schrödinger equation for bound and quasi-bound levels, JQSRT 186, 1567–178 (2017) C.M. Western, PGOPHER: A program for simulating rotational, vibrational and electronic spectra, JQSRT 186, 221–242 (2017) Stark et al., Fourier-transform spectra of the A2Σ+-X2П Δv=0 of OH and OD, J. Opt. Soc. Am. B 11, 3-32 (1994) J. A. Coxon, Optimum molecular constants and term values for the X2П (v≤ 5) and A2Σ+ (v≤3) states of OH, Can. J Phys., 58, 933 (1980)

Line Intensity and Transition Dipole Moment Function Molpro chemistry package. Calculation method. Multireference configuration Interaction (MRCI) Basis set. aug-cc-pv6z J. Luque et al., Transition probabilities in the A2Σ+-X2П electronic system of OH, JCP 109, 439 (1998) C.W. Bauschlicher Jr. and S.R. Langhoff, Theoretical determination of the radiative lifetime of the A2Σ+-X2П state of OH, JCP 87, 4665 (1987) A.P. Bittencourt et al., The fitting of potential energy and transition moment functions using neural networks: transition probabilities in OH (A2Σ+−X2П), CP 297, 153–161 (2004)

Overall Method for The Production of Line Lists R.J. Le Roy, RKR1: A computer program implementing the first-order RKR method for determining diatomic molecule potential, JQSRT 186, 158–166 (2017) R.J. Le Roy, A computer program for solving the radial Schrödinger equation for bound and quasi-bound levels, JQSRT 186, 1567–178 (2017) C.M. Western, PGOPHER: A program for simulating rotational, vibrational and electronic spectra, JQSRT 186, 221–242 (2017) Stark et al., Fourier-transform spectra of the A2Σ+-X2П Δv=0 of OH and OD, J. Opt. Soc. Am. B 11, 3-32 (1994) J. A. Coxon, Optimum molecular constants and term values for the X2П (v≤ 5) and A2Σ+ (v≤3) states of OH, Can. J Phys., 58, 933 (1980)

Transformation from Hund’s Case b to Case a Matrix elements from LEVEL output Matrix elements input to PGopher J.S.A. Brooke et al., Line strengths of rovibrational and rotational transitions in the X2П ground state of OH, JQSRT 168, 142-157 (2016)

Overall Method for The Production of Line Lists R.J. Le Roy, RKR1: A computer program implementing the first-order RKR method for determining diatomic molecule potential, JQSRT 186, 158–166 (2017) R.J. Le Roy, A computer program for solving the radial Schrödinger equation for bound and quasi-bound levels, JQSRT 186, 1567–178 (2017) C.M. Western, PGOPHER: A program for simulating rotational, vibrational and electronic spectra, JQSRT 186, 221–242 (2017) Stark et al., Fourier-transform spectra of the A2Σ+-X2П Δv=0 of OH and OD, J. Opt. Soc. Am. B 11, 3-32 (1994) J. A. Coxon, Optimum molecular constants and term values for the X2П (v≤ 5) and A2Σ+ (v≤3) states of OH, Can. J Phys., 58, 933 (1980)

New Spectroscopic Constants for A2Σ+ State (in cm-1)   v=0 v=1 v=2 v=3 v=4 T0 32420.90884(21) 35409.50797(57) 38202.5736(17) 40796.1079(53) 43181.740(23) Bv 16.9651988(72) 16.129506(23) 15.28676(18) 14.4223(10) 13.5165(10) Dv 0.00206467(40) 0.00204754(23) 0.00205568(43) 0.0020646(36) 0.0021427(82) Hv 1.28331(83)×10-7 1.1238(79)×10-7 1.49(26)×10-7 Lv -2.1250(48)×10-11 -2.602(86)×10-11 γv 0.226169(62) 0.216936(91) 0.2129(71) 0.195955(59) 0.1862(47) γD -4.789(29)×10-5 -4.465(33)×10-5 -0.000179(13) γH 4.57(31)×10-9

Weighted Residuals

Einstein A Values of A2Σ+-X2П (v′,v″) Av′v″ (s-1) Av′v″ (s-1) (Luque et al.) 0,0 1.467×106 1.451×106 0,1 5.905×103 6.921×103 1,0 4.750×105 4.643×105 1,1 8.422×105 8.595×105 1,2 7.302×103 8.207×103 2,0 9.706×104 9.202×104 2,1 7.022×105 6.852×105 2,2 4.696×105 4.472×105 3,0 1.775×104 1.551×104 3,1 2.484×105 2.374×105 3,2 7.125×105 6.928×105 3,3 2.083×105 1.931×105 4,0 3.316×103 2.850×103 4,1 6.841×104 6.310×104 4,2 3.928×105 3.777×105 4,3 5.717×105 5.495×105

Observed and Simulated OH Spectrum Observed spectrum from Stark et al. Simulated spectrum Temperature: 4000 K

Conclusion OH A-X lines were collected from literature and fit in order to calculate a more complete and updated OH linelist. New transition dipole moment function was calculated using Molpro. J dependence of the transition dipole matrix elements were calculated using transition dipole matrix elements from LEVEL as input to PGopher.

Acknowledgements Bernath group. Dr. James Hodges for his help. Dr. James Brooke for providing OH ground state data. Dr. John Coxon for providing OH A-X observed data. NASA for their support.