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

2. 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)

3. 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, (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)

4. 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, (2005)

5. 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)

6. 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)

7. 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)

8. 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)

9. 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, (2016)

10. 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)

11. New Spectroscopic Constants for A2Σ+ State (in cm-1)
v=0
v=1
v=2
v=3
v=4 T0
(21)
(57)
(17)
(53)
(23) Bv
(72)
(23)
(18)
(10)
(10) Dv
(40)
(23)
(43)
(36)
(82) Hv
(83)×10-7
1.1238(79)×10-7
1.49(26)×10-7 Lv
(48)×10-11
-2.602(86)×10-11 γv
(62)
(91)
0.2129(71)
(59)
0.1862(47) γD
-4.789(29)×10-5
-4.465(33)×10-5
(13) γH
4.57(31)×10-9

12. Weighted Residuals

13. 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

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

15. 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.

16. 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.