1. High-resolution Spectroscopy of the A1Π(vˊ=0-10)–X1Σ+(vˊˊ=0) Bands in 13C18O
J.L. Lemaire (Inst. des Sciences Moleculaires d’Orsay), M. Eidelsberg (Obs. de Paris), A.N. Heays (Leiden), L. Gavilan (UMPC), S.R. Federman (U. of Toledo), G. Stark (Wellesley), J.R. Lyons (ASU), N. de Oliveira, and D. Joyeux (SOLEIL)
This research was supported by grants from NASA and CNRS-PCMI program

2. Outline
Background
New Results from SOLEIL
Concluding Remarks

3. Processes affecting mix of isotopologues
Background
Processes affecting mix of isotopologues
Isotope Charge Exchange – favors 13C16O
It has lower zero-point energy
13C+ + 12C16O → 12C+ + 13C16O – ΔE (ΔE/k ≈ 35 K)
Selective Isotopic Photodissociation – favors more abundant isotopic variant
Dissociation occurs through line absorption at far UV wavelengths
More abundant variant has lines that are more optically thick, shielding itself from further dissociation

4. Background
Results on diffuse molecular clouds (Sheffer et al. 2008, ApJ, 687, 1075)
Selective Isotope Photodissociation
13CO also self shielded
Isotope Charge Exchange

5. Importance of self shielding (Sheffer et al. 2008)
Background
Importance of self shielding (Sheffer et al. 2008)

6. Background
Results depend on f-values for isotopologues (Sheffer et al. 2002, ApJ, 574, L171)

7. SOLEIL Experiments
DESIRS beamline with a VUV FTS at SOLEIL Synchrotron

8. SOLEIL Experiments
The FTS (de Oliveira et al. 2009, Rev. Sci. Instru., 80, ; de Oliveira et al. 2011, Nature Photonics, 5, 149)
Resolving power as high as 750,000 (here we used 350,000)
Based on wave front division instead of amplitude division
Relies on modified bimirror configuration requiring only flat mirrors
Path difference scanning through translation of one reflector

9. SOLEIL Experiments Need calibration band: use B – X (0,0)
This band is isolated
For 12C16O, its band f-value is well characterized (with weighted uncertainty of 6%)
For 13C18O, close-coupling model of interaction between B 1Σ+ and D′ 1Σ+ indicates f-value varies less than 1.7% among isotoplogues (Stark et al. 2014, ApJ, 788, 67)
Fit of 12C16O band (Eidelsberg et al. 2012, A&A, 543, 69)

10. Our previous related work using SOLEIL
SOLEIL Experiments
Our previous related work using SOLEIL
Gavilan et al. 2013, J. Phys. Chem. A, 117, 9644 – terms values for 13C16O
Hakalla et al. 2016, RSC Advances, 6, – deperturbation analysis for 12C17O
Federman et al. 1997, ApJ, 477, L61 – relative f-values for 12C16O
Jolly et al. 1997, J. Phys. B, 30, 4315 – comparison of experimental and theoretical f-values for 12C16O
Eidelsberg et al. 1999, A&A, 346, 705 – recommended f-values for 12C16O

11. SOLEIL Experiments
Comparison of bands

12. SOLEIL Experiments
A–X vˊ=3 band (red: perturbing band; blue unidentified lines)

13. SOLEIL Experiments
Example of reduced term values (1/I and 2/II newly detected)

14. SOLEIL Experiments
Graphical representation of perturbations

15. SOLEIL Experiments
Detected 4 new perturbing bands – 11Σ+ and 21Π affecting vˊ=0 band; 31Π and 41Π affecting vˊ=3 and 8 bands, respectively
Fraction of f-value – 11Σ+ (32.1%) and 21Π (12.5%) for vˊ=0; 31Π (6.4%) and 41Π (4.6%) for their respective bands
Additional unidentified lines seen in spectra of vˊ=0,1,2,8,10 bands
These lines contribute between 0.1 to 11.4% for their respective bands’ f-values
Confirm many of the perturbations seen by Haridass et al. (1994, J. Mol. Spec., 167, 334)
See additional, weaker perturbations associated with e3Σ- (vˊ=1), aˊ3Σ+ (vˊ=9,12), I1Σ- (vˊ=2), and D1Δ (vˊ=4)

16. Concluding Remarks
Work in press – Lemaire et al. et al. (2016, J. Phys. B)
Next steps:
Complete deperturbation analysis of A–X bands in 13C17O
Analyze perturbations in B–X series of bands
Obtain f-values for A–X and triplet-singlet bands in 13C16O
Obtain f-values for bands involving the B, C, and E states with greater precision (<5%) for photochemical models