1. Photodissociation Workshop Kasteel oud Poelgeest, Leiden 3-5 February2015 Photodissociation in the Solar Nebula: Models and Meteorites James R. Lyons School of Earth & Space Exploration Arizona State University

2. Isotopic Photodissociation Topics Spin-forbidden CO 2 photolysis – Mars atmosphere SO 2 photolysis (~200 nm) – early Earth atmosphere Oxygen isotopes in Sun and meteorites CO photodissociation in solar nebula & protoplanetary disks

3. Geochemical delta notation

4. Mass-independent fractionation on a 3-isotope plot  17 O SMOW  18 O SMOW slope 0.52 (TF)  17 O O-MIF

5. Nair et al. (1994) 167 nm 227 nm Schmidt et al. 2013

6. 185 nm Mars atmosphere Schmidt et al. 2013

7. Farquhar et al. 2000 pyrites barites Record of S-MIF in sedimentary rocks

8. Kasting 2001 (from Kasting et al. 1989) pO 2 < 10 -6 atm Low-O 2 atmospheric sulfur chemistry Pavlov & Kasting 2002

9. v2v2 SO 2, H 2 S and CS 2 absorption cross sections

10. ab initio: Ran et al. 2007 v 2 =9 8 7 Lyons 2008

11. Wavelength shift of SO 2 isotopologues Lyons 2008 3632

12. Lyons (2007) Calc rock values

13. Ono, Whitehill, Lyons 2013 SO 2 + hv experiments

17. Ayres et al. 2013 G94 HR96 Oxygen isotopes in the solar system McKeegan et al. 2011 (inferred) photosphere (2004)

18. Gharib-Nezhad et al. 2015 HR96 Oxygen isotopes in the solar system McKeegan et al. 2011 (inferred)

19. Self-shielding in a 2-D disk snowline H2OH2O

20. Lyons & Young 2005 Self-shielding of CO in outer disk surface G 0 =500

21. Chakraborty et al. 2008, 2012

24. Chakraborty et al. 2013 SiO + OH  SiO 2 + H

25. HD 36981

26. Influence of CO E   ) – X(0) dissociation probabilities Lyons (2014)

27. 12 C 16 O transmission spectra measured at Soleil

28. Stark et al. 2014 Isotopic CO E   ) – X(0) absorption cross sections

31. Summary 1.Spin-forbidden CO 2 photolysis: No hyperfine assist. High quality ab initio cross sections from Schmidt et al. (2013). 2.SO 2 photolysis: Isotopic shifting of vibronic peaks, with 32 SO 2 rotational features copied, works. SO 2 is not the MIF source. 3.Solar photosphere oxygen isotopes consistent with Genesis inferred photosphere isotope ratios. Latest CO vib f-values close to HR96. 4.High-resolution CO E-X & C-X isotopic cross sections exhibit C 16 O and C 18 O self-shielding initially, but not at later times. Need 1217 and 1218 dissociation probabilities for CO E(0)-X.

32. Acknowledgements Colaborators: Glenn Stark, Alan Heays, Michelle Eidelsberg, Jean-Louis Lemaire Steve Federman, Douglas Blackie, Juliet Pickering, Andreas Pack, Tom Ayres Student (ASU): Ehsan Gharib-Nezhad Soleil DESIRS beamline: Nelson de Oliveira, Laurent Nahon Funding: NASA Origins of Solar Systems NASA Astrobiology/Exobiology