Catalytic effect of ice in ozone depletion - a first principles study

Presentation given in 2010 as an internal King's College London postgraduate seminar for the physics department. In this seminar we explore the effect that a charged ice interface can have on the dissociation of CFCs in the atmosphere.

Transcript

1. Catalytic effect of ice in ozone depletion - a first principles study James Finn, King’s College London james.finn@kcl.ac.uk Sunday, 21 March 2010
2. ➡ Introduction ➡ What is Ozone Depletion ➡ Current models ➡ Tools used ➡ Results ➡ Conclusion ➡ Future work Overview Norway, 2008 Benasque Spain, 2010 Sunday, 21 March 2010
3. Humanities Greatest Threats Global Warming Ozone Depletion Sunday, 21 March 2010
4. Humanities Greatest Threats Comet Collisions Global Warming Ozone Depletion Sunday, 21 March 2010
5. What is Ozone Depletion? NASA Ozone Watch O O O O3 Cl- Cl Active Chlorine Ozone Sunday, 21 March 2010
6. Cl Photodissociation Model Molina, Nobel Prize for Chemistry 1985 Cl C Cl O O O Cl OCl O O OCl O Cl O O ħυ Self Propagating Reaction Cl Sunday, 21 March 2010
7. Seasonal Variation? Data from ftp://toms.gsfc.nasa.gov Total Ozone Mapping Spectrometer (TOMS) Sunday, 21 March 2010
8. Cl Photo-Heterogeneous Catalysis Model Cl C Cl O O O Cl OCl O O OCl O Cl O O ħυ Self Propagating Reaction Cl Ice Sunday, 21 March 2010
9. Cl Photo-Heterogeneous Catalysis Model Solomon, Nobel Peace Prize 2007 Cl C Cl O O O Cl OCl O O OCl O Cl O O ħυ Self Propagating Reaction Cl Ice Sunday, 21 March 2010
10. Cosmic Rays Potential correlation between the altitude loss of ozone loss and the peak CR ionisation rate sics Reports 487 (2010) 141–167 155 b e in the pre-ozone hole (October 1979 for Antarctica and March 1979 for the Arctic) and March 1998 for the Arctic) versus latitude. (b) Cosmic ray ionization rate and ozone loss ntarctica, was obtained by subtracting the altitude distribution curve of the pre-ozone b Physics Reports 487 (2010) 141–167 Contents lists available at ScienceDirect Physics Reports journal homepage: www.elsevier.com/locate/physrep Cosmic-ray-driven electron-induced reactions of halogenated molecules Physics Reports 487 (2010) 141–167 Contents lists available at ScienceDirect Physics Reports journal homepage: www.elsevier.com/locate/physrep Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change Qing-Bin Lu Department of Physics and Astronomy and Departments of Biology and Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, Canada Sunday, 21 March 2010
11. Cosmic Rays Potential correlation between the altitude loss of ozone loss and the peak CR ionisation rate sics Reports 487 (2010) 141–167 155 b e in the pre-ozone hole (October 1979 for Antarctica and March 1979 for the Arctic) and March 1998 for the Arctic) versus latitude. (b) Cosmic ray ionization rate and ozone loss ntarctica, was obtained by subtracting the altitude distribution curve of the pre-ozone b Physics Reports 487 (2010) 141–167 Contents lists available at ScienceDirect Physics Reports journal homepage: www.elsevier.com/locate/physrep Cosmic-ray-driven electron-induced reactions of halogenated molecules Physics Reports 487 (2010) 141–167 Contents lists available at ScienceDirect Physics Reports journal homepage: www.elsevier.com/locate/physrep Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change Qing-Bin Lu Department of Physics and Astronomy and Departments of Biology and Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, Canada Polar Stratospheric Clouds Sunday, 21 March 2010
12. Cosmic Ray Model e- Ice Ice + e- Ice Cl Cl C Cl Cl O O O Cl O O O Cl O Cl O O O Cl Cl Cl C Cl Cl Lu, Sanche, PRL 87 (2001) Sunday, 21 March 2010
13. e- Ice Ice + e- Ice Cl Cl C Cl Cl O O O Cl O O O Cl O Cl O O O Cl Cl Cl C Cl Cl Sunday, 21 March 2010
14. Quantum Mechanical Tools DFT Hamiltonian ! Schrödinger Equation ! Sunday, 21 March 2010
15. Self Interaction Correction ! ΔEH = -εEH [m(↑) - m(↓)] ΔEXC = -α(EXC [m(↑), m(↓)] - EXC [m(↓), m(↓)]) partial SIC α ε LSDA LSDA 1 1 0.1 0.2 0.0 0.2 Force Pairing M. d’Avezac PRB (2005) Sunday, 21 March 2010
16. Gas Phase Dissociation Calculation AEA [eV] LSDA 0.80 pSIC[0.0,0.2] 2.15 pSIC[0.1,0.2] 1.75 Experiment ~2.0 Energy Gain 1.24 eV SIC Parameters: α - 0.0 ε - 0.2 Sunday, 21 March 2010
17. Ice Reconstruction Structural Reorganisation Baletto, et al. PRL 95 (2005) Sunday, 21 March 2010
18. Ice Surface Dissociation Paper in preparation. In agreement with experiments by M. Bertin et al. Far. Disc. 141 (2009) 293 Sunday, 21 March 2010
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21. Dissociation Energy 0.00 eV 1.24 eV Sunday, 21 March 2010
22. Dissociation Energy 0.00 eV 1.24 eV 2.15 eV Gas Phase Gain < Surface Gain Sunday, 21 March 2010
23. Halogen binding ➡How does the ice surface deform during the dissociative process? Sunday, 21 March 2010
24. Halogen binding Formation of three surface hydrogen bonds ➡How does the ice surface deform during the dissociative process? Sunday, 21 March 2010
25. Electron localisation ➡Does this dissociative reaction form a “free radical”? Sunday, 21 March 2010
26. Electron localisation Formation of a Cl- radical ➡Does this dissociative reaction form a “free radical”? Sunday, 21 March 2010
27. Conclusion ➡ CR deposition of excess electrons on ice surfaces within PSC’s have a correlation with ozone depletion ➡ Anionic ice surfaces catalyses the reaction: ➡ CFC’s are more likely to dissociate on a charged ice surface CCl4 - CCl3 + Cl- Sunday, 21 March 2010
28. Future Work ➡ In depth study of water dimer (H2O)2 ➡ Using TD-DFT ➡ FIR Optical spectra using fictitious laser pulse ➡ TD Code: Octopus Octopus http://www.tddft.org Sunday, 21 March 2010
29. Future Work ➡ In depth study of water molecule with NO ➡ Using TD-DFT ➡ FIR Optical spectra using fictitious laser pulse ➡ Roles in atmospheric chemistry ➡ Biologically important ➡ Tough molecule to model Sunday, 21 March 2010
30. Acknowledgements Michel Bockstedte Erlangen University Uwe Bovensiepen Duisburg-Essen, University Angel Rubio ETSF, San Sebastian Somesh Battacharya ICTP, Trieste Sandro Scandolo ICTP, Trieste Carlo Cavazzoni (Cineca, Bologna, IT) U. Ndonmouo (Tolouse, France) V. Diep (Perdue Univ. USA) Francesca Baletto KCL, London octopus Sunday, 21 March 2010