Pathways for HCl formation in HO+ClO reaction

Abstract

The structure, energetics and the intrinsic reaction coordinate (IRC) pathways for the two crucial transition structures, TS3 and DA, leading to HCl formation on the singlet [H, Cl, O₂] potential energy surface viz., min HCl+¹O₂ and HO₂+Cl ———min HCl+¹O₂ channels have been investigated at differentlevels of sophistication. Of the two transition structures, the latter has been shown to be energetically low-lying compared to the former and the crucial difference between their structures has been identified as the angle of approach of the attacking chlorine atom. The reaction coordinate in both the reactions has been characterized as a complex mode involving a change in all internal coordinates.

References

1. D. A. Albritton, R. T. Watson and P. J. Aucamp, Scientific Assessment of Ozone Depletion: 1994; World Meteorological Organization, Geneva, Switzerland, 1996.
2. C. H. Jackman, E. L. Fleming, S. Chandra, D. B. Considine and J. E. Rosenfield, J. Geophys. Res., 1996, 101, 28753.
3. S. Solomon, R. W. Portmann, R. R. Garcia, L. W. Thomason, L. R. Poole and M. P. McCormick, J. Geophys. Res., 1996, 101, 6713.
4. M. B. McElroy and R. J. Salawitch, Science, 1989, 243, 763.
5. R. A. Stachnik, J. C. Hardy, J. A. Tarsala and J. W. Waters, Geophys. Res. Lett., 1992, 19, 1931.
6. H. A. Michelsen, R. J. Salawitch, M. R. Gunson, C. Aellig, N. Kampfer, M. M. Abbas, M. C. Abrams, T. L. Brown, A. Y. Chang, A. Goldman, F. W. Irion, M. J. Newchurch, C. P. Rinsland, G. P. Stiller and R. Zander, Geophys. Res. Lett., 1996, 23, 2361.
7. R. Toumi and S. Bekki, Geophys. Res. Lett., 1993, 20, 2447.
8. M. T. Leu and L. L. Lin, Geophys. Res. Lett., 1979, 6, 425.
9. A. R. Ravishankaran, F. L. Eisele and P. H. Wine, J. Chem. Phys., 1983, 78, 1140.
10. A. J. Hills and C. J. Howard, J. Chem. Phys., 1984, 81, 4458.
11. A. J. Burrows, T. J. Wallington and R. P. Wayne, J. Chem. Soc., Faraday Trans 2, 1984, 80, 957.
12. G. Poulet, G. Laverdat and G. Le Bras, J. Phys. Chem., 1986, 90, 159.
13. J. B. Lipson, M. J. Elrod, T. W. Beiderhase, L. T. Molina and M. J. Molina, J. Chem. Soc., Faraday Trans., 1997, 93, 2665.
14. M. K. Dubey, M. P. McGrath, G. P. Smith and F. S. Rowland, J. Phys. Chem. A, 1998, 102, 3127.
15. R. Sumathi and S. D. Peyerimhoff, Presented at EGS, Hague99 meeting, April 23, 1999; R. Sumathi and S. D. Peyerimhoff, Presented at Bunsentagung 1999, May 13, 1999; R. Sumathi and S. D. Peyerimhoff, J. Phys. Chem. A, 1999, 103, 7515.
16. C. S. Kegley-Owen, M. K. Gilles, J. B. Burkholder and A. R. Ravishankara, J. Phys. Chem. A, 1999, 103, 5040.
17. J. B. Lipson, T. W. Beiderhase, L. T. Molina, M. J. Molina and M. Olzmann, J. Phys. Chem. A, 1999, 103, 6540.
18. C. Gonzales and H. B. Schlegel, J. Chem. Phys., 1989, 90, 2154; C. Gonzales and H. B. Schlegel, J. Phys. Chem., 1990, 94, 5523; L. Deng and T. Ziegler, Int. J. Quantum Chem., 1994, 52, 731.
19. M. J. Frisch, G. W. Trucks, M. H. Gordon, P. M. W. Gill, M. W. Wong, J. B. Foresman, B. G. Johnson, H. B. Schlegel, M. A. Robb, E. S. Replogle, R. Gomperts, J. L. Andres, K. Raghavachari, J. S. Binkley, C. Gonzalez, R. J. Martin, D. J. Fox, B. J. Defrees, J. Baker, J. J. P. Stewart and J. A. Pople, Gaussian 94, Gaussian Inc., Pittsburgh PA, 1994.
20. H.-J. Werner and P. J. Knowles, with contributions from J. Almlof, R. D. Amos, M. J. O. Deegan, S. T. Elbert, C. Hampel, W. Meyer, K. Peterson, R. Pitzer, A. J. Stone and P. R. Taylor, MOLPRO, 1994, version 94.10.
21. R. Sumathi and M. T. Nguyen, J. Phys. Chem. A, 1998, 102, 412; R. Sumathi and A. K. Chandra, Chem. Phys., 1994, 181, 73.