View PDF Version
 
DOI: 10.1039/A709160E (Paper) Reference Section for: J. Chem. Soc., Faraday Trans., 1998, 94, 1391-1396

UV–VIS absorption cross-sections and atmospheric lifetimes of CH2Br2, CH2I2 and CH2BrI

(Note: The full text of this document is currently only available in the PDF Version )

Juliane C. Mössinger, Dudley E. Shallcross and R. Anthony Cox

Abstract

The UV–VIS absorption spectra of CH2Br2, CH2I2 and CH2BrI have been measured over the wavelength range 215–390 nm using a dual-beam diode array spectrometer. The spectra consist of broad continuous absorption bands. CH2Br2 exhibits its maximum cross-section of σ=2.71(±0.16)×10-18 cm2 molecule-1 at λ=219 nm. The magnitude of the peak cross-sections for the iodine-containing molecules above λ=210 nm are σ=1.62(±0.10)×10-18 cm2 molecule-1 at λ=248 nm and σ=3.78(±0.23)×10-18 cm2 molecule-1 at λ=288 nm for CH2I2, and σ=5.67(±0.34)×10-18 cm2 molecule-1 at λ=215 nm and σ=2.34(±0.14)×10-18 cm2 molecule-1 at λ=267 nm for CH2BrI. The temperature dependence of the absorption cross-sections was investigated over the temperature range 348–250 K. A decline in the cross-sections with decreasing temperature was observed in the tail of the spectra. At the peaks the opposite effect was observed. All three gases have been found in the atmosphere and the atmospheric photolysis rates of CH2Br2, CH2I2 and CH2BrI were calculated as a function of altitude and solar zenith angle using the measured cross-sections. Model calculations show that, during sunlit hours, CH2I2 and CH2BrI will be photolysed within minutes and hours, respectively. The photolysis of CH2Br2 is much slower and reaction with the OH radical is the dominant atmospheric loss process.

References

  1. W. L. Chameides and D. D. Davies, J. Geophys. Res., 1980, 85, 7383 CrossRef CAS.
  2. M. E. Jenkin, R. A. Cox and D. E. Candeland, J. Atmos. Chem., 1985, 2, 359 CrossRef CAS.
  3. L. A. Barrie, J. W. Bottenheim, R. C. Shnell, P. J. Crutzen and R. A. Rassmussen, Nature (London), 1988, 334, 138 CrossRef CAS.
  4. J. W. Bottenheim, L. A. Barrie, E. L. Atlas, L. E. Heidt, H. Niki, R. A. Rassmussen and P. B. Shepson, J. Geophys. Res., 1990, 95, 18555 CrossRef CAS.
  5. B. J. Finlayson-Pitts, F. E. Livingston and H. N. Berko, Nature (London), 1990, 343, 622 CAS.
  6. R. B. Chatfield and P. J. Crutzen, J. Geophys. Res., 1990, 95, 22319 CrossRef.
  7. D. Davies, J. Crawford, S. Liu, S. McKeen, A. Bandy, D. Thornton, F. Rowland and D. Blake, J. Geophys. Res., 1996, 101, No D1, 2135.
  8. H. B. Singh, L. J. Salas and R. E. Stiles, J. Geophys. Res., 1983, 88, 3684 CAS.
  9. Th. Class and K. Ballschmiter, J. Atmos. Chem., 1988, 6, 35 CrossRef CAS.
  10. S. M. Schauffler, L. E. Heidt, W. H. Pollock, T. M. Gilpin, J. F. Vedder, S. Solomon, R. A. Lueb and E. L. Atlas, Geophys. Res. Lett., 1993, 20, 2567 CAS.
  11. F. Laturnus, C. Wiencke and H. Kloeser, Marine Environ. Res., 1995, 41, No2, 169 Search PubMed.
  12. S. Klick and K. Abrahamsson, J. Geophys. Res., 1992, 97, 12683 CrossRef CAS.
  13. C. Schall and K. G. Heumann, Fres. J. Anal. Chem., 1993, 346, 717 Search PubMed.
  14. R. M. Moore, B. Webb and A. Tokarczyk, J. Geophys. Res.-Oceans, 1996, 101, No C9, 20899 Search PubMed.
  15. L. Carpenter, personal communication, 1997.
  16. S. A. Penkett, et al., Scientific Assessment of Ozone Depletion: 1994, Global Research and Monitoring Project-Report No. 37, World Meterological Society, Geneva, ch. 10 Search PubMed.
  17. L. T. Molina, M. J. Molina and F. S. Rowland, J. Phys. Chem., 1982, 86, 2672 CrossRef CAS.
  18. D. Gillotay, P. C. Simon and L. Dierickx, Aeron. Acta, 1988, 35, 1 Search PubMed.
  19. G. Schmitt and F. J. Comes, J. Photochem., 1980, 14, 107 CrossRef CAS.
  20. J. B. Koffend and S. R. Leone, Chem. Phys. Lett., 1981, 81, 136 CrossRef CAS.
  21. C. M. Roehl, J. B. Burkholder, G. K. Moortgart, A. R. Ravishankara and P. J. Crutzen, J. Geophys. Res.-Atmos., 1997, 102, No11D, 12819 Search PubMed.
  22. A. M. Hough, The Calculation of Photolysis Rates for use in Global Tropospheric Modelling Studies, United Kingdom Atomic Energy Authority, Report R13259, Harwell, 1988 Search PubMed.
  23. K. S. Law and J. A. Pyle, J. Geophys. Res., 1983, 98, 18372.
  24. S. Miyano and H. Hashimoto, Bull, Chem. Soc. Jpn., 1971, 44, 2865.
  25. S.-Q. Man, W. M. Kwok and D. L. Phillips, J. Chem. Phys., 1995, 99, 15 705 CAS.
  26. S. J. Lee and R. Behrson, J. Phys. Chem., 1982, 86, 728 CAS.
  27. L. J. Butler, E. J. Hintsa, S. F. Shane and Y. T. Lee, J. Chem. Phys., 1987, 86, 2051 CrossRef CAS.
  28. S.-Q. Man, W. M. Kwok, D. L. Phillips and A. E. Johnson, J. Chem. Phys., 1996, 105, 5842 CrossRef CAS.
  29. M. Ito, P.-K. C. Huang and E. M. Kosower, Trans. Faraday. Soc., 1961, 51, 1662 RSC.
  30. R. S. Mulliken, J. Chem. Phys., 1940, 8, 382 CrossRef CAS.
  31. H. Okabe, Photochemistry of Small Molecules, Wiley, Chichester, 1978, pp. 44–49 Search PubMed.
  32. C. N. Banwell and E. M. McCash, Fundamentals of Molecular Spectroscopy, McGraw-Hill, 4th edn., 1994, pp. 19 and 164–167 Search PubMed.
  33. O. V. Rattigan, E. Lutman, R. L. Jones and R. A. Cox, Photochem. Photobiol., A, 1992, 69, 125 CrossRef.
  34. T. J. Wallington and M. D. Hurley, Chem. Phys. Lett., 1992, 189, 437 CrossRef CAS.
  35. A. Mellouki, R. K. Talukdar, A.-M. Schmoltner, T. Gierczak, M. J. Mills, S. Solomon and A. R. Ravishankara, Geophys. Res. Lett., 1992, 19, 2059 CrossRef CAS.
  36. M. Bilde, J. Sehested, O. J. Nielsen, T. J. Wallington, R. J. Meagher, M. E. McIntosh, C. A. Piety, J. M. Nicovich and P. H. Wine, J. Phys. Chem. A, 1997, 101, 8035 CrossRef CAS.
  37. O. V. Rattigan, D. E. Shallcross and R. A. Cox, J. Chem. Soc., Faraday Trans., 1997, 93, 2839 RSC.
  38. J. J. Orlando, G. S. Tyndall and T. J. Wallington, J. Phys. Chem., 1996, 100, 7026 CrossRef CAS.
  39. R. Vogt, P. J. Crutzen and R. Sander, Nature (London), 1996, 383, 327 CrossRef CAS.
Click here to see how this site uses Cookies. View our privacy policy here.