Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

H2O on Io? IR spectra of SO2/H2O mixed ices in the 5000-450 cm−1 region


Laboratory transmission IR spectra of relatively thick films (up to ∼500 μm) of mixed H2O and SO2 ices were measured at several temperatures between 10 and 130 K in the range 5000-450 cm−1. In addition to the strong features due to crystalline SO2 the spectra reveal bands at ∼3668 cm−1, 3634 cm−1 (with some structure) and 3300 cm−1 which are identified with H2O in SO2 environment. Also, there is no overlap between any of the H2O bands with the 3584 cm−1 band of SO2 at any temperature in the above range. The implication of this result is that H2O, if present on Io, must be far less than 1 part in 105 SO2.

This is a preview of subscription content, log in to check access.


  1. Barbe, A., Delahaigue, A. and Jouve, P.: 1971, Spectre infrarouge à l'état solide des molécules isotopiques de SO2,Spectrochim. Acta A27, 1439–1446.

  2. Bregman, J.D., Salama, F., Allamandola, L.J., Sandford, S.A., Witteborn, F.C., Cruikshank, D.P.: 1993, The identification of H2O on Io: A new strong band at 3587 cm−1 (2.788 μm),Bull. Am. Astron. Soc. 25, 851–852.

  3. Cruikshank, D.P., Jones, T.J. and Pilcher, C.B.: 1978, Absorption bands in the spectrum of Io,Astrophys. J. 225, L89-L92.

  4. Fanale, F.P., Johnson, T.V. and Matson, D.L.: 1974, Io: A surface evaporite deposite?,Science 186, 922–924.

  5. Fanale, F.P., Brown, R.H., Cruikshank, D.P. and Clark, R.N.: 1979, Significance of absorption features in Io's reflectance spectrum,Nature 280, 761–763.

  6. Howell, R.R., Nash, D.B., Geballe, T.R. and Cruikshank, D.P.: 1989, High-resolution infrared spectroscopy of Io and possible surface material,Icarus 78, 27–37.

  7. Khanna, R.K., Zhao, G., Ospina, M.J. and Pearl, J.C.: 1988, Crystalline sulfur dioxide: crystal field splittings, absolute intensities, and complex refractive indices,Spectrochim. Acta 44A, 581–586.

  8. Nash, D.B. and Fanale, F.P.: 1977, Io's surface composition based on reflectance spectra of sulfur/salt mixtures and proton irradiation experiments,Icarus 31, 40–80.

  9. Nash, D.B.: 1994, On Io's 2.788-μm band: Origin by SO2 or H2O?,Icarus 107, 418–421.

  10. Pearl, J.C., Hanel, R., Kunde, V., Maguire, W., Fox, K., Gupta, S., Ponnamperuma, C. and Raulin, F.: 1979, Identification of gaseous SO2 and new upper limits for other gases on Io,Nature 280, 755–758.

  11. Redington, R.L. and Milligan, D.E.: 1962, Infrared spectroscopic evidence for the rotation of the water molecule in solid argon,J. Chem. Phys. 37, 2162–2166.

  12. Salama, F., Allamandola, L.J., Witteborn, F.C., Cruikshank, D.P., Sandford, S.A. and Bregman, J.D.: 1990, The 2.5–5.0 μm spectra of Io: Evidence for H2S and H2O frozen in SO2,Icarus 83, 66–82.

  13. Salama, F., Allamandola, L.J., Sandford, S.A., Bregman, J.D., Witteborn, F.C. and Cruikshank, D.P.: 1994, Is H2O present on Io? The detection of a new strong band near 3590 cm−1 (2.79 μm),Icarus 107, 413–417.

  14. Schmitt, B., De Bergh, C., Lellouch, E., Maillard, J.-P., Barbe, A. and Doute, S.: 1994, Identification of Three Absorption Bands in the 2-μm Spectrum of Io,Icarus 111, 79–105.

  15. Schriver, A., Schriver, L. and Perchard, J.P.: 1988, Infrared matrix isolation of complexes between water and sulfur dioxide: identification and structure of the 1:1, 1:2, and 2:1 species,J. Mol. Spectrosc. 127, 125–142.

  16. Smythe, W.D., Nelson, R.M. and Nash, D.B.: 1979, Spectral evidence for SO2 frost or adsorbate on Io's surface,Nature 280, 766–767.

  17. Trafton, L.: 1975, Detection of a potassium cloud near Io,Nature 258, 690–692.

  18. van Thiel, M., Becker, E.D. and Pimentel, G.: 1957, Infrared studies of Hydrogen bonding of water by the matrix isolation technique,J. Chem. Phys. 27, 486–490.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Dahmani, R., Khanna, R.K. H2O on Io? IR spectra of SO2/H2O mixed ices in the 5000-450 cm−1 region. Astrophys Space Sci 236, 125–133 (1996).

Download citation


  • Thick Film
  • Strong Feature
  • Laboratory Transmission