Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Water, Formation and Photodissociation

  • José Cernicharo Quintanilla
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_5277-1




Water vapor can be formed in gas phase and on the ice mantles of dust grains (see “ Water in the Universe”). Once formed, the molecule is mainly destroyed by photodissociation through the effect of UV photons. In gas phase the molecule can be formed in low-temperature clouds through the chain of reactions:
$$ {\mathrm{H}}^{+}+\mathrm{O}\to \mathrm{H}+{\mathrm{O}}^{+}{\mathrm{H}}_2+{\mathrm{O}}^{+}\to \mathrm{O}{\mathrm{H}}^{+}+\mathrm{H}{\mathrm{H}}_3^{+}+\mathrm{O}\to \mathrm{O}{\mathrm{H}}^{+}+{\mathrm{H}}_2/{\mathrm{H}}_2{\mathrm{O}}^{+}+\mathrm{H}\mathrm{O}{\mathrm{H}}^{+}+{\mathrm{H}}_2\to {\mathrm{H}}_2{\mathrm{O}}^{+}+\mathrm{H}{\mathrm{H}}_2{\mathrm{O}}^{+}+{\mathrm{H}}_2\to {\mathrm{H}}_3{\mathrm{O}}^{+}+\mathrm{H}{\mathrm{H}}_3{\mathrm{O}}^{+}+{\mathrm{e}}^{\hbox{--}}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{H}/\mathrm{O}\mathrm{H}+{\mathrm{H}}_2 $$


Water Vapor Chemical Process Electronic State Bioorganic Chemistry Interstellar Medium 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Department of AstrophysicsLaboratory of Molecular AstrophysicsIorrejón de Ardoz, MadridSpain