Photochemistry of interstellar molecules
- Stief, L. J.
- Dec 1, 1971.
- Physical Description:
- 1 electronic document
- Restrictions on Access:
- Unclassified, Unlimited, Publicly available.
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- The photochemistry of two diatomic and eight polyatomic molecules is discussed quantitatively. For an interstellar molecule, the lifetime against photodecomposition depends upon the absorption cross section, the quantum yield or probability of dissociation following photon absorption, and the interstellar radiation field. The constant energy density of Habing is used for the unobserved regions of interstellar radiation field, and the field in obscuring clouds is estimated by combining the constant flux with the observed interstellar extinction curve covering the visible and ultraviolet regions. Lifetimes against photodecomposition in the unobscured regions and as a function of increasing optical thickness in obscuring clouds are calculated for the ten species. The results show that, except for CO, all the molecules have comparable lifetimes of less than one hundred years. Thus they can exist only in dense clouds and can never have been exposed to the unobscured radiation. The calculations further show that the lifetimes in clouds of moderate opacity are of the order of one million years.
- Other Subject(s):
- NASA Technical Reports Server (NTRS) Collection.
- Document ID: 19720013134.
Accession ID: 72N20784.
Symp. on Interstellar Molecules; Oct. 1971; Charlottesville, VA; United States.
- No Copyright.
View MARC record | catkey: 15947134