Definition
Reaction rate coefficients are the phenomenological coefficients occurring in rate expressions for elementary chemical reactions. They can be determined either experimentally or theoretically. Bimolecular rate coefficients are expressed in units of cm3 s−1 and unimolecular ones in units of mol. s−1. Typical values for interstellar chemistry are 10−9 cm3 s−1 for ion-neutral reactions and 10−11 cm3 s−1 for neutral-neutral reactions.
For example, for the reaction
where the letters represent either neutral or charged atoms or molecules, the rate at which the reaction occurs is kn(A)n(B), with n the number density of a species in units of cm3 when the reaction rate coefficient k is expressed in cm3 s−1.
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Charnley, S.B. (2015). Reaction Rate Coefficient. In: Gargaud, M., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-44185-5_1350
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DOI: https://doi.org/10.1007/978-3-662-44185-5_1350
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-662-44184-8
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