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CAMP 1.0.0
Chemistry Across Multiple Phases
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Wennberg NO + RO2 reactions are branched reactions with one branch forming alkoxy radicals plus \(\ce{NO2}\) and the other forming organic nitrates [Wennberg2018] . The rate constants for each branch are based on an Arrhenius rate constant and a temperature- and structure-dependent branching ratio calculated as:
\begin{align} k_{nitrate} & = \left(X e^{-Y/T}\right) \left(\frac{A(T, \mbox{[M]}, n)}{A(T, \mbox{[M]}, n) + Z}\right) \\ k_{alkoxy} & = \left(X e^{-Y/T}\right)\left(\frac{Z}{Z + A(T, \mbox{[M]}, n)}\right) \\ A(T, \mbox{[M]}, n) & = \frac{2 \times 10^{-22} e^n \mbox{[M]}}{1 + \frac{2 \times 10^{-22} e^n \mbox{[M]}}{0.43(T/298)^{-8}}} 0.41^{(1+[log( \frac{2 \times 10^{-22} e^n \mbox{[M]}}{0.43(T/298)^{-8}})]^2)^{-1}} \end{align}
where \(T\) is temperature (K), [M] is the number density of air (molecules \(\mbox{cm}^{-3}\)), \(X\) and \(Y\) are Arrhenius parameters for the overall reaction, \(n\) is the number of heavy atoms in the \(\ce{RO2}\) reacting species (excluding the peroxy moiety), and \(Z\) is defined as a function of two parameters ( \(\alpha_0, n\)):
\[ Z( \alpha_0, n) = A(T = 293 \mbox{K}, \mbox{[M]} = 2.45 \times 10^{19} \frac{\mbox{molec}}{\mbox{cm}^3}, n) \frac{(1-\alpha_0)}{\alpha_0} \]
More details can be found in Wennberg et al. (2018) [Wennberg2018] .
Input data for Wennberg NO + RO2 equations has the following format:
The key-value pairs reactants, and both sets of products are required. Reactants without a qty value are assumed to appear once in the reaction equation. Products without a specified yield are assumed to have a yield of 1.0.
When X is not included, it is assumed to be 1.0, when Y is not included, it is assumed to be 0.0 K, when a0 is not included, it is assumed to be 1.0, and when n is not included, it is assumed to be 0. The unit for time is assumed to be s, but inclusion of the optional key-value pair time unit = MIN can be used to indicate a rate with min as the time unit.