Table 1. Reaction Rates Used for the Different Model Runs Reaction Rate Coefficients Used in Model Run Reference HCN + OH rightarrow productsa A = 1.2 middot 10-13, $\displaystyle\frac{E_{a}}{R}$ = 400 a, c Sander et al. [2003] HCN + O(1D) rightarrow productsb k = 1 middot 10-10 a, b, c Cicerone and Zellner [1983] HCN + hnu rightarrow products absorption cross sections of HCl a, b, d Sander et al. [2000] HCN + OH rightarrow productsc k0 = 4.28 middot 10-33, d, e, f, g Strekowski [2001] kinfinity = 4.25 middot 10-13 e$^{-\frac{1150}{T}}$ Fc = 0.8 HCN + O(1D) rightarrow productsa,d A = 7.7 middot 10-11, $\displaystyle\frac{E_{a}}{R}$ = ­100 d, e, f, g Strekowski [2001] CH3CN + OH rightarrow productsa,e A = 7.8 middot 10-13, $\displaystyle\frac{E_{a}}{R}$ = 1050 f, g Sander et al. [2003] aRate coefficient is expressed by k = A middot e$^{\left(-\frac{Ea}{RT}\right)}$, where A is given in $\displaystyle\frac{cm^{3}}{molec .\cdot s}$ and T is the temperature in K. bRate coefficient (given in $\displaystyle\frac{cm^{3}}{molec.\cdot s}$) is assumed constant throughout the atmosphere. cTermolecular reaction parameterized as k = $\displaystyle\frac{k_{0}\left[M\right] \cdot k_{\infty}} {k_{0}\left[M\right] + k_{\infty}}$ middot Fc$^{\left(1 + \left(lg\left(k_{0} \left[M\right] / k_{\infty} \right)\right)^{2} \right)^{-1}}$, with k0 in $\displaystyle\frac{cm^{6} }{molec.^{2} \cdot s}$ and kinfinity in $\displaystyle\frac{cm^{3} }{molec.\cdot s}$, [M] is the molecular air density. dRate coefficient given is for forming products other than HCN + O(3P). eAn HCN yield of 100% and 30% was assumed for the runs f and g, respectively.