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.